What do sediment cores from the Bay of Kiel have to do with fishing and tourism?

Authors: Mirjam Perner (GEOMAR), Florian Scholz (Universität Hamburg), Timo Spiegel (GEOMAR)

Retrieval of a sediment core in the Kiel Bight (Photo: Stefanie Böhnke-Brandt).

The Baltic Sea is undergoing drastic environmental changes due to climate change, leading to increased stratification of the water column and more frequent algal blooms. These changes result in oxygen depletion (hypoxia) in coastal waters, with severe consequences for ecosystems and the regional economy. Our study area, Kiel Bight in the southwestern Baltic Sea, is particularly known for frequent hypoxic events in late summer. One major concern in this context is the release of toxic hydrogen sulfide from the seafloor. When oxygen-depleted or hydrogen sulfide-containing bottom waters rise to shallower depths through upwelling, they can cause mass fish die-offs.

Hydrogen sulfide-containing sediment core from Kiel Bight (Photo: Mirjam Perner).

The DAM project PrimePrevention focuses on identifying the factors driving the formation of hydrogen sulfide-containing bottom waters. To this end, research cruises are conducted to measure oxygen and hydrogen sulfide concentrations in the water column using sensors and to collect water and sediment samples for geochemical and microbiological analyses.

Pore water extraction from a sediment core (Photo: Florian Scholz).

All available environmental data will be used to develop a numerical model that predicts hydrogen sulfide release based on a few key controlling variables. The results aim to help identify the most affected regions and assess the risks posed by hypoxic events to stakeholders such as tourism, fisheries, and aquaculture.