You are here:
EFFECTS OF 17B ESTRADIOL AND ETHINYL ESTRADIOL ON REPRODUCTIVE INDICATORS IN LABORATORY-EXPOSED CUNNER, TAUTOGOLABRUS ADPERSUS
Citation:
Mills, L J., R GutjahrGobell, D Borsay, M Huber, AND G Zaroogian. EFFECTS OF 17B ESTRADIOL AND ETHINYL ESTRADIOL ON REPRODUCTIVE INDICATORS IN LABORATORY-EXPOSED CUNNER, TAUTOGOLABRUS ADPERSUS. Presented at The 1st Biennial Conference on the Biology of Taugtog and Cunner, Sponsored By NOAA and CT Dept of Environmental Protection, Mystic CT, November 30-December 1, 1999.
Description:
Cunner (Tautogolabrus adspersus) are being studied in our laboratory to evaluate how 17 - estradiol and ethinyl estradiol affect their reproductive success. Cunner was selected because this species spawns daily, is common in estuarine areas, is easily obtainable, and is amenable to laboratory holding. Both 17 -estradiol and ethinyl estradiol are environmental estrogens that have been detected in concentrations causing estrogenic effects in fish from rivers receiving sewage treatment effluent. In our experiments, fish of both sexes were exposed through subcutaneous implant of the test estrogen in a controlled release matrix (ethylcellulose and ethoxylated castor oil). In two eight week experiments, male and female laboratory-held cunner were taken from winter conditions, injected with the appropriate treatment, and gradually acclimated to spring spawning conditions over a period of several weeks. Treatments tested in these experiments were uninjected control, matrix-injected control, and 0.05, 0.5 or 2.5 mg/kg concentrations of either 17 -estradiol or ethinyl estradiol. Egg production and egg viability were recorded daily over the eight week exposure period. Over the course of the experiment, fish treated with the lowest concentration of 17 -estradiol produced more eggs per female than any other treatment, while cunner given the highest concentration produced fewer viable eggs. In the fish treated with ethinyl estradiol, the highest concentration yielded the highest number of eggs per female, while viability of eggs from fish treated with the lowest concentration was half that of controls. Gonadosomatic index (GSI) was determined at the end of each experiment for all surviving fish. Males treated with 17 -estradiol showed a concentration-related increase in GSI while those treated with ethinyl estradiol exhibited a concentration-related decrease. In a third experiment, egg production, egg fertility and egg viability were recorded daily for two weeks in spawning fish before they were treated, and then for another two weeks after the fish were injected with the appropriate treatment. Treatments for this experiment were matrix-injected controls, 0.05 or 0.5 mg/kg 17 -estradiol, 0.05 or 0.5 mg/kg ethinyl estradiol, and a combination of both estrogens at their lowest dose. Preliminary results indicate egg production per female decreases dramatically in treatments with ethinyl estradiol alone, but this effect is offset to some degree in the combination treatment. Overall, results of these experiments suggest that exposure to estrogens can impact the reproductive success of cunner.