A HEALTH RISK EVALUATION FOR PALLID STURGEON (SCAPHIRHYNCHUS ALBUS) IN THE LOWER PLATTE RIVER USING SHOVELNOSE STURGEON (SCAPHIRHYNCHUS PLATORYNCHUS) AS A SURROGATE

Authors

Matthew S. Schwarz, U.S. Fish and Wildlife Service
Christina D. Lydick, U.S. Fish and Wildlife Service
Donald E. Tillit, U.S. Geological Survey
Diana M. Papoulias, U.S. Geological Survey
Timothy S. Gross, U.S. Geological Survey

Date of this Version

2006

Comments

Published by the U.S. Fish and Wildlife Service, 1-119, (2006)

Abstract

Most sturgeon species worldwide have been in steep decline since the 1900s. This research evaluated shovelnose sturgeon health, reproduction, and exposure to environmental contamination in the lower Platte River. Shovelnose sturgeon served as a surrogate species for the endangered pallid sturgeon and their health was assessed by incorporating measurements of general health with hepatic, immune, and reproductive system biomarkers. Environmental contaminants were measured in water, potential pallid sturgeon food items (cyprinid minnows), and shovelnose sturgeon digesta, liver, and blood plasma. Contaminants detected in shovelnose sturgeon at concentrations of concern included PCBs, selenium, and atrazine. Total PCBs in carcasses (n = 8) averaged 0.32 μg/g ww. Selenium averaged 4.8 μg/g dw in carcasses (n = 30) and 80 percent of individuals sampled were within the 4 to 6 μg/g threshold range for reproductive impairment in sensitive fish species. Pallid sturgeon food items had significantly (p < 0.05) greater concentrations of Hg, Se, and Zn than shovelnose sturgeon digesta. Atrazine was detected in all blood plasma samples analyzed (n = 50) at concentrations from 0.24 to 28 μg/L, but was not detected in liver (n = 19). Although the effects of atrazine exposure to shovelnose sturgeon are unknown, results of this study and previous work by others indicate that it may be disrupting steroidogeneisis. Gross observations and condition indices seem to indicate that shovelnose sturgeon from the lower Platte River are healthy; however, reproductive biomarkers and histological examination of gonads indicate potential reproductive impairment as indicated by ovicular atresia, abnormal estrogen to testosterone ratios, and high concentrations of vitellogenin in males. Pallid sturgeon may be especially at risk to contaminants in the lower Platte River that bioaccumulate and cause reproductive impairment because they have a more piscivourus diet, greater maximum life-span, and a longer reproductive cycle than shovelnose sturgeon. Strategies to reduce shovelnose sturgeon and pallid sturgeon exposure to environmental contaminants in the lower Platte River are presented.