Multigenerational exposure of the estuarine sheepshead minnow (Cyprinodon variegatus) to 17 ß-estradiol. I. organism-level effects over three generations.

A 280-d study examined the effects of 17ß-estradiol (E2) on reproduction and development of the sheepshead minnow (Cyprinodon variegatus) exposed from the parental (F0) through three subsequent (F1, F2, and F3) generations and evaluated the need for multigenerational assessments of the risks of endocrine-disrupting chemicals. This first three-generation study exposed adult F0 and F1 fish to measured concentrations of 0.01, 0.04, 0.08, 0.2, and 0.3 µg E2/L; the F2 and F3 generations were exposed to 0.2 µg E2/L or less. The cumulative 21-d production of normal embryos was significantly reduced in the F0 generation at 0.3 µg E2/L and in the F1 and F2 generations at 0.08 µg E2/L or more. The daily reproductive rate was significantly reduced in all three generations at 0.08 µg E2/L or more during spawning days 8 to 14 and 15 to 21. The proportion of infertile eggs from F1 fish was significantly increased above that of the solvent controls at 0.04 and 0.2 µg E2/L and from F2 fish at 0.04 µg E2/L or more. Changes in liver, kidney, and gonadal tissues were seen in the F0 and F1 generations exposed to 0.2 µg E2/L or more. The female gonadosomatic index was significantly decreased at 0.3 µg E2/L in the F0 and F1 generations. Estradiol affected the hepatosomatic index only in female F1 fish, but not in a dose-dependent manner. All F1 fish in 0.3 µg E2/L appeared to be phenotypically female. Our results indicate that life-cycle exposure to E2 significantly decreased embryo production by F1 and F2 fish at concentrations lower than those affecting the F0 generation, and they emphasize the importance of evaluating the impact of an estrogenic chemical on reproduction through a minimum of two (F0 and F1) generations.

Temporal and spatial comparisons of the reproductive biology of northern Gulf of Mexico (USA) red snapper (Lutjanus campechanus) collected a decade apart.

In studies done a decade apart, we provide evidence of a recent shift toward a slower progression to sexual maturity as well as reduced egg production, especially among young, small female red snapper, in the Gulf of Mexico (Gulf). Slower maturation rates (among fish ≤6 years old), lower GSI values and decreased spawning frequency were observed, and were especially pronounced in the northwestern Gulf. Furthermore, an Index of Reproductive Importance showed that young fish (ages 2-7) are contributing far less to the spawning stock in recent years, while older fish (>8 years) are contributing more, when compared to fish from the same age groups sampled in the previous decade. Coincident with these changes in reproductive output, fishing pressure has steadily declined gulf-wide, and spawning stock biomass and spawning potential ratio have increased. Thus, it is possible that the age structure of the red snapper stock is becoming less truncated, or that reproductive effort observed is due to the temporary influence of recent strong year classes produced in 2004 and 2006 as they begin to reach full reproductive potential. If the latter is true, careful documentation of the stock's reproductive dynamics during a time of population growth provides new understanding at the meta-population spatial and decadal temporal scales. In contrast, if the former is true, a truncated age structure due to overharvest can limit the productivity of the Gulf red snapper stock. In addition, we have learned that red snapper females in the northwestern Gulf collected on natural reefs and banks have much higher reproductive output than those on artificial reefs in the form of standing and toppled oil and gas platforms, thus making the need to know the relative abundance of females found on these disparate habitats an important next step toward better-understanding factors impacting the reproductive dynamics of this species.

Exposure of three generations of the estuarine sheepshead minnow (Cyprinodon variegatus) to the androgen, 17beta-trenbolone: effects on survival, development, and reproduction.

Estimating long-term effects of endocrine-disrupting chemicals on a species is important to assessing the overall risk to the populations. The present study reports the results of a 42-week exposure of estuarine sheepshead minnows (Cyprinodon variegatus) to the androgen, 17beta-trenbolone (Tb) conducted to determine if partial-(F0) or single-generation (F1) fish exposures identify multigenerational (F0-F3) effects of androgens on fish. Adult F0 fish were exposed to 0.007, 0.027, 0.13, 0.87,and 4.1 microg Tb/L, the F1 generation to < or =0.87 microg Tb/L, the F2 fish to < or =0.13 microg Tb/L, and the F3 fish to < or =0.027 microg Tb/L. The highest concentrations with reproducing populations at the end of the F0, F1, and F2 generations were 4.1, 0.87, and 0.027 microg Tb/L, respectively. Reproduction in the F0, F1, and F2 generations was significantly reduced at 0.87, 0.027, and 0.027 microg Tb/L, respectively. Fish were significantly masculinized in the F1 generation exposed to 0.13 microg Tb/L or greater. Female plasma vitellogenin was significantly reduced in F0 fish exposed to > or =0.87 microg Tb/L. Gonadosomatic indices of the F0 and F1 generations were significantly increased at 0.87 and 0.13 microg Tb/L in the F0 and F1 generation, respectively, and were accompanied by ovarian histological changes. Reproduction was the most consistently sensitive measure of androgen effects and, after a life-cycle exposure, the daily reproductive rate predicted concentrations affecting successive generations. The present study provides evidence that a multiple generation exposure of fish to some endocrine-disrupting chemicals can result in developmental and reproductive changes that have a much greater impact on the success of a species than was indicated from shorter term exposures.