Contaminants of emerging concern in tributaries to the Laurentian Great Lakes: II. Biological consequences of exposure

<div><p>The Laurentian Great Lakes contain one fifth of the world’s surface freshwater and have been impacted by human activity since the Industrial Revolution. In addition to legacy contaminants, nitrification and invasive species, this aquatic ecosystem is also the recipient of Contaminants of Emerging Concern (CECs) with poorly understood biological consequences. In the current study, we documented the presence, concentrations, and biological effects of CECs across 27 field sites in six Great Lakes tributaries by examining over 2250 resident and caged sunfish (<i>Lepomis ssp</i>.) for a variety of morphological and physiological endpoints and related these results to CEC occurrence. CEC were ubiquitous across studies sites and their presence and concentrations in water and sediment were highest in effluent dominated rivers and downstream of municipal wastewater treatment plant discharges. However, even putative upstream reference sites were not free of CEC presence and fish at these sites exhibited biological effects consistent with CEC exposure. Only the Fox River exhibited consistent adverse biological effects, including increased relative liver size, greater prominence of hepatocyte vacuoles and increased plasma glucose concentrations. Canonical Redundancy Analysis revealed consistent patterns of biological consequences of CEC exposure across all six tributaries. Increasing plasma glucose concentrations, likely as a result of pollutant-induced metabolic stress, were associated with increased relative liver size and greater prominence of hepatocyte vacuoles. These indicators of pollutant exposure were inversely correlated with indicators of reproductive potential including smaller gonad size and less mature gametes. The current study highlights the need for greater integration of chemical and biological studies and suggests that CECs in the Laurentian Great Lakes Basin may adversely affect the reproductive potential of exposed fish populations.</p></div

Biological endpoints in resident male sunfish.

<p>(A) hepatosomatic index; (B) prevalence of vacuoles in hepatocytes ranked on a severity scale of 1 to 4; (C) plasma vitellogenin concentration (μg/mL); and (D) plasma glucose concentration (mg/mL). Sample river location located above panels (A) and (B), with columns representing upstream to downstream within each river from left to right. Specific sample site identification can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.t001" target="_blank">Table 1</a>. Column graphs indicate mean + standard deviation in panels (A) and (B). Box-and-whisker plots indicate range, 25^th and 75^th percentiles, and mean values in panels (C) and (D). Statistical significance (Kruskal-Wallis with Dunn’s post-test; p<0.05) within panels are identified by letters. P-values are summarized in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s016" target="_blank">S4 Table</a>. Sample size provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s015" target="_blank">S3 Table</a>.</p

Canonical redundancy analysis for water samples and biological results.

<p>(A) Resident females, (B) Resident males, (C) Caged females, and (D) Caged males. Number in parentheses on axes indicate the percent variability that is explained by that axis. Sample site information can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.t001" target="_blank">Table 1</a>. Sample class information can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.t002" target="_blank">Table 2</a>. Biological response information can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.t004" target="_blank">Table 4</a>, Figs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.g002" target="_blank">2</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.g005" target="_blank">5</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s006" target="_blank">S6</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s009" target="_blank">S9</a> Figs, and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s015" target="_blank">S3 Table</a>.</p

CEC concentration in sediment summed by class.

<p>CEC concentration in sediment summed by class.</p

Biological endpoints in resident female sunfish.

<p>(A) hepatosomatic index; (B) prevalence of vacuoles in hepatocytes ranked on a severity scale of 1 to 4; (C) plasma vitellogenin concentration (μg/mL); and (D) plasma glucose concentration (mg/mL). Sample river location located above panels (A) and (B), with columns representing upstream to downstream within each river from left to right. Specific sample site identification can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.t001" target="_blank">Table 1</a>. Column graphs indicate mean + standard deviation in panels (A) and (B). Box-and-whisker plots indicate range, 25^th and 75^th percentiles, and mean values in panels (C) and (D). Statistical significance (Kruskal-Wallis with Dunn’s post-test; p<0.05) within panels are identified by letters. P-values are summarized in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s016" target="_blank">S4 Table</a>. Sample size provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s015" target="_blank">S3 Table</a>.</p

Sample site information.

<p>Sample site information.</p

Biological endpoints in caged male sunfish.

<p>(A) hepatosomatic index; (B) prevalence of vacuoles in hepatocytes ranked on a severity scale of 1 to 4; (C) plasma vitellogenin concentration (μg/mL); and (D) plasma glucose concentration (mg/mL). Sample river location located above panels (A) and (B), with columns representing upstream to downstream within each river from left to right. Specific sample site identification can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.t001" target="_blank">Table 1</a>. Column graphs indicate mean + standard deviation in panels (A) and (B). Box-and-whisker plots indicate range, 25^th and 75^th percentiles, and mean values in panels (C) and (D). Statistical significance (Kruskal-Wallis with Dunn’s post-test; p<0.05) within panels are identified by letters. P-values are summarized in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s016" target="_blank">S4 Table</a>. Sample size provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s015" target="_blank">S3 Table</a>.</p

Biological endpoints in caged female sunfish.

<p>(A) hepatosomatic index; (B) prevalence of vacuoles in hepatocytes ranked on a severity scale of 1 to 4; (C) plasma vitellogenin concentration (μg/mL); and (D) plasma glucose concentration (mg/mL). Sample river location located above panels (A) and (B), with columns representing upstream to downstream within each river from left to right. Specific sample site identification can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.t001" target="_blank">Table 1</a>. Column graphs indicate mean + standard deviation in panels (A) and (B). Box-and-whisker plots indicate range, 25^th and 75^th percentiles, and mean values in panels (C) and (D). Statistical significance (Kruskal-Wallis with Dunn’s post-test; p<0.05) within panels are identified by letters. P-values are summarized in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s016" target="_blank">S4 Table</a>. Sample size provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184725#pone.0184725.s015" target="_blank">S3 Table</a>.</p

Ecotoxicogenomics to Support Ecological Risk Assessment: A Case Study with Bisphenol A in Fish

Effects of bisphenol A (BPA) on ovarian transcript profiles as well as targeted end points with endocrine/reproductive relevance were examined in two fish species, fathead minnow (<i>Pimephales promelas</i>) and zebrafish (<i>Danio rerio</i>), exposed in parallel using matched experimental designs. Four days of waterborne exposure to 10 μg BPA/L caused significant vitellogenin induction in both species. However, zebrafish were less sensitive to effects on hepatic gene expression and steroid production than fathead minnow and the magnitude of vitellogenin induction was more modest (i.e., 3-fold compared to 13 000-fold in fathead minnow). The concentration–response at the ovarian transcriptome level was nonmonotonic and violated assumptions that underlie proposed methods for estimating hazard thresholds from transcriptomic results. However, the nonmonotonic profile was consistent among species and there were nominal similarities in the functions associated with the differentially expressed genes, suggesting potential activation of common pathway perturbation motifs in both species. Overall, the results provide an effective case study for considering the potential application of ecotoxicogenomics to ecological risk assessments and provide novel comparative data regarding effects of BPA in fish

Ecotoxicogenomics to Support Ecological Risk Assessment: A Case Study with Bisphenol A in Fish

Effects of bisphenol A (BPA) on ovarian transcript profiles as well as targeted end points with endocrine/reproductive relevance were examined in two fish species, fathead minnow (<i>Pimephales promelas</i>) and zebrafish (<i>Danio rerio</i>), exposed in parallel using matched experimental designs. Four days of waterborne exposure to 10 μg BPA/L caused significant vitellogenin induction in both species. However, zebrafish were less sensitive to effects on hepatic gene expression and steroid production than fathead minnow and the magnitude of vitellogenin induction was more modest (i.e., 3-fold compared to 13 000-fold in fathead minnow). The concentration–response at the ovarian transcriptome level was nonmonotonic and violated assumptions that underlie proposed methods for estimating hazard thresholds from transcriptomic results. However, the nonmonotonic profile was consistent among species and there were nominal similarities in the functions associated with the differentially expressed genes, suggesting potential activation of common pathway perturbation motifs in both species. Overall, the results provide an effective case study for considering the potential application of ecotoxicogenomics to ecological risk assessments and provide novel comparative data regarding effects of BPA in fish