Difference between revisions of "Pollution and pelagic fish"
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| − | Fish are through their gills continuously in direct contact with their environment. Unlike [[pollution and sea birds|sea birds]] and [[pollution and marine mammals|marine mammals]] they can therefore directly adsorb contaminants from their environment. Fish can therefore both be contaminated by eating and by direct uptake from the water. Large carnivorous fish will also experience problems from [[biomagnification|biomagnifying]] substances like [[methylmercury]] and [[organochlorine compounds]]. | + | Fish are through their gills continuously in direct contact with their environment. Unlike [[pollution and sea birds|sea birds]] and [[pollution and marine mammals|marine mammals]] they can therefore directly adsorb contaminants from their environment. Fish can therefore both be contaminated by eating and by direct uptake from the water. Large carnivorous fish will also experience problems from [[biomagnification|biomagnifying]] substances like [[methylmercury]] and [[organochlorine compounds]].<ref>↑ Kennish, M. J. (1996): Practical Handbook of Estuarine and Marine Pollution, CRC Press 524 pp</ref> |
<u>'''Heavy metals'''</u> | <u>'''Heavy metals'''</u> | ||
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Organochlorine pesticides in the 1960s very often caused acute toxic effects in fish. This for instance caused fisheries in the Laguna Madre, a bay in Texas, to collapse. This was caused by pesticides sprayed on nearby agricultural areas. <ref name="pub">Clark, R,B., 1999. Marine pollution. Oxford University press, Fourth edition, pp 161</ref> | Organochlorine pesticides in the 1960s very often caused acute toxic effects in fish. This for instance caused fisheries in the Laguna Madre, a bay in Texas, to collapse. This was caused by pesticides sprayed on nearby agricultural areas. <ref name="pub">Clark, R,B., 1999. Marine pollution. Oxford University press, Fourth edition, pp 161</ref> | ||
| − | [[Effects of xenoestogens in eels]] | + | Case study 1:[[Effects of xenoestogens in eels]] |
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Revision as of 15:50, 16 July 2009
Fish are through their gills continuously in direct contact with their environment. Unlike sea birds and marine mammals they can therefore directly adsorb contaminants from their environment. Fish can therefore both be contaminated by eating and by direct uptake from the water. Large carnivorous fish will also experience problems from biomagnifying substances like methylmercury and organochlorine compounds.[1]
Heavy metals
Methylmercury can biomagnify to high values in large carnivorous fish. These fish are also more active, causing them to need more oxygen. To extract more oxygen, they have to pump more water through their gills, causing them also to adsorb more contaminants. Unlike marine mammals and (possibly) sea birds, fish can't demethylate methylmercury, nor can they excrete it efficiently. Therefore old carnivorous fish often contain very large amounts of methylmercury, making them unfit for human consumption.[2]
Organochlorine compounds
Chronic PCB contamination might affect the breading success of benthic fishes. The starry flounder population in the San Fransisco Bay displayed reduced breading success in the 1980's. Although the San Francisco bay had a relatively low PCB content, the eggs of the flounders displayed elevated PCB levels. This might lead to reduced number of eggs which hatch, bu also to reduced survivel of the juveniles, which might suffer from growth anomalies. Organochlorine pesticides in the 1960s very often caused acute toxic effects in fish. This for instance caused fisheries in the Laguna Madre, a bay in Texas, to collapse. This was caused by pesticides sprayed on nearby agricultural areas. [2]
Case study 1:Effects of xenoestogens in eels
References
- ↑ ↑ Kennish, M. J. (1996): Practical Handbook of Estuarine and Marine Pollution, CRC Press 524 pp
- ↑ 2.0 2.1 Clark, R,B., 1999. Marine pollution. Oxford University press, Fourth edition, pp 161
- ↑ http://www.milieurapport.be/nl/feiten-cijfers/MIRA-T/milieuthemas/verspreiding-van-zware-metalen/zware-metalen-in-organismen-(uitgezonderd-mens)/zware-metalen-in-paling/
