Reconstructing possible causes for darkening of Skagerrak Coastal Water during the past century
Darkening of the Skagerrak Water during the middle part of the 1900s was assumed to be due to eutrophication. Over the past decades, as a discharge of nutrients from e.g., sewage to the sea has decreased, the water clarity is still declining. This is suggested to be due to increased input of terrestrially derived organic matter draining into coastal waters via increased precipitation.
Time series data documenting this development over the past century (from pre-eutrophication to present-day conditions), and the impacts this may have had on the ecological quality, hardly exist. However, because many coastal areas serve as sediments traps, analyses of dated sediment cores can provide quantitative information about possible temporal changes in the supply and source of organic matter to the coastal ecosystem.
Also, the associated fossil assemblages of benthic foraminifera (protists) reflect possible temporal changes in the environmental conditions.
The MSc-theses will focus on analyses of dated sediment cores from the southern Skagerrak/Kattegat. The students will attend a cruise and collect their own study material. Geochemical analyses of various environmental proxies will include e.g., total organic C, total N, stable isotopes, trace metals and fossil benthic foraminifera in dated sediment cores. Sediment-, organic carbon- and benthic foraminiferal accumulation rates will be calculated to reconstruct possible changes in Corg sources and ecological quality during the past centuries.
The MSc theses will be part of the NFR-funded project “A green-blue link made browner”, project owner: the University of Bergen.