Lead is reported to be an endocrine disruptor. In the current study, we exposed female Prussian carp to artificial feed, supplemented with five doses of dietary Pb (0, 1 (control), 8, 13, 24, and 49 mg/kg) over either a 24-month period or a 12-month period, followed by further 12 months where the fish were fed the control diet. Periodically, oocyte maturation, gonadosomatic index (GSI), ability...

The weakly electric fish from the main channel of the Amazon river, Sternarchogiton nattereri, offers a striking case of morphological variation. Females and most males are toothless, or present only few minute teeth on the mandible, whereas some males exhibit exaggerated, spike-like teeth that project externally from the snout and chin. Androgens are known to influence the expression of sexual...

The reproductive aspects of Hemiramphus brasiliensis were analyzed with a view to verify the temporal dynamics of reproduction. This paper presents data on sex ratio, length at first sexual maturity, macroscopic and histological aspects of gonad development, gonadosomatic index (GSI), reproductive period, and fecundity of H. brasiliensis. The fishes were captured from the coastal waters of Rio ...

In the present study, the female Clarias batrachus, held under long photoperiod (13L:11D), were exposed to high water temperature either constantly (24 h) and/or in form of thermopulse of 6 h and 12 h durations, separately, at different times of the day/night cycle for six weeks during the early post-spawning and late post-spawning phases of its reproductive cycle. The effects of high water tem...

Feral carps (Cyprinus carpio) were collected in spring 2001 from five sites along the lower course of Ebro River (Spain) with the aim of investigating the existence of endocrine-disrupting effects. Several findings (low gonadosomatic index (GSI), plasmatic vitellogenin (VTG), depressed levels of testosterone, and histological alterations in gonads) detected in male carps downstream of Zaragoza'...

Understanding the interaction between sexual and natural selection within variable environments is crucial to our understanding of evolutionary processes. The handicap principle predicts females will prefer males with exaggerated traits provided those traits are indicators of male quality to ensure direct or indirect female benefits. Spatial variability in ecological factors is expected to alte...

College of Marine Studies, University of Delaware 700 Pilottown Road, Lewes, Delaware 19958 Present address: UT-Houston Medical School. Laboratory for Neuroendocrinology, P.O. Box 20708, Houston, Texas 77225 Abstract.-Male weakfish, Cynoscion regalis, were collected from the southwest portion ofDelaware Bay from April through September in 1990 and 1991. Morphometric measurements ofthe sonic mus...

Since the early 1980s, the population of European eels (Anguilla anguilla) has dramatically declined. Nowadays, the European eel is listed on the red list of threatened species (IUCN Red List) and is considered as critically endangered of extinction. Pollution is one of the putative causes for the collapse of this species. Among their possible effects, contaminants gradually accumulated in eels...

It is well established that reproduction is sensitive to the state of energy reserves, and that there is a balance between energy homeostasis and fertility. In this view, this study examined the effects of different diets on growth and reproductive performance of fresh water angelfish. Twenty four pairs of angelfish (weighing 3.58 ± 0.24 g) were fed with four types of diets including live earth...

The effect of the number of spawnings on several biochemical components of ovary, hepatopancreas, and haemolymph was investigated. Shrimps of two origins were compared; wild-caught and pond-reared spawners. Individually tagged females were sampled at the end of a production period in a commercial hatchery. Females with multiple spawnings had a higher Ž . gonadosomatic index GSI , increased leve...