Reconnaissance of Surface Water Estrogenicity and the Prevalence of Intersex in Smallmouth Bass (Micropterus Dolomieu) Inhabiting New Jersey

Abstract

The observation of testicular oocytes in male fishes has been utilized as a biomarker of estrogenic endocrine disruption. A reconnaissance project led in the Northeastern United States (US) during the period of 2008-2010 identified a high prevalence of intersex smallmouth bass on or near US Fish & Wildlife Service National Wildlife Refuges that included the observation of 100% prevalence in smallmouth bass males collected from the Wallkill River, NJ, USA. To better assess the prevalence of intersex smallmouth bass across the state of New Jersey, a tiered reconnaissance approach was initiated during the fall of 2016. Surface water samples were collected from 101 (85 river, 16 lake/reservoir) sites across the state at base-flow conditions for estrogenicity bioassay screening. Detectable estrogenicity was observed at 90% of the sites and 64% were above the US Environmental Protection Agency trigger level of 1 ng/L. Median surface water estrogenicity was 1.8 ng/L and a maximum of 6.9 ng/L E2Eq_BLYES was observed. Adult smallmouth bass were collected from nine sites, pre-spawn during the spring of 2017. Intersex was identified in fish at all sites, and the composite intersex prevalence was 93.8%. Prevalence across sites ranged from 70.6% to 100%. In addition to intersex, there was detectable plasma vitellogenin in males at all sites. Total estrogenicity in surface water was determined at these fish collection sites, and notable change over time was observed. Correlation analysis indicated significant positive correlations between land use (altered land; urban + agriculture) and surface water estrogenicity. There were no clear associations between land use and organismal metrics of estrogenic endocrine disruption (intersex or vitellogenin). This work establishes a baseline prevalence of intersex in male smallmouth bass in the state of New Jersey at a limited number of locations and identifies a number of waterbodies with estrogenic activity above an effects-based threshold.

Keywords: bioassay; endocrine disruption; estrogen; fish; intersex; land use; smallmouth bass.

Figure 1

Surface water and fish sampling locations throughout New Jersey. Ranges of total estrogenicity (ng/L E2Eq_BLYES) are binned as below detection (BD), low (0.23–0.80), medium (0.80–2.00) and high (>2.00). Values are those from the fall 2016 sampling. Dominant land-use designations are colormetrically depicted across the landscape.

Figure 2

(A) Seasonal variation in EEQ_BLYES at the fish collection sites. (B) Intersex severity in male smallmouth bass collected from New Jersey during the spring of 2017. Intersex prevalence (%) is indicated at the base of each vertical bar. Error bars denote standard error of the mean. Statistical differences in intersex severity are indicated above vertical bars. Bars denoted with different letters indicate statistically significant differences (α = 0.05). Site abbreviations are defined in Table 1. Dotted line indicates the USEPA effects-based trigger value (EBT) of 1 ng/L E2Eq. BD indicates values below detection.

Figure 3

Plasma vitellogenin in female and male smallmouth bass collected in New Jersey during the spring of 2017. Sites are ordered along the x-axis based on decreasing intersex severity observed in male fish. Box and whisker plots with 95% confidence intervals. Black dots indicate outliers. Bars denoted with different letters indicate statistically significant differences (α = 0.05). Site abbreviations are defined in Table 1.