Changes in biodiversity and food webs of northern freshwater ecosystems in response to climate and environmental shifts

Freshwater resources are of vital importance for human societies and wildlife. However, the world’s surface freshwaters are increasingly threatened by a range of stressors caused by human activities, leading to degradation that jeopardizes the biodiversity and ecosystem services they provide. The impacts of these stressors are complex, and recent research particularly emphasizes the importance of understanding how multiple stressors interact across space and time to influence freshwater ecosystems. Addressing this challenge requires the understanding of the underlying food web structure and the biological interactions within freshwater communities. While stressors may directly affect multiple species or trophic levels, their impacts on a single species also have the potential to cascade and pose indirect effects on the entire ecosystem, owing to the interactions between species.

My research aims to understand the combined impacts of climate change and other human-induced stressors on freshwater food webs and biodiversity in the northern high-latitude regions, including the Arctic. These regions are warming at a rate considerably faster than the global average. Warming and increases in catchment vegetation (i.e., landscape greening), along with regional stressors such as nutrient pollution and atmospheric acid deposition, will alter catchment biogeochemical processes and the delivery of nutrients and carbon, resulting in rapid environmental alterations in northern freshwater ecosystems. However, there is still a substantial knowledge gap regarding how biological communities in these ecosystems respond to such changes. Addressing this gap is globally relevant, given the widespread effects of climate change and the particularly abundant freshwater resources in northern landscapes.

In this presentation, I will introduce the biodiversity trends observed in northern freshwater ecosystems in the context of climate change. I will also discuss the importance of adopting a food web perspective to assess the impacts of stressors. Ecological tracers, such as fatty acid biomarkers, are particularly useful for evaluating shifts in animal diets and food web dynamics in response to environmental changes. Additionally, I will discuss how the combined effects of climate change and landscape recovery from atmospheric acid deposition may disrupt a key ecosystem service, i.e., the production and trophic transfer of essential omega-3 fatty acids in northern lakes. These omega-3 fatty acids are vital for the growth, reproduction, and overall well-being of a wide range of organisms, including fish and humans. A reduction in the supply of omega-3 fatty acids could have profound negative consequences for the health of animals and entire ecosystem. Overall, this presentation will highlight the importance of understanding and addressing the complex challenges that northern freshwater ecosystems are facing in a rapidly changing environment.