Piscivorous Mammalian Wildlife as Sentinels of Methylmercury Exposure and Neurotoxicity in Humans

Abstract

The purpose of this chapter is to provide an overview of how piscivorous (fi sh-eating) wildlife can be used to complement existing public health strategies to assess the neurotoxic risks of methylmercury. A brief introduction concerning the use of wildlife as model sentinel organisms in the fi eld of environmental neurotoxicology is provided. Next, selected scientifi c examples are detailed that illustrate how data from piscivorous wildlife may provide pertinent, real-world information on the bioavailability of methylmercury and environmental exposures. Information concerning methylmercury's subclinical (e.g., perturbations in brain neurochemistry and neuroendocrine hormones) and clinical (structural and functional defi cits) neurological effects across organisms is also discussed.

Brains of Native and Alien Mesocarnivores in Biomonitoring of Toxic Metals in Europe

“…Those mammals fulfill many criteria of good bioindicators, as they are numerous, common and may be legally hunted. Moreover, they have a relatively small home range, are long-lived and present in their habitats throughout the year, and their biology is well understood [ 21 , 25 , 75 , 76 ]. The mink has been used in experimental Hg intoxication and data on Hg brain concentration from laboratory and field investigations are quite rich in comparison to Pb and Cd ( Table 4 ).…”

“…Characteristic Hg-related changes in the brain involve structural degeneration (especially in the occipital cortex and cerebellum) to cause visual, cognitive and neurobehavioral deficits. The central and peripheral nervous systems of wild mammals are the primary targets for MeHg toxicity as this form of Hg is readily absorbed from the diet and can easily pass the blood–brain barrier [ 19 , 21 ]. When it comes to wild terrestrial mammals, data on the tissue concentrations of Hg and MeHg toxicity are more plentiful for semiaquatic piscivorous carnivores (such as the North American river otter Lontra canadensis , Eurasian otter Luta lutra , and American mink Neovison vision ) than for other species, and usually concern the liver and kidneys [ 22 – 25 ].…”

The Gut Microbial Community Structure of the North American River Otter (Lontra canadensis) in the Alberta Oil Sands Region in Canada: Relationship with Local Environmental Variables and Metal Body Burden

“…Moreover, river otter populations in North America have suffered dramatic declines as a result of habitat degradation (Lariviere and Walton 1998). Due to its sensitivity to disturbances, small home range, and nonmigratory and fish consumption behavior (apex predator), the river otter is considered a sentinel species of freshwater ecosystems (Basu 2012).…”

Assessment of mercury and selenium tissular concentrations and total mercury body burden in 6 Steller sea lion pups from the Aleutian Islands

“…1) [1]. Steller sea lions are piscivorous marine mammals that biomagnify relatively high Hg concentrations through the diet and easily transfer Hg through the placenta to the developing fetus [2] similar to other piscivorous mammals [3,4]. Steller sea lions from the Aleutian Islands are part of the western distinct population segment (DPS) which are genetically different from the Steller sea lions found in Southeast Alaska.…”

“…Monomethyl mercury (MeHg + ) has been known to have adverse effects on reproductive, immunological, and neurological functions in humans and rats [13-16]. MeHg + can cross the blood-brain barrier as well as other organs such as the placenta and gastrointestinal tract, and > 90% of ingested MeHg + can be absorbed into blood [3,4,17]. Thus, MeHg + distribution is systemic, reaching all vital organs including the brain, and accumulates in several tissues including erythrocytes, muscle, and hair [16].…”