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Assessment of the St. Louis River AOC fish tumors and other deformities beneficial use impairment
Hoffman, J., V. Blazer, AND P. Mazik. Assessment of the St. Louis River AOC fish tumors and other deformities beneficial use impairment. St. Louis River Summit, Superior, WI, March 14 - 15, 2017.
Impact statement: US EPA Areas of Concern are Great Lakes coastal communities that were identified as having substantial impairment of beneficial uses associated with aquatic resources owing to a legacy of water and sediment contamination. These beneficial uses are analogous to ecosystem services. Among those beneficial use impairments (BUI) is “Tumors and Other Deformities in Fish.” Here, we present a novel methodology for assessing this BUI and demonstrates its application in the St. Louis River Area of Concern. The methodogy and assessment will be used by the AOC leads (Minnesota, Wisconsin, Fond du Lac Band of Lake Superior Chippewa) to determine their progress towards BUI removal.
The Fish Tumors and Other Deformities Beneficial Use Impairment (BUI) was listed as one of nine BUIs at the time the St. Louis River AOC was designated in 1987. At the time, no formal studies had been conducted to estimate the prevalence of either fish tumors or deformities. To assess the current status of fish tumors and deformities in the AOC, adult white suckers (Catostomus commersonii) were sampled during the spawning period in May during 2011, 2013 and 2015. We measured each fish, determined its sex and age (sagittal otolith), sampled dorsal muscle tissue for carbon and nitrogen stable isotope ratios to determine river versus lake residency, and conducted a necropsy-based assessment to document grossly visible abnormalities. Pieces of any observable abnormalities were preserved for subsequent histological analyses. A total of 622 white sucker were surveyed from 2011 through 2015. Of these, 27 (4.3%) white suckers had skin neoplasms, all of which were papillomas. A total of 29 (4.7%) of the white suckers had liver neoplasms. Sex and age were significantly associated with skin neoplasia incidence, whereas only age was significantly associated with liver neoplasia incidence. Neither neoplasia type was significantly associated with habitat use, indicating that neoplasia incidence did not change with increasing feeding in the AOC relative to Lake Superior. Further, there was not a significant difference in skin or liver neoplasia incidence between migratory white sucker captured below the dam and land-locked white sucker captured above Fond du Lac Dam. We conclude that incidence rates of contaminant-related internal and external tumors and deformities in resident benthic fish species do not exceed incidence rates from unimpaired areas elsewhere in the Great Lakes Basin.