Occurrence and effects of a spring oxygen minimum layer in a stratified coastal water

Abstract

The combined effect of pelagic respiration and stratification resulted in the development of an oxygen minimum layer in early April 1988 in the Kattegat, Denmark. Strong wind mixing in mid-March created a cold and homogeneous surface layer above a saltier and warmer bottom layer. This was followed by a large outflow of low salinity Baltic Proper water, which covered the higher salinity Kattegat water and created a surface layer trapping the cold former surface water as an intermediate layer for several weeks. The vertical position of the pycnocline changed during April and May, which resulted in fish mortality when fish trapped in the bottom nets were exposed to the oxygen minimum layer. At the end of May, the oxygen minimum layer was no longer distinguishable from the Kattegat bottom water. -from Authors