One of the most current topics in climate research is the impact of extreme events such as heat waves or cold spells on biological communities in ecosystems. The consequences of climate change can be seen particularly clearly in the Arctic, as the region is warming faster than the rest of the world. It therefore offers scientists a unique opportunity to better understand processes and relationships between environmental factors such as temperature, soil or nutrients and biological communities. In a recent study published in the journal Scientific Reports, researchers from the Alfred Wegener Institute, the Helmholtz Centre for Environmental Research - UFZ and the Helmholtz Centre Hereon used modern AI methods to investigate how temperature anomalies affect Arctic fjords. The data suggest that there is a direct correlation between temperature extremes and the total number of marine organisms living in the studied Arctic ecosystem. The results also show the potential of AI-supported analyses to gain new insights from scientific data.
“We were able to see that in 'Atlantic' phases, in which heat waves occurred more frequently, the amount of living organisms in the fjords significantly exceeds the normal amount than in 'Arctic' phases, which are dominated by cold periods,” says Prof Philipp Fischer, first author and Head of the AWI Center for Scientific Diving and of the research group “In situ ecology” at the Biological Institute Helgoland of the Alfred Wegener Institute (AWI). “What is particularly important, however, is that the temperature anomalies not only appear to influence the total number of organisms, but also trigger complex shifts in the community composition.” For example, certain biotic groups, such as jellyfish, fish or worms, experienced fluctuating, interannual peaks, during which significantly more individuals lived in the ecosystem than during the long-term average.
The results suggest that climate change not only influences specific environmental variables, but also has profound structural effects on entire ecosystems and their trophic structures. “This could indicate a so-called maximum 'community carrying capacity'.” Community carrying capacity describes the idea that there is a maximum number of individuals of a particular species that can live permanently in a habitat without harming it. “In our study, this could indicate that the carrying capacity of the Arctic ecosystem may increase significantly during warm phases, even for species that are otherwise more likely to occur in the Atlantic. Allowing an unusually large amount of biomass in the Arctic region, which then strongly influences this sensitive system. In contrast, during cold spells, the carrying capacity of the system drops to an anomalously small biomass,” says Philipp Fischer.
Which groups or species build up or break down more biomass at a given time, depends not only on the actual composition of the community and their reciprocal interactions, but also on external factors such as the available food or the water body currently prevailing in the system. If these factors change due to anthropogenic or environmental influences, the carrying capacity of the system and possibly also the tropical structure will change. “For the first time, we were able to establish a link between extreme environmental conditions and the response of the biotic community across different trophic levels from jellyfish to fish.”
AI-supported method reveals complex relationships
The researchers recorded the data for the study using an underwater observatory in Svalbard. “Since 2012, we have been recording high-resolution physical data in seconds at the AWIPEV station in Ny-Ålesund - continuously throughout the year, even during the polar winter, in months of darkness and outside temperatures of sometimes below -40 degrees Celsius,” says Philipp Fischer. “At the same time, we monitor the biological community all year round using a state-of-the-art, AI-supported fish observatory - with a temporal resolution of 30 minutes."
The researchers analyzed these unique data sets of abiotic and biotic parameters using AI-supported methods and thus determined the total and group-specific quantity of fish, jellyfish and crustaceans, among others. “Our study shows that complex relationships in ecosystems can be made tangible using modern scientific methods, especially in the course of digitalization,” summarizes Philipp Fischer. “The species composition and diversity in the area studied varies greatly each year, which makes it much more difficult to recognize consistent patterns in the relationship between environmental variables and the biotic community. However, with the help of AI, we were able to recognize clear relationships between climate extremes and biological communities that have not yet been demonstrated in this form – that is in situ – in the real world.”
The study thus makes an important contribution to better understanding the functional relationships and interactions within the Arctic. This is essential in order to realistically assess the consequences of climate change on ecosystems in the future - and not just in Arctic coastal areas.
Original publication
Fischer, P., Brix, H., Bussmann, I. et al. Effects of marine heat waves and cold spells on a polar shallow water ecosystem. Sci Rep 15, 20168 (2025). https://doi.org/10.1038/s41598-025-05621-w