Uptake of environmental contaminants by small mammals in pickleweed habitats at San Francisco Bay, California

Abstract

Small mammals were live-trapped in pickleweed (Salicornia virginica) habitats near San Francisco Bay, California in order to measure the uptake of several contaminants and to evaluate the potential effects of these contaminants on the endangered salt marsh harvest mouse (Reithrodontomys raviventris). Tissues of house mice (Mus musculus), deer mice (Peromyscus maniculatus), and California voles (Microtus californicus) from nine sites were analyzed for chemical contaminants including mercury, selenium, cadmium, lead, and polychlorinated biphenyls (PCBs). Concentrations of contaminants differed significantly among sites and species. Mean concentrations at sites where uptake was greatest were less than maximum means for the same or similar species recorded elsewhere. Harvest mice (Reithrodontomys spp.) were captured only at sites where concentrations of mercury or PCBs were below specific levels in house mice. Additional studies aimed at the protection of the salt marsh harvest mouse are suggested. These include contaminant feeding studies in the laboratory as well as field monitoring of surrogate species and community structure in salt marsh harvest mouse habitats.

Assessment of mercury concentrations in small mammals collected near Las Vegas, Nevada, USA

“…Other mammalian studies report mercury concentrations in liver that are equal to, or greater than, mercury concentrations in kidney (Fortin et al, 2001;Porcella et al, 2004). A literature review located several studies reporting mercury concentrations in liver (Clark et al, 1992;Fortin et al, 2001;Lord et al, 2002;Porcella et al, 2004). Several other metal concentration studies also reported values for the liver (Neithammer et al, 1985;Hegstrom and West, 1989;Ma et al, 1991;Pascoe et al, 1994a;Laurinolli and Bendell-Young, 1996;Peles and Barrett, 1997;Nyangababo, 2001;Torres and Johnson, 2001b;Smith et al, 2002).…”

“…It has been well documented that small mammals residing in contaminated areas can bioaccumulate contaminants in various body tissues (Beyer et al, 1985;Neithammer et al, 1985;Hegstrom and West, 1989;Ma et al, 1991;Clark et al, 1992;Dodds-Smith et al, 1992;Pascoe et al, 1994b;Mace et al, 1997;Peles and Barrett, 1997;Appleton et al, 2000;Metcheva et al, 2001;Nyangababo, 2001;Torres and Johnson, 2001a,b;Smith et al, 2002;Schroder et al, 2003). The majority of these studies have focused on Superfund sites (www.epa.gov/superfund), seasonal wetlands, landfills, mining operations, sludge disposal sites, or other sites that are all heavily contaminated.…”

“…The most common tissues analyzed in past studies were liver and kidney, respectively, while a few papers reported contaminant concentrations in whole body homogenate (carcass), muscle and fat (Neithammer et al, 1985;Hegstrom and West, 1989;Ma et al, 1991;Clark et al, 1992;Dodds-Smith et al, 1992;Pascoe et al, 1994a;Mace et al, 1997;Peles and Barrett, 1997;Appleton et al, 2000;Nyangababo, 2001;Torres and Johnson, 2001a,b;Smith et al, 2002). Limited data exist, which evaluate the efficiency of using hair mercury concentrations, to monitor mercury body burdens in small mammals.…”

“…Limited data exist, which evaluate the efficiency of using hair mercury concentrations, to monitor mercury body burdens in small mammals. However, several studies were located that examined hair mercury concentrations in relation to the mercury concentrations in internal organs in mammals such as: wild mice, deer mice, house mice, California voles, wild mink, river otter, muskrats, raccoons, and opossums (Burton et al, 1977;Clark et al, 1992;Burger et al, 1994;Jones et al, 1996;Stevens et al, 1997;Fortin et al, 2001;Lord et al, 2002;Porcella et al, 2004).…”

Microtus californicus (Rodentia: Cricetidae)

“…M. californicus was presumed to inhabit large, contiguous, and relatively stable habitats prior to human alteration but now may be restricted to ungrazed and less-disturbed grasslands, potentially containing a large number of exotic plant species (Getz 1985). Contaminants in salt-marsh habitats surrounding San Francisco Bay (including mercury, selenium, cadmium, and lead) may further jeopardize populations of M. californicus (Clark et al 1992). Although captured individuals carried trace amounts of each contaminant, individuals appeared relatively healthy and able to tolerate current contaminant levels, which were below maximum levels recorded elsewhere for other mice and vole populations (Clark et al 1992).…”