Ocean Acidification Could Promote Toxic Algae Blooms

If carbon dioxide concentrations in the atmosphere and in the ocean continue to rise, this could fuel the mass development of toxic algae, with far-reaching consequences for the pelagic food web, an international team of researchers has found.

In a two-month field experiment off the Canary Islands, an international group of scientists led by the GEOMAR Helmholtz Centre for Ocean Research Kiel has uncovered a possible consequence of ocean acidification that could massively affect the marine food web.

The team, including Nicole Aberle-Malzahn from NTNU’s Department of Biology, has described how the toxic alga Vicicitus globosus strongly increased its abundance at carbon dioxide concentrations above 600 ppm (parts per million) and went into mass development above 800 ppm. These results were published in the 19 November issue of Nature Climate Change.

“In our near-natural test environments these algal blooms had a strong negative effect on the rest of the plankton community, particularly the diverse groups of zooplankton. These tiny animals are extremely important for the marine food web. The collapse of the food chain also influenced other important processes driven by the marine biota, such as the carbon transport to depth,” explains Prof. Dr. Ulf Riebesell, Professor of Biological Oceanography at GEOMAR and first author of the study.

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