Final Report: BUI Delisting Studies in the Rochester Embayment AOC, 2013-2014

Abstract

Substantial evidence of live mink was observed along the shoreline of the Genesee River portion of the RE AOC, which supports delisting the “mink are present and are reproducing” criterion of the Degradation of Fish and Wildlife Populations and the Loss of Fish and Wildlife Habitat BUIs. According to the USFWS Habitat Suitability Index Model, habitat appears to be highly suitable (85%) for mink along the Genesee River shoreline of the RE AOC, which supports delisting of the Loss of Fish and Wildlife Habitat BUI.For total mercury chemical analysis: a. No amphibian, crayfish and lower trophic level fish samples exceeded the published dietary lowest observed adverse effect level (LOAEL) for mink. b. All upper trophic level fish samples exceeded the published dietary LOAEL for mink (500 ng/g), by 13% on average. For PAH, PCB and dioxin (CDD)/furan (CDF) chemical analyses: a. None of the 12 composited mink prey samples exceeded dietary LOAELs for total PCBs (960,000 pg/g) and TEQ for CDD/CDF (9.2 pg/g). b. Ten of the 12 samples did not exceed the dietary LOAEL for PAHs, co-planar PCBs, and CDD/CDF combined (9.2 pg/g). c. One upper trophic level fish sample exceeded the dietary LOAEL for PAHs by 147% because it contained ~100 times more PAHs (which accounted for 95% of total TEQ in that sample) than the other two samples. d. One lower trophic level fish sample exceeded the dietary LOAEL for PCB TEQ by 4% because it contained ~90 times more PCB 126 (which accounted for 93% of total TEQ in that sample) than the other two samples. Mink hazard assessment: a. Using the “highest exposure” mink diet found in published literature (92% from aquatic sources), and using mean concentrations of BUI contaminants found in 2 potential mink prey in the Genesee River portion of the RE AOC, the maximum dietary exposure of mink would be 81% of the LOAEL for total mercury, 23% of the LOAEL for total PCBs, and 69% of the LOAEL for total TEQ (PAHs + CDD/CDF + co-planar PCBs). This is the “worst case” diet scenario. b. Using the average of six mink diets reported in published literature (65% from aquatic sources) comparable to what mink would eat in the Genesee River portion of the RE AOC, and using mean concentrations of BUI contaminants found in potential mink prey in the study area, the dietary exposure of mink would be 48% of the LOAEL for total mercury, 13% of the LOAEL for total PCBs, and 40% of the LOAEL for total TEQ. This is the “likely” diet scenario. It would be reasonable to delist the Bird or Animal Deformities or Reproductive Problems BUI in the RE AOC because: a. Except for total mercury (13% above) and total TEQ (3.4% below; CDD/CDF, PAH and co-planar PCB TEQ combined) in upper trophic level fish, mean concentrations of BUI contaminants in the other three mink prey groups (crayfish, amphibians, lower trophic level fish) were far below dietary LOAELs for mink. b. Using a worst case diet (92% aquatic) for mink, and the analytically-determined mean concentrations of BUI contaminants in potential prey, a hazard assessment showed that the dietary LOAELs for total mercury, total PCBs, and total TEQ would not be exceeded for mink in the Genesee River portion of the RE AOC.