In fish reproduction

In fish reproduction, the best-investigated pheromone system is that of the goldfish [Carassius auratus). Here, sex steroids and prostaglandins play important roles. The female produces two pheromones sequentially a preovulatory primer pheromone and a postovulatory prostaglandin pheromone that act on the male. 

Flouriot, G., F. Pakdel, B. Ducouret, Y. Ledrean and Y. Valotaire. Differential regulation of two genes implicated in fish reproduction vitellogenin and estrogen receptor genes. Mol. Reprod. Dev. 48 317-323, 991. 

Balon, E.K. 1984. Patterns in the evolution of reproductive styles in fishes. In Fish Reproduction Strategies and Tactics (Ed. by G.W. Potts R.J. Wootton), pp 35-53. London Academic Press. 

Compounds Affecting Rq>roduction Compounds that can affect reproductive function include several drugs and occupationally important chemicals such as solvents and pesticides as well as a number of environmentally relevant com-fxrunds. A group of chemical compounds that has received much attention recently is endocrine disrupters, many of which are halogenated hydrocarbons, e.g., PCBs. These are known to induce feminization in fish and other animal species.1.5/ There is intense debate about the significance of these compounds to human health. Tobacco smoke and ethyl alcohol also have major effects on human reproduction, the effects of alcohol being especially important. Table 5.17 lists compounds that may disturb the functions of female and male reproductive functions. 

Concentrations of PCBs in fish from each of the Great Lakes currently exceed the GLWQA objectives for the protection of aquatic life. Similarly, concentrations of some substances (e.g., PCBs, Hg, mirex, toxaphene) in Great Lakes fish continue to exceed acceptable guidelines for human consumption. Documented effects in the Great Lakes include reproductive failure, congenital abnormalities and induction of tumours in various aquatic, terrestrial and avian species (23). 

Apart from the wide range of neurotoxic and behavioral effects caused by OPs, many of which can be related to inhibition of AChE, other symptoms of toxicity have been reported. These include effects on the immune system of rodents (Galloway and Handy 2003), and effects on fish reproduction (Cook et al. 2005 Sebire et al. 2008). In these examples, the site of action of the chemicals is not identified. Indirect effects on the immune system or on reproduction following initial interaction with AChE of the nervous system cannot be ruled out. It is also possible that OPs act directly on the endocrine system or the reproductive system, and phosphorylate other targets in these locations (Galloway and Handy 2003). 

Garcia-Reyero, N. and Denslow, N.D. (2006). Applications of genomic technologies to the study of organochlorine pesticide-induced reproductive toxicity in fish. Journal of Pesticide Science 31, 252-262. 

Munkittrick, K.R., McMaster, M.E., McCarthy, L.H. et al. (1998). An overview of recent studies on the potential of pulp-mill effluents to alter reproductive parameters in fish. Journal of Toxicology and Environmental Health-Part B-Critical Reviews 1, 347-371. 

Nash, J.P., Kime, D.E., and van der Ven, L.T.M. et al. (2004). Long term exposures to environmental concentrations of the pharmaceutical ethynylestradiol causes reproductive failure in fish. Environmental Health Perspectives 112, 1725-1733. 

Qrasman KA, Scanlon PF, Fox GA. 1998. Reproductive and physiological effects of environmental contaminants in fish-eating birds of the Great Lakes a review of historical trends. Environ Monit Assess 53 117-145. 

Negative externalities arise when an action by an individual or a group implies harmful effects on others such as unintended dispersion of chemicals to land, air and water air pollution effects on health forest growth or fish reproduction. When negative externalities are generated they should be internalized into the market economy. By internalizing the externalities the economic value of environmental impacts are allocated to the pollution sources and included in the economics of the activities causing the problem. This would also allow for the market to function properly and thereby reach a socially optimal level of environmental impacts. 

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