Biomonitoring recycled water in the Santa Ana River Basin in southern California

Effects of bifenthrin on sex differentiation in Japanese Medaka (Oryzias latipes)

Bifenthrin (BF) is a pyrethroid insecticide used in urban and agricultural applications. Previous studies in early life stages of fish have indicated anti-estrogenic activity; however, estrogenic activity has been observed in adults. To test the hypothesis that BF impairs sex differentiation, larval Japanese Medaka were exposed to BF during a critical developmental window for phenotypic sexual differentiation. Fish were exposed to environmentally relevant concentrations of BF (0.15 μg/L and 1.5 μg/L), a single concentration (0.3 mg/L) of an estrogen receptor (ER) antagonist (ICI 182,780), and an ER agonist (0.2 ug/L) (17β-estradiol). Fish were exposed at 8 days post hatch (dph) larvae for 30 days. Phenotypic sex, secondary sexual characteristics (SSC) and genotypic sex were investigated at sexual maturity (8 weeks). A trend towards masculinization (p = 0.06) based on the presence of papillary processes in anal fin rays of Japanese Medaka was observed in fish exposed to the lowest concentration of BF. However, genotypic gender ratios were not altered. These results show sex differentiation was not significantly altered by larval exposure to BF in Japanese medaka.

Evaluation of chemical, molecular, and traditional markers of fecal contamination in an effluent dominated urban stream

In this paper we present a quantitative sanitary survey of the Middle Santa Ana River, in southern California, utilizing a variety of source tracking tools, including traditional culture-dependent fecal markers (Enterococcus and Escherichia coli by IDEXX), speciation of enterococci isolates, culture-independent fecal markers (human-specific HF183 Bacteroides and Enterococcus by quantitative polymerase chain reaction, qPCR), and chemical markers of sewage and wastewater (nutrients, enantiomeric fraction (EF) of propranolol and ethylenediaminetetraacetic acid). To facilitate comparison of these different methods, data are interpreted in a loading (i.e., mass per time) framework that enables a quantitative apportionment of fecal markers and nutrients to specific source waters in the Middle Santa Ana River. Multiple lines of evidence support the hypothesis that Enterococcus in the Middle Santa Ana River originates primarily from in situ growth in streambed sediments, not from significant and persistent sources of untreated human waste. The EF of propranolol of tertiary treated wastewater effluent is in the range (0.42 to 0.71) previously reported for raw sewage, making EF of propranolol an unsuitable marker for fecal pollution, at least at this site. The human fecal marker HF183 Bacteroides was detected at a few sites, although not in a source of disinfected and tertiary treated wastewater effluent. Based on the results presented here and prior experience at other sites in southern California, HF183 Bacteroides would appear to be a candidate marker of fecal contamination for inland waters, although more qPCR measurements in disinfected wastewater effluent are needed to account for variations due to treatment plant performance and other factors. More generally, our results support the notion that regrowth of fecal indicator bacteria (FIB) in river sediments may lead to a decoupling between FIB and pathogen concentrations in the water column and thus limit the utility of FIB as an indicator of recreational waterborne illness in inland waters.

Site-specific profiles of estrogenic activity in agricultural areas of California's inland waters

To evaluate the occurrence and sources of compounds capable of feminizing fish in agriculturally impacted waterways of the Central Valley of California, water samples were extracted and subjected to chemical analyses as well as in vitro and in vivo measurements of vitellogenin in juvenile rainbow trout (Oncorhynchus mykiss). Among the 16 sites sampled, 6 locations frequently exhibited elevated concentrations of estrogenic substances with 17beta-estradiol equivalents up to 242 ng/L in vitro and 12 microg/kg in vivo. The patterns of activity varied among sites, with two sites showing elevated activity only in vitro, two showing elevated activity only in vivo, and two showing elevated activity in both assays. Sequential elution of solid-phase extraction (SPE) disks followed by bioassay-guided fractionation was used to characterize water samples from the two locations where activity was observed in both bioassays. The highest estrogenic activity was observed in the most nonpolar fractions (80-100% methanol eluent) from the Napa River, while most of the activity in the Sacramento River Delta eluted in the 60% methanol eluent. Quantitative analyses of SPE extracts and additional HPLC fractionation of the SPE extracts by GC-MS/MS and LC-MS/MS indicated concentrations of steroid hormones, alkylphenol polyethoxylates, and herbicides that were at least 1-3 orders of magnitude below bioassay 17beta-estradiol equivalent calculations. Given the different patterns of activity and chemical properties of the estrogenic compounds, it appears that estrogenic activity in these agriculturally impacted surface waters is attributable to multiple compounds. Further investigation is needed to identify the compounds causing the estrogenic activity and to determine the potential impacts of these compounds on feral fish.

Estrogenic activity and reproductive effects of the UV-filter oxybenzone (2-hydroxy-4-methoxyphenyl-methanone) in fish

Previous studies in extracts of sediments surrounding municipal outfalls off the coast of California, USA and effluents of New York City, NY, USA indicated the UV-filtering agent, oxybenzone (CAS# 131-57-7; benzophenone-3) as a potential estrogen. The effects of oxybenzone on estrogenic activity and reproduction were evaluated using a 14-day juvenile rainbow trout assay for plasma vitellogenin and a subsequent 21-day Japanese medaka reproduction assay. Significant induction of vitellogenin was observed in the rainbow trout at the 1000 microg/L nominal concentration (749 microg/L median measured value) of oxybenzone which was approximately 75 times greater than the concentrations observed in previous wastewater effluent. Vitellogenin induction was also observed in the 1000 microg/L nominal concentration (620 microg/L median measured) of oxybenzone in male Japanese medaka (Oryzias latipes) after 21 days of exposure. The number of eggs produced per female per day exposed to the same concentration (620 microg/L) were significantly lower after 7 days, but returned to control values after 21 days. Fertilized eggs were then monitored for 20 days to assess hatching success. The overall percentage of fertilized eggs collected during the 21-day exposure that hatched was significantly lower in the 620 microg/L oxybenzone concentration. There was also a temporal effect at this concentration as egg viability (percentage of fertilized eggs that hatched) was diminished 13-15 days after eggs were collected. All three oxybenzone concentrations (16, 132, and 620 microg/L) and the 50 ng/L estradiol positive control showed reduced hatching of eggs at day 15, and the 132 and 620 microg/L oxybenzone concentrations diminished the percentage of eggs that hatched on days 13-15. These data indicate that the UV-filter oxybenzone alters endocrine or reproduction endpoints in two fish species, but at concentrations significantly higher than those measured in the environment.