Ocean Acidity Having Major Impact On Arctic Food Web Species
December 3, 2013

Ocean Acidity Having Major Impact On Arctic Food Web Species

April Flowers for redOrbit.com - Your Universe Online

Tiny crustaceans, known as copepods, live just beneath the surface of the ocean. A research expedition to the Arctic, part of the Caitlin Arctic Survey, found that these tiny animals are more likely to battle for survival if ocean acidity continues to rise.

The study, published in Proceedings of the National Academy of Sciences (PNAS), revealed that copepods that move large distances, migrating vertically across a wide range of pH conditions, have a better chance of surviving.

Ocean chemistry is being changed by the increasing level of carbon dioxide in our atmosphere. This change leads to seawater moving down the pH scale towards acidity. The fastest rates of acidification on the planet are already being experienced in regions of the Arctic Ocean. Combined with sea-ice loss and warming temperatures, the impacts of climate change are likely to hit Arctic marine life first.

The research team from the University of Exeter and the Plymouth Marine Laboratory observed that the natural range of temperature and acidity under the ice that copepods experience on a day-to-day basis corresponded to their responses to the ocean acidification conditions predicted for 100 years' time.

Dr Ceri Lewis from the University of Exeter said, "Our study found that some marine animals may not be able to survive the impact of ocean acidification, particularly the early-life stages. This unique insight into how marine life will respond to future changes in the oceans has implications that reach far beyond the Arctic regions."

Copepods are one of the most abundant marine animals and are found around the globe. They are a vital food source for a wide variety of other marine life and can serve as bio-indicators to provide an early warning system for the health of the environment.

Until recently, scientists have found it difficult to document what copepods and other marine life do when the Arctic Ocean is covered by sea ice. More specifically, they haven't been able to determine what conditions the copepods experience. The scientists worked alongside polar explorers as part of the Caitlin Arctic Survey. They camped in winter conditions on the Arctic ice at temperatures of -40⁰F, risking frost bitten fingers, in order to collect this novel data.

Dr Helen Findlay from Plymouth Marine Laboratory said, "Our work has shown that life experience matters when it comes to surviving stressors. More studies are needed that link the natural environmental conditions to laboratory experiments. Ceri and I are planning to continue this line of work through a PhD studentship next year."

The oceans absorb an estimated 30 percent of carbon dioxide released by humans into the atmosphere. Carbon emissions are set to rise, meaning that the world's oceans are likely to suffer from increased acidification in the coming years. The study findings demonstrate how these changes are likely to impact globally important species like copepods.

Organisms with a limited natural habitat are likely to suffer the most under changing climatic and oceanic conditions than those with a larger range, according to the study. Future studies will investigate whether habitat type can be used to predict the vulnerability of different species.