Stefano Bonaglia, PhD Department of Geological Sciences, Stockholm University
Stefano Bonaglia, Department of Geological Sciences, Stockholm University

How would you describe your project in a few sentences?

During my BEAM-funded project I finalized a study on nitrogen cycling in the transition layer from oxic to anoxic water of the Baltic Proper. Results suggest that the Baltic Sea hosts a full nitrogen cycle at the pelagic oxic-anoxic interface and that in situ production of N2O, a potent greenhouse gas, might be as important as N2 production.

In addition, I could carry on with a collaboration with scientists from the new Department of Marine Sciences (University of Gothenburg) to study the nitrogen removal capacity in the sediments of the Gulf of Bothnia (Northern Baltic). By means of in situ incubations with chamber landers, we could show that denitrification is the most important nitrate-reducing process in this system. Anammox, which has never been investigated before in the Gulf of Bothnia, could account for a substantial fraction of the total N2 yield by the sediment.

What are your most important results, and for whom are they particularly useful?

Results from these studies are of general importance for modelers and stakeholders who require up-to-date budgets on nitrogen removal. Given the impacts of current anthropogenic pressures on the Baltic Sea coastal area, an increasing number of fjords and estuaries are becoming hypoxic or anoxic. Studies like those carried out for the current project provide direct evidence on the capacity of the Baltic marine environment to “self-defend” from enhanced nutrient release and eutrophication.

How can it assist an ecosystem-based management of the marine environment?

These results may be used to set baselines for implementation of the ecosystem based management programs, such as the HELCOM Baltic Sea Action Plan.