tag:theconversation.com,2011:/us/topics/blue-green-algae-7325/articlesBlue-green algae – The Conversation2022-06-06T05:59:22Ztag:theconversation.com,2011:article/1837282022-06-06T05:59:22Z2022-06-06T05:59:22ZAustralia has overshot three planetary boundaries based on how we use land<figure><img src="https://images.theconversation.com/files/467102/original/file-20220606-16-ocqxbp.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4096%2C3280&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>We used to believe the world’s resources were almost limitless. But as we spread out across the planet, we consumed more and more of these resources. For decades, scientists have warned we are approaching the limits of what the environment can tolerate.</p>
<p>In 2009, the influential Stockholm Resilience Centre first published its <a href="https://www.nature.com/articles/461472a">planetary boundaries</a> framework. The idea is simple: outline the global environmental limits within which humanity could develop and thrive. This concept has become popular as a way to grasp our impact on nature. </p>
<p>For the first time, we have <a href="https://www.climateworkscentre.org/resource/living-within-limits-adapting-the-planetary-boundaries-to-understand-australias-contribution-to-planetary-health">taken these boundaries</a> – which can be hard to visualise on a global scale – and applied them to Australia. We found Australia has already overshot three of these: biodiversity, land-system change and nitrogen and phosphorus flows. We’re also approaching the boundaries for freshwater use and climate change. </p>
<p>The nation’s land use is a key contributor to these trends, with natural systems under increasing pressure as a result of many land management practices. Luckily, we already know many of the solutions for living within our limits, such as waste management, conservation and restoration of natural lands in conjunction with agriculture, and shifts in food production. </p>
<h2>What are planetary boundaries?</h2>
<p>In 2015, scientists took stock of how humanity was tracking, <a href="https://www.science.org/doi/10.1126/science.1259855">warning</a> four of nine boundaries had already been crossed. </p>
<p>While such warnings make global headlines, they can also leave people wondering, “What does this actually mean for me?”</p>
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<figcaption><span class="caption">This TED talk on planetary boundaries has helped popularise this approach.</span></figcaption>
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Read more:
<a href="https://theconversation.com/can-your-actions-really-save-the-planet-planetary-accounting-has-the-answer-104005">Can your actions really save the planet? 'Planetary accounting' has the answer</a>
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<p>This is the question we have sought to answer for Australia and its land use sector. We took five of these global boundaries and calculated what Australia’s “share” of those would be in our <a href="https://www.climateworkscentre.org/resource/living-within-limits-adapting-the-planetary-boundaries-to-understand-australias-contribution-to-planetary-health/">new technical report</a>. </p>
<p>We then went one step further, breaking down what these boundaries mean for Australia’s land use industries, such as agriculture and forestry.</p>
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<a href="https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="fallen trees in tasmania" src="https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/467106/original/file-20220606-12-tpqupv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Land-system change can pose major threats for nature.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<h2>These limits are not abstractions – they’re real</h2>
<p>These are real-world limits. Pushing past them has real-world consequences.</p>
<p>Take nitrogen and phosphorus flows, which refers to the levels of these chemicals in the nation’s waterways.</p>
<p>In around 50% of our river catchments, we already have concentrations of nitrogen and phosphorus past the safe level for the health of the environment. These chemicals are applied as fertiliser to cropland and pasture. If there’s too much, it can run off into waterways. Once in our rivers, these chemicals can fuel dangerous algal blooms which can force the closure of popular recreational areas, fill lakes with weeds and hurt fish and other wildlife. </p>
<p>Tackling one environmental issue often has benefits for others. Improving water quality has benefits for biodiversity, because the plants and animals supported by those rivers have better water to live off and in.</p>
<p>Why does biodiversity matter? The diversity of life on our continent <a href="https://www.nature.com/articles/nature11148">plays a critical role</a> in keeping ecosystems stable and sustaining vital services – such as fresh air and water – they provide to wildlife and to us.</p>
<p>It’s well known areas with lower numbers of species and lower genetic diversity prove <a href="https://www.nature.com/articles/ncomms10122">generally less resilient</a> to shocks. That means these environments are at higher <a href="https://www.nature.com/articles/s41559-019-0797-2">risk of tipping</a> into a state where they can no longer provide the services vital to life. </p>
<p>Different species occupy different niches within ecosystems, meaning the loss of one or two can erode the functioning of the system as a whole.</p>
<p>Protecting and restoring biodiversity is therefore critical to achieving planetary health. Unfortunately, biodiversity is among the boundaries Australia has already overshot. The number of species threatened by our activities is growing, and many of our endangered animals are at risk of extinction. </p>
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<a href="https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dead fish algal bloom" src="https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/467104/original/file-20220606-16-6986u0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Fertiliser overuse can trigger algal blooms and kill fish and other water species.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<h2>We know what we need to do</h2>
<p>With <a href="https://www.climateworkscentre.org/resource/living-within-limits-adapting-the-planetary-boundaries-to-understand-australias-contribution-to-planetary-health/">this report</a>, we contribute to the national conversation about how Australia can stay within its fair share of planetary limits and contribute to the global effort for sustainable development.</p>
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Read more:
<a href="https://theconversation.com/biodiversity-loss-has-finally-got-political-and-this-means-new-thinking-on-the-left-and-the-right-116910">Biodiversity loss has finally got political – and this means new thinking on the left and the right</a>
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<p>Agriculture, forestry and other land use industries also have a critical role to play in reducing emissions and sequestering carbon. But the land use sector is under increasing pressure from growing populations, the impacts of climate change and extreme weather events.</p>
<p>Understanding what sustainability means in practical, measurable terms for Australia’s land use sector is vital to enable humanity to continue to prosper.</p><img src="https://counter.theconversation.com/content/183728/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Romy Zyngier does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>For the first time, we calculated Australia’s share of planetary environmental boundaries and found we’ve shot past three already.Romy Zyngier, Senior Research Manager, Climateworks CentreLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1658662021-11-12T13:36:08Z2021-11-12T13:36:08ZNeurotoxins in the environment are damaging human brain health – and more frequent fires and floods may make the problem worse<figure><img src="https://images.theconversation.com/files/428985/original/file-20211028-23-ey0fbd.jpg?ixlib=rb-1.1.0&rect=242%2C177%2C3352%2C2204&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Wildfire smoke contains a mixture of toxic pollutants that can be harmful to both the lungs and the brain. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/california-wildfires-royalty-free-image/1281624333?adppopup=true">Bloomberg Creative/ Bloomberg Creative Photos via Getty Images</a></span></figcaption></figure><p>In the summer of 2021, a toxic, smoky haze stemming from <a href="https://www.nbcnews.com/western-wildfires">Western wildfires</a> wafted across large parts of the United States, while hurricanes wrought extensive flooding in the southern and eastern U.S. Air quality websites such as <a href="https://www.airnow.gov">AirNow</a> warned of <a href="https://www.npr.org/2021/07/21/1018865569/the-western-wildfires-are-affecting-people-3-000-miles-away">hazardous conditions</a> on the U.S. East Coast from Western forest fires 3,000 miles away, with recommendations to stay indoors. </p>
<p>Journalists reported the immediate impact of lives lost and homes and property destroyed, but more insidious dangers escaped notice. Few people realize that these <a href="https://www.npr.org/2021/09/11/1035241392/climate-change-disasters-mental-health-anxiety-eco-grief">climate change-fueled</a> <a href="https://www.washingtonpost.com/world/interactive/2021/cop26-extreme-weather-climate-change-action/">disasters</a> – both fires and <a href="https://doi.org/10.1080/10807030903051309">floods</a> – could <a href="https://doi.org/10.1080/10962247.2017.1401017">adversely affect human health</a> in longer-term ways. </p>
<p>I’m a <a href="https://scholar.google.com/scholar?as_ylo=2017&q=Arnold+Eiser&hl=en&as_sdt=0,39">scientist-author</a> who studies the links between environmental factors and the development of neurological disorders, which is the <a href="https://rowman.com/ISBN/9781538158074/Preserving-Brain-Health-in-a-Toxic-Age-New-Insights-from-Neuroscience-Integrative-Medicine-and-Public-Health">subject of my recent book</a>. My <a href="https://doi.org/10.1016/j.brainres.2017.06.032">research on this topic</a> adds to a growing body of evidence that <a href="https://www.nytimes.com/2019/07/15/climate/flooding-chemicals-health-research.html">more frequent environmental disasters</a> may be raising <a href="https://doi.org/10.1007/s11356-015-4913-9">human exposure to neurotoxins</a>.</p>
<h2>Neurotoxic smoke</h2>
<p>Many scientists have identified links between <a href="https://doi.org/10.1016/j.bj.2018.06.001">air pollution</a> in various forms, including from <a href="https://theconversation.com/breathing-wildfire-smoke-can-affect-the-brain-and-sperm-as-well-as-the-lungs-166548">forest fire smoke</a>, and an increased risk and prevalence of adverse health effects, including brain disorders. </p>
<p>Wildfire smoke is a mixture of <a href="https://health.ny.gov/environmental/outdoors/air/smoke_from_fire">countless noxious chemical compounds</a>. Fires burning <a href="https://www.theguardian.com/world/2021/aug/09/fires-rage-around-the-world-where-are-the-worst-blazes%20and%20Australia">across the warming planet</a> – from California to Greece and Australia – are adding dangerous particulate matter to the atmosphere that includes <a href="https://doi.org/10.5772/intechopen.97204">neurotoxic heavy metals</a> such as mercury, lead, cadmium and manganese nanoparticles. <a href="https://theconversation.com/whats-in-wildfire-smoke-a-toxicologist-explains-the-health-risks-and-which-masks-can-help-164597">These toxins</a> are an added environmental burden on top of the pollutants emitted by factories, power plants, trucks, automobiles and other sources. </p>
<p>The greatest potential for health problems comes from minuscule particles, smaller than 2.5 microns – or PM 2.5 (for context, the width of a human hair is typically 50 to 70 microns). This is, in part, because <a href="https://doi.org/10.1164/rccm.201903-0635LE">tiny particles are easily inhaled</a>; from the lungs, they enter the bloodstream and circulate widely throughout the body. <a href="https://doi.org/10.3389/fphys.2020.00155">In the brain</a> they may inflame the microglial cells, the brain’s defensive cells, causing harm to neurons instead of protecting them. Studies show that these extremely tiny particles may damage neurons or brain cells by <a href="https://doi.org/10.1016/j.tins.2009.05.009">promoting inflammation</a>. Brain inflammation can lead to conditions <a href="https://doi.org/10.3233/JAD-180631">like dementia</a> and <a href="https://doi.org/10.1097/JOM.0000000000000451">Parkinson’s disease</a>, a movement disorder in adults.</p>
<p>In addition, <a href="https://doi.org/10.1001/jamapediatrics.2018.3101">prenatal</a> and <a href="https://doi.org/10.1097/EDE.0000000000001109">early-life exposure</a> to air pollution has been linked to an increased risk of autism spectrum disorder in children. Research suggests that <a href="https://doi.org/10.1001/jamanetworkopen.2021.7508">air pollution exposure</a> during these critical periods, particularly in the third trimester of pregnancy and the first few months of life, <a href="https://doi.org/10.1515/tnsci-2016-0005">may impair normal neural development</a>. </p>
<h2>Waterborne neurotoxins</h2>
<p>As part of my book research, I investigated potential links between environmental neurotoxins and related health effects in Finland. Seeking unique environmental factors that might underlie the disproportionately high rates of fatal dementia that occurred in Finland in the past decade, I found that <a href="https://doi.org/10.1016/j.brainres.2017.06.032">water pollution</a> – exacerbated by flooding, use of fertilizer and higher water temperatures – may be affecting brain health. </p>
<p>As I reviewed the environmental concerns in Finland, the widespread presence of <a href="https://www.usgs.gov/centers/kswsc/science/cyanobacterial-blue-green-algal-blooms-tastes-odors-and-toxins-0?qt-science_center_objects=0#qt-science_center_objects">blue-green algae in waterways</a> stood out to me. Though it’s commonly called algae, blue-green algae is actually a type of bacteria called cyanobacteria. These toxic microorganisms thrive and proliferate in warm waterways when excessive nutrients, particularly phosphorus from fertilizer runoff, pour into fresh and brackish water. It produces <a href="https://www.epa.gov/cyanohabs/health-effects-cyanotoxins">cyanotoxins</a>. </p>
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<a href="https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Blue-green algae bloom on surface of lake with trees in the distance." src="https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=372&fit=crop&dpr=1 600w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=372&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=372&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=468&fit=crop&dpr=1 754w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=468&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=468&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Harmful blooms of blue-green algae on lakes and ponds can be toxic to humans and dogs alike.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sefton-park-lake-in-liverpool-which-has-been-closed-off-news-photo/1228294229?adppopup=true">Peter Byrne/PA Images via Getty Images</a></span>
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<p>One of these cyanotoxins, β-methylamino-L-alanine, or BMAA, is linked to <a href="https://doi.org/10.3389/fnagi.2020.00026">neurodegenerative disorders</a> including amyotrophic lateral sclerosis, or ALS, Parkinson’s disease and Alzheimer’s disease.
In particular I was struck by scientists’ finding high levels of BMAA in <a href="https://doi.org/10.1073/pnas.0914417107">mollusks and fish found in the Baltic Sea</a>, which could potentially play a role in Finland’s high incidence of dementia, as fish is heavily consumed there.</p>
<p>Blue-green algae is found in <a href="https://www.cdc.gov/habs/index.html">rivers, lakes and seas</a>. Its presence is a widespread problem for humans, dogs and wildlife in the U.S. and Canada, as well as around the globe. In 2020, <a href="https://www.bbc.com/news/world-africa-54234396">more than 300 elephants in Botswana died</a> after drinking from water sources contaminated by the cyanobacteria that cause these algal blooms. Blue-green algae is so widely present in Finland that scientists there have developed <a href="https://www.utu.fi/en/news/news/novel-testing-device-will-reveal-whether-water-contains-toxic-blue-green-algae">a quick test to determine whether it is present or not.</a></p>
<h2>Mold neurotoxins</h2>
<p>In Finland, warm, humid air creates the perfect conditions for mold to grow, and water-damaged buildings are particularly susceptible. Some species emit mycotoxins, or mold toxins. Long-term exposure to mycotoxins, even at low levels, can present <a href="https://doi.org/10.1080/00039896.2003.11879142">serious health hazards</a> for both people and animals. </p>
<p>Mold spores are tiny, making them easy to inhale or ingest. Inside the body they can trigger an immune response, leading to chronic inflammation. Ultimately, exposure to these spores may cause <a href="https://doi.org/10.1016/j.shaw.2020.01.003">cognitive impairment</a>, including memory loss, irritability, numbness, tremors and other symptoms. Such a situation is likely to develop after a region has experienced the flooding of residences or workplaces in the weeks after they have been damaged.</p>
<p>Mold toxins, particularly <a href="https://doi.org/10.1002/mnfr.200600137">ochratoxin A</a>, can trigger inflammation that may harm neurons and brain function. It has been <a href="https://doi.org/10.1016/j.jns.2006.06.006">specifically implicated</a> in Parkinson’s disease. </p>
<h2>Reducing risk and a way forward</h2>
<p>Education, greater awareness of environmental health concerns and public action are the best ways to minimize risks from environmental neurotoxins.</p>
<p>By learning to recognize blue-green algae, people may avoid swimming or boating near it and avoid letting their pets near it too. Consumers can advocate for greater environmental monitoring of food and water sources. Exercise that involves sweating can <a href="https://doi.org/10.1155/2017/3676089">help eliminate neurotoxic substances</a>. But before you exercise outdoors, it is prudent to check air quality on an app or website like <a href="https://www.airnow.gov/">AirNow</a>, a partnership of federal, state, local and tribal agencies.</p>
<p>If environmental policies aren’t put into place to mitigate the health risks posed by environmental neurotoxins, <a href="https://doi.org/10.4172/2161-0460.1000249">research suggests</a> that we may continue to experience increases in a variety of neurodegenerative disorders as the toxins rise. Many of these conditions are labeled idiopathic, or lacking a known cause. The neurotoxic connection is rarely considered, and environmental health hazards are <a href="https://doi.org/10.1186/s12909-020-02458-x">often overlooked in American health care</a>. This is in large part because environmental health is rarely taught in medical education, which can lead to a lack of awareness about potential diagnoses related to an environmental illness.</p>
<p>The U.S. Environmental Protection Agency is currently <a href="https://www.epa.gov/system/files/documents/2021-10/draft-policy-assessment-for-the-reconsideration-of-the-pm-naaqs_october-2021_0.pdf">reevaluating</a> air quality standards for particulate matter. A new EPA <a href="https://www.epa.gov/system/files/documents/2021-09/_epaoig_20210929-21-e-0264.pdf">inspector general report</a> calls for a strategic plan to control harmful algal blooms. Ohio, a leading state for public policy initiatives aimed at neurotoxic algal blooms, <a href="https://grist.org/politics/toxic-algae-blooms-are-multiplying-the-government-has-no-plan-to-help">now regulates</a> cyanotoxins in drinking water and advises farmers against adding fertilizer when the ground is saturated or when rain is in the forecast. </p>
<p>Since <a href="https://doi.org/10.1038/s41586-019-1468-9">climate change may be a driver for rising neurotoxins</a>, cutting greenhouse gas emissions and ensuring better environmental stewardship are essential to human health. Achieving this will require strong international and domestic efforts and a wide range of interventions by governments around the world. But all of these efforts must begin with a deeper and more widespread understanding of the profound nature of this problem – which should be a universal, nonpartisan concern. </p>
<p>[<em>Over 115,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-newsletter-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p><img src="https://counter.theconversation.com/content/165866/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arnold R. Eiser does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Pollution from more frequent floods and wildfires – exacerbated by the warming climate – is threatening human health and poses particular risks to the brain.Arnold R. Eiser, Emeritus Professor of Medicine, Drexel UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1098802019-01-15T19:13:34Z2019-01-15T19:13:34ZThe Darling River is simply not supposed to dry out, even in drought<figure><img src="https://images.theconversation.com/files/253808/original/file-20190115-180516-1t15oz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Puddles in the bed of the Darling River are a sign of an ecosystem in crisis.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/62459458@N08/27243660252">Jeremy Buckingham/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The <a href="https://www.mdba.gov.au/managing-water/drought-murray-darling-basin/fish-deaths-lower-darling">deaths of a million or more fish</a> in the lower Darling River system over the past few weeks should come as no surprise. Quite apart from specific warnings given to the NSW government <a href="https://www.smh.com.au/national/nsw-ignored-warnings-on-threat-of-fish-kills-20190113-p50r4v.html">by their own specialists</a> in 2013, scientists have been warning of devastation <a href="https://www.sciencedirect.com/science/article/pii/S0022169499001912">since the 1990s</a>. </p>
<p>Put simply, ecological evidence shows the Barwon-Darling River is not meant to dry out to disconnected pools – even during drought conditions. Water diversions have disrupted the natural balance of wetlands that support massive ecosystems. </p>
<p>Unless we allow flows to resume, we’re in danger of seeing one of the worst environmental catastrophes in Australia. </p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
</strong>
</em>
</p>
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<h2>Dryland river</h2>
<p>The Barwon-Darling River is a “dryland river”, which means it is <a href="http://www.publish.csiro.au/MF/MF94161">naturally prone</a> to periods of extensive low flow punctuated by periods of flooding. </p>
<p>However, the presence of certain iconic river animals within its channels tell us that a dry river bed is not normal for this system. The murray cod, dead versions of which have recently bought graziers to tears and politicians to retch, are the sentinels of permanent deep waterholes and river channels – you just <a href="https://www.mdba.gov.au/sites/default/files/archived/mdbc-NFS-reports/2202_factsheet_native_murray_cod.pdf">don’t find them</a> in rivers that dry out regularly.</p>
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<p>Less conspicuous is the large river mussel, <a href="https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:2c316d50-67ff-46e7-a98e-e988bbaa1312"><em>Alathyria jacksoni</em></a>, an inhabitant of this system for thousands of years. Its shells are abundant in Aboriginal middens along the banks. These invertebrates are unable to tolerate low flows and low oxygen, and while dead fish will float (for a while), shoals of river mussels are probably dead on the river bed. </p>
<p>This extensive drying event will cause regional extinction of a whole raft of riverine species and impact others, such as the <a href="https://www.abc.net.au/news/2018-02-25/get-to-know-the-rakali-australias-native-water-rat/9464212">rakali</a>. We are witnessing an ecosystem in collapse.</p>
<h2>Catastrophic drying</h2>
<p>We can see the effects of permanent drying around the world. The most famous example is the drying of the Aral Sea in Central Asia. Once the world’s fourth largest inland lake, it was reduced to <a href="http://science.sciencemag.org/content/241/4870/1170">less than 10% of its original volume</a> after years of water extraction for irrigation. </p>
<p>The visual results of this exploitation still shock: images of large fishing boats stranded in a sea of sand, abandoned fishing villages, and a vastly changed microclimate for the regions surrounding the now-dry seabed. Its draining has been <a href="https://theconversation.com/worlds-worst-environmental-disaster-set-to-be-repeated-with-controversial-new-dam-in-africa-107070">described</a> as “the world’s worst environmental disaster”. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-drained-the-aral-sea-once-before-but-there-are-no-free-refills-this-time-round-32513">Humans drained the Aral Sea once before – but there are no free refills this time round</a>
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<p>So, what does the Aral Sea and its major tributaries and the Darling River system with its tributary rivers have in common? Quite a lot, actually. They both have limited access to the outside world: the Aral Sea basin has no outflow to the sea, and while the Darling River system connects to the River Murray at times of high flow, most of its water is held within a vast network of wetlands and floodplain channels. Both are semi-arid. More worryingly, both have more the 50% of their average inflows extracted for irrigation.</p>
<p>There is one striking difference between them. The Aral Sea was a permanent inland lake and its disappearance was visually obvious. The wetlands and floodplains of the Barwon-Darling are mostly ephemeral, and the extent of their drying is therefore hard to visualise.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/its-time-to-restore-public-trust-in-the-governing-of-the-murray-darling-basin-109797">It's time to restore public trust in the governing of the Murray Darling Basin</a>
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<figure class="align-center zoomable">
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<span class="caption">An orphaned ship in former Aral Sea, near Aral, Kazakhstan.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Aralship2.jpg">Wikipedia</a></span>
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<p>All the main tributaries of the Darling River have floodplain wetland complexes in their lower reaches (such as the Gwydir Wetlands, Macquarie Marshes and Narran Lakes). When the rivers flow they absorb the water from upstream, filling before releasing water downstream to the next wetland complex; the wetlands acting like a <a href="http://www.publish.csiro.au/MF/MF10106">series of tipping buckets</a>. Regular river flows are essential for these sponge-like wetlands.</p>
<p>So, how has this hydrological harmony of regular flows and fill-and-spill wetlands changed? And how does this relate to the massive fish kills we are seeing in the lower Darling system? </p>
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Read more:
<a href="https://theconversation.com/how-is-oxygen-sucked-out-of-our-waterways-109795">How is oxygen 'sucked out' of our waterways?</a>
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<p>While high flows will still make it through the Barwon-Darling, filling the floodplains and wetlands, and connecting to the River Murray, the low and medium flow events have disappeared. Instead, these are captured in the upper sections of the basin in artificial water storages and used in irrigation. </p>
<p>This has essentially dried the wetlands and floodplains at the ends of the tributaries. Any water not diverted for irrigation is now absorbed by the continually parched upstream wetlands, leaving the lower reaches vulnerable when drought hits. </p>
<p>By continually keeping the Barwon-Darling in a state of low (or no) flow, with its natural wetlands dry, we have reduced its ability to cope with extended drought.</p>
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<strong>
Read more:
<a href="https://theconversation.com/why-a-wetland-might-not-be-wet-103687">Why a wetland might not be wet</a>
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<p>While droughts are a natural part of this system and its river animals have adapted, they can’t adjust to continual high water caused in some areas by water diversions – and they certainly can’t survive long-term drying. </p>
<p>The Basin Plan has <a href="https://theconversation.com/it-will-take-decades-but-the-murray-darling-basin-plan-is-delivering-environmental-improvements-93568">come some way</a> in restoring some flows to the Barwon-Darling, but unless we find a way to restore more of the low and medium flows to this system we are likely witnessing Australia’s worst environmental disaster.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/it-will-take-decades-but-the-murray-darling-basin-plan-is-delivering-environmental-improvements-93568">It will take decades, but the Murray Darling Basin Plan is delivering environmental improvements</a>
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<img src="https://counter.theconversation.com/content/109880/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fran Sheldon receives funding from the Australian Research Council and has at times undertaken paid contract work for the Murray Darling Basin Authority and the Commonwealth Environmental Water Holder.</span></em></p>Mass fish deaths are a blaring warning sign for the heath of the Murray Darling Basin, but just as worrying is the sight of dry areas in the Darling.Fran Sheldon, Professor, Australian Rivers Institute, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1097972019-01-15T00:44:38Z2019-01-15T00:44:38ZIt’s time to restore public trust in the governing of the Murray Darling Basin<figure><img src="https://images.theconversation.com/files/253604/original/file-20190114-43535-1d0sshz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Going all the way back: rules for the Murray Darling Basin are in Australia's constitution. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/knitspirit/6720844065/in/photolist-beU5MP-8X9mR-gpetZD-898fn-898oW-6bto8Q-gcGfG5-gcGqAo-gcGVqX-gcJ7Xa-gcJEGT-bWuaqo-A9Jtk-2ckQ4H1-5wiQ27-TWN2k7-SHUNYy-Tqkj5Y-SHT5YJ-TWMgbW-TWJJos-TqjQrw-SLE8uc-TLp69S-TNQWQ2-TLrJro-TLteGf-TLtqEs-SHUqk7-SHSV3b-SHVSqb-SLEyXg-SHTaoA-SLEq4z-TqjPkd-TNNSve-25cXy5z-9fJfG-9fJsp-9fH4r-nKvb-9fJFp-9fJ7a-9fHDq-9fHuu-9fJmN-9fGUe-9g8AT-9fHeQ-9fHXF">KnitSpirit/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>Fish deaths in the <a href="https://www.abc.net.au/news/2019-01-08/second-fish-kill-in-darling-river-at-menindee/10696632">Darling River</a> have once more raised the public profile of incessant political controversies about the Murray Darling Basin. These divisive debates reveal the deeply <a href="https://www.mdpi.com/2073-4441/10/2/113">contested nature of reforms to water policy in the Basin</a>.</p>
<p>It feels like Australia has been here before – algae blooms are not uncommon in these rivers. In 1992, the Darling suffered the <a href="https://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526">world’s largest toxic algal bloom</a>, over 1,000 kilometres long. This crisis became an iconic catalyst, and helped prompt the state and federal governments agreeing to <a href="https://www.mdpi.com/2073-4441/10/2/113">water reforms in 1994</a>.</p>
<p>Hopefully, our current crisis may be an opportunity to shine a strong light on the complexities of governing the Basin, and initiate the meaningful reforms needed to restore public trust.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-is-oxygen-sucked-out-of-our-waterways-109795">How is oxygen 'sucked out' of our waterways?</a>
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</p>
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<h2>Forewarned is forearmed</h2>
<p>The rivers of the basin are unique and precious. Australia needs high quality and independent science to understand them and guide their management. Unfortunately in 2012 state and federal governments cut three important programs that provided vital research on the Basin’s rivers: </p>
<ul>
<li>the <a href="https://www.publish.csiro.au/mf/mf09043">Sustainable Rivers Audit</a> (an independent scientific audit of river health) </li>
<li>a dedicated <a href="http://www.seaci.org">climate science program</a></li>
<li>the acclaimed <a href="https://onlinelibrary.wiley.com/toc/14428903/2014/15/s1">Native Fish Program</a>, which combined applied research with community engagement.<br></li>
</ul>
<p>So while yesterday’s announcement of A$5 million funding to a new <a href="https://www.theage.com.au/environment/sustainability/ecological-disaster-emergency-meeting-called-with-more-fish-deaths-imminent-20190113-p50r4u.html">native fish recovery program</a> is welcome, good science alone is not enough. Good policy processes and robust institutions are needed to apply this information. We cannot continue to <a href="https://www.smh.com.au/national/nsw-ignored-warnings-on-threat-of-fish-kills-20190113-p50r4v.html">ignore expert warnings</a>.</p>
<h2>A crisis of trust</h2>
<p>Since a 2017 Four Corners program exposed disturbing allegations of <a href="https://www.abc.net.au/4corners/pumped/8727826">water theft and corruption</a>, the media has revealed a host of further probity issues.</p>
<p>These and a plethora of formal inquiries into MDB governance indicates a crisis of trust, legitimacy and public confidence – in short, a <a href="http://www.tai.org.au/sites/default/files/P531%20The%20Basin%20files%20Vol%20I%20%20%5BWEB%5D.pdf">loss of authority</a>.</p>
<p>The <a href="https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Rural_and_Regional_Affairs_and_Transport/MurrayDarlingPlan/Report">2018 federal Senate inquiry</a> documents a litany of concerns, while disturbing evidence given at a <a href="http://www.mdbrc.sa.gov.au/sites/g/files/net3846/f/david_bell_final_witness_statement.pdf?v=1529025595,%202018.%20755%2047">South Australian Royal Commission</a> raised substantive doubts about failures to heed the best scientific advice in the development of the Basin Plan.</p>
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<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
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<h2>More Commonwealth oversight is not enough</h2>
<p>Without doubt pressure is mounting for more reforms. The Senate’s Rural and Regional Affairs Committee and the <a href="https://www.pc.gov.au/inquiries/current/basin-plan/draft">Productivity Commission</a> have recommended splitting the Murray Darling Basin Authority into two entities – the MDB Corporation and a MDB Regulator – in order to clearly separate the Commonwealth’s regulatory oversight from other roles.</p>
<p>These proposals deserve critical scrutiny. Structural reorganisation can provide an illusion of government action, but can have long-term effects on the efficacy and justice of water governance.</p>
<p>The Murray Darling has a unique place in Australia’s history, environment, economy and culture. Agreements about its governance have their origins in debates leading up to Federation in 1901. Any renegotiation needs to respect the Constitution and the different legal powers of the states and the Commonwealth.</p>
<p>So reform to institutional arrangements need bespoke design. These are the legitimate remit of our discursive democracy. Nonetheless, the <a href="http://www.oecd.org/governance/oecd-principles-on-water-governance.htm">OECD’s 12 water governance principles</a> usefully provide guidance about the need for clarity of roles, transparency, effectiveness, efficiency and broad stakeholder engagement.</p>
<p>Current calls for reorganisation focus on clarifying the Commonwealth’s regulatory role, but this is fairly narrow. Reforms are needed at all scales. </p>
<p>The governance challenges in the MDB require modernisation and redesign of arrangements across regional, state and Commonwealth agencies. This includes structuring “constructive tensions” that ensure transparency and accountability. Just like the police don’t control the courts, we need to more clearly define and separate roles in the water sector.</p>
<h2>Embracing radical transparency</h2>
<p>We need all water agencies to adopt a formal charter of transparency and openness. All state and Commonwealth agencies should open their books to scrutiny, rather than hiding information behind claims of “commercial in confidence” or opaque “freedom of information” processes. </p>
<p>Greater transparency measures should also be a condition of all water licences. It’s entirely feasible to create <a href="https://theconversation.com/tax-returns-for-water-satellite-audited-statements-can-save-the-murray-darling-81833">modern monitoring regimes</a>, using state-of-the art digital metering coupled with annual water-use declarations. These would be similar to tax returns enforced with random audits and satellite verification of areas irrigated. If made publicly available, all interested parties could audit water extractions.</p>
<p>But doubts don’t exclusively focus on irrigators’ compliance. We also need to address the states and their willingness and capability to enforce regulations. Policies of radical transparency could be supported with openly available water data. With digital meters and automated gauging of river flows, we could create a computer platform where anybody could develop river models using real data, in near real-time.</p>
<p>Harnessing the power of citizen involvement, trust and openly sharing information has been a hallmark of <a href="https://theconversation.com/joan-kirner-united-farmers-and-conservationists-to-care-for-the-land-42746">Australia’s landcare</a> and natural resource management. This is where we should look for the <a href="https://blogs.crikey.com.au/rooted/2010/11/16/murray-murmurings-rethinking-the-basin-plan/">next generation</a> of governance in the Basin.</p>
<p>Open books means communities, industries, research and educational institutions can all help monitor our <a href="https://www.cogitatiopress.com/politicsandgovernance/article/view/1221">institutions</a> and ensure rivers are managed in the public’s interest.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/recent-australian-droughts-may-be-the-worst-in-800-years-94292">Recent Australian droughts may be the worst in 800 years</a>
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<p>Finally, droughts should not come as surprise. They are a recurrent feature of the Basin. With climate change, <a href="http://www.seaci.org">more frequent and intense droughts</a> are predicted. As a nation we can do better than lurching from crisis to crisis each time drought returns.</p>
<p>We need careful deliberation about the institutions that will rebuild public confidence and restore trust in the governing of the Murray Darling. It’s time to develop a 21st century system that is cooperative, transparent and just.</p><img src="https://counter.theconversation.com/content/109797/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Alexandra operates a small independent research and consulting business, Alexandra and Associates, that has at times undertaken paid contract work for the Murray Darling Basin Authority and other government agencies involved in water and rivers. He is also an irrigator in Southern Victoria - not in the Murray Darling.
He was a former executive at the MDBA between 2008 and 2013 with wide ranging responsibilities including for native fish and assessing riverine health. He received no funding for the preparation of this article and has no conflicts of interest.</span></em></p>Public confidence in the institutions in charge of the Murray Darling Basin has plummeted – with good reason.Jason Alexandra, PhD candidate, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1097952019-01-14T03:32:36Z2019-01-14T03:32:36ZHow is oxygen ‘sucked out’ of our waterways?<figure><img src="https://images.theconversation.com/files/253587/original/file-20190114-43544-kywlhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dead fish are a source of food for bacteria, which then extract oxygen from the river. </span> <span class="attribution"><span class="source">AAP</span></span></figcaption></figure><p>A million fish <a href="https://www.farmonline.com.au/story/5847386/menindee-fish-kill-how-did-we-get-here/">have died </a>in the Murray Darling basin, as oxygen levels plummet due to major algal blooms. Experts have warned we could see more mass deaths this week. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
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<p>Fingers have been pointed at <a href="https://www.abc.net.au/radionational/programs/breakfast/murray-darling-authority-blames-historic-water-mismanagement/10707358">poor water management</a> after a long period of drought. However, mass fish deaths can also be caused by <a href="https://www.mdba.gov.au/media/mr/blackwater-widespread-after-river-murray-floods">floods</a>, and even raw sewage. </p>
<p>So what’s going on when oxygen gets “<a href="https://www.washingtonpost.com/local/officials-algae-bloom-suffocated-thousands-of-fish-to-death-in-anne-arundel-creeks/2012/05/23/gJQAlHBQkU_story.html?noredirect=on&utm_term=.56d73e28c58d">sucked out of the water</a>”?</p>
<p>The phenomenon is very well known to water quality engineers; we call it “<a href="https://en.wikipedia.org/wiki/Biochemical_oxygen_demand">biochemical oxygen demand</a>”. To understand it, we need to talk about a little bit of biology and a little bit of chemistry.</p>
<h2>When oxygen meets water</h2>
<p>Oxygen molecules are soluble in water in the same way that sugar is soluble in water. Once its dissolved, you can’t see it (and, unlike sugar, oxygen is tasteless).</p>
<p>The maximum amount of oxygen that you can dissolve in water depends on a number of factors, including the water temperature, ambient air pressure, and salinity. But roughly speaking, the maximum amount of dissolvable oxygen, known as the “saturation concentration” is typically around 7-10 milligrams of oxygen per litre of water (7-10 mg/L).</p>
<p>This dissolved oxygen is what fish use to breathe. Fish take water in through their mouths and force it through their gill passages. Gills, like our lungs, are full of blood vessels. As water passes over the thin walls of the gills, dissolved oxygen is transferred into the blood and then transported to the fish’s cells. The higher the oxygen concentration in the water, the easier it is for this transfer to occur.</p>
<p>Once in the cells, the oxygen molecules play a key role in the process of “aerobic respiration”. The oxygen reacts with energy-rich organic substances, such as sugars, carbohydrates and fats to break them down and release energy for the cells. The main waste product from this process is carbon dioxide (CO₂). This is why we all need to breathe in oxygen and we breathe out carbon dioxide. Fish do that too. A simple way to express this is: </p>
<blockquote>
<p>Organic substances + Oxygen <strong>→</strong> Carbon dioxide + Water + Energy</p>
</blockquote>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Hunter River in NSW suffered a ‘blackwater’ event in 2016 when floodwaters washed organic matter into the river.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/fishyone1/8656877471/in/photolist-ebYL58-GuAxFi-buSxYC-z3sHAC-fme1DD-St3t6w-Ty6ocr-e55Wyx-71NNaQ-6fYpAT-71NN7w-RHG8LB-S1zBex-RFezrY-QV76Pq-S9K9Yo-RDyqed-S91LqS-EDSL4Q-2j7DqY-F9mCKh-RHG9ti-CAeVuQ-D5oh6-RGYU4q-fC2mGs-9ncWH2-9ncWJv-VD65hC-mtEuy-Sc3mbh-u63Lh-gR1pEh-D5nJc-Ty6naB-5W83b5-St3sP9-3EvNxZ-TKADyi-Sb3rHV-D5nPv-FDGejb-ji7vDV-e9YFqS-D5ocQ-D5on9-26JwULu-aDoagB-Si2Mvv-aX3QXa">Andrew S/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>What is the <em>biochemical oxygen demand</em>?</h2>
<p>Just like fish and people, many bacteria gain energy from processes of aerobic respiration, according to the simplified chemical reaction shown above. Therefore, if there are organic substances in a waterway, the bacteria that live in that waterway can consume them. This is an important process of “biodegradation” and is the reason our planet is not littered by the carcasses of animals that have died over many thousands of years. But this form of biodegradation also consumes oxygen, which comes from dissolved oxygen in the waterway.</p>
<p>Rivers can replenish their oxygen from contact with the air. However this is a relatively slow process, especially if the water is stagnant (flowing creates turbulence and mixes in more oxygen). So if there is a lot of organic matter present and bacteria are feasting on it, oxygen concentrations in the river can suddenly drop.</p>
<p>Obviously, “organic substances” can include many different things, such as sugars, fats and proteins. Some molecules contain more energy than others, and some are easier for the bacteria to biodegrade. So the amount of aerobic respiration that will occur depends on the exact chemical nature of the organic substances, as well as their concentration. </p>
<p>Therefore, instead of referring to the concentration of “organic substances”, we more commonly refer to the thing that really matters: how much aerobic respiration the organic substances can trigger and how much oxygen this will cause to be consumed. This is what we call the <em>biochemical oxygen demand</em> (BOD) and we usually express it as a concentration in terms of milligrams of oxygen per litre of water (mg/L).</p>
<p>Like us, bacteria don’t consume all of the food which is available to them instantly – they graze on it over time. Biodegradation therefore can take days, or longer. So when we measure the BOD of a contaminated water sample, we need to assess how much oxygen is consumed (per litre of water) over a specified period of time. The standard period of time is usually five days and we refer to this value as the BOD5 (mg/L).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Murray cod pull oxygenated water through their gills, transferring it to their bloodstream. Without oxygen in the water, they die.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/guochai/1292824702/in/photolist-2Yf4K5-8xW2iy-8xSZ6B-8xW2gW-cBYHsu-27c8rtW-96HaXU-HnKMwP-TBMM1X-eQifMT-72Pjt7-HB6XfP-j9oPN-52uxN-7p96Tq-5kX7uP-5HTBuH-5HTDf2-rd6XeD-5HTDHk-5HTG16-UD8kbh-5HTCnx-5hdMKF-5HXSYy-5HTC3c-5HTCSc-5HTDZZ-VESXhd-VJafgn-8MvmSc-VVzpzc-27c8qCY-5HTDxD-UG5PRv-UG48Ji-eatLpZ-UD8jH3-5HXVBb-BTkoP8-UD8k55-52Md5n-UD8jJf-VJabVV-UG3Rvg-dEJDZf-VkptbE-VVB8FV-UgkTd7-26o6cdB">Guo Chai Lim/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>As I mentioned earlier, clean water might only have a concentration of dissolved oxygen of up to around 7-10 mg/L. So if we add organic material in a concentration which has a higher BOD5 than this, we can expect it to deplete the ambient dissolved oxygen concentration during the next five days.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/more-of-us-are-drinking-recycled-sewage-water-than-most-people-realise-92420">More of us are drinking recycled sewage water than most people realise</a>
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<p>This phenomena is the main reason for which biological sewage treatment was invented. Raw (untreated) municipal sewage can have a BOD5 of 300-500 mg/L. If this were discharged to a clean waterway, the typical base-level of 7-10 mg/L of oxygen would be consumed, leaving none available for fish or other aquatic organisms. </p>
<p>So the purpose of biological sewage treatment is to grow lots of bacteria in large tanks of sewage and provide them with plentiful oxygen for aerobic respiration. To do this, air can be bubbled through the sewage, or sometimes surface aerators are used to churn up the sewage. </p>
<p>By supplying lots of oxygen, we ensure the BOD5 is effectively consumed while the sewage is still in the tanks, before it’s released to the environment. Well treated sewage can have a BOD5 as low as 5 mg/L, which can then be further diluted as it’s discharged to the environment.</p>
<p>In the case of the Darling river, the high BOD load was created by algae, which died when temperatures dropped. This provided a feast for bacteria, lowering oxygen, which in turn killed hundreds of thousands of fish. Now, unless we clean the river, those rotting fish could become fodder for another round of bacteria, triggering a second de-oxygenation event.</p><img src="https://counter.theconversation.com/content/109795/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stuart Khan is affiliated with the Australian Water Association, and is on a water quality advisory committee for the NHMRC. </span></em></p>Hundreds of thousands of fish have died in low-oxygen water. Here’s what actually happened to the oxygen, and why we might see more deaths in the coming weeks.Stuart Khan, Professor of Civil & Environmental Engineering, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1096462019-01-10T03:41:40Z2019-01-10T03:41:40ZExplainer: what causes algal blooms, and how we can stop them<p>Outbreaks of algae have killed up to a <a href="https://www.abc.net.au/news/2019-01-08/second-fish-kill-in-darling-river-at-menindee/10696632">million fish</a> in the Murray Darling Basin over the last two weeks. The phenomena of “algae blooms”, when the population of algae in a river rapidly grows and dies, can be devastating to local wildlife, ecosystems and people. But what are algae blooms? What causes them, and can we prevent them?</p>
<p>Microscopic algae are fundamental to life on earth. These tiny plants provide the fuel that drives marine and freshwater foodwebs, and via photosynthesis, they gobble up carbon dioxide to help counteract emissions, and provide us with oxygen to breathe. Besides rivers, streams, lakes, estuaries and the coast, they can also be found in <a href="https://en.wikipedia.org/wiki/Algae#Distribution">diverse environments</a> such as snow, soil, and in corals.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526">Are toxic algal blooms the new normal for Australia's major rivers?</a>
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<hr>
<p>But when humans channel agricultural run-off, sewerage and stormwater discharge into waterways, we dramatically increase the amount of nutrients such as nitrogen and phosphorus. This creates an imbalance, because some microscopic algae are supremely effective at mopping up nutrients and can grow very quickly, dividing up to once a day and quickly overtaking other species. The result is an algal bloom.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=624&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=624&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=624&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=785&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=785&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=785&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cyanobacteria (blue-green algae) under a microscope.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>So why don’t we have algal blooms all the time? This is because algae don’t just require nutrients to grow. Like any plant, factors such as temperature and light availability are also important in determining how quickly algae grow and whether they form blooms. Blooms also need slow moving or still water to become established.</p>
<p>In Australia, our algal blooms are typically in freshwaters. The main group of algae responsible for this are known as blue-green algae, or more accurately, cyanobacteria. They regularly bloom in warmer weather in our reservoirs, lakes and slow flowing rivers. In 2016, for example, <a href="https://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526">1,700km of the Murray River</a> was affected by an algal bloom. </p>
<p>There are many ways they impact the environment and economy. Some algal blooms are toxic, requiring expensive water treatment and – in extreme cases – shutdown of water supplies. This isn’t just a problem in Australia. In 2014, some <a href="https://www.ecowatch.com/toxic-algae-bloom-leaves-500-000-without-drinking-water-in-ohio-1881940537.html">500,000 people</a> in the US were left without drinking water due to a toxic algal bloom in Lake Erie.</p>
<p>The toxins can also affect domestic animals, such as dogs, when they drink contaminated water, and limit use of lakes and rivers for swimming, boating and fishing. Even when algal blooms are not toxic, they unbalance the food web, reducing the number of species of animals and plants. </p>
<p>They can also reduce oxygen levels at night, as they switch from photosynthesis (producing oxygen) during the day, to a process called <a href="https://en.wikipedia.org/wiki/Cyanobacteria#Respiration">respiration</a> at night where they use oxygen. Low oxygen can stress and even kill fish and other animals if they cannot escape this.</p>
<p>At some point, algal blooms crash when conditions become unsuitable. The resulting dead algae break down, providing an ideal food source for bacteria. This is when waters can become smelly, often with a rotten egg smell. As the bacteria multiply, they suck the oxygen out of the water. At this point, oxygen levels become low both day and night. </p>
<p>If the area of low oxygen is extensive, such as a whole lake or many kilometres of a river system, fish and other animals may not be able to escape to more suitable oxygen levels, and major fish deaths typically occur.</p>
<p>In other areas of the world, algal blooms have caused such severe oxygen conditions that thousands of square kilometres of ocean around the world are now known as <a href="https://www.scientificamerican.com/article/oceanic-dead-zones-spread/">dead zones</a>, where no animals can live. These vast dead zones are not something we ever want to see in Australia.</p>
<h2>So what can be done about blooms?</h2>
<p>There are a wide range of <a href="https://www.epa.gov/nutrient-policy-data/control-and-treatment">treatments</a> that can be used to control blooms, for example, aerating the water, and adding clays and chemicals, but the catch is they are <a href="http://www.owrb.ok.gov/quality/standards/pdf_standards/scenicrivers/Dodds%20et%20al%202008.pdf">very expensive</a> on a large scale. </p>
<p>Ideally, the problem should be tackled at the source. This means reducing nutrient loads to our waterways. There has already been progress on this in our cities where sewage treatment plants have been upgraded to <a href="https://www.scientificamerican.com/article/wastewater-is-key-to-reducing-nitrogen-pollution/">reduce nutrient loads</a> to waterways. But tackling nutrients coming from agriculture – erosion, fertilisers, animal waste – is much more <a href="https://environment.des.qld.gov.au/assets/documents/reef/costings-report.pdf">challenging and expensive</a> because of the vast areas involved. So this remains work in progress.</p>
<p>It’s also very difficult to <a href="https://www.smithsonianmag.com/science-nature/can-scientists-forecast-algal-blooms-pest-outbreaks-like-we-do-weather-180967998">predict when blooms will occur</a>; despite being simple plants, algae have an amazing range of strategies to grow and survive. But as we learn more about their complexity our ability to model and predict blooms will improve. This is crucial to managing risks to water supplies and preventing major environmental effects, such as fish deaths.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/toxin-linked-to-motor-neuron-disease-found-in-australian-algal-blooms-95646">Toxin linked to motor neuron disease found in Australian algal blooms</a>
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<p>Ultimately there are no quick fixes to algal blooms. Given the pressure we put on our waterways, they are here to stay. In fact they are likely to increase due to increasing temperatures and more extreme conditions, such as droughts. We know what we need to do to reduce the scale and likelihood of blooms: the challenge is devoting the resources to achieve it.</p><img src="https://counter.theconversation.com/content/109646/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michele Burford receives funding from the Australian Research Council, State and local governments for her algal research.</span></em></p>Algae blooms have killed hundreds of thousands of fish in the last two weeks, but what exactly are they and how do we get them under control?Michele Burford, Professor - Australian Rivers Institute, and Dean - Research Infrastructure, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/998182018-07-17T10:46:56Z2018-07-17T10:46:56ZPigments from microbes provide clue to evolution in ancient oceans – but weren’t pink a billion years ago<figure><img src="https://images.theconversation.com/files/227876/original/file-20180716-44076-p499t1.jpg?ixlib=rb-1.1.0&rect=308%2C242%2C1628%2C1153&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cyanobacteria filled the ancient oceans and used chlorophyll to harvest the sun's energy.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/28594931@N03/4726914132">Specious Reasons</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Possibly the most <a href="https://doi.org/10.1126/sciadv.1603076">significant event in the evolution of life</a> on Earth occurred 2.4 billion years ago. That was when the amount of oxygen in the atmosphere and ocean surface waters rapidly increased – setting the stage for a new phase of life on our planet.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1155&fit=crop&dpr=1 600w, https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1155&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1155&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/227886/original/file-20180716-44103-139nuoz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1451&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Most of the forms of life we’re familiar with are relatively recent additions to the planet.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:LifeTimeline-TemplateImage-20170116.png">Drbogdan</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Oxygen is produced by photosynthesis, a process that evolved in a type of bacteria <a href="http://www.ucmp.berkeley.edu/bacteria/cyanointro.html">called cyanobacteria</a>. Also known – incorrectly – as blue-green algae, you can encounter them today as pond scum.</p>
<p>Cyanobacteria are prokaryotes: simple single-celled organisms. <a href="http://www.ucmp.berkeley.edu/greenalgae/greenalgae.html">True algae</a> are eukaryotes: more complex, larger organisms. Both perform the same photosynthetic reactions to turn energy from the sun into oxygen and food molecules. The first true algae, as well as other single-celled eukaryotes, arose at least 1.4 billion years ago, but, mysteriously, appear to have remained in the background of life for another 800 million years, at which point they <a href="https://doi.org/10.1042/ETLS20180039">rapidly expanded in number and diversity</a>.</p>
<p><a href="https://doi.org/10.1073/pnas.1803866115">New research</a> by Australian National University earth scientists <a href="https://nationalmaglab.org/about/around-the-lab/meet-the-users/nur-gueneli">Nur Gueneli</a>, <a href="https://scholar.google.com/citations?user=oqL0DAUAAAAJ&hl=en&oi=ao">Jochen Brocks</a> and colleagues confirms the early importance of cyanobacteria in the primordial oceans and provides insights into why it took so long for the true algae to become the base of the food chain.</p>
<h2>Billion-year-old biomarkers</h2>
<p>Much of our knowledge of evolutionary history comes from the fossil record. Unfortunately, soft-bodied organisms, such as algae, rarely leave fossils. But researchers can recover the biomolecules they contained that are resistant to degradation. Found within ancient sediments, scientists can use these molecular fossils, <a href="http://summons.mit.edu/biomarkers/what-is-a-biomarker/">called biomarkers</a>, to identify what types of organisms were present when the sediments formed.</p>
<p>The new study published in the Proceedings of the National Academy of Science examined extracts of 1.1 billion-year-old sediments from 140 to 200 meters below the surface of a site in Mauritania. This corner in northwest Africa was once covered by an ocean. The researchers didn’t detect any biomarkers indicative of eukaryotes, but did find biomarkers indicating that several types of prokaryotes had been present. So no true algae, but plenty of evidence of photosynthetic bacteria. Of particular interest, they found molecules, <a href="http://physicsopenlab.org/2016/07/04/porphyrins-the-colors-of-life/">called porphyrins</a>, that are the remains of <a href="https://www.worldofmolecules.com/colors/chlorophyll.htm">chlorophyll</a>, the molecular basis of photosynthesis.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=756&fit=crop&dpr=1 754w, https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=756&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/227877/original/file-20180716-44070-1h0p9yy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=756&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chemical structure of a simple porphyrin ring. The porphyrin in chlorophyll has a magnesium atom in the middle.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Porphyrin.svg">Lukáš Mižoch</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Using a clever analysis, the scientists were able to identify with near certainty what organisms were the source of the porphyrins. <a href="https://www.webelements.com/nitrogen/isotopes.html">Nitrogen has two atomic forms, called isotopes</a>, the most common of which, ¹⁴N, has an atomic weight of 14 while the rare isotope, ¹⁵N, has an atomic weight of 15. Although ¹⁴N is preferred, the various enzymes that make chlorophyll also incorporate ¹⁵N in proportions that differ among different classes of photosynthetic organisms. So the ratio of ¹⁴N to ¹⁵N in porphyrin molecules, which have four nitrogen atoms, can indicate what type of organism produced them. By measuring the N-isotope ratios in the porphyrins from the sediments, the scientists were able to trace the molecules to the cyanobacteria.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/227854/original/file-20180716-44100-1435prr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A vial of pink-colored porphyrins recovered from sediments that are more than a billion years old.</span>
<span class="attribution"><a class="source" href="http://dx.doi.org/10.1073/pnas.1803866115">The Australian National University</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Not pink, but green</h2>
<p>A dramatic picture in the Gueneli paper showed that some of the extracts of the ancient sediments were brilliant pink. News coverage ran with headlines focused on Earth’s “oldest color” being bright pink. But that’s not quite right.</p>
<p>In order to do its chemical job, the porphyrin in chlorophyll contains a magnesium atom that’s responsible for its green color. This is what makes leaves and algae look green. But in these pink extracts, the porphyrin turned out to have a nickel atom instead. Most likely the nickel replaced the magnesium sometime over the billion-plus years the molecules <a href="https://doi.org/10.1098/rstb.1991.0083">aged in the sediments</a>.</p>
<p>So pink was not the original color of the chlorophyll. It must have been green, as it is in living plants today.</p>
<h2>Algae take over from bacteria</h2>
<p>The researchers’ major conclusion is that 1.1 billion years ago, photosynthetic bacteria, most likely dominated by cyanobacteria, were the base of the food chain in the ocean. Because the bacteria were small, they would sink slowly and be degraded by other bacteria high in the water column. Little of the precious nutrients they contained would reach the ocean bottom.</p>
<p>Nutrient distribution throughout an ocean depends upon <a href="https://oceanservice.noaa.gov/facts/upwelling.html">upwelling from the bottom</a>. So most of the ocean would be nutrient-poor, restricting the development of a community of larger organisms.</p>
<p>In addition, cyanobacteria survive better than eukaryotic algae when nutrients are low, which would further <a href="https://doi.org/10.1042/ETLS20180039">restrict the evolution of these larger-celled photosynthetic organisms</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/227906/original/file-20180716-44070-1fmw20b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">True algae have larger and more complex cells than the cyanobacteria they took over from.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/noaaphotolib/9787178153">NOAA MESA Project</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>What caused the shift about 650 million years ago from an ocean dominated by cyanobacteria to one dominated by true algae? One of the authors of the PNAS paper, geobiologist Jochen Brocks, points out in a recent review article that this shift occurred a mere <a href="https://doi.org/10.1042/ETLS20180039">4 million years after the end of a worldwide glaciation</a>, during which the oceans were frozen for more than 50 million years. Then the glaciers melted, probably because rising carbon dioxide levels created a greenhouse effect, heating the Earth. The temperature of the oceans rose rapidly, possibly killing many remaining cyanobacteria. In addition, as the glaciers melted, vast amounts of nutrients would have been swept into the oceans, reversing the competitive disadvantage for the algae, that then were able to evolve and expand.</p>
<p>With the arrival of these larger, rapidly-settling algae as the basis of the food chain, the stage was set for the evolution and expansion of larger eukaryotic consumers.</p><img src="https://counter.theconversation.com/content/99818/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patricia L. Foster receives funding from the US Army Research Office. She is a member of the American Association for the Advancement of Science, Union of Concerned Scientists and Concerned Scientists at IU.</span></em></p>Did you recently hear news that Earth’s oldest pigments were hot pink? That’s not quite right. When they were in living bacteria a billion years ago, they were performing photosynthesis – and green.Patricia L. Foster, Professor Emerita of Biology, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/619732016-07-19T10:07:46Z2016-07-19T10:07:46ZWhy toxic algae blooms like Florida’s are so dangerous to people and wildlife<figure><img src="https://images.theconversation.com/files/130974/original/image-20160718-1906-1abr85k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Detail from a satellite photo of Lake Okeechobee's algae bloom and the St. Lucie canal into which water was released. Rising water levels from heavy winter rains had water managers worried that water would breach the dike.</span> <span class="attribution"><a class="source" href="http://earthobservatory.nasa.gov/IOTD/view.php?id=88311">NASA</a></span></figcaption></figure><p>Reported cases of algal blooms, when algae grow rapidly from an influx of nutrients in waterways, have been rising at an <a href="http://science.sciencemag.org/content/321/5891/926">exponential rate</a> in recent decades. Industrialized countries have the highest incidence with North America, Europe and eastern Asia being hotbeds for new cases <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996450/">due to runoff</a> from industry and cities as well as these areas’ intensive use of manufactured fertilizers.</p>
<p>These events often cause a noticeable change in the color and smell of natural water bodies and may be accompanied by highly visible fish kills or even respiratory distress in humans who inhale tiny, aerosol particles created by wind and waves.</p>
<p>A highly visible new case recently developed in Florida, where a particularly intense bloom of blue-green algae (cyanobacteria) formed in Lake Okeechobee, the largest freshwater lake in the state. As is often the case with today’s larger, more intense blooms, the event was visible to satellites orbiting in space. This year’s Lake Okeechobee bloom was <a href="http://earthobservatory.nasa.gov/IOTD/view.php?id=88311">first noticed</a> on Landsat 8 images during early May 2016 and persisted through at least midsummer.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/RFNc9gPi5dA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>While blooms of this nature are not uncommon in Lake Okeechobee, this one received more attention because of its intensity and size – it covered 33 square miles. Also, the bloom was exported to the coast when water managers released water from Lake Okeechobee in response to several months of heavy rainfall and <a href="http://www.sun-sentinel.com/local/palm-beach/fl-algae-fighting-measures-20160714-story.html">concerns</a> that rising water levels in the lake, which is contained by a dike, would cause flooding.</p>
<p>Upon reaching the coast through two man-made diversions that short-circuit the lake’s natural, southerly flow to the Everglades, the bloom persisted instead of dispersing, causing economic damage to local tourism, fishing and boating businesses. Florida’s governor subsequently declared a state of emergency in three of the hardest-hit counties on the Atlantic coast and in one county on the Gulf coast.</p>
<p>Apart from the economic damages, Floridians are also bothered by the environmental degradation these events cause. What are the environmental and health dangers from this sort of large-scale algal bloom?</p>
<h2>Bloom types and basic bloom mechanics</h2>
<p>Blue-green algae are one of three types of single-celled algae that frequently cause harmful blooms in coastal waters. In Florida and elsewhere, the blue-greens tend to bloom in fresh water and at the upper ends of estuaries, near where freshwater runoff first starts to mix with coastal seawater. The other two algal types, diatoms and dinoflagellates, tend to bloom at more seaward locations (especially the dinoflagellates). </p>
<p>While the fundamental causes of coastal algal blooms are well understood, there is considerable uncertainty about the details. A large part of the debate involves determining which cocktail of nutrients – whether it’s nitrate, ammonia, orthophosphate or organic nutrients such as urea – promotes one particular bloom type over another.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/130975/original/image-20160718-2138-hbvp6k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Algae blooms from excess nutrients in the waterways are common and becoming more common in developed countries.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Florida_Algae_Bloom_01.jpg">John Moran/EPA</a></span>
</figcaption>
</figure>
<p>One of the well-understood fundamentals about algal blooms is that land use has a strong bearing on the types of nutrients that are delivered downstream to bloom-prone water bodies. </p>
<p>Urban development introduces new nutrients from sewage, manufactured fertilizer and rain-borne emissions from burned fuel to downstream parts of local drainage basins. Agriculture, especially row crops, can introduce manufactured fertilizer in large amounts to drainage basins. Intensive animal feed lots may also introduce excessive nutrients; <a href="http://www.newsobserver.com/news/technology/article32817855.html">hog farms in North Carolina </a> and <a href="http://nepis.epa.gov/Exe/ZyNET.exe/9101QS95.TXT?ZyActionD=ZyDocument&Client=EPA&Index=Prior+to+1976&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C70thru75%5CTxt%5C00000025%5C9101QS95.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL">duck farms on Long Island</a> are two well-known examples of intensive animal production leading to harmful algal blooms and lowered water quality. In Florida’s case, intensive feed lots are not common, but the other two land-use types are.</p>
<p>Also well-understood is that water stagnation encourages blooms by giving the algae enough time to remain in calm surface waters where the light needed for photosynthesis is most abundant. In Florida and elsewhere, water is withdrawn from rivers and streams for various municipal, agricultural and industrial purposes, and these withdrawals tend to increase the incidence of stagnation. On the other hand, there are coastal areas both inside and outside of Florida that are relatively immune to stagnation and algal-bloom formation because tidal flushing is strong there.</p>
<p>Once blooms have formed, they can have two types of effects, indirect and direct. The most prominent indirect effect is low dissolved oxygen in the water, or hypoxia. During a bloom, the algae produce dissolved oxygen while they photosynthesize during the day, but then consume dissolved oxygen at night in the dark as they respire.</p>
<p>Although the balance between these two opposing processes (photosynthesis vs. respiration) can be either positive or negative, the trend toward hypoxia becomes stronger as the algae from the bloom start to die off and decompose. First, the sick and dying cells stop producing as much oxygen through photosynthesis, and then the total amount of respiration surges once nonphotosynthetic bacteria start to break down the newly abundant, dead algae cells for food. </p>
<p>Hypoxia can lasts minutes to months, but is nearly permanent in some bodies of water.</p>
<h2>Harms to many organisms</h2>
<p>Why should we be concerned about hypoxia? Basically, the answer is that hypoxia determines which animals can survive in a given body of water.</p>
<p>Hypoxia and anoxia (the complete absence of dissolved oxygen) kill aquatic organisms of all sizes, but the less-mobile bottom animals are usually the first to go. In some cases, hypoxia/anoxia spreads throughout much of the water body, resulting in fish kills. Even if fish kills do not occur, the likely loss of bottom animals eliminates a critically important food supply for the fish community.</p>
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<a href="https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/130976/original/image-20160718-2150-1e4xckx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The algae bloom this summer was so large in Lake Okeechobee that it was visible from space.</span>
<span class="attribution"><a class="source" href="http://earthobservatory.nasa.gov/IOTD/view.php?id=88311">NASA</a></span>
</figcaption>
</figure>
<p>Many aquatic animals, especially larger predators such as fish, obtain their energy from food webs that include bottom animals; even fish and other aquatic animals that do not eat bottom animals directly may be affected. A <a href="http://icesjms.oxfordjournals.org/content/57/4/1091.full.pdf">study of European fisheries</a> revealed that this food-web effect translated into a dramatically changed composition of the fish community over a period of decades. As algal blooms became more common, highly valued fish that were once abundant in the harvest became scarce.</p>
<p>Toxicity, however, is the most direct effect of algal blooms. Some types of bloom are never toxic, but still cause harmful hypoxia, and others are toxic in some cases but not others. </p>
<p>Blooms of algal types such as the red tide organism (<em>Karenia brevis</em>, a dinoflagellate) always appear to be toxic once the blooms exceed a threshold density of cells. <em>Karenia</em>’s toxic product, brevitoxin, mostly kills fish, although other marine life, including dolphins and manatees, have also been killed by red tide. Nutrients released from the decomposing fish are believed to prolong the blooms.</p>
<p>The toxins from various types of algal blooms can become dangerously concentrated within shellfish, especially filter-feeding clams, mussels, oysters and scallops. While the detection of blooms often leads to the closure of shellfish beds by authorities, human deaths have occurred in areas where such regulation does not exist, and also in areas where new blooms are believed to be forming for the first time, catching people off-guard.</p>
<p>One study identified 2,124 cases of saxitoxin poisoning in the Philippines, with <a href="http://ojs.wpro.who.int/ojs/index.php/wpsar/article/view/302/485">120 deaths between 1983 and 2002</a>. These cases were attributed to <em>Pyrodinium bahamense</em>, the same dinoflagellate that blooms intensively in Tampa Bay, apparently without becoming very toxic (yet). </p>
<p>Researchers are starting to suspect that asthma and other human respiratory ailments are <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2683400/">more related to algal blooms than previously believed</a>. Also, there is concern that with continued environmental change, blooms that are presently mildly toxic could become far more toxic in the future. </p>
<h2>Possible remedies</h2>
<p>Given these economic, environmental, and human-health impacts at the coast, what can be done? In Florida, managers release freshwater from the interior to the coast for flood control and water supply. But ecosystem health at the coast must also be managed. </p>
<p>In accordance with the U.S. Clean Water Act, the Total Maximum Daily Load (TMDL) program, which sets pollution limits in bodies of water, is being implemented to lessen the nutrient runoff that fuels algal blooms. The TMDL program provides a geographic accounting of pollutant sources, including excessive nutrient runoff. Yet new blooms keep forming.</p>
<p>In addition to TMDLs, further development and implementation of <a href="https://theconversation.com/forecasting-dead-zones-and-toxic-algae-in-us-waterways-a-bad-year-for-lake-erie-43747">best management practices for agricultural and urban land use</a> needs to continue with the goal of curbing excessive nutrient runoff, particularly during rainy periods.</p>
<p>Detailed computer models of water circulation should be used more routinely in the course of water management to predict where coastal algal blooms are likely to form. Finally, natural wetland buffers should be used to intercept nutrients before they reach the coast (provided this does not cause a different set of problems in the interior), and the construction of <a href="https://theconversation.com/reducing-water-pollution-with-microbes-and-wood-chips-58852">engineered treatment wetlands</a> should be considered.</p>
<p>In the Lake Okeechobee case, restoration of flow to the Everglades may go a long way toward solving Florida’s current problems at the coast.</p><img src="https://counter.theconversation.com/content/61973/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ernst B Peebles received funding from the South Florida Water Management District via a subcontract under Florida Gulf Coast University to research algal blooms in the Caloosahatchee River estuary, Florida.</span></em></p>Toxic algae blooms like the intense one now fouling Florida’s waterways harm wildlife and people in various ways. They’re also on the rise.Ernst B. Peebles, Associate Professor of Biological Oceanography, University of South FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/595262016-05-17T19:35:12Z2016-05-17T19:35:12ZAre toxic algal blooms the new normal for Australia’s major rivers?<figure><img src="https://images.theconversation.com/files/122796/original/image-20160517-15912-fntov8.JPG?ixlib=rb-1.1.0&rect=447%2C1289%2C1308%2C1971&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blue-green algae in the Murray River upstream of Mildura in April.</span> <span class="attribution"><span class="source">Darren Baldwin</span>, <span class="license">Author provided</span></span></figcaption></figure><p>For much of this year, up to 1,700 kilometres of the Murray River has been hit by a serious outbreak of potentially toxic <a href="https://theconversation.com/watch-out-australia-a-red-hot-summer-means-blue-green-algae-49585">blue-green algae</a>, which has flourished in the hotter-than-average conditions. After three months, the river is now <a href="http://www.abc.net.au/news/2016-05-12/rain-helps-murray-river-recover-from-prolonged-blue-green-algae/7408334">recovering</a> with the arrival of wet weather. But we are unlikely to have seen the last of these poisonous microbes.</p>
<p>Large blue-green algal blooms are a relatively new phenomenon in inland waterways. In 1991 an algal bloom <a href="http://insidestory.org.au/no-triple-bypass-no-miracle-cure-just-a-long-haul-back">affected more than 1,000 km of the Darling River</a>, the first time such an event had been reported in an Australian river, and one of the few times internationally. It was an environmental disaster, <a href="http://www.sciencearchive.org.au/nova/017/017key.html">killing livestock</a> and striking a telling blow against Australia’s reputation as a clean, green farming nation. </p>
<p>The response was decisive: a state of emergency was declared, and the bloom ultimately gave rise to significant investment by state and federal governments into freshwater research, particularly in the Murray-Darling Basin. </p>
<h2>Why no emergency now?</h2>
<p>Fast forward two and a half decades to the latest bloom afflicting the Murray River, one of Australia’s most socially, economically and culturally significant waterways. The past decade has seen four similar blooms on the Murray River: in 2007, 2009, 2010 and now. Yes, they have garnered press attention, but there has not been the same call to arms that we saw when the Darling River was struck in 1991. </p>
<p>It is almost as if such significant environmental events are now simply seen as the new normal. Why the apparent complacency?</p>
<p>The 2007, 2009 and 2010 algal blooms on the Murray River all happened during the <a href="https://theconversation.com/au/topics/millennium-drought">Millennium Drought</a>, and hence were probably ascribed to an aberration in the weather. In reality, the situation may have more to do with how we manage water in Australia – particularly during periods of scarcity, such as the one we <a href="https://theconversation.com/environmental-score-card-shows-australia-is-once-again-in-decline-58583">may well be entering now</a>. </p>
<p>Those three earlier events all started in <a href="http://lakehume.org.au/">Lake Hume</a>, a large reservoir in the Murray River’s upper reaches, originally created in the 1930s to help “drought-proof” Australia. All of the blooms began after the water level was drawn down to below 10% of the lake’s capacity. At these low levels, disturbances (such as when transferring water between the Snowy River and Murray River systems) can easily lead to the mixing of warm surface waters (ideal for bloom formation) with nutrient-rich water at the bottom of the reservoir (ideal for feeding the bloom). </p>
<p>The resulting blooms were then released downstream into the Murray River by managed water releases from Lake Hume. The blooms most likely reformed in other constructed water bodies downstream – most notably <a href="http://lakemulwala.org.au/">Lake Mulwala</a>, a shallow reservoir about 250 km along the river from Lake Hume. </p>
<p>Lake Mulwala’s principal purpose is to create hydraulic pressure to allow irrigation water to be diverted into farmland in southern New South Wales and northern Victoria. As a result, its shallow depth and mostly still waters make it an ideal incubator for blue-green algae.</p>
<h2>The climate factor</h2>
<p>This year’s algal bloom on the Murray River is different. The main blue-green alga in the current outbreak, <em>Chrysosporium ovalisporum</em>, has previously been reported in the river, but generally in very low numbers. It has never before formed a bloom in the Murray River since monitoring began in 1978. But crucially, this species flourishes in very warm temperatures; <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4247250/">overseas blooms</a> of this species have occurred when water temperatures reach 26°C. </p>
<p>The other difference between the current and earlier blooms is that, when this year’s event started, Lake Hume was much fuller, at about 30% capacity. So reservoir operation probably had less to do with the bloom’s formation than other factors, such as the climate. Both the maximum and minimum temperatures were <a href="http://www.bom.gov.au/climate/current/month/aus/summary.shtml">consistently above the long-term average</a> during the past few months, as was the amount of sunlight reaching the surface of Lake Hume. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122797/original/image-20160517-15939-s81nwm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The algae-stricken river at Barmah in northern Victoria.</span>
<span class="attribution"><span class="source">Darren Baldwin</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We still do not know exactly what triggered this year’s bloom, but if it was indeed a result of unusually warm temperatures, it is very likely that we will see more blooms of this type in the future. </p>
<p>Are we really ready for recurrent blue-green algal blooms on the Murray River? These blooms come at a significant economic cost: drinking water has had to be <a href="http://www.abc.net.au/news/2016-05-12/rain-helps-murray-river-recover-from-prolonged-blue-green-algae/7408334">specially treated</a> to remove potential toxins, and the bloom has impacted on regional tourism, coinciding with the Labour Day and Easter long weekends. It also hit farmers, who had to get drinking water for their livestock from elsewhere. </p>
<p>More importantly, what do these frequent blooms say about how we manage water in this country – especially as we start to see the impacts of climate change on our environment? Dwindling water could mean more than just drought – it could also fill much of the water that remains with poisonous microbes.</p><img src="https://counter.theconversation.com/content/59526/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Darren Baldwin has received funding from the Murray-Darling Basin Authority to study blue-green algal blooms in the Murray River , including the current bloom. </span></em></p>Toxic algal blooms were unheard of in Australia’s major waterways before 1991. Now the Murray River has been struck by four major events in less than a decade, with more likely in the future.Darren Baldwin, Environmental Scientist, La Trobe UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/529812016-01-20T00:43:55Z2016-01-20T00:43:55ZExposure to algae toxin increases the risk of Alzheimer’s-like illnesses<figure><img src="https://images.theconversation.com/files/108489/original/image-20160119-31831-1eolgpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blue-green algae blooms are increasing in size and frequency as global temperatures rise.</span> </figcaption></figure><p>A paper published today suggests chronic exposure to an environmental toxin may increase the risk of neurodegenerative illness. </p>
<p>For the first time, researchers have shown that feeding vervet monkeys a toxin produced by blue-green algae resulted in protein deposits in the brain, consistent with those seen in human Alzheimer’s.</p>
<p>Neurodegenerative disease is an umbrella term which includes Alzheimer’s, Parkinson’s and motor neurone disease (MND). The causes remain largely unknown, and the role of environmental factors is poorly understood. </p>
<p>Owing to its role in an unusual illness suffered by Chamorro villagers on the Pacific island of Guam, researchers <a href="http://www.sciencedirect.com/science/article/pii/S0031942200860185">have been investigating</a> an algal toxin called <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3194113/">BMAA</a> for more than 40 years. </p>
<p>The Chamorros’ diet was contaminated with BMAA and they suffered from dementia as well as a combination of symptoms typical of Alzheimer’s, Parkinson’s and MND. </p>
<p>In the study published today in the <a href="http://rspb.royalsocietypublishing.org/">Royal Society Proceedings B</a>, researchers fed vervets fruit: some with BMAA, some with a placebo and some with a known inhibitor of BMAA, an amino acid called L-serine. </p>
<p>After 140 days, they detected protein tangles and plaques, a hallmark of neurodegenerative disease, in the brain tissue of all the animals fed BMAA, but not in the placebo animals. While the role of tangles and plaques in neurodegeneration has not been conclusively established, they are the prime suspects for causing the death of brain cells. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/108520/original/image-20160119-29798-enw848.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/108520/original/image-20160119-29798-enw848.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108520/original/image-20160119-29798-enw848.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108520/original/image-20160119-29798-enw848.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108520/original/image-20160119-29798-enw848.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108520/original/image-20160119-29798-enw848.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108520/original/image-20160119-29798-enw848.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The cause of neurodegenerative disease remains largely unknown, and the role of environmental factors is poorly understood.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/evilmutent/14373309286/">Hugo Chisholm/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>This is the first time researchers have been able to produce Alzheimer’s-like protein deposits in an animal model with an environmental toxin. </p>
<p>Even more fascinating was that the vervets fed BMAA plus L-serine showed a significant reduction in the number and density of protein tangles in the brain. This suggests that L-serine may be useful as a preventive therapy in people at risk of neurodegenerative illness. </p>
<p>L-serine was first reported to block BMAA toxicity in cell culture in 2013, but this is the first evidence it can prevent the formation of protein deposits in the brain. </p>
<h2>Testing the hypothesis</h2>
<p>What makes these findings so compelling is that while we’ve known for decades that BMAA was toxic, this is the first time it has been shown to directly cause disease. </p>
<p>BMAA was first suspected as a neurotoxin when it was linked to the Alzheimer’s-like illness in Guam, which at its peak killed 25% of the men of one village. </p>
<p>When the search for a genetic link turned up nothing, environmental triggers became the focus. BMAA was isolated from flour made from cycad seeds, which the villagers used to make tortillas. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/108517/original/image-20160119-29762-1gc59qn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/108517/original/image-20160119-29762-1gc59qn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108517/original/image-20160119-29762-1gc59qn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108517/original/image-20160119-29762-1gc59qn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108517/original/image-20160119-29762-1gc59qn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108517/original/image-20160119-29762-1gc59qn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108517/original/image-20160119-29762-1gc59qn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">People who live by lakes that have frequent algal blooms are at a higher risk of MND.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/mpcaphotos/23008172424/">MPCA Photos/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>The <a href="http://www.ncbi.nlm.nih.gov/pubmed/3603037">very first experiment</a> done in the 1980s found that BMAA was able to cause symptoms consistent with neurodegeneration, but was quickly discounted when it was argued that an equivalent human dose would require the consumption of more than 1,000 kilograms of cycad seed flour. And so BMAA was off the hook, at least for a few years. </p>
<p>A key missing puzzle piece was how BMAA might stick to proteins as was seen in the cycad flour. Its chemical structure meant it was water-soluble, so how was it building up in the flour? </p>
<p>It wasn’t until more than 40 years later that a plausible explanation was proposed. <a href="https://theconversation.com/toxic-load-blue-green-algaes-role-in-motor-neuron-disease-16041">A 2013 paper I worked on</a> reported that BMAA was similar in structure to another amino acid that humans use when they make proteins. So similar in fact, that we showed it could be mistakenly inserted into the protein chain when they were synthesised, rendering them toxic and subsequently killing cells. </p>
<h2>Role of blue-green algae</h2>
<p>Not only do the findings of today’s study provide evidence for what we’ve long suspected, they implicate a widely distributed toxin in a growing and formidable human health problem: dementia. </p>
<p>BMAA is made by blue-green algae (more accurately known as cyanobacteria). The algae have evolved over 3.5 billion years to grow in fresh and salt water, in the desert crusts of Qatar, and in the thermal pools of Yellowstone National Park, in Wyoming. </p>
<p>Blooms commonly occur where nutrients are high, such as in areas where agricultural run-off occurs, and can be identified by their bright green colour and putrid smell. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/108534/original/image-20160119-29750-5vphx1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/108534/original/image-20160119-29750-5vphx1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108534/original/image-20160119-29750-5vphx1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108534/original/image-20160119-29750-5vphx1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108534/original/image-20160119-29750-5vphx1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108534/original/image-20160119-29750-5vphx1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108534/original/image-20160119-29750-5vphx1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cyanobacterial mats in Yellowstone National Park. Pretty but toxic.</span>
<span class="attribution"><span class="source">scepdoll/flickr</span></span>
</figcaption>
</figure>
<p>The problem is these blooms are increasing in size and frequency as global temperatures rise. And Australia is not immune, having had the world’s <a href="https://books.google.com.au/books?id=FGu5V3_xjxQC&pg=PA330&lpg=PA330&dq=algal+bloom+in+the+summer+of+1991%E2%80%9392+australia&source=bl&ots=yWqZ3ut62v&sig=xEErROo7DpMSoxxzhVmRTiDJcxY&hl=en&sa=X&ved=0ahUKEwi7wou3kLfKAhXIX5QKHZioADgQ6AEISjAJ#v=onepage&q=algal%20bloom%20in%20the%20summer%20of%201991%E2%80%9392%20australia&f=false">largest freshwater</a> algal bloom in the summer of 1991–92 in the Barwon-Darling river system. </p>
<p>Even more concerning, and similar to what was observed on Guam, there is <a href="http://www.drrachie.com/research/2016/1/18/watering-wheat-with-bmaa-contaminated-water-results-in-bmaa-accumulating-in-roots-and-leaves">evidence</a> that BMAA can be absorbed into the proteins of grain crops if they’re irrigated with contaminated water.</p>
<p>We also <a href="http://discovermagazine.com/2011/may/22-seafood-toxins-causing-als-alzheimers-parkinsons">know</a> that BMAA concentrates in seafood, such as mussels, pink shrimp, prawns and lobsters, when they grow in waters where blooms flourish. </p>
<p>Studies <a href="http://www.tandfonline.com/doi/abs/10.3109/17482960903278485#.Vp3U7GR97dQ">show</a> that people who live by lakes subject to frequent algal blooms have an increased risk of contracting MND. The risk is even higher if you live downwind, suggesting a role for inhalation as a route for toxicity. </p>
<p>While the risk for exposure via these routes for those of us who have a balanced diet and live in the city is probably low, we simply don’t know how much BMAA is present in the environment because food and water is not routinely screened. <a href="http://www.ncbi.nlm.nih.gov/pubmed/26651568">Methods are available</a>, but they’re expensive and require a high level of skill to conduct accurately. This makes them impractical to implement on a commercial level. </p>
<p>Also, blue-green algae does not always make BMAA – ideal conditions include precise concentrations of nutrients and warm temperatures. </p>
<p>So if BMAA is already distributed throughout the environment, meaning we’ve all been potentially exposed to some degree, why don’t we all have some form of dementia? </p>
<p>Recent scientific modelling <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4197338/">suggests</a> that multiple “triggers” are required for disease to occur. Iin the case of neurodegeneration it’s likely you need a combination of genetic susceptibility, exposure to any number of environmental toxins (including BMAA) and other triggers as yet unknown. </p>
<p>In the meantime, the best advice is to take precautions – reduce your risk of exposure to BMAA by staying away from green, smelly blooms, don’t drink the water and take heed of warning signs. </p>
<p>Because even though we now know BMAA can cause disease, we don’t yet have a cure, so there’s much more work to do.</p><img src="https://counter.theconversation.com/content/52981/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rachael Dunlop is an inventor on a patent pending for L-serine as a treatment for neurodegenerative disease. She receives funding from The Institute for Ethnomedicine, Jackson, WY. </span></em></p>For the first time, researchers have shown that feeding vervet monkeys a toxin produced by blue-green algae resulted in protein deposits in the brain, consistent with those seen in human Alzheimer’s.Rachael Dunlop, Visiting associate , Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/495852015-10-22T19:07:29Z2015-10-22T19:07:29ZWatch out, Australia: a red-hot summer means blue-green algae<figure><img src="https://images.theconversation.com/files/99294/original/image-20151022-19646-167uhf4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pretty, but also pretty nasty.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File%3ACSIRO_ScienceImage_4628_Bluegreen_algae_in_irrigation_drain.jpg">Willem van Aken/CSIRO/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>As the Bureau of Meteorology has <a href="http://www.bom.gov.au/climate/enso/archive/ensowrap_20150915.pdf">already warned us</a>, Australia is in for a hot, dry summer as the <a href="https://theconversation.com/when-the-indian-ocean-and-el-nino-join-forces-things-can-get-hot-and-dry-48969">current El Niño</a> takes hold. Those conditions are ideal for blue-green algae to bloom in lakes, ponds and reservoirs.</p>
<p>Photosynthesising bacteria, also known as cyanobacteria, are found in all aquatic environments from the tropics to the poles. Most species have no adverse impact on the environment, but a few have nastier effects, and some are toxic to humans and animals. </p>
<p>Blue-green algae can form vast “blooms”, some large enough to be seen from space. In the Australian drought summers of 2009 and 2010, for example, hundreds of kilometres of the Murray River suffered <a href="http://www.ncbi.nlm.nih.gov/pubmed/22081581,%20http://www.abc.net.au/news/2009-03-28/potentially-toxic-algae-bloom-threatens-murray/1633630">major cyanobacterial blooms</a>, which hampered the use of water for drinking, agriculture and recreation.</p>
<p>These blooms occur mostly in still water bodies and can be found throughout Australia. Some blue-green algae form visible surface scums, while others remain hidden in the water column. Some live in freshwater; others float in the open ocean or even live on the sea bed.</p>
<h2>Tiny and toxic</h2>
<p>The toxins produced by some blue-green algae can affect the nervous system, the liver and kidneys, or be toxic to cells more generally. Humans can be affected by drinking contaminated water or eating affected shellfish. Direct contact with water can also cause itching and rashes. Worse still, the toxins can remain in the water even after the blue-green algae themselves have vanished - in some cases for weeks, depending on the conditions. </p>
<p>Larger blooms tend to occur where there is an excess of nutrients, often the result of fertiliser runoff from intensive agriculture or other degradation of the catchment system. This means that, throughout Australia, the <a href="http://www.ncbi.nlm.nih.gov/pubmed/20598731">potential for blooms is increasing</a>. </p>
<p>Water temperature also influences algal blooms, for two reasons. First, blue-green algae grow faster in warmer water and, second, warmer temperatures increase “thermal stratification”, in which a warmer surface layer overlies deeper, cooler water. Stratification allows cyanobacteria to flourish in the warmer sunlit surface waters because of their unique ability to make themselves float.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/99295/original/image-20151022-7999-p8yjxy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This bloom in Western Australia’s Shark Bay was big enough for NASA to spot it from space.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File%3AShark_Bay_Phytoplankton_in_Bloom.jpg">NASA</a></span>
</figcaption>
</figure>
<p>So how do you steer clear of blue-green algae? The obvious tips are to avoid drinking untreated water from still, calm water bodies, and to be mindful of children or dogs playing by the water.</p>
<p>Green surface scum is the most obvious tell-tale sign of an algal bloom, but not all species of cyanobacteria form scums. Discolouration of the water, particularly a green colour, can also indicate the presence of blue-green algae. Some species, such as <em>Microcystis</em>, give off a distinctive odour, although some other blue-green algae also create musty-smelling chemicals that are non-toxic.</p>
<p>It is comforting to know that if water quality is at risk, your local water authority is probably on top of it already, and will typically erect warning signs each summer. Many lakes and reservoirs are routinely closed for recreational use to protect the public from toxic blooms during the hotter months. </p>
<h2>Blooming hot</h2>
<p>The forecast hot, dry summer is likely to be a boon for blooms, given that blue-green algae prefer warm, still water. This means that areas that typically get algal blooms might find they are bigger and longer-lasting this summer. In Australia’s southern states, the blooms might also start earlier in the summer and last longer into autumn. </p>
<p>But the scale of blooms also depends on nutrients, so reducing the amount of nutrients that are washed off the land during rainfall events can provide a way of controlling them. This can be done by reducing land degradation, for example, reducing erosion, creating vegetation buffer zones along river banks, and avoiding excessive fertiliser use. </p>
<p>Some of these processes will take time to implement and therefore won’t help us this summer. But combating cyanobacteria in the longer term will help to protect the environment, allow continued recreational use of water and, most importantly, protect our precious drinking water.</p><img src="https://counter.theconversation.com/content/49585/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anusuya Willis works for the Australian Rivers Institute, Griffith University, and receives funding from the Australian Research Council and Seqwater. Anusuya is also a member of the Greens political party. </span></em></p><p class="fine-print"><em><span>Michele Burford receives funding from the Australian Research Council and Seqwater</span></em></p>With El Niño ramping up, Australia is in for a long, hot, dry summer - perfect conditions for blue-green algae. And that innocuous-looking pond scum can pack a toxic punch if you’re not careful.Anusuya Willis, Research Fellow, Australian Rivers Institute, Griffith UniversityMichele Burford, Professor of Aquatic Ecology, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/303922014-08-15T15:39:04Z2014-08-15T15:39:04ZThe way the wind blows may not be enough to prevent ocean ‘dead zones’ growing<figure><img src="https://images.theconversation.com/files/56609/original/rjgvxz7b-1408105600.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Enormous algal blooms off Cornwall, which can lead to low oxygen waters.</span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Cwall99_lg.jpg">NASA</a></span></figcaption></figure><p>The world’s oceans are plagued with the problem of “dead zones”, areas of high nutrients (such as nitrogen and phosphorus) in which plankton blooms cause a major reduction of oxygen levels in the water. Sea creatures need oxygen to breathe just as we do, and if oxygen levels fall low enough <a href="http://www.newscientist.com/article/dn14835-marine-dead-zones-leave-crabs-gasping.html">marine animals can suffocate</a>. This commonly happens around coastlines where fertilisers are washed from fields into rivers and the sea, but also mid-ocean, where currents trap waters in gyres (large systems of rotating ocean currents).</p>
<p>To date most studies have shown that these dead zones have been growing with global warming. But a <a href="http://www.sciencemag.org/content/345/6197/665">recent study</a> published in Science by Curtis Deutsch and colleagues suggests that the ocean’s largest anoxic zone – where there has been a total depletion of oxygen – in the eastern tropical North Pacific, may in fact shrink due to weakening trade winds caused by global warming. </p>
<p>The <a href="http://oceanservice.noaa.gov/education/kits/currents/05currents2.html">trade winds</a> drive water away from the coast, and the gap is filled by new cold and nutrient-rich waters that come up from the deep. These nutrients trigger algae and plankton blooms upon which larger animals feed, which builds up an accumulation of organic matter. As bacteria decompose this organic matter the oxygen in the water is depleted. This causes low oxygen areas, such as the <a href="http://depts.washington.edu/aog/oxygen-minimum-zones/">oxygen minimum zones</a> (OMZs) with very low oxygen content found at intermediate ocean depths.</p>
<p>Weaker trade winds would mean less upwelling of these deep nutrient-rich waters, and consequently less plankton and less oxygen depletion. Deutsch and colleagues affirm that although initial oxygen content will be lower due to higher temperatures, oxygen demand will decrease as trade winds do. So, the result would be that low oxygen areas in the tropical north Pacific would shrink.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/56547/original/2ktvn4dh-1408028153.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/56547/original/2ktvn4dh-1408028153.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/56547/original/2ktvn4dh-1408028153.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/56547/original/2ktvn4dh-1408028153.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/56547/original/2ktvn4dh-1408028153.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/56547/original/2ktvn4dh-1408028153.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/56547/original/2ktvn4dh-1408028153.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Map showing low oxygen areas (in blue).</span>
<span class="attribution"><a class="source" href="http://www.washington.edu/news/2014/08/07/oceans-most-oxygen-deprived-zones-to-shrink-under-climate-change/">C. Deutsch/University of Washington</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A natural problem exacerbated by man</h2>
<p>Natural dead zones can be found worldwide, particularly near regions where strong upwelling occurs. These natural dead zones have typically had low oxygen levels over huge lengths of time, due to ocean circulation patterns that prevent mixing. Although these OMZs are natural, they can become larger and more intense due to human activities, such as prolonged and intensive use of fertilisers, changes in land use, deforestation, soil erosion, global warming, and waste waters from cities or industry. All these are well known to cause algal blooms and so drive the expansion of oxygen-depleted areas. In fact, dead zones caused by these human factors have <a href="https://theconversation.com/coastal-dead-zones-on-the-rise-15496">increased over time</a>. Naturally occurring OMZs have also been expanding <a href="http://www.newscientist.com/article/dn16477-global-warming-could-suffocate-the-sea.html">as temperature rises</a>, so the paper’s prediction that such oxygen minimum zones would shrink flies in the face of previous studies.</p>
<h2>Rising temperatures pose problems</h2>
<p>Animals increase their respiration rates as temperature rises, so they need more oxygen to breathe at higher temperatures. Warmer water also dissolves less oxygen, so as climate change warms the oceans the amount of oxygen decreases, making the effects on marine life even more acute.</p>
<p>Warming also encourages <a href="http://centerforoceansolutions.org/climate/impacts/ocean-warming/water-column-stratafi/">water stratification</a>, where the water separates into layers based on temperature or salinity, creating a physical barrier that prevents oxygen reaching deeper waters.</p>
<p><a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2009.02094.x/abstract">Previous studies</a> have predicted a weakening of trade winds in tropical areas, but have also forecasted changes to low-pressure weather fronts over coastlines that would lead to stronger winds, sufficient to replace any upwelling effect lost by weaker trade winds. </p>
<p>It seems likely that, in the same way, greater water stratification will lead to a worsening and expansion of dead zones, counteracting any effect the weakening trade winds might have to halt the process of de-oxygenation, and the paper’s authors acknowledge that this is possible.</p>
<p>Taking everything into account, it seems that the process of warming oceans under climate change will inexorably lead to larger areas of oxygen-poor ocean, with all the knock-on effects for marine life that entails.</p><img src="https://counter.theconversation.com/content/30392/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Raquel Vaquer-Sunyer does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The world’s oceans are plagued with the problem of “dead zones”, areas of high nutrients (such as nitrogen and phosphorus) in which plankton blooms cause a major reduction of oxygen levels in the water…Raquel Vaquer-Sunyer, Marie Curie post-doctoral researcher, Lund UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/160412013-09-25T21:01:34Z2013-09-25T21:01:34ZToxic load: blue-green algae’s role in motor neuron disease<figure><img src="https://images.theconversation.com/files/31918/original/h53k9xjt-1380085395.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pretty but deadly: researchers now understand how blue-green algae is linked to neurodegenerative diseases.</span> <span class="attribution"><span class="source">Mark Sadowski</span></span></figcaption></figure><p>Scientists have known for <a href="https://www.jstage.jst.go.jp/article/plantbiotechnology/25/3/25_3_227/_article">some time now</a> that exposure to blue-green algae is linked to increased incidence of several neurodegenerative diseases. But the reason for the link has been a mystery until now. Research published in the journal PLOS ONE today may have the answer.</p>
<p>An algal toxin called BMAA has long been <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3194113/?tool=pmcentrez&rendertype=abstract">associated</a> with the increased incidence of a motor neurone disease called amyotrophic lateral sclerosis (ALS). But for many years, the hypothesis suffered <a href="http://www.ncbi.nlm.nih.gov/pubmed/16990532">repeated blows</a> as sceptics poked at the gaping hole in the theory – the lack of a plausible mechanism. </p>
<p>Now, a team of cell biologists and ethnobotanists, including myself, has revealed that BMAA mimics an amino acid that our bodies naturally use to make proteins called L-Serine. Mistaking the toxin for the amino acid, the body incorporates it into human proteins, rendering them harmful.</p>
<p>Because people can have low levels of exposure to BMAA over long periods, it can take between 10 and 15 years before ALS appears. But the time from diagnosis to death can be as short as 3 years. </p>
<h2>How fruit bats in Guam provided clues</h2>
<p>BMAA was first identified <a href="http://www.sciencedirect.com/science/article/pii/S0031942200860185?via=ihub">over 40 years ago</a>, but was not linked to disease until ethnobotanist Paul Cox descended into the jungles of the Pacific island of Guam. </p>
<p>He was searching for the causes of a devastating neurological disease called amyotrophic lateral sclerosis/
Parkinson’s dementia like-complex (ALS/PDC), which had killed nearly half the adult indigenous population, the Chamorros.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/31919/original/gmgqjykn-1380085869.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/31919/original/gmgqjykn-1380085869.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/31919/original/gmgqjykn-1380085869.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/31919/original/gmgqjykn-1380085869.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/31919/original/gmgqjykn-1380085869.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/31919/original/gmgqjykn-1380085869.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/31919/original/gmgqjykn-1380085869.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">BMAA was first identified in the jungles of Guam.</span>
<span class="attribution"><span class="source">NASA's Earth Observatory</span></span>
</figcaption>
</figure>
<p>Although about 20 genes have been <a href="http://en.wikipedia.org/wiki/Amyotrophic_lateral_sclerosis#Genetic_factors">linked to ALS</a>, around 90% of cases are of unknown cause and there’s no cure. Predictably, a search for genetic causes on Guam quickly reached a dead end.</p>
<p>But the trip was not wasted. Cox noted that <a href="http://www.sbs.com.au/shows/costa/listings/detail/i/4/article/7767/Cycad-Ceremony">like Australian Aboriginals</a>, the Chamorros relied heavily on the seeds of the cycad palm to make flour for tortillas and dumplings. Also like their Australian counterparts, they knew the unwashed flour contained a “poison” so they washed it thoroughly before use. </p>
<p>Cox and his colleague Sandra Banack found a neurotoxin in the flour, but it was in such low quantities that locals would need to consume over one tonne of it before they got sick.</p>
<h2>Tasty but nasty treat</h2>
<p>Also of interest to Cox and Banack was the Chamorros’ voracious appetite for fruit bat coconut soup – a delicacy described by the locals as “like nothing you’ve ever tasted.” </p>
<p>The bats also ate the cycad seeds but curiously they had what appeared to be exorbitantly high levels of BMAA for what they consumed. </p>
<p>An analysis of their tissue found BMAA stuck to their proteins, enabling it to concentrate in their flesh; when the Chamorros ate the bats, they got a huge dose of BMAA. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/31921/original/wr5pncrd-1380087013.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/31921/original/wr5pncrd-1380087013.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/31921/original/wr5pncrd-1380087013.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/31921/original/wr5pncrd-1380087013.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/31921/original/wr5pncrd-1380087013.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/31921/original/wr5pncrd-1380087013.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/31921/original/wr5pncrd-1380087013.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Like Australian Aboriginals, the Chamorros used Cycad palm seeds to make flour.</span>
<span class="attribution"><span class="source">Pamla J. Eisenberg</span></span>
</figcaption>
</figure>
<p>This process, now termed “bioconcentration” has since been observed in shellfish, crustaceans and sharks. But how is it linked to neurodegeneration?</p>
<p>BMAA has been found in the brain tissue of ALS/PDC patients from Guam, as well as Alzheimer’s patients from North America. Other populations that also consume cycad flour – the Kii Peninsula of Japan and Western Papua New Guinea – have also experienced clusters of amyotrophic lateral sclerosis.</p>
<p>An elegant Google Maps analysis of New Hampshire in the United States tracked ALS patients to having lived by lakes or other bodies of water that were subject to frequent algal blooms.</p>
<h2>Natural doesn’t mean safe</h2>
<p>The idea that non-human amino acids can cause disease is not a new one; plants make thousands of mimics that have been linked to human and animal illnesses. Neurolathyrism, for example, is a permanent paralytic condition that predominantly occurs in famine-affected areas, and is caused by an unusual amino acid called ODAP. </p>
<p>In our lab, we’ve spent more than ten years looking at the drug used in Parkinson’s disease, called levodopa or <a href="http://en.wikipedia.org/wiki/L-DOPA">L-DOPA</a>, which is very similar to the human amino acid tyrosine. </p>
<p>Like BMAA, L-DOPA can also be “mis-incorporated” into our proteins, and also like BMAA, the resulting proteins do not fold correctly and build up as “junk” inside the cell over time. This “junk” eventually chokes the cell, sending it into programmed cell death or suicide. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/31926/original/76q8hw42-1380088003.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/31926/original/76q8hw42-1380088003.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/31926/original/76q8hw42-1380088003.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/31926/original/76q8hw42-1380088003.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/31926/original/76q8hw42-1380088003.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/31926/original/76q8hw42-1380088003.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/31926/original/76q8hw42-1380088003.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An aerial photo of a blue green algae plume stretched across some 800km of the Murray River between Albury and west of Swan Hill, in north-west Victoria, April 2009.</span>
<span class="attribution"><span class="source">AAP</span></span>
</figcaption>
</figure>
<p>Cell suicide induced by misfolded proteins is now <a href="http://www.hindawi.com/isrn/cell.biology/2013/256404/">known</a> to occur in a variety of neurodegenerative disorders such as Alzheimer’s, Parkinson’s, and importantly, ALS.</p>
<h2>Blue-green algae and ALS</h2>
<p>The size and frequency of algal blooms, which typically appear as a green carpet on lakes and rivers, is increasing with rising water temperatures and an excessive richness in nutrients in bodies of water, such as lakes (eutrophication). </p>
<p>Indeed, Australia is the proud owner of the <a href="http://www.water.nsw.gov.au/Water-Management/Water-quality/Algal-information/Dangers-and-problems/Dangers-and-problems/default.aspx">largest fresh-water algal bloom</a>, which occurred in the summer of 1991/1992 covering 1,200 kilometres of the Barwon-Murray basin. But if we’re all being exposed to BMAA, then why then do we all not have ALS?</p>
<p>With an incidence of about one in 100,000 ALS is relatively rare; exposure to BMAA alone does not appear to be sufficient to cause disease. Like many illnesses, it’s likely that ALS is a multifactorial condition requiring several factors to come together to trigger disease. </p>
<p>Research is beginning to point the finger at the role of <a href="http://www.nature.com/scitable/topicpage/protein-misfolding-and-degenerative-diseases-14434929">poorly functioning recycling and refolding machinery</a> in our cells. As these age, their function declines and likely contributes to neurodegenerative disorders.</p>
<p>BMAA might be just one factor in this devastating disease, but at least we now know how it might be causing toxicity. And because we have evidence for a role for BMAA replacing L-serine, these findings might go some way to developing a therapy. That is something for patients, many of whom have nothing.</p><img src="https://counter.theconversation.com/content/16041/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rachael Dunlop is a co-inventor on a patent for L-serine use in neurodegenerative disorders. She receives funding from the Institute for Ethnomedicine, WY, USA. </span></em></p>Scientists have known for some time now that exposure to blue-green algae is linked to increased incidence of several neurodegenerative diseases. But the reason for the link has been a mystery until now…Rachael Dunlop, Post-doctoral fellow, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.