Difference between revisions of "Pollution and pelagic fish"
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Revision as of 10:05, 17 July 2009
Fish are through their gills continuously in direct contact with their environment. Unlike sea birds and marine mammals they can with these gills directly adsorb contaminants from their environment. Fish can therefore both be contaminated by eating and by direct uptake from the water. As they form the top of the food chain, large carnivorous fish will also experience problems from biomagnifying substances like methylmercury and organochlorine compounds.[1]
Heavy metals
Heavy metals are thought to display a variety of sublethal effects on fishes. Also, the presence of high concentrations of heavy metals forces the fishes to produce metallothioneins. The energy they have to spend on the production of these detoxifying proteins can no longer be used on growth or reproduction. Although adult marine fishes are thought to be rather protected from the effects of heavy metal concentration, the embryos and gametes are quite vulnerable. [2]
Organochlorine compounds
Organochlorine pesticides in the 1960s very often caused acute toxic effects in fish. When sprayed on agricultural areas near the coast, the pesticides tended to ended up in large doses in nearby bays, resulting in massive local fish mortalities. This for instance caused fisheries in the Laguna Madre, a bay in Texas, to collapse. [3] When present at concentrations which don't cause acute toxicity, these organochlorines can also accumulate in the fishes. It is also thought that these can lead to various sublethal effects. In the Elbe estuary in Germany chronic exposure has lead to reduced productive success, damage to the liver, kidneys and intestines.[2]
Case studies
Case study 1:Effects of xenoestogens in eels
