Hazard assessment of selenium and other trace elements in wild larval razorback sucker from the Green River, Utah

Contaminant investigations of the Green River in northeastern Utah have doc umented selenium contamination at sites receiving irrigation drainage. The Green River provides critical habitat for four endangered fishes including the largest extant riverine population of endangered razorback sucker. Alth ough 2175 larval razorback suckers were collected from the river between 19 92 and 1996, very few juveniles have been captured within recent decades. S elenium concentrations were measured in larval razorback suckers collected from five sites in the Green River (Cliff Creek, Stewart Lake Drain, Sports man's Drain, Greasewood Corral, and Old Charlie Wash) to assess the potenti al for adverse effects on recruitment of larvae to the juvenile stage and t he adult population. Larvae from all sites contained mean selenium concentr ations ranging from 4.3 to 5.8 mu g/g. These values were at or above the pr oposed toxic threshold of 4 mu g/g for adverse biological effects in fish, which was derived from several laboratory and field studies with a wide ran ge of fish species. At two sites, Cliff Creek and Stewart Lake Drain, selen ium concentrations in larvae increased over time as fish grew, whereas sele nium concentrations decreased as fish grew at Sportsman's Drain. Evaluation of a 279-larvae composite analyzed for 61 elements demonstrated that selen ium and, to a lesser extent, vanadium mere elevated to concentrations repor ted to be toxic to a wide range of fish species. Elevated selenium concentr ations in larval razorback suckers from the five sites suggest that seleniu m contamination may be widespread in the Green River, and that survival and recruitment of larvae to the juvenile stage may be limited due to adverse biological effects. Selenium contamination may be adversely affecting the r eproductive success and recruitment of endangered razorback sucker. (C) 200 0 Academic Press.