Patricia Kaiser

A changing Arctic Ocean? – Impacts of climate change on Arctic pelagic communities and processes

The Arctic Ocean is a unique ecosystem characterized by several distinct features, such as phases of prolonged darkness (polar night) or daylight (midnight sun), perennial or seasonal sea ice cover as well as an extremely pulsed cycle of primary production. Despite the fact that the Arctic Ocean and its adjacent ice-covered seas are areas that are most rapidly and strongly affected by global warming, studies are still scarce. Increasing temperatures are resulting in a change in extent, thickness and seasonal cover of Arctic sea ice, with current models predicting an ice-free Arctic Ocean by mid-century. Such alterations will strongly affect not only ice-associated biota, but also pelagic and benthic communities beneath the ice. Besides the melting of sea ice, several studies indicate substantial changes in zooplankton communities and biodiversity due to climate change, with North Atlantic species shifting further north in their distribution. Atlantic species are generally smaller and have lower lipid content than their polar congeners. Thus, such displacements in the species composition will severely impact secondary production of the Arctic seas and pelagic-benthic coupling processes.

As the ice cover is shrinking we will likely observe a shift from ice algae to phytoplankton dominated primary production in marginal ice zones. To comprehend the impact, one objective of my PhD is to evaluate the contribution of ice algae on the nutrition of zooplankton. Further, to predict the consequences of rising water temperatures, my second objective is to establish species-specific temperature sensitivities of Arctic vs boreal Atlantic zooplankton species. Finally, to observe ongoing alteration, long-term changes in mesozooplankton abundance, distribution and species composition over the last 20 years in Fram Strait will be analyzed.

The overall aim of this project is to gain a better understanding of ongoing climate change and its consequences on the pelagic communities and processes in the Arctic Ocean.