M4 PM Endocrine Disruption in Fish (Part 2)
Monday, 14 November 2005: 1:50 PM - 5:30 PM in Ballroom 4

(IRW-1116-377343) Relationships between reproductive endpoints measured in flatfish collected near an outfall in Orange County, California.

Irwin, M¹, Reyes, J², Steinert, S³, Hwang, W¹, Armstrong, J⁴, Sakamoto, K⁴, Kelley, K², Schlenk, D¹, ¹ University of California Riverside, Riverside, CA, USA² California State University Long Beach, Long Beach, CA, USA³ CSC Biomarker Laboratory, San Diego, CA, USA⁴ Orange County Sanitation District, Fountain Valley, CA, USA

ABSTRACT- Estrogenic activity in fish has primarily been evaluated using vitellogenin (vtg) expression in male and juvenile animals. Although the response has been widespread in field and laboratory studies, the relevance of the response to higher-level adverse effects, particularly in the field, is less than clear. Previous evaluations of vtg within flatfish species collected near the Orange County Sanitation District (OCSD) outfall and stations as far as 7.7 km down current indicated bioavailable estrogens within demersal flatfish populations. In order to evaluate the persistence of estrogenic activity and relationships to reproduction and development, fish were sampled in the winter and summer of 2003 and 2004 from the same locations and vtg, plasma estradiol (E2) concentrations, gonadosomatic indices (GSI), sperm DNA damage, development and gender ratios were measured in English Sole (Pleuronectes vetulus) and Hornyhead Turbot (Pleuronichthys verticalis). Variable levels of vtg were continually observed in plasma samples from fish collected in the locations analyzed. Vtg expression and plasma E2 levels were significantly correlated in female Hornyhead Turbot and both sexes of English Sole. A positive relationship was demonstrated between plasma E2 levels and sperm DNA damage. Rather than an expected feminization of populations, a trend toward masculinization was observed particularly at the OCSD outfall, as indicated by gender ratios and significantly higher GSI in males versus males from the reference station. These results are consistent with previous studies showing vtg expression in male flatfish, but no alteration in overall flatfish abundance at the sampled sites.

Key words: endocrine disruptor, vitellogenin, estradiol, DNA damage