The basis of the marine food web in the Arctic, the phytoplankton, responds to heatwaves much differently than to constantly elevated temperatures.
The basis of the marine food web in the Arctic, the phytoplankton, responds to heatwaves much differently than to constantly elevated temperatures. This has been found by the first targeted experiments on the topic, which were recently conducted at the Alfred Wegener Institute’s AWIPEV Station. The phytoplankton’s behaviour primarily depends on the cooling phases after or between heatwaves, as shown in a study just released in the journal Science Advances.
Heatwaves, which we’ve increasingly seen around the globe in recent years, are also becoming more and more common in the Arctic. During a heatwave, not only the air but also the ocean grows warmer – the temperature is substantially higher than the seasonal mean value for at least five consecutive days. But how these short-term temperature fluctuations affect polar organisms remains largely unclear. To shed light on this aspect, a team led by Dr Klara Wolf (Universities of Hamburg and Konstanz) and Dr Björn Rost from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) has now used experiments to investigate how single-cell algae, the phytoplankton, respondact to these extreme events. Given the phytoplankton’s role as the basis of the marine food web, changes in it could resonate throughout the entire Arctic ecosystem.
In incubation experiments at the AWIPEV Station in Svalbard, the researchers allowed natural phytoplankton communities from nearby Kongsfjorden to grow for 20 days under various conditions – normal and increased but constant temperatures (2° C, 6° C, 9° C). For comparison, they subjected the phytoplankton to repeated heatwaves of varying intensity (6° C, 9° C) , each lasting five days with a three-day cooling phase at the seasonal mean temperature (2° C) in between. Different types of samples were collected at defined intervals in order to characterise the physiological responses and any potential species shifts.
Read more at Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
Image: AWI biologist Dr Clara Hoppe (right and, PhD student Klara Wolf are taking algae samples at Kongsfjord, Spitsbergen, which they are going to use for analyzing the chemical composition of the phytoplankton and how much carbon the algae have bound. This fieldwork in Ny-Ålesund, Spitzbergen is part of the AMUST project, an incubation experiment planned and run by AWI biologists Björn Rost and Dr Clara Hoppe. The group is investigating how phytoplankton from the Kongsfjord is reacting in different climate settings, especially to a warming and more acid ocean. (Photo: Paolo Verzone)
