Hypoxia is a well-described phenomenon in the offshore waters of the Baltic Sea
with both the spatial extent and intensity of hypoxia known to have increased due to anthropogenic
eutrophication, however, an unknown amount of hypoxia is present in the coastal zone.
report on the widespread unprecedented occurrence of hypoxia across the coastal zone of the
Baltic Sea. We have identified 115 sites that have experienced hypoxia during the period 1955-2009 increasing the global total to ca. 500 sites, with the Baltic Sea coastal zone containing
over 20% of all known sites worldwide. Most sites experienced episodic hypoxia, which is a
precursor to development of seasonal hypoxia.
The Baltic Sea coastal zone displays an alarming
trend with hypoxia steadily increasing with time since the 1950s effecting nutrient biogeochemical
processes, ecosystem services, and coastal habitat.