Exposure of Juvenile Lake Sturgeon to Contaminants of Emerging Concern (CECs), Including Polybrominated Diphenyl Ethers (PBDEs): Location Differences and Effects on Thyroid Hormones

Abstract

Contaminants of emerging concern (CECs) are ubiquitous throughout aquatic environments. Previous research has shown that CECs can have detrimental effects on fish biology, potentially leading to population impacts. Specifically, polybrominated diphenyl ethers (PBDEs), a class of CECs, have been shown to alter thyroid hormones in fish, which can impact development, endocrine system functioning, and possibly imprinting. These impacts can lead to reproductive effects and population declines, which have serious implications for species of conservation priority, such as the Lake Sturgeon Acipenser fulvescens. To assess the effects of CECs and PBDEs, Lake Sturgeon were evaluated at rearing facilities within the Great Lakes basin during 2017-2018 to determine (1) whether exposure to CECs and PBDEs differs between facility locations and (2) whether changes in whole-body PBDE concentrations correlate with changes in thyroid hormones (triiodothyronine [T 3 ] and thyroxine [T 4 ]), which could indicate impacts to imprinting. Exposure to CECs and PBDEs differed among sites. The CECs that were detected in water across all sites included atrazine, hexachlorobenzene, N,N-diethyl-meta-toluamide (DEET), desethylatrazine, erythromycin, and metformin, with the highest concentrations (except for DEET) measured at the Maumee River (Ohio) streamside rearing facility.We detected PBDEs in every sample of water, food, and Lake Sturgeon eggs and whole bodies, and there were no differences in lipid-normalized total PBDE concentrations in whole bodies across sites. Concentrations of total PBDE and the PBDE congeners 47, 99, 100, 153, 154, and 209 in fish tissues did not correlate with serum T 3 and T 4 levels, indicating that observed concentrations were unlikely to negatively impact Lake Sturgeon rearing for the biological endpoints assessed. Overall, this study exemplifies a cautionary tale since CECs and PBDEs were identified throughout Lake Sturgeon habitat and in hatchery food sources. Fisheries managers should be aware of the potential for CEC and PBDE impacts even though current observed levels do not seem to be impacting Lake Sturgeon rearing success.

Exposure to and Biomarker Responses From Legacy and Emerging Contaminants Along Three Drainages in the Milwaukee Estuary, Wisconsin, USA

“…This result differed slightly from similar data collected along the Maumee River (C. M. Custer et al, 2020) where no associations were detected between those or other biomarkers and PBDE exposure. These swallow results from the Milwaukee estuary, however, were similar to thyroid hormone work done on juvenile lake sturgeon in the Great Lakes, which also had only weak (T3, r 2 = 0.04) or nonsignificant (T4 in serum, p > 0.05) correlations with total PBDE concentrations (Hummel et al, 2022). Because of the large number of correlations ( n = 300) in the present study and the low r 2 value for PBDE associations, these associations from the Milwaukee estuary sites could be due to chance alone and should be viewed with caution without further corroborating evidence.…”

“…Two, amphetamine and iopamidol, were detected in most liver tissues but were not detected in sediment. Iopamidol, however, was detected in two of three water samples collected at three lake sturgeon ( Acipenser fulvescens ) rearing facilities in the Milwaukee area (Hummel et al, 2022) but in only three of 13 sturgeon tissue samples. N,N ‐Diethyl‐meta‐toluamide was detected in all nestling samples including those from the reference lake.…”

“…N,N ‐Diethyl‐meta‐toluamide was detected in all nestling samples including those from the reference lake. Hummel et al (2022) detected DEET in three of three water samples in the Milwaukee area but also in the food samples from commercial sources that were fed to the sturgeon at the rearing facilities. Between these two sources (water and food), DEET was detected in 13 of 13 sturgeon whole‐body and egg samples at those facilities.…”

“…Desethylatrazine, detected in all nestling samples, was only detected in sediments at three sites in 2017 and none of the sites in 2018. Desethylatrazine is nearly always detected in water samples (Anderson et al, 1997), even in urban‐dominated drainages, and was detected in all three water samples in the Milwaukee area (Hummel et al, 2022). Desethylatrazine was not detected in sturgeon tissue, which contrasts with the tree swallow data.…”

Assessing Contaminants of Emerging Concern in the Great Lakes Ecosystem: A Decade of Method Development and Practical Application

“…Similarly, blood samples taken from lake sturgeon provided information about the occurrence and possible origins of select CECs that might contribute to understanding why sturgeon populations are struggling to recover in the Great Lakes (Banda et al, 2020). For example, studies on juvenile lake sturgeon from a streamside hatchery indicated that although exposure to CECs was occurring, this did not impact thyroid hormone titers enough to affect imprinting in the fish (Hummel et al, 2022). In other studies, collection of resident sunfish found a prevalence of adverse physiological effects at agriculturally dominated sites that would not necessarily have been predicted based solely on contaminant measurements (Cipoletti et al, 2020; Jorgenson et al, 2018; Thomas et al, 2017).…”