Ocean warming to cancel increased CO2-driven productivity

April 27, 2017

University of Adelaide researchers have constructed a marine food web to show how climate change could affect our future fish supplies and marine biodiversity.

Published today in Global Change Biology, the researchers found that high CO2 expected by the end of the century which causes ocean acidification will boost production at different levels of the food web, but ocean warming cancelled this benefit by causing stress to marine animals, preventing them using the increased resources efficiently for their own growth and development. The result was a collapsing food web.

"Humans rely heavily on a diversity of services that are provided by ocean ecosystems, including the food we eat and industries that arise from that," says project leader Professor Ivan Nagelkerken, from the University's Environment Institute.

"Our understanding of what's likely to happen has been hampered by an over-reliance on simplified laboratory systems centred on single levels of the food web. In this study, we created a series of three-level food webs and monitored and measured the results over a number of months to provide an understanding of future food webs under climate change."

The researchers constructed marine food webs based on plants which use sunlight and nutrients to grow (algae), small invertebrates that graze on the plants (such as shrimp), and fish that in turn prey on small invertebrates. They had 12 large aquaria with different species to mimic seagrass, open sand and rocky reef habitats, simulating tidal movements with circular currents.

The food webs were exposed to the levels of ocean acidification and warming predicted for the end of this century. Over several months, the researchers assessed the basic processes that operate in food webs like predation and growth of organisms.

"Elevated carbon dioxide concentrations boosted plant growth; more plant food meant more small invertebrates, and more small invertebrates, in turn, allowed the fish to grow faster," says PhD candidate Silvan Goldenberg, who is supervised by Professor Nagelkerken and Professor Sean Connell.

"However, ocean warming cancelled this benefit of elevated carbon dioxide by causing stress to the animals, making them less efficient feeders and preventing the extra energy produced by the plants from travelling through the food web to the fish. At the same time, fish were getting hungrier at higher temperatures and started to decimate their prey, the small invertebrates."

The researchers found that ocean warming would be an overwhelming stressor that made food webs less efficient, neutralised the 'fertilising' effect of elevated carbon dioxide and threw the fragile relationship between predators and prey off balance.

"The consequences for marine ecosystems are likely to be severe," says Professor Nagelkerken. "Oceans in the future may provide less fish and shellfish for us to eat, and larger animals that are at the top of the food web, in particular, will suffer. We hope this study will provide predictive understanding which is critical for effective fisheries management."
-end-
Media Contact:

Professor Ivan Nagelkerken
Environment Institute
University of Adelaide
Mobile: +61 (0)477 320 551
ivan.nagelkerken@adelaide.edu.au

Silvan Goldenberg, PhD candidate
University of Adelaide
Phone: +61 8 8313 5513, Mobile: +61 414 239 386
silvan.goldenberg@adelaide.edu.au

Robyn Mills, Media Officer
University of Adelaide
Phone: +61 (0)8 8313 6341, Mobile: +61 (0)410 689 084
robyn.mills@adelaide.edu.au

University of Adelaide

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.