Cruise report from R/V Aranda week 45-46, 2019

Type: Report
Author: Karin Wesslander


The surface temperature was normal for the season and varied between 8-11° C. At the west coast a pycnocline was observed at 10-20 meters and in the Baltic Proper the surface water was well mixed down to 30-40 meters. 
The levels of nutrients in the surface water (0-10 m) were low but had started to increase at some stations. The concentration of phosphate, dissolved inorganic nitrogen and silicate was lower than normal in the surface at Skagerak and Kattegat, the dissolved inorganic nitrogen was close to the detection limit. Phosphate levels were normal in the Baltic Proper while the dissolved inorganic nitrogen was lower than normal in the Western Gotland Basin. Silicon levels were above normal at most stations in the Baltic Sea. 
In Hanö Bight and in the Bornholm Basin hypoxia was noted from 70 meters and it were anoxic conditions close to the bottom at the Bornholm Basin. Hypoxia was noted from 60-70 meters in the Eastern Gotland Basin and hydrogen sulphide was measured from 135 meters at station BY15 and from 70 meters at station BY20. At BY20 it was small amounts of oxygen at 115 meters but anoxia occurred again below that. In the Western Gotland Basin hypoxia was noted from 60-80 meters and anoxia from 70-90 meters.