Assessment of Reproductive Effects in Largemouth Bass (Micropterus salmoides) Exposed to Bleached/Unbleached Kraft Mill Effluents

Abstract

This study evaluated the potential effects of different concentrations of bleached/unbleached kraft mill effluent (B/UKME) on several reproductive endpoints in adult largemouth bass (Micropterus salmoides). The kraft mill studied produces a 50/50 mix of bleached/unbleached market pulp with an estimated release of 36 million gal of effluent/day. Bleaching sequences were C90d10EopHDp and CEHD for softwood (pines) and hardwoods (mainly tupelo, gums, magnolia, and water oaks), respectively. Bass were exposed to different effluent concentrations (0 [controls, exposed to well water], 10, 20, 40, or 80%) for either 28 or 56 days. At the end of each exposure period, fish were euthanized, gonads collected for histological evaluation and determination of gonadosomatic index (GSI), and plasma was analyzed for 17beta-estradiol, 11-ketotestosterone, and vitellogenin (VTG). Largemouth bass exposed to B/UKME responded with changes at the biochemical level (decline in sex steroids in both sexes and VTG in females) that were usually translated into tissue/organ-level responses (declines in GSI in both sexes and in ovarian development in females). Although most of these responses occurred after exposing fish to 40% B/UKME concentrations or greater, some were observed after exposures to 20% B/UKME. These threshold concentrations fall within the 60% average yearly concentration of effluent that exists in the stream near the point of discharge (Rice Creek), but are above the <10% effluent concentration present in the St. Johns River. The chemical(s) responsible for such changes as well as their mode(s) of action remain unknown at this time.

Environmental contaminants and biomarker responses in fish from the Rio Grande and its U.S. tributaries: Spatial and temporal trends

“…The HSI range for RGB bass was 0.6-1.5%, which is also typical for Micropterus sp. Liver enlargement has been reported in largemouth bass from PCB-contaminated sites (Adams and McLean, 1985) as well as in other fishes exposed to contaminants in both field and laboratory studies (see review by Dethloff and Schmitt, 2000 and subsequent studies by Sepú lveda et al, (2001Sepú lveda et al, ( , 2003. The liver represented 0.5-1.5% of body weight in most male and female bass collected from the MRB in 1995, but enlarged livers were detected in bass from a few PCB-and pesticide-contaminated sites (Blazer et al, 2002).…”

“…In the MRB, ovotestis was detected in male bass of both species, but a high percentage (N50%) of affected fish was only observed in smallmouth bass at one site and none were detected in carp (McDonald et al, 2002). Baldigo et al (2000) detected similar percentages of both largemouth and smallmouth bass at some Hudson River (New York) sites, but no intersex males were reported among the largemouth bass exposed to paper mill effluents by Sepú lveda et al (2001Sepú lveda et al ( , 2003.…”

“…In contrast, Wainwright et al (2001) noted a positive correlation between GSI carcass concentrations of p,pV-DDE and plasma androgen concentrations in male carp from resacas and settling basins in the lower Rio Grande valley. Changes in GSI have been reported in fish exposed to a variety of endocrine-modulating substances (e.g., Sepú lveda et al, 2001;Orlando et al, 2004); however, such differences may only become apparent as the spawning season approaches.…”

Effects of hexazinone and atrazine on the physiology and endocrinology of smolt development in Atlantic salmon

“…Changes in liver weight have been associated with vitellogenesis in both sexes (Jalabert, 2005), and with increased detoxification of xenobiotics (Zhou et al, 1999;Sepulveda et al, 2001). The observed increase in HSI following ATZ exposure is most likely due to the enhanced activity of xenobiotic biotransformation.…”

Dietary exposure of largemouth bass to OCPs changes expression of genes important for reproduction

“…Fish were euthanized by submersion in a water bath containing 50-110 ppm tricaine methanesulfonate (MS-222) and sacrificed by a sharp blow to the head followed by cervical transection in accordance with the University of Florida's Institutional Animal Care and Use Committee (IACUC) guidelines. Blood was collected from the caudal vein for plasma E 2 and 11-KT measurements, which were performed using a radioimmunoassay (RIA) as previously described (Sepúlveda et al, 2001). Liver and gonadal tissues were excised, immediately flash frozen in liquid nitrogen, and stored at −80 °C until RNA was isolated.…”