Biogeochemistry in Coastal Seas
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Aquatic Nutrient Cycles

The status of aquatic ecosystems in general is largely determined by the availability of essential nutrients like nitrogen, phosphorus and silicic acid, and by the oxygen content of the water. River-Sea systems and coastal seas are amongst the most productive of the world’s ecosystems, but high anthropogenic nutrient inputs e.g. from traffic, agriculture and wastewater treatment may lead enhanced algal blooms (eutrophication) and declining oxygen concentrations in bottom waters.

Healthy river-sea ecosystems are able to process these nutrient inputs by microbial turnover potentially removing a substantial part of excess nutrients before they reach the coastal ocean. This turnover may also bring historical nutrient loads from the sediments (the legacy of past industrial pressure) back into the water column, again fuelling eutrophication. Especially in dynamic regions like the coastal ocean this balance between nutrient sources and sinks are hard to predict and a challenge for our investigations.

Within the working group “Aquatic nutrient cycles” marine biologists and geoscientists jointly investigate nutrients and oxygen dynamics in the coastal ocean, quantify the fluxes and asses their impact on ecosystem functions. We apply novel underwater observation technology and stable isotope techniques.