Fish are on the move in Australia’s waters. In southern Australia, scientists, commercial and recreational fishers, divers and beach-goers are reporting the presence of new species. The movement of species, as fish follow warming waters aided by strengthening ocean currents, are clearly observable changes occurring in our oceans as a result of climate change.
The 2012 Marine Report Card, a comprehensive review of these climate-related changes in Australia’s oceans, was released today. It details the already significant effects on our oceans and marine life.
More than 80 of Australia’s leading marine scientists contributed to the Card, and another 30 experts were reviewers. While it doesn’t provide a grade – unlike school report cards – it provides information in regards to ocean acidification, sea level rise, ocean currents and a range of biological groups. It considers what is already happening, what may happen in the future and what actions are underway to prepare for further changes.
The Card and the detailed reports behind it demonstrate that climate change is already affecting the oceans and coasts around Australia. We are discovering changes almost everywhere we look.
There is evidence of extensive southward movements of warm water fish and plankton species into southern Australia, a decline in the abundance of cold-water species such as rock lobster, and damage to marine species with shells as a result of ocean acidification.
These changes are likely to be the first of many that will have profound effects on our iconic fish, turtle, seabird and mammal species. Some clear risks are identified: Australia’s iconic coral reefs remain extremely vulnerable to warming waters and acidification and, if current trends continue, coral reefs as we know them are unlikely to exist by the middle of this century.
Off the east coast of Australia, the southward flowing East Australia Current is warming and pushing further south. This region is a global warming hotspot, one of about 20 such ocean regions where the rate of warming is faster than than the global average. Just as Nemo was carried south to Sydney by the East Australian Current, large open ocean fish like tuna and billfish are moving south with these warming waters.
This is good news for recreational fishers in southern states, who are seeing species such as striped marlin, yellowfin tuna and dolphin fish moving into their region. Closer to shore, yellowtail kingfish and cobia are being captured further south. The abundance of smaller coastal species such as sardines may increase in future - stronger upwelling of cool nutrient rich water in a range of coastal locations is expected to enhance their food supply.
While not directly linked to climate change, a marine heat wave along the west coast early in 2011 saw manta rays and whale sharks, usually found much further north, reported as far south as Albany in Western Australia. Marine algae were killed as waters warmed, and the northern abalone fishery was closed after stocks suffered mass mortality.
Such extreme events represent a window into a warmer world – in which a process known as “tropicalisation” will see tropical marine species replace cool water species.
The overall impact on coastal systems of many changes is unknown, but both positive and negative impacts are expected for marine-based tourism industries and for commercial and recreational fishers.
This mini-IPCC report for Australia’s oceans highlights that our science community, supported by national funding initiatives, is widely engaged in research, monitoring and observing programs to increase our understanding of climate change impacts and inform management. Fishers, divers and other citizen scientists from around Australia are also playing a valuable role in reporting changes.
Global negotiations to reduce greenhouse gas emissions into the atmosphere are the only true solution to climate change. These mitigation efforts are critical, but even when implemented they won’t immediately halt climate change. An average rise in global temperatures this century of 2-4ºC is highly likely; in some areas warming will be greater, in others it will be less.
Adaptation – the business of responding to climate change – will be necessary and is already underway in many marine regions. As species move south, fishing boats are following them, and fisheries managers are considering management changes needed as species cross state boundaries or as stock productivity increases or decreases.
Conservation managers are beginning to climate-proof breeding sites for turtles and seabirds. As beach temperatures rise, more turtles hatch as females - manipulation of nest temperatures may be required to ensure enough males are hatched. Nesting little penguins can overheat on very hot days, so managers are investigating ways to cool burrows and nest boxes, including planting vegetation to provide additional shade.
Up-to-date information, such as that contained in the Marine Report Card, is needed to assist ocean managers and policy makers to improve and justify actions to help our marine ecosystems adapt to the impacts of climate change, while also raising general awareness of what is happening just off our beaches.
Climate change has been characterised as an irreversible experiment with our land and oceans systems, but the changes reported to date should provide further impetus to try and stop the experiment.
The 2012 Marine Report Card is co-edited by CSIRO’s Elvira Poloczanska, Alistair Hobday and Anthony Richardson. It is funded by the Australian Government Department of Climate Change and Energy Efficiency, through the Marine Biodiversity and Resources Adaptation Network, the Fisheries Research and Development Corporation, and CSIRO’s Climate Adaptation Flagship.