Scientists warn of climate impacts on Antarctic food chain

Scientists at the National Oceanic and Atmospheric Administration and the British Antarctic Survey have warned of the impacts of climate change on marine ecosystems and advised that reducing fishing pressure is an option for mitigating the overall consequences for marine biota.

In a paper published in Plos One, the researchers examined the potential for rising ocean temperatures to impact the growth of Antarctic krill, Euphausia superba, in the Scotia Sea with knock on effects for krill dependent predators such as whales, penguins, seals, and fish.

They found that the projected effects of ocean warming on krill biomass were strongest in the northern Scotia Sea, with a ≥40% decline in the mass of individual krill, and a 25% chance that krill biomass will fall below an established depletion threshold, with consequent risks for some predator populations, especially penguins. Average penguin abundance declined by up to 30% of its unimpacted level, with up to a 50% chance of falling below the depletion threshold.

In addition, depletion, the study found that simulated krill fishing at currently permitted harvest rates further increased risks for depletion, while stopping fishing offsets the increased risks associated with ocean warming in the model to some extent.

“Our findings indicate the importance of identifying vulnerable marine populations and targeting protection measures at appropriate spatial scales, and the potential for spatially-structured management to avoid aggravating risks associated with rising ocean temperatures. This may help balance tradeoffs among marine ecosystem services in an uncertain future.”

The article, Impacts of rising sea temperature on krill increase risks for predators in the Scotia Sea, is available here.