Subject area Aquatic Ecology

We study food web interactions in aquatic ecosystems and how these systems are affected by changing environments due to climate change, changes in species composition or the presence of dams or fish farms. 

Food webs of aquatic ecosystems are complex with several trophic levels and organisms that can feed on more than one level over their life. Like the European perch that feed on zoo plankton at small body sizes and can switch to a fish diet at larger sizes. Within species, the behaviour and appearance can vary among individuals and populations depending on the conditions they experience. We study how fish population dynamics, body growth and diet are affected by changing environments and how these responses vary during the fish’ lifetime.

We also use genetic tools to investigate speciation processes and how different morphs, same species with different appearances and function in the food web, of certain species develop and occupy different niches in inland lakes in Northern Sweden. 

We also use genetic tools together with analysis of fish scales to study life-history variation in Atlantic salmon and brown trout.

We study how pollution affects aquatic organisms and their ability to find food, avoid predators, reproduce etc. 

Hand in hand with global climate change, chemical pollution is a major driver of habitat degradation and biodiversity loss around the globe. The quantity and diversity of chemicals that contaminate our ecosystems is immense and still growing, ranging from heavy metals, pesticides and PFAS, to various pharmaceuticals and personal care products.

We apply multidisciplinary approaches to study how aquatic wildlife are exposed and respond to such pollutants. Specifically, we study the occurrence and behaviour of chemical pollutants in the environment, using state-of-the-art liquid chromatography mass spectrometry (LC-MS) to analyse the presence of contaminants in water, sediment, and aquatic biota collected in river, lake, and marine environments, both from within Sweden and internationally. We also study how chemical pollutants affect (the behaviour of) aquatic wildlife, such as fish and macroinvertebrates. For this, we use controlled exposure experiments in laboratory settings or semi-field conditions (e.g., mesocosms). In addition, we increasingly use remote-sensing technology, biologging devices, and/or slow-release chemical implants to study how fish respond to chemical pollution in their natural habitats. 

We furthermore study how chemicals may impact aquatic wildlife within the broader context of environmental change, including potential interactive effects between various chemicals, and with temperature increase, habitat degradation etc. In addition, we are committed to enhancing environmental protection by improving the reliability and relevance of ecotoxicity data used in the risk assessment and regulation of chemicals.

We study animal behaviour from both applied and fundamental perspectives.

The way animals behave is important for navigating their environments and engaging with other organisms they encounter. Evolutionary processes have fine-tuned the behaviours that animals display in response to stimuli in and around them, but rapidly changing environmental conditions are now forcing many animals to adapt their behaviours. In the aquatic ecology group, we study how environments and physiological states affect behaviour and behavioural decisions in aquatic animals, primarily fish. We study these processes in controlled laboratory setups, where we can easily manipulate stimuli, as well as in the wild, where animals are exposed to the real-world complexities of their natural habitats.

Some topics/questions that we specialise in are:

Movement and migration

We use remote tracking and biologging devices, from simple PIT-tags to advanced satellite tags, to study animal behaviour and physiology in the wild. These powerful techniques allow us to study a wide range of topics that help us better understand why animals behave the way they do. For example, where do animals move to and why? Or how do animals interact with their environment and all its resources? Once we better understand these processes, we can use this knowledge to develop applications and improve management strategies that ensure sustainable development while safeguarding wildlife. As an example, we are tracking Baltic salmon to understand when they begin migration, and the route they take to overcome hydropower dams and reach the sea. Furthermore, together with various collaborators, we have established extensive acoustic telemetry infrastructures all across Sweden— including the Baltic Sea, along the Swedish west coast, and our larger lakes—that help us study the movements of a wide range of fish species.

Social and collective behavior

Most animals live in a social environment, from highly structured societies to loosely structured social groups, and anything in-between. Thus, social interactions and group formation are fundamental for the survival of many species. There is still much to learn, however, as many questions remain. For example, how do resource-sharing conflicts get resolved in group-living fishes? How do dominance hierarchies emerge and how can they break down? In what environments is group-living and cooperation favored?

Furthermore, considering social and collective behaviour is critical for understanding how human activities impact the movement and behaviours of wildlife. Despite this, most of the research on anthropogenic impacts focuses on the behaviour of individual animals, and seldom considers how stressors might affect animal collectives and the interactions between them. We ask whether emerging pollutants can disrupt the formation and composition of animal groups, and how this might affect collective behaviour. We do this using high-resolution field and laboratory tracking technologies, such as remote tracking devices (e.g. telemetry) and video tracking software (e.g. AI powered video tracking).

A variety of human impacts can severely affect aquatic ecosystems. In our research group we research the following:

Anthropogenic noise

Human induced anthropogenic noise has changed the acoustic environment in our marine and freshwater ecosystems and has been recognized as a critical pollutant both globally and nationally. Noise from e.g. shipping, boating, and energy production dominates the underwater soundscape and affects large areas, covering a wide spectrum of primarily low frequencies (<1000 Hz) that overlaps with the hearing and perception of many aquatic organisms. We investigate effects of noise on behaviour and physiology in fish and marine mammals in the wild to improve our understanding of the impact of noise pollution. We also research possible solutions to dampen noise from boats by using for example eel grass (Zostera marina) that also works as a natural erosion protection and habitat restoration.

Hydropower plants

We study the effects of hydropower facilities and their operations on ecosystems and organisms as well as the effectiveness of various mitigation measures. This includes inventories of riparian vegetation and benthic invertebrates before and after restoration, tracking of fish to study migration in regulated rivers with a special focus on fish passages, and mapping of different stressors to evaluate the potential risk of compromised fish health with restored connectivity.  

Climate change

Fish in northern lakes and rivers are also vulnerable to climate change. We study how changes in their environment, like an increase in temperature and a decrease in nutrients, affect fish communities and the food webs they are part off. We also help with developing management actions to minimize these impacts. Specifically, we investigate critical environmental factors affecting Arctic charr, using field sampling, historical data and population models. In addition, we study how interactions with other species (e.g. brown trout and Eurasian minnow) impact responses of artic char.