Review on the effects of pollution on marine fish life and fisheries in the North Sea

Abstract

Information on possible effects of pollution on fish life is reviewed with special emphasis to the North Sea.Concentrations of heavy metals are high in onshore waters, sediments and organisms. Offshore regions are considered to be not endan ered. In estuaries concentrations of certain heav metals are often surpassing thresholds, which have %een experimentall demonstrated to produce subLthal effects on marine organisms. Also mussel culture areas had to be cLsed due to excess of cadmium contamination. Mercury in fillets of cod in the southern North Sea sometimes reaches 0.3 ppm representing ! 4 of the legal limit. Reductions of inputs are necessary due to the bioaccumulative and toxic potential of heavy metals.Organocblonne contamrnation of water, sediments and organisms is higher in the southern than in the northern North Sea. In offshore areas clearly elevated levels of PCB's, which are the dominating organochlorine compound in marine or anisms, have been analyzed. At present only a minor fraction of total organochlorine residues accumufa7ed in marine biota is analyzed. Margins between experimentally derived lethal levels and those occurring in marine biota are narrow suggesting that sublethal effects mi ht occur. One of the special concerns in the context of organochlorine contamination has to be seen in k e potential of these substances affectin the re roductive capaci of marine organisms. Reduction measures are urgently necessary and shoulcfinclu8e substances withTioaccumulative and toxicological potential, which are not presently included in Marine Monitoring Programmes.Impact of otl pollution is considered to be a regional problem, although especially in estuaries concentrations in the water column might be hi h Input through oil platforms has led to local reductions in benthic communities. Measures have to%etaken, to further reduce these inputs also in view to avoid contamination of fish in the vicinity of oil fields.Oxygen depletron in German and Danish coastal waters has been shown to be a severe degradation in coastal water quality resulting in significant impact on fish PO ulations. Indications for large-scale avoidance reactions of low DO-areas and mortalities of fish and fenthos or anisms have been demonstrated. It is suspected that the low DO-situations are related to increasej nutrients input and high ph toplankton production. Improvement of the situation can only be expected, if input of nutrienrs is redruced.Reasons for the occurrence of toxic plankton blooms are not understood. An intensified research is necessary, to avoid damage to fisheries and mariculture.Although activity of radionucleids in North Sea waters is increased due to input of radioactive material from La Hague and Sellafield reprocessing units, the present levels of activity are not considered to be a threat for marine life.The same holds for thennal pollution, which is, depending on the recipient area, expected to have only local effects.Sewage sludge dumping and discharge of untreated sewage introduce significant amounts of acco...

Biological Aspects and Fisheries Management of Tilapia Fish Oreochromis niloticus (Linnaeus, 1758) in El-Bahr El-Faraouny Canal, Al-Minufiya Province, Egypt

“…Also, this may be attributed to the highly increased pollution of the water of El-Bahr El-Faraouny Canal. Saleh (1980), Dethlefsen and Tiews (1985) and Khallaf et al (2003) mentioned that, pollution increased the susceptibility of fish to diseases and increased the mortality rates. This is farther shown by the exploitation ratio (E) and fishing mortality (F) in the present study as 0.43 and 0.50, respectively.…”

Impacts of contaminant sources on marine fish abundance and species richness: a review and meta-analysis of evidence from the field

“…Review articles addressing contamination effects in fish have focused on nitrogen enrichment (Micheli 1999, Nixon & Buckley 2002, Breitburg et al 2009), sewage outflows (Pastorok & Bilyard 1985, Grigg 1994, and regional impacts of contamination (Dethlefsen & Tiews 1985, Nagai 2003, Hylland et al 2006a. No comprehensive review examining the effects of contamination on fish abundance and diversity currently exists.…”

Cellular responses in the skin of the trout (Oncorhynchus mykiss) exposed to temperature elevation

“…Thermal pollution, unlike many other stressors, has mainly local effects, e.g. in the outlet of power plant cooling systems (Dethlefsen & Tiews, 1985). The effects of thermal pollution are known to be cumulative with the effects of other stressors (Umminger & Gist, 1973).…”