MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(GRO-1117-728467) Fry production of eastern mosquitofish collected from Florida streams receiving pulp and paper mill effluents.

Noggle, J^{1, 2}, Smith, J², Bradley, W³, Gross, T^{1, 2}, ¹ USGS-FISC-CARS, Gainesville, FL, USA² University of Florida, Gainesville, FL, USA³ NCASI, Vanceboro, NC, USA

ABSTRACT- Female mosquitofish with varying degrees of male gonopodial development have been observed in pulp and paper mill effluent-receiving streams for the past two decades. Impacts of this masculinization phenomenon on reproductive success have not been directly addressed despite speculation of negative impacts. The current study evaluated fry production and masculinization in females collected from two effluent-receiving streams in Florida over two reproductive seasons (one month the first year and four months the second year). The discharging mills differed greatly in furnish, processing, and product. In addition, only one mill was subject to EPA Cluster Rule. Potential exposure was documented by GC/MS analysis of wood extractives in water samples from field sites (e.g., phytosterols, resin and fatty acids). Morphological masculinization was consistent between years for one mill (overall average of 1.45+0.03) while the response was only detected the second year of study at the other mill (1.22+0.02 year one and 1.39+0.03 year two). Fecundity appeared reduced in the first year single collection for both effluent-exposed sites (average reduction of 5 to 8 number fry per female). However, population structures implied mosquitofish at effluent-exposed sites may have started reproducing sooner than at unexposed sites. Fry production over several months the second year affirmed different reproductive patterns in females among sites and through the season. Furthermore, overall fecundities were higher in females from one exposed site relative to respective references. Variation in fecundity among all sites, regardless of exposure, ranged 2 fry per female. For both years of fry production, fecundity did not correlate with anal fin elongation. Rather than negatively impacting fecundity, pulp and paper mill effluent exposure may be stimulating modified reproductive strategies in mosquitofish influenced by changes in environmental and ecological factors as opposed to chemical exposure.

Key words: Mosquitofish, masculinization, pulp and paper mill effluent, reproduction