Concentrations of Cadmium, Cobalt, Lead, Nickel, and Zincin Blood and Fillets of Northern Hog Sucker (Hypenteliumnigricans) from Streams Contaminated by Leadâ•fiZinc Mining: Implications for Monitoring

Lead (Pb) and other metals can accumulate in northern hog sucker (Hypentelium nigricans) and other suckers (Catostomidae), which are harvested in large numbers from Ozark streams by recreational fishers. Suckers are also important in the diets of piscivorous wildlife and fishes. Suckers from streams contaminated by historic Pb–zinc (Zn) mining in southeastern Missouri are presently identified in a consumption advisory because of Pb concentrations. We evaluated blood sampling as a potentially nonlethal alternative to fillet sampling for Pb and other metals in northern hog sucker. Scaled, skin-on, bone-in ‘‘fillet’’ and blood samples were obtained from northern hog suckers (n = 75) collected at nine sites representing a wide range of conditions relative to Pb–Zn mining in southeastern Missouri. All samples were analyzed for cadmium (Cd), cobalt (Co), Pb, nickel (Ni), and Zn. Fillets were also analyzed for calcium as an indicator of the amount of bone, skin, and mucus included in the samples. Pb, Cd, Co, and Ni concentrations were typically higher in blood than in fillets, but Zn concentrations were similar in both sample types. Concentrations of all metals except Zn were typically higher at sites located downstream from active and historic Pb–Zn mines and related facilities than at nonmining sites. Blood concentrations of Pb, Cd, and Co were highly correlated with corresponding fillet concentrations; log–log linear regressions between concentrations in the two sample types explained 94% of the variation for Pb, 73–83% of the variation for Co, and 61% of the variation for Cd. In contrast, relations for Ni and Zn explained \12% of the total variation. Fillet Pb and calcium concentrations were correlated (r = 0.83), but only in the 12 fish from the most contaminated site; concentrations were not significantly correlated across all sites. Conversely, fillet Cd and calcium were correlated across the range of sites (r = 0.78), and the inclusion of calcium in the fillet-to-blood relation explained an additional 12% of the total variation in fillet Cd. Collectively, the results indicate that blood sampling could provide reasonably accurate and precise estimates of fillet Pb, Co, and Cd concentrations that would be suitable for identifying contaminated sites and for monitoring, but some fillet sampling might be necessary at contaminated sites for establishing consumption advisories. The killing of potentially valuable fish for the sole purpose of monitoring contaminant concentrations is becoming increasingly unpopular among natural resource management agencies and their constituents, and it is inappropriate for rare, threatened, or endangered species. Previous studies have demonstrated the utility of muscle biopsy sampling as an alternative to sampling fillets and whole fish for monitoring mercury (Hg) and selenium (Se) and for obtaining samples for genetic and other biologic analyses (summarized by Schmitt and Brumbaugh 2007).The analysis of scales and fin tissue has also been evaluated for a number of metals including lead (Pb) and Hg (Sauer and Watabe 1989; Rashed 2001a, b; Lake et al. 2006; Gremillion et al. 2005; Rolfhus et al. 2008). Blood sampling has long been employed for monitoring Pb in humans (Barbosa et al. 2005) and in wildlife (Henny 2003). The utility of blood sampling for monitoring Pb, cadmium (Cd), and Hg has been demonstrated in a few fish species (Brumbaugh et al. 2005; Schmitt and Brumbaugh 2007), but investigation for other metals has been limited. C. J. Schmitt (&) W. G. Brumbaugh T. W. May Columbia Environmental Research Center, US Geological Survey, 4200 New Haven Road, Columbia, MO 65201, USA e-mail: [email protected] 123 Arch Environ Contam Toxicol (2009) 56:509–524 DOI 10.1007/s00244-009-9288-9