Global climate change is creating rapid changes in the polar regions. Warming of the surface oceans, melting of sea-ice and glaciers, ocean acidification, changes in currents and climate – these factors all have great consequences for polar marine ecosystems and their productivity.

Current NIOZ research in the Arctic and Antarctic focuses on trace metal dynamics and biological availability, as well as phytoplankton ecology, microbiology and biogeochemical fluxes. For our work in the polar regions, our scientists have often been invited on board of the icebreaker RV Polarstern, of the Alfred Wegener Institute for Polar and Marine Research (AWI) in Bremerhaven, Germany.

Trace elements & phytoplankton

Warming of Arctic terrestrial regions has caused an increase in river discharge, which adds to the freshening of surface waters and intensifies stratification. These climatically-induced changes influence the distribution and solubility of many trace elements and dissolved organic matter in the ocean.

In turn, changes in trace elements influence the composition and dynamics of marine phytoplankton. Since the Arctic Ocean is the source of the world ocean’s deep circulation via exchanges with the North Atlantic, changes in these biogeochemical cycles in the Arctic have implications for the world oceans.

In the ocean surrounding Antarctica, the amount of phytoplankton that can be sustained is lower than expected due to the very low availability of trace metals, notably iron.

In the western Antarctic Peninsula glaciers are an important source of iron, but much is still unknown about its importance for phytoplankton productivity. The cycling of iron is strongly affected by its sources and sinks, among others the availability for the microbial community. At the same time microbial activity affects iron solubility and availability.

These complex interactions demand further investigation into the cycling of bio-essential metals, especially iron. This will allow us to assess how rapidly warming ecosystems in both the Arctic and Antarctic are affected by physicochemical changes caused by global climate change.

Shifts in the composition and size of phytoplankton species directly affect the efficiency of the food web. Moreover, a system’s net production results from the gross production minus the losses. Whether predation or viral lysis is the dominant loss factor will determine the flow of carbon and nutrients, respectively to higher trophic levels or to dissolved organic matter and increased activity of the microbial loop.