Cycling of biogenic elements in the seafloor of brackish and marine settings: effects of spatial and temporal oxygen gradients

Seminarium

PhD student Astrid Hylén will give her midterm seminar. Björn Andersson will act as opponent. Per Hall is the supervisor and Helle Ploug is the examiner.

The oxygen concentrations are declining in the oceans, with major effects on many biogeochemical cycles. The aim of this thesis is to investigate how benthic cycles of biogenic elements respond to spatial and temporal oxygen gradients, with focus on nitrogen and phosphorus cycling. The main study area is the Baltic Sea, which has suffered from eutrophication for decades, resulting in the largest human-induced hypoxic area in the world. Projects in the thesis include following the response of benthic biogeochemical cycles after natural and forced oxygenation events, measuring dark benthic nitrogen fixation and comparing sediment-water fluxes of nitrogen and phosphorus measured all over the Baltic Sea during ca two decades.