The marine food web in the Arctic, which is based on phytoplankton, has been found to respond differently to heatwaves compared to constantly elevated temperatures. Recent experiments conducted at the Alfred Wegener Institute’s AWIPEV Station revealed that the behaviour of phytoplankton depends on cooling phases after or between heatwaves. Heatwaves are becoming more common in the Arctic due to increasing global temperatures, but their impact on polar organisms remains unclear. A study in the journal Science Advances led by Dr Klara Wolf and Dr Björn Rost investigated how single-cell algae respond to extreme heat events and their findings could have implications for the entire Arctic ecosystem.
The researchers conducted incubation experiments at the AWIPEV Station in Svalbard using natural phytoplankton communities from nearby Kongsfjorden. The phytoplankton was exposed to various temperature conditions, including normal and increased but constant temperatures as well as repeated heatwaves of varying intensity. The results showed that stable temperatures led to accelerated growth and higher productivity with minimal changes in species composition, while heatwaves had more complex effects. The cooling phases between heatwaves were found to play a significant role in the productivity of phytoplankton, highlighting the need to study the effects of temperature fluctuations on polar organisms.
Dr Björn Rost stated that gaining a mechanistic understanding of how heatwaves impact the polar regions is just beginning. The study identified the need to investigate how heatwaves and phytoplankton-related processes interact in order to better predict the implications of fluctuating temperatures. While stable warming can increase productivity, some heatwaves can decrease it, emphasizing the importance of understanding the effects of variable temperatures. Improved projections and models regarding Arctic ecosystem changes in response to climate change will require a closer examination of temperature fluctuations and their impact on primary production.
The findings of the study suggest that predictions about potential biodiversity changes in the Arctic ecosystem must take into account the effects of variable temperatures, particularly the cooling phases. Phytoplankton, as the basis of the food web, plays a crucial role in the ecosystem, and changes at this level can have cascading effects on higher trophic levels, including fisheries. Understanding how heatwaves impact phytoplankton can provide valuable insights into ecosystem dynamics and help guide conservation efforts. Overall, the study highlights the need for further research on the effects of temperature fluctuations on polar organisms to improve our understanding of climate change impacts on Arctic ecosystems.