Aarhus University Seal

Marine Ecology

We work with research, innovation, consultancy and monitoring, as well as popular research communication and education mainly related to the marine coastal zone, particularly in Denmark and Greenland. Our research aims to provide new and better knowledge on how the structure and function of ecosystems react to human-induced changes, such as nutrient loads (eutrophication), climate change and the introduction of non-native/invasive species. Monitoring documents the status and changes of ecosystems and, together with our research, forms the basis for consultancy, popular research communication, teaching and the development of nature-based solutions in the field of algae cultivation, conservation/restoration of plant societies (seagrass, seaweed forests, etc.), consultancy on biogeochemical turnover and storage of carbon and nutrients, as well as technological developments in management and research. The main purpose of our activities is to promote sustainable use of the coastal zone.

Research areas in brief


Per Andersen

Special Consultant

Eelgrass and macro-algae (seaweed) ecology

We particularly focus on which factors (including humanly-induced) regulate the prevalence, biomass and growth of the coastal zone's plants, how the plants affect the function of the coastal ecosystems, and how plant and algae communities can be used as indicators of organic quality. We also conduct research into optimising the cultivation of macroalgae – both at sea and in land-based systems, and how naturally occurring and cultivated macroalgae and their constituents can be exploited commercially.


Oxygen depletion and substance turnover in the seabed

In the past approx. one hundred years, oxygen depletion has increased in frequency, prevalence, duration and intensity as a result of eutrophication (increased supply of nutrients and organic matter) and climate change. Theoxygen content of the bottom water is of crucial importance for the living conditions for benthic flora, fauna and fish. In addition, oxygen depletion affects the chemical and biological turnover in the seabed, for example, it reduces the seabed’s ability to retain nutrients and toxic hydrogen sulphide. We conduct research on the triggers behind oxygen depletion and the effects of oxygen depletion on ecosystems. We provide consultancy on oxygen depletion and prepare four annual national reports on the oxygen depletion situation in the inner Danish waters for the Danish Environmental Protection Agency.


Marine biodiversity

We work with documenting and monitoring marine flora and seaweed as well as plant plankton and microzooplankton, including non-native and invasive species. Among other things, we study how biodiversity can be protected, maintained and developed, for example in connection with a reduction in eutrophication (increased nutrient input), the development and use of nature-based solutions, e.g. in connection with the production of seaweed in our coastal waters and fjords, as well as the conservation and establishment of seaweed forests and eel grass meadows.


Turnover of nutrients and carbon

We conduct research on the turnover of nutrients and carbon in Arctic waters, with a focus on how the production and degradation of phytoplankton algae influence the exchange of carbon dioxide between the sea and the atmosphere. We focus on the effects of climate change in terms of changes in the prevalence of sea ice in time and space and the effects of the increased supply of fresh water to the Arctic fjords as a result of melting glaciers and the ice sheet. We also conduct research on the turnover of nutrients and carbon in Danish waters, focusing on the linkage between the turnover in the seabed and the water column.


Marine instruments/Nature-based solutions

We conduct research on how eelgrass, macroalgae (seaweed) and other marine plants (salt marshes) can function as marine instruments by reducing the amount of available nutrients to plankton, absorbing, retaining and removing carbon dioxide (CO2) in the form of living biomass and increased organic content in the seabed (Blue Carbon), reducing the resuspension of bottom material and protecting the coast against erosion. In addition, we conduct research on aquaculture of seaweed to remove nitrogen and phosphorus from the coastal zone and the effects of establishing reef structures (stone reefs, hanging reefs and wind turbine foundations) on biodiversity, production and nutrient turnover. 


New methods

We conduct research on the development of new methods based on new technology, e.g. in the form of drones, underwater video (including the use of "ROV"), satellite monitoring and digital imaging and analysis in connection with monitoring of and research in, among other things, the prevalence of eel grass and seaweed as well as algae blooms and jellyfish. We also study the use of environmental DNA (eDNA, small pieces of DNA) to trace the presence of marine plants and other organisms as well how they contribute to the carbon pool in the seabed.


Marine plankton communities and toxic algae

We work with monitoring marine plankton (micro-algae and microzooplankton) as well as toxic algae and algae blooms for the Danish Environmental Protection Agency. Our research includes plankton dynamics in relation to nutrient availability, grazing from benthic fauna and zooplankton and hydrographic conditions. In addition, we study the long-term development of plankton communities, where we focus on the effects of climate change and eutrophication (increased nutrient input)/load with nutrients. We focus on biodiversity, non-native species (including invasive/harmful species) and algae blooms.


Marine surveillance in Denmark and Greenland

By far, the largest part of the marine surveillance is handled by the Danish Environmental Protection Agency (Denmark) and the Greenland Institute of Natural Resources (West Greenland). We are responsible for surveillance in East Greenland and some surveillance in West Greenland and Danish waters. In Denmark and West Greenland, we mainly contribute to monitoring as a consultant and sparring partner to the authorities re. the maintenance and development of monitoring. In addition, we are involved in the interpretation of surveillance data in a research context and in connection with the assessment of the state of the marine environment. We are academically responsible for national monitoring in Denmark.