ANTARCTIC KRILL COULD COPE OCEAN ACIDIFICATION
Antarctic krill (Euphausia superba) have a keystone role in the Southern Ocean, as the primary prey of Antarctic predators. But these tiny crustaceans have dropped by 80 percent since the 1970s, probably, in part to ice cover loss caused by global warming. This ice loss removes a primary source of food for krill: ice-algae, that grow on the surface of sea ice. While previous studies indicate some life stages of Antarctic krill may be vulnerable to ocean acidification, a new study found that adult krill can face acidification levels predicted within the next 100-300 years.
Oceans around the world are becoming more acidic as they absorb increasing amounts of CO2 from the atmosphere, in a process called ocean acidification, but a new research suggests adult Antarctic krill are resilient to this increasing ocean acidity and may not be affected by the predicted CO2 levels.
Ocean acidity is known to have negative effects on a wide range of marine species, as well as in some freshwater species, causing decreased mineralization or dissolution of calcium carbonate shells, decreased or delayed growth, increased mortality and delayed reproduction or abnormalities in offspring, including embryonic development of Antarctic krill.
Despite the finding is only focused on adults, other stages may be more vulnerable, so krill persistence will depend on how krill responds to acidification in synergy with other stressors, such as ocean warming and antarctic ice loss. The ability of krill to maintain their acid-base balance under acid seawater may be the key to their successful survival, maturity and growth in a future high CO2 world.
Photo: Antarctic krill (Euphausia superba) by Jan van Franeker, Wageningen Marine Research
Reference (Open Access): Ericson et al. 2018 Adult Antarctic krill proves resilient in a simulated high CO2 ocean. Communications Biology
[ Image cescription: A krill is under a layer of ice, these tiny marine animals are shrimp-like crustaceans.]
