Sensitivity of lake sturgeon (Acipenser fulvescens) early life stages to 2,3,7,8‐tetrachlorodibenzo‐P‐dioxin and 3,3′,4,4′,5‐pentachlorobiphenyl

Donald E. Tillitt, Justin A. Buckler, Diane K. Nicks, James S. Candrl, Rachel A. Claunch, Robert W. Gale, Holly J. Puglis, Edward E. Little, Tiffany L. Linbo, Mary Baker

The aquatic foodweb of the Great Lakes has been contaminated with polychlorinated biphenyls (PCBs) since the mid-20th Century. Threats of PCB exposures to long-lived species of fish, such as lake sturgeon (Acipenser fulvescens), have been uncertain due to a lack of information of the relative sensitivity of the species. The objective of this study was to evaluate the sensitivity of early life stage lake sturgeon to 3,3',4,4',5-pentachlorobiphenyl (PCB 126) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure. Mortality, growth, morphological and tissue pathologies, swimming performance, and activity levels were used as assessment endpoints. Pericardial and yolk sac edema, tubular heart, yolk sac hemorrhaging, and small size were the most commonly observed pathologies in both TCDD and PCB-126 exposures, beginning as early as 4 day post-fertilization, with many of these pathologies occurring in a dose-dependent manner. Median lethal (LD50) concentrations for PCB 126 and TCDD in lake sturgeon were 5.4 (95% confidence interval, CI, 3.9-7.4) and 0.61 (95% CI 0.47-0.82) ng/g-egg, respectively. The resulting relative potency value for PCB 126 (REP = 0.11) was greater than the World Health Organization estimate for fish (toxic equivalency factor = 0.005), suggesting current risk assessments may underestimate PCB toxicity toward lake sturgeon. Swimming activity and endurance were reduced in lake sturgeon survivors from the median lethal doses at 60 days post-fertilization. Threshold and median toxicity values indicate lake sturgeon, like other Acipenser species, are more sensitive to PCB and TCDD than the other genera of sturgeon, Scaphirhynchus, found in North America. Indeed, lake sturgeon populations in the Great Lakes and elsewhere are susceptible to PCB/TCDD-induced developmental toxicity in embryos and reductions in swimming performance. This article is protected by copyright. All rights reserved.