Odense Fjord, Denmark
Main Contributors:
Other Contributors:
Summary
Hypoxia and anoxia are to a certain scale natural phenomena in many deep fjords. In Odense Fjord, high biomass of algae and eutrophication has contributed to hypoxia. Since the early 1980s, more or less widespread hypoxia has been observed nearly every autumn in Danish coastal waters. The causes of hypoxia in Denmark are related to increased nutrient loads and natural physical factors (e.g. weather) affecting the timing and duration of hypoxia. Hypoxic events in Danish estuaries are not in phase with the open waters; the most severe hypoxic episode in estuaries was reported in 1997 when parts of the Mariager Fjord turned completely anoxic. The response of marine benthic macrofaunal communities to seasonal hypoxia in coastal Denmark is a collapse or mass mortality.
Type of regime shift
Ecosystem type
- Marine & coastal
Land uses
- Fisheries
Spatial scale of the case study
- Local/landscape (e.g. lake, catchment, community)
Continent or Ocean
- Europe
Region
- North Europe
Countries
- Denmark
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Key References
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Conley J, Carstensen J, Ærterbjerg G, Christensen PB, Dalsgaard T, Hansen J, Josefsen A. 2007. Long-term changes and impacts of hypoxia in Danish coastal waters. Ecological Applications 17, 165-184.
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Karlson K, Rosenberg R, Bonsdorff E. 2002. Temporal and spatial large-scale effects of eutrophication and oxygen deficiency on benthic fauna in Scandinavian and Baltic waters: A review. Oceanography and Marine Biology 40, 427-489.
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Lundholm N, Clarke A, Ellegaard M. 2010. A 100-year record of changing Pseudo-nitzschia species in a sill-fjord in Denmark related to nitrogen loading and temperature. Harmful Algae 9, 449-475.
