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The Baltic Sea, especially southern and eastern regions
Falandysz, J.; Trzosinska, A.; Szefer, P.; Warzocha, J.; Draganik, B. (2000). The Baltic Sea, especially southern and eastern regions, in: Sheppard, C.R.C. (Ed.) Seas at the millennium: an environmental evaluation: 1. Regional chapters: Europe, The Americas and West Africa. pp. 99-120
In: Sheppard, C.R.C. (Ed.) (2000). Seas at the millennium: an environmental evaluation: 1. Regional chapters: Europe, The Americas and West Africa. Pergamon: Amsterdam. ISBN 0-08-043207-7. XXI, 934 pp., meer
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| Beschikbaar in | Auteurs |
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Documenttype: Revisie
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| Auteurs | | Top |
- Falandysz, J.
- Trzosinska, A.
- Szefer, P.
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- Warzocha, J., meer
- Draganik, B.
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| Abstract |
This chapter describes the ecological situation in the Baltic Proper, focusing on the southern and eastern coasts, and describes the main problems which have arisen there in the second half of the 20th century. Eutrophication of the Baltic Proper is an on-going process which has been well documented for more than 40 years and which increased very rapidly during the 1970s. At present the nutrient concentrations in the photic zone are stable, though at a level sufficiently high to support intensive primary production. Extremely large loads of organic matter, nitrogen and phosphorus from land-based sources as well as large anoxic areas of the seafloor have a great impact on the cycling of nutrients. The most important effects of eutrophication are increasing primary production, decrease in water transparency and increase in organic matter sedimentation, and accelerating depletion of oxygen in the deep layers. Most typical marine species do not occur in the Baltic Proper, or else occur here at the edge of their ecological range. Thus even small changes in environmental conditions influence their spatial distribution. The main factors limiting the biodiversity and the immigration of marine organisms are low salinity and low water temperature. There are four groups of natural immigrants in the Baltic flora and fauna: the Northwest European euryhaline marine and brackish-water species, the freshwater species, and (third and fourth groups) glacial relicts, which reached the Baltic either through ice-dammed lakes from Siberia or by a westerly marine route. Because of its semi-enclosed nature, the Baltic Sea is vulnerable to adverse impacts of large-scale anthropogenic inputs. Significant quantities of chemical substances have been discharged into the Baltic Sea from industrial wastewaters, municipal sewage, agricultural run-off, atmospheric fallout, marine paints, dumping of wastes, and chemical warfare agents as well as sediments dredged from the port canals during the 20th century. Pollution of the Baltic Sea with persistent, toxic and bioaccumulative compounds has become a real threat to Baltic wildlife, notably some birds of prey and marine mammals. Following a ban on use of some organochlorine pesticides and alkyl mercury in the 1960s-70s and the restrictions on the use of some organo-chlorinated industrial chemicals, their concentrations now appear to be decreasing in all types of samples and at all locations, and there is also an improvement in the population status of higher predators in recent years. |
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