Annual and seasonal evaluation of reproductive status in hornyhead turbot at municipal wastewater outfalls in the Southern California Bight

Abstract

Treated wastewater effluent containing endocrine-disrupting chemicals is discharged into the coastal waters of the Southern California Bight (SCB) daily. The present study investigated changes in indicators of reproductive health and environmental estrogen exposure in hornyhead turbot (Pleuronichthys verticalis) near wastewater outfalls. Fish were collected from discharge areas, farfield stations, and a reference location in the SCB to examine spatial and temporal patterns. Fish from the Orange County outfall farfield site were younger and less sexually mature than fish from other sites. The sex ratio was skewed in some fish from outfall sites as well as from the Dana Point reference site. However, no consistent pattern in sex ratio was present over time. Low-level induction of vitellogenin was frequently observed in male fish from all sites, suggesting widespread exposure to estrogenic compounds, but did not appear to impact reproductive function as there was no incidence of gonad abnormalities (ova-testis). Analysis of historical hornyhead turbot trawl data indicated that populations are either increasing or stable in the SCB; thus, environmental estrogen exposure was not adversely impacting fish abundance. Additional research is needed to determine the cause of the estrogenic response in hornyhead turbot and whether the source of the estrogenic compounds is a consequence of historical contamination or of ongoing sources or representative of baseline characteristic of this species.

Trophic transfer and effects of DDT in male hornyhead turbot (Pleuronichthys verticalis) from Palos Verdes Superfund site, CA (USA) and comparisons to field monitoring

“…Several DDT isomers were found to bind the estrogen receptor in Japanese medaka (Chakraborty et al, 2011) and Atlantic salmon (Tollefsen et al, 2003), to alter gonadal development (Zaroogian et al, 2001), to depress plasma testosterone, and to induce vitellogenesis in juvenile male summer flounder in vivo (Mills et al, 2001). Induction of vitellogenin (VTG), an estrogen-dependent precursor egg yolk protein, and disruption of steroid hormones in flatfish from this site have also been noted in several studies (Schlenk et al, 2005; Rempel-Hester et al, 2009; Forsgren et al 2012; Reyes et al 2012). Induction of VTG in males has been shown to indicate exposure to estrogenic contaminants and potential reproductive impairment (Kidd et al, 2007).…”

Integrated coastal effects study: Synthesis of findings

“…Sampling and preservation methods for biological samples can be found in Vidal et al [32] and Forsgren et al [33]. The concentration of VTG was also measured in plasma.…”

“…One half of the gonad from each fish was preserved for histological analysis of sex, maturity state (based on the degree of gonad development [33]), and abnormalities in sexual development (e.g., presence of eggs in male gonad). The remaining half of the gonad was weighed to calculate the half gonadal somatic index (0.5 GSI), a measure of reproductive status.…”

Molecular Analysis of Endocrine Disruption in Hornyhead Turbot at Wastewater Outfalls in Southern California Using a Second Generation Multi-Species Microarray

“…Our objective was to use the microarray tool to assess gene expression levels for key biomarkers of endocrine disruption. Levels in plasma of vitellogenin, testosterone, estradiol, cortisol and thyroxine were determined in the fish selected for microarray analysis [Table 1] [19,32-34]. Table 1 reveals that there is substantial variation in hormone levels among the fish collected from different sites and between fish from the same site.…”

“…Plasma concentrations of steroid hormones and thyroxine levels and vitellogenin protein levels were measured as described in [19,34,61]. The methods are outlined below.…”