380 Environmental Toxicology and Chemistry, Vol. 21, No. 2, pp. 380–389, 2002 Printed in the USA 0730-7268/02 $9.00 + .00 A TEMPERATE REEF FISH, TAUTOGOLABRUS ADSPERSUS, (WALBAUM) AS A POTENTIAL MODEL SPECIES FOR LABORATORY STUDIES EVALUATING REPRODUCTIVE EFFECTS OF CHEMICAL EXPOSURE RUTH E. GUTJAHR-GOBELL,* MARINA HUBER,DORANNE J. BORSAY HOROWITZ,GERALD E. ZAROOGIAN, and LESLEY J. MILLS U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, 27 Tarzwell Drive, Narragansett, Rhode Island 02882 ( Received 5 February 2001; Accepted 5 August 2001) Abstract—In ecotoxicological testing, there are few studies that report on reproductive output (egg production) of marine or estuarine fish. Cunner (Tautogolabrus adspersus) were studied as a potential model species to evaluate the impact of pollutants with estrogenic activity on reproduction in estuarine fish populations. Cunner inhabit marine and estuarine areas where contaminant discharges are likely. Baseline values for cunner gonadosomatic index (GSI), hepatosomatic index (HSI), and plasma vitellogenin (VTG) were determined in a field reference site (April 1999–December 1999). Male and female GSI indicated that cunner spawning is synchronized. Female HSI and VTG increased prior to GSI. From our laboratory observations, cunner are suitable for conducting experiments with reproductive endpoints indicative of both exposure (vitellogenin levels) and effects (egg production). However, cunner are not sexually dimorphic and stripping ripe fish is the only method to distinguish sex. In preparation for laboratory exposure studies with cunner, we designed a laboratory experimental holding system to accommodate cunner’s reproductivebehavior, a vertical spawning run to the water surface. Cunner were successfully acclimated from overwintering torpor to spawning condition in the laboratory by gradually changing the environmental conditions of fish held at winter conditions (4°C and 9:15-h light:dark photoperiod) to spawning condition (18°C and 15:9-h light:dark photoperiod). Our results show that cunner successfully spawned daily in the laboratory. They produced fertile eggs in our experimental system designed to accommodate cunner’s vertical spawning runs, demonstrating that male and female reproductive behavior was synchronized in the laboratory. Our observations indicate that cunner would be a useful model species for evaluating reproductive effects of environmental contaminants in laboratory studies. Keywords—Tautogolabrus adspersus Experimental system Reproductive function Vitellogenin Fish INTRODUCTION Many industrial and domestic wastes containing both nat- ural and man-made chemicals eventually reach estuarine eco- systems [1–4]. There is public and scientific concern that some of these chemicals, especially those with estrogenic activity, may exert negative environmental effects by disrupting the reproductive processes of exposed wildlife [5–7]. Anthropo- genic estrogens in aquatic environments include polyaromatic hydrocarbons and polyhalogenated aromatic hydrocarbons, in- cluding polychlorinated biphenyls, tetrachlorinated dibenzo- dioxins, tetrachlorinated dibenzofurans, and certain pesticides and their metabolites (e.g., DDT and dieldrin) [8–13]. Addi- tionally, the main estrogenic compound of the combined oral contraceptive pill, ethinyl estradiol, and the natural estrogens, 17-estradiol and estrone, have been detected in rivers re- ceiving sewage treatment effluent at concentrations that cause estrogenic effects in male rainbow trout [2,4,14]. In oviparous vertebrates like fish, the production of eggs by the female depends on the transmission of an estrogenic signal from the ovary to intracellular estrogen receptors in the liver, triggering the synthesis of essential egg components such as the egg-yolk protein precursor vitellogenin. A number of * To whom correspondence may be addressed (gobell.ruth@epa.gov). Atlantic Ecology Division contribution 0044. Mention of trade names of commercial products does not constitute endorsement or recommendation for use by U.S. Environmental Pro- tection Agency. contaminants found in aquatic environments may interfere with fish egg production by interfering with normal estrogen receptor response. Yet in ecotoxicological testing, there are few studies that report on reproductive output (egg production) of marine and estuarine species exposed to contaminants in the laboratory. Black and others [15] studied the effects of a mixture of polychlorinated biphenyls by intraperitoneal injec- tion on egg production of the small estuarine fish Fundulus heteroclitus. Sheepshead minnow (Cyprinodon variegatus), another small estuarine fish, has also been studied for the effects of estrogenic chemicals on vitellogenin induction in mature male fish [16,17]. In fresh water, Ankley and coworkers describe a short-term test in which they measure fecundity, egg fertility, and development in fathead minnow (Pimephales promalas) exposed to methoxychlor and methyltestosterone [18]. Cunner, Tautogolabrus adspersus (Walbaum), a northern member of the primarily tropical Labridae family, have a wide range along the western North Atlantic coast from South Car- olina, USA, to Nova Scotia, Canada [19]. Cunner are common in shallow inshore waters near sheltered rock substrates, wharves, wrecks, and reefs. Like other wrasses, cunner use these habitats as a shelter or cover for protection during their evening quiescence and during their overwintering torpor [20]. Because cunner are found inshore, they may experience greater exposure to industrial discharges, agricultural runoff, and sew- age treatment effluent than offshore species [1]. Cunner’s per- sistence in shallow, inshore estuarine environments during