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Marine reserves help fish resist climate change invaders

Southeast Australia is an ocean warming “hotspot” – a region where temperature at the ocean’s surface is increasing more rapidly than elsewhere. That means this part of Australia is like an outdoor laboratory…

Maria Island’s protected waters have given us insight into how species respond to warmer temperatures. Paul Benjamin

Southeast Australia is an ocean warming “hotspot” – a region where temperature at the ocean’s surface is increasing more rapidly than elsewhere. That means this part of Australia is like an outdoor laboratory for understanding nature’s response to climate change.

In research published this week in Nature Climate Change, we found that marine reserves in this regional “hotspot” are important in reducing the effects of climate change on different species.

As oceans warm, subtropical species migrate into temperate regions. This creates new communities where groups of species may meet for the first time.

One species that has already extended its range is the spiny sea urchin. This urchin has grazed down the seaweed beds attached to rocky reefs as it has moved southward, leaving a swath of barren patches in its path.

Habitat reserves protected from fishing within marine reserves appear to deter the urchin. Here, predatory lobsters grow to a size where they can feed on incoming urchins. Marine reserves can also give a diverse set of predatory fish the opportunity to develop. These fish may feed on other warm-water migrants, making it harder to colonise the area.

A barren area left by spiny sea urchins, which have moved into Tasmanian waters in southeast Australia and caused widespread change. Rick Stuart-Smith

However, unless there is long-term data, it is virtually impossible to understand how biological communities respond to steady increases in temperature as opposed to year-to-year temperature variability.

We need to know which species are present and how their numbers fluctuate through time. Such data are rare, which makes it hard to know whether protection from fishing will lead to healthier ecosystems that have greater resilience (that is, the capacity to resist and recover following a disturbance).

But we do have one useful data set. Over 20 years, information has been collected on the fishes from the Maria Island Marine National Park in Tasmania and nearby sites open to fishing. This allows us to look into the past to understand what has changed.

With warming water, fishes that eat seaweed have increased in both the protected and fished communities. These herbivorous species are typically limited to more tropical latitudes where warmer temperatures speed their digestion of seaweed. But now they are being seen in areas previously too cool for them.

The proliferation of herbivores has led to greater numbers of species in the region as a whole, and because many of these species have new characteristics, also greater diversity in the functional roles species play in these communities.

By supporting large species such as the blue-throated wrasse, reserves stop warm-water species invading. Rick Stuart-Smith

Communities in the marine reserve also turned out to be quite resilient. The number and diversity of species in the reserve remained more stable from year to year, as well as across decades, when compared to areas that have been open to fishing.

Reserves also limited colonisation by warm-water species moving into the area. This might be because the reserves supported the return of large-bodied temperate species, such as the blue-throated wrasse, which may feed on new migrants.

Our results have shown us marine reserves have the potential to buffer climate-related biological variability, as well as to limit the spread of range-extending species.

While marine reserves are valuable for creating thriving biological communities, they also help us understand ecological change in the absence of fishing. The new knowledge gained from Maria Island was possible because the long-term data on fish species could be usefully compared against nearby fished areas.

So marine reserves can be a critical reference to help us better understand the interaction between natural changes and human influences.

If our findings play out in other marine reserves, we can be assured that protected habitat networks will enhance the health of our oceans in an era of human influence and climate change.

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22 Comments sorted by

  1. David Arthur

    resistance gnome

    Thanks for this article, Dr Bates.

    I read these results as potentially supporting an argument for at least a patchwork of marine reserves up and down Australia's East Coast. The boundaries of any such reserves would ideally be locate so as to minimise spread of invasive species.

    This is in contrast with terrestrial conservation efforts, which are often concerned with maintaining connectivity so as to facilitate species movement - due to landscape-scale anthropogenic disruption.

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    1. Amanda Bates

      Lecturer in Macroecology at University of Southampton

      In reply to David Arthur

      Hello David,

      As on land, I suspect that marine reserves will also be important habitats for species in decline. However, to add to this understanding, we also found that small, young individuals arriving from warmer latitudes were not as abundant in the reserve sites in comparison to fished sites. We think this might be due to the presence of larger fish-eating predators in the reserve. Our findings suggest that reserves may play different roles for different species as the distributions of species change though time.

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    2. Wade Macdonald

      Technician

      In reply to Amanda Bates

      Amanda,

      You could also point out that predator prey relationships in reserves can have a detrimental impact on biodiversity and fishing.

      Quote..." Where a reserve is designed to support fisheries through sustained spillover of adults into fished areas, increased abundance of predators within the reserve can limit the site’s effectiveness. If predators are consuming the same target species the fishermen are harvesting, they essentially become competitors for that prey source. Spillover of…

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    3. Adrian Meder

      Conservation sector

      In reply to Wade Macdonald

      The thing is Wade, no Australian marine reserves are or were 'designed to support fisheries through sustained spillover of adults into fished areas'. They're designed for conservation purposes (some have been shown to provide spillover, coincidentally, others not). That could be a reason why the author didn't point it out. There are examples internationally of this reserve design approach, but the argument isn't relevant to Australia.

      They do support fisheries management, for example by showing…

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    4. Wade Macdonald

      Technician

      In reply to Adrian Meder

      In the absence of fishing but stuff all else.

      Dredging nup, deviation mining nup, invasive species from ballast release nup, seismic exploration nup, landbased pesticides nup.

      http://www.smh.com.au/environment/seismic-testing-in-fishers-sights-20130424-2iepk.html#ixzz2n4eJMerA

      http://mobile.bloomberg.com/news/2013-11-25/namibian-study-shows-that-tuna-catch-plunges-on-oil-exploration.html

      Read Colin Creighton comments....

      "Indeed, fishing is the only one of these impacts that is managed…

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    5. Adrian Meder

      Conservation sector

      In reply to Wade Macdonald

      Meanwhile, the article is about evidence demonstrating the benefits of marine reserves for resilience to the impacts of environmental change, and highlights the valuable information they can provide to managers that need to manage these impacts. Changing the subject makes it difficult to argue the merit of these findings

      But aside from changing the subject again... deviation mining - who could argue with that - sounds perverted - but is it relevant to no-take marine reserves - whatever it is?

      I do agree with what appears to be your argument that marine reserves NOT in an area cannot possibly protect that area from a severe one-off event. Not one bit. No sir.

      They can provide some really useful long-term data for managing long term environment changes though, which affords them a lot of value, in my view. Lets not deviate from the issue or the evidence.

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    6. Wade Macdonald

      Technician

      In reply to Adrian Meder

      I have no problem with that and support sanctuary zones for sound scientific research purposes. In SA we have had aquatic reserves some since the 70's. We have statewide bans on snapper, no beach net haul fishing or prawn trawling within three nautical miles of shore to protect seagrasses etc etc.....

      There will always be issues over management but this current conservation advocacy on marine park benefits is painting a non holistic picture on the science as there are many other factors both natural…

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    7. Adrian Meder

      Conservation sector

      In reply to Ben Diggles

      I'm pretty sure the author of that article hasn't had much of a role in designing Australian marine reserve networks or the objectives underpinning them.

      I'd suggest that particular article has misunderstood the place of marine reserves in the Australian conservation and fisheries management context, much like Wade has in talking about predator-prey relationships in reserves designed specifically to enhance fisheries yields - a spatial management model (currently) irrelevant to Australia…

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    8. Adrian Meder

      Conservation sector

      In reply to Wade Macdonald

      We're both rec fishers, but we seem to have a very different understanding of the extent to which no-take marine reserves actually ban fishing - in my experience fishing quality is determined by the likelihood and size of the catch, not the size of the water body in which I can catch it. I've fished the Pacific, Tasman, Southern and Indian Oceans, and various lakes (Taupo is big, Big Brook dam is not), rivers, streams and brooks - and had a very good time in each, despite the relative lack of access…

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    9. Wade Macdonald

      Technician

      In reply to Adrian Meder

      Adrian ,

      It is obvious that even before the implementation of the zones these areas were productive for fishers. I think that claiming sound fisheries management couldn't achieve this great fishing seen there today without large closures is a partial position.

      While you may not see ENGO's as agenda driven I can tell you that groups like PEW have massive agendas, these are well known and documented even by other conservation groups. They only got involved in marine science after a nation wide…

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    10. Adrian Meder

      Conservation sector

      In reply to Wade Macdonald

      Australia has good fisheries management, so yeah. They were good fishing spots back in the day. Most fishing spots were.
      The key point here is that everyone who knows these spots thinks they still are good fishing spots. That just doesn't work if, as the rec fishing lobby groups so tirelessly claim, marine parks 'lock us out'.

      I'm not going to go into the tinfoil hat stuff about secret ENGO agendas. No one involved with decision making, in the mainstream media, or indeed in wider society takes any of that seriously, I can assure you.

      We need to debate the issue if we want to make real progress. And if our arguments must stray into conspiracy theories to support a case, that case isn't going to be taken seriously either - realistically.

      Just kidding - I heard they were reptilians sent to Australia to enforce the New World Order (I'm actually not kidding about that - a bloke did offer me that theory once, he seemed to know what he was talking about at the time).

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    11. Wade Macdonald

      Technician

      In reply to Adrian Meder

      Adrian,

      People do take ENGO agendas seriously. This is why Senator Richard Colbeck raised PEW's involvement in parliament and in his media releases. He was not the only one.

      I still remember the leaked labor report that said fishers would be muted. I sent both labor and liberal ministers evidence from foreign ENGO websites that used misinformation to try and undermine sound local policy through the submission process. These groups say it isn't about fishing while at the same time running anti…

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    12. Adrian Meder

      Conservation sector

      In reply to Wade Macdonald

      Do you buy the premise of the fishing mag article in your link, and believe that the authors did not write it with a political agenda front of mind?

      In relation to the amendment to the precautionary principle (which hasn't actually happened by the way). It shouldn't be surprising that scientists charged with (and may have even built a career on) maximising the economic opportunities of a particular resource would encourage a less precautionary approach to managing that resource. Though you are…

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    13. Wade Macdonald

      Technician

      In reply to Adrian Meder

      Adrian the coral sea zone and the state based marine parks proposal in SA were political not scientific as I already explained. Adelaide had a marine parks meeting at Burnside town hall and hundreds couldn't attend because there was already over 1000 anglers in the hall so many drove off, walked away.

      I still remember the zone at port moorowie that forgot the town existed. My workmate has a son with cerebral palsy and they fish the safe waters off moorowie adjacent their shack. They have a special chair onboard for their son so he can fish. Lucky us anglers went into bat against the ENGO's who care not about anything but their own agenda.

      As I said my mate's work was affected and many other citizens were also dudded.

      Lets just accept the fact I have both a social and environmental conscience but you and the ENGO's don't when it comes to marine parks.

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  2. Colin Creighton

    Chair, Climate adaptation, Marine Biodiversity and Fisheries

    Hi Amanda - thanks for the article. I come though to a different conclusion than you. To me - the answer is all about repairing habitat and then making sure all impacts, fishing, dredging, water quality from catchments, estuary and nearshore habitat losses to development, seismic surveys and so on are managed with sustainability the key. Marine park reservations without repairing the cause of the impacts are a nonsense.
    Indeed, fishing is the only one of these impacts that is managed with sustainability the goal.
    Example, the 2013 flood on the Clarence killed all the benthos - polycheates, bivalves, amphipods and so on for the bed of the entire estuary. Think over 150 km long dead zone. The cause - drainage of wetlands and then acidic runoff from exposed acid sulphate soils. Not a marine park anywhere in sight of course.
    So my priority - repair habitats, reduce impacts and manage sustainably all uses.

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    1. Amanda Bates

      Lecturer in Macroecology at University of Southampton

      In reply to Colin Creighton

      Hello Colin, Thanks for your thoughts. What I was most excited about was the new ecological understanding gained by this work. Hopefully this understanding will inform appropriate off-reserve adaptive management actions to ensure our fisheries and other natural resources are managed in an ecologically sustainable way in the face of a warming climate. Importantly long-term monitoring of protected and fished reference areas is essential to ensure management choices are well informed.

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    2. Colin Creighton

      Chair, Climate adaptation, Marine Biodiversity and Fisheries

      In reply to Amanda Bates

      Yep Amanda - if only we actually managed and monitored estuarine and marine Australia for all the benefits they provide. Unfortunately instead we have the simplistic policy of lines on a map [called parks]. Marine systems are [excuse the pun] so fluid and impacts are predominately from our land based activities.
      More understanding, better management all informed by research and monitoring - we are totally agreed on that.

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  3. Bruce WILDCARD Davey

    4th generation Professional Fisherman at WILDCARD WILDCAUGHT Pty Ltd

    Very courageous thank you Colin Creighton good to see factual balance in a cloudy MPA debate.
    Academia inevitably takes the high environmental moral ground and the Fishing Industry becomes the sacrificial prawn as a sidelined minority where more often than not expensive populous Govt. environmental propaganda simply masquerades as good environmental marine policy.
    Always left to do the actual environmental heavy lifting Fishers rarely can enter the debate usually labelled by academia as having…

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    1. Colin Creighton

      Chair, Climate adaptation, Marine Biodiversity and Fisheries

      In reply to Bruce WILDCARD Davey

      Thanks Bruce. Yep i have seen segments of your film plus of course know some of the participants etc.

      Note though - we cannot turn this Conversation article into a broad debate about marine parks - the moderators will ask us to stick to the specific topic at hand. So i will sign off now.

      Catch up and discuss further the broader issues sometime. i am sure we have lots to discuss! If you are into reading about habitat repair - see the Revitalising Australia's Estuaries Business case - its on the FRDC web site.

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  4. Jim Inglis

    retired

    The East Australian Current has been flowing south and taking varying volumes of warm water into the SW Tasman from the Coral Sea for as long as we have had anti-clockwise prevailing winds around our coastline.

    That has had the effect of always transporting warm water migrants southward in this erratic warm current.

    I would suggest that 20 years of data would not tell you the full story.

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