Plankton 2015: an assessment of Australia's oceans using plankton as ecosystem indicators

Plankton 2015 is an assessment of the state of the oceans around Australia using plankton as indicators of ecosystem change. It is based primarily on plankton data from the Australian Integrated Marine Observing System (IMOS)... [ view full abstract ]

Plankton 2015 is an assessment of the state of the oceans around Australia using plankton as indicators of ecosystem change. It is based primarily on plankton data from the Australian Integrated Marine Observing System (IMOS) and supplemented by data from other historical and current plankton studies. The assessment provides ecosystem indicators for climate change, ocean acidification, productivity supporting fisheries, biodiversity, and ecosystem health. We find that there have been substantial changes in plankton communities in response to climate change: the distribution of phytoplankton on the east coast of Australia has shifted ~300 km south since the 1950s, and in temperate regions warm-water species are taking over from cool-water species. These changes are likely to lower ecosystem productivity, as warmer-water species are generally smaller and less nutritious for fish to eat. There is less information on impacts of ocean acidification on plankton species, but there is some limited evidence of potential thinning and increased porosity of shells of pteropods in northern Australia over past 30 yrs with increased acidity. We describe a general decline in copepod biodiversity from tropical Australia to the Antarctic ice sheet; this will provide a baseline to assess future changes in biodiversity. There have also been widespread blooms of harmful algae and jellyfish in recent years, but short time series preclude assessment of whether this is unusual. It is hoped that the data underpinning Plankton 2015 will be useful in marine reporting and inform policy makers, marine managers, scientists and the public of changes at the base of the marine food web and their potential implications for higher trophic levels and ourselves.