Climate change: How krill and other key species are changing in the polar regions

Prof. Dr Bettina Meyer, head of the working group Ecophysiology of pelagic key species at the Alfred Wegener Institute and Professor at the University Oldenburg.

Antarctic Krill

Polar pelagic key species

Endogenous clocks

Antarctic krill represents with up to 500 million tonnes the largest biomass of any multicellular wildlife species on the planet. In the Southern Ocean, krill is the central food for numerous predators such as baleen whales, seals, penguins, fish and seabirds. However, krill are threatened from several sides: reduced extent and duration of winter sea-ice cover due to regional warming around the Antarctic Peninsula is causing population shifts, increasing krill fisheries and at the same time the recovery of baleen whales that feed on krill are affecting the krill stock. Our research objective is to understand how krill can adapt to environmental changes and to what extent the distribution of baleen whales is influenced by krill distribution and fisheries. These data are central to modelling future krill and baleen whale population trends and predicting possible consequences that population shifts of these groups may have on the marine ecosystem in the future.

To understand the adaptability of key polar species to climate change, we are investigating, in addition to the impact of rising temperatures on their fitness, how the biological clock affects the life cycle of key polar species. Biological clocks allow organisms to anticipate seasonal environmental changes and regulate their physiology accordingly. The daily 24-hour cycle of light and darkness and the annual 12-month cycle of changing day length are the two most important zeitgebers for internal clocks and do not change with anthropogenic warming. The adaptation of organisms to these cycles plays an important role in the functionality of ecosystems. With the warming of the Southern Ocean, due to anthropogenic climate change, the close relationship between highly seasonal rhythms of the polar environment (food availability, day length, sea-ice cover) and the seasonal rhythmicity of important life functions (sexual maturity, growth, lipid accumulation) of key organisms, which have evolved over millions of years, may go out of sync. Such miss-match has consequences for the population development of these organisms in the future and due to their key position in the food web, for the entire ecosystem.