As part of a larger survey on cumulative effects within the Saint John River basin (Canada), a fish survey was conducted near Edmundston (NB, Canada) in the fall of 1999 using slimy sculpin (Cottus cognatus) and white sucker (Catostomus commersoni). The discharge environment receives effluent from the pulp mill, a paper mill, three sewage discharges, and tributaries receiving agricultural runoff. Sculpin collected downstream of the sewage discharges and pulp mill effluent had greater growth, condition, and liver size but no significant differences in gonad size. Stable isotope data indicated slimy sculpin did not move between sites. Female sculpin collected downstream of the paper mill showed no significant differences in length, body weight, age, condition factor, liver size, and gonad size compared to fish from reference sites. Female white sucker collected downstream of the pulp mill did not differ significantly in any measured parameter compared to reference fish. Liver sizes of white sucker from the Saint John River were outside the range considered to be indicative of uncontaminated riverine sites. In 2000, sculpin collected downstream from a poultry‐processing facility had larger livers and lower condition factors, suggesting that the site is contaminated. We found no significant differences in sculpin length, weight, condition (except for males), and liver size in sculpin collected downstream from the pulp mill in October 2001. The responses of slimy sculpin and white sucker differed, perhaps in relation to differences in life history characteristics. Results from this study indicate the slimy sculpin is a suitable fish species for monitoring rivers that receive multiple industrial and municipal effluents.

The goal of this study was to assess the responses of fathead minnows (FHM) exposed to known endocrine-disrupting substances (EDS) in our labs. As well, we wanted to examine the applicability and sensitivity of the full lifecycle FHM test for use on-site, exposing fish to a complex environmentally relevant Canadian effluent. Fathead minnows exposed from the egg stage to ethinylestradiol (EE2, 0-32 ng/L) or methyltestosterone (MT, 0-3200 ng/L) had decreased growth (length, weight) at high concentrations. Development of secondary sex characteristics was a sensitive indicator of exposure to androgen and estrogen. Fish exposed to MT showed premature male sex characteristics such as nuptial tubercles by 30 days post-hatch (dph). These changes were more dramatic in older fish (at 60 and 90 dph), which showed premature male sex characteristics at very low MT concentrations (100 ng/L). Fish exposed to 3.2 ng/L EE2 had premature development of ovipositors at 60 dph. As well, exposure to very high MT concentrations (1000 and 3200 ng/L) caused development of ovipositors after 60 days (but not at 20 and 30 dph), presumably due to aromatization of MT to methylestradiol (as suggested by other researchers). The fathead minnow lifecycle assay, tested with a known estrogen and androgen, proved to be useful for detection of EDS-related changes caused by a real-life effluent mixture. Lifecycle exposures of fathead minnow eggs to bleached sulphite mill effluent (BSME) showed changes in secondary sex characteristics and growth. In contrast to EE2 and MT, fish exposed to BSME had increased growth. Changes in secondary sex characteristics of fish were seen in both male and female minnows exposed to BSME, but there was an overall shift towards increasing numbers of female fish (based on external sex). The full lifecycle assay provides a definitive test for reproductive/EDS effects, and it appears that some of the most sensitive endpoints we studied were the premature development of secondary sex characteristics.

To assess the potential effects of exposure to bleached sulfite mill effluent, long-term fathead minnow (Pimephales promelas) exposures were carried out on-site at the pulp mill secondary treatment lagoons. Exposure concentrations included 0, 1, 3, 10, 30, 50, or 100% final effluent, with the synthetic estrogen ethinylestradiol (10 ng/L) as a positive control compound. Fertilized minnow eggs were hatched in effluent and monitored through 140 d posthatch. The effluent produced a significant increase in the growth (length, weight, condition factor) of female fish (but not male fish). Exposure to high effluent concentrations resulted in a majority of fish with female secondary sex characteristics. Male fish with female characteristics and female fish with male sex characteristics were present at effluent concentrations of > or = 30%, but not in fish exposed to control water from the Saint John River. Effluent exposures (> or = 30%) also produced a reduction in the number of fish with testes, and most fish had ovaries when examined internally. A sensitive and meaningful endpoint was a decrease in reproduction. Fish exposed to 1 - 3% effluent produced a similar number of eggs to control fish; however, exposure to 10% effluent reduced egg production by over 80%. Fish exposed for an entire life cycle to > or = 30% effluent failed to produce eggs. The research demonstrates the feasibility and potential usefulness of on-site flow-through fish life-cycle exposures for the assessment of pulp mill final effluents.

Yellow perch captured downstream of a bleached sulfite mill had reduced gonad size and fecundity, and circulating steroid levels declined in goldfish exposed to final effluent for 21 d. To assess bleached sulfite mill (BSM) effluent, long-term fathead minnow (Pimephales promelas) growth and reproduction tests were carried out in a flow-through bioassay trailer at the mill secondary treatment lagoons. Fertilized P. promelas eggs were hatched in effluent (0, 1, 3.2, 10, 32, 50, and 100% final effluent with 10 ng/L ethinylestradiol as a positive control compound) and monitored through to 30, 60, and 125 d posthatch. The effluent caused a significant increase in the growth of fish; this effect was evident within 30 d. Fish had changes in secondary sex characteristics at maturity: Male fish had ovipositors in effluent concentrations as low as 3.2%. Higher effluent concentrations (32-100%) resulted in a majority of fish that looked externally like females. Changes in external sex characteristics were the most sensitive endocrine disruption-specific endpoints and required four months of exposure. Exposure to low BSM effluent concentrations (3.2%) resulted in female fish that had male sex characteristics (tubercles and dorsal fin dots). This masculinization of female fish was statistically significant at 10% effluent and was not seen in control fish. Concentrations of final effluent in the Saint John River (Canada) range from less than 1% to 15%, depending on the season and river flow. The research assesses some of the changes seen in fathead minnows exposed to this complex effluent, and demonstrates a threshold of <10% BSM effluent for the most sensitive effects.