Climate change may be collapsing marine food webs
A new study shows that human-caused global warming is leading to the collapse of marine food webs.

Joseph Scalise | Apr 19, 2018

Researchers at the University of Adelaide have found that global warming is greatly harming commercial fish stock levels by depleting food sources throughout the ocean, a newstudypublished inPLOS Biologyreports.

This new research shows how climate change affects and collapses marine food webs. In the study, researchers found that increased temperatures reduce energy flow from the primary food producers at the bottom of the web, which then takes away food from the intermediate consumers and top predators.

Those disturbances in energy transfer are problematic because they decrease food availability for large carnivores, which can then lead to negative impacts for a wide range of different marine organisms.

"Healthy food webs are important for maintenance of species diversity and provide a source of income and food for millions of people worldwide," said lead author Hadayet Ullah, a PhD student at the University of Adelaide, according to Phys.org. "Therefore, it is important to understand how climate change is altering marine food webs in the near future."

To see the impact of rising temperatures, the researchers built 12 large 1,600 liter tanks that mimicked predicted conditions of elevated ocean temperature and acidity caused by increasing greenhouse gasses. All of the tanks contained a wide range of different species, including fish, algae, shrimp, sponges, and snails.

The team monitored the mini-food webs for six months. In that time, they recorded the survival, growth, biomass, and productivity of all animals and plants in the tanks. They then used that information to create a sophisticated food web model.

After the study, scientists found that, while climate change increased plant productivity, that rise was largely the result of algae known as cyanobacteria. Unfortunately, such changes do not support food webs because cyanobacteria are typically not consumed by herbivores. As a result, rising temperatures only harm food webs.

Understanding how ecosystems function under global warming is not easy to do. Most research uses simple or short-term experiments based on just a few species. The team hope their study will shed more light on the way warm waters affect all ocean life and help lead to more detailed and more thorough research.

"If we are to adequately forecast the impacts of climate change on ocean food webs and fisheries productivity, we need more complex and realistic approaches, that provide more reliable data for sophisticated food web models," said study co-author Ivan Nagelkerken, a professor at theUniversity of Adelaide, according toScience Daily.

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