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Warming Ocean Portends Troubling Changes at the Base of the Marine Food Web

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NOAA MESA Project

Conducting research of potentially vital importance to marine and coastal zone resource policy makers and managers, fisheries managers, fishing communities and stakeholders worldwide, researchers from the University of East Anglia’s (UEA) School of Environmental Sciences and School of Computing Sciences and the University of Exeter have found that warming ocean temperatures pose potentially grave risks to the marine food web.

The research team for the first time determined that ocean temperature – as well as light and nutrient levels – has a direct impact on the chemical cycles, diversity and productivity of phytoplankton populations, microscopic marine organisms that form the base of the marine food web and play an outsized role in absorbing atmospheric carbon dioxide (CO2).

As lead researcher Dr. Thomas Mock explained in a UEA news report,

“Phytoplankton, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere. As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries so it is incredibly important for food security.

Changes at the base of the marine food web

“Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before.”

More specifically, the research team found that marine micro algae apparently don’t produce as many ribosomes as when temperatures are lower. Rich in phosphorous, ribosomes assemble the proteins essential to phytoplankton life functioning.

A reduction in ribosomes leads to the production of more nitrogen as opposed to phosphorous, which increases the demand for nitrogen in the oceans. This, in turn, would eventually lead to more blue-green algae, or cyanobacteria, which fix atmospheric nitrogen as part of their basic life functioning.

Source: World Resources Institute

Source: World Resources Institute

Cyanobacteria also soak up oceanic oxygen, creating low oxygen, hypoxic, conditions that have led to the creation of large and growing marine and coastal area “dead zones” devoid of the seafood species we rely on as sources of food and nutrition. Dead zones have formed in areas such as the Mississippi River delta in the Gulf of Mexico, where large quantities of nitrogen from terrestrial sources, such as fertilizer runoff from farms, flows out via river deltas into the ocean.

“The impact of temperature on marine phytoplankton resource allocation and metabolism,” appears in the September 8, 2013 online edition of Nature Climate Change.

Main image credit: Source: NOAA MESA Project

Featured image credit: Pulpolux!!!, courtesy flickr

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