The European Atlas of the Seas offers many map layers produced with ocean chemistry data. Dissolved oxygen is one key parameter that can be used to assess climate change trends and this week, since January is well underway, we present a map of dissolved oxygen concentration in the surface waters of European seas with an example from the winter period.
Dissolved oxygen in water is crucial for the aquatic life and, together with salinity and temperature, largely defines biological diversity and water quality. If the amount of dissolved oxygen drops below normal levels, that affects the water quality and can lead to eutrophication, which “encourages plant growth that can take oxygen from the water and kill fish and other animals.”
Oxygen can dissolve better in cold water. That is the reason why in Winter and early Spring, dissolved oxygen concentrations are usually higher. You can easily observe this phenomenon in the map as the Baltic Sea is tainted in red (higher concentration) and the Mediterranean Sea, in the South, is blue (lower concentration).
It is noted that deeper waters of the same basins tell a very different story, with the Baltic displaying anoxic conditions (total absence of oxygen), as a result of its natural enclosed basin conditions and human-induced eutrophication.
Explore the map and compare the dissolved oxygen concentration in different seasons with the European Atlas of the Seas!
Data displayed in this map were provided by EMODnet.
The Map of the week was initially published on the EMODnet website.
 Data are from 2010
 Definition of te Cambridge Dictionary