Toxicants and osmoregulations in fish
In: Netherlands Journal of Zoology. E.J. Brill: Leiden. ISSN 0028-2960; e-ISSN 1568-542X, more
Also appears in:Osse, J.W.M.; Hollingworth, C.E. (Ed.) (1992). The Threatened World of Fish: Proceedings of the 7th International Ichthyology Congress, The Hague (The Netherlands), August 26-30, 1991. Netherlands Journal of Zoology, 42(2-3). E.J. Brill: Leiden. 524 pp., more
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| Keywords |
Marine/Coastal; Brackish water; Fresh water |
| Authors | | Top |
- Wendelaar Bonga, S.E.
- Lock, R.A.C.
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| Abstract |
Fish are extremely sensitve to many water-born toxicants, besause these affect the gills by increasing the permeability to water and ions of the gill epithelium and by inhibition of the ion exchange activity of the chloride cells. The compensatory responses of the fish will significantly increase the energy required for the maintenance of water and ion homeostatis, and this will result in reduced growth and reproduction. The effects of toxicants are to a great extent comparable to those of stressors such as confinement, transport, and handling, not only where the endocrine and metabolic responses are concerned, but also with respect to the osmoregulatory disturbances produced. Stressors may affect osmoregulation indirectly through the action of catecholamines on the gills. Furthermore, stressors induce immunosuppression and this may result in gill damage by infectious agents. Many toxicants evoke a stress response, and thus it is difficult to determine the mechanism of action of toxicants on the gills, because the specific effects of the toxicants are hard to distinguish from the effects of non-specific stress responses on the gills; This further implies that the negative effects of many toxicants and non-toxicant stressors on gill structure and hydromineral balance are additive. This aspect needs more attention in aquaculture. |
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