ABSTRACT
This chapter will address the concentrations and possible effects of selected persistent organic contaminants (POCs) in marine mammals of the Arctic region. Other recent sources of information concerning POCs in Arctic marine mammals include Letcher et al. (1996, 1998), Becker et al. (1997), Bernhoft et al. (1997), Muir et al. (1997), Weis and Muir (1997), Addison and Smith (1998), De March et al. (1998), Norstrom et al. (1998), Wiberg et al. (1998 and 2000), Krahn et al. (1999), O’Hara et al. (1999), Becker (2000), Kucklick et al. (2001) and Seagars and Garlich-Miller (2001). Arctic marine mammals are long-lived, develop large lipid or fat depots, and many occupy high trophic levels in the lipid-rich, Arctic marine food webs. These factors are important in the uptake and magnification of persistent, lipophilic organic contaminants. Bowhead whales (Balaena mysticetus), which feed almost exclusively on copepods, euphausiids and amphipods (Lowry, 1993), account for some of the lowest tissue concentrations of ‘bioaccumulating’ organochlorines (OCs), and correspondingly occupy the lowest trophic level of marine mammals addressed in this chapter (Hoekstra et al., 2000a, b). Pacific walrus (Odobenus rosmarus divergens) and Atlantic walrus (Odobenus rosmarus rosmarus) typically feed on mollusks, but also may occasionally eat ringed seals (Pusa hispida) (Fay, 1960; Lowry and Fay, 1984). Other Arctic marine mammals feed on a combination of invertebrates, fish and/ or mammals. One class of POCs, the polycyclic aromatic hydrocarbons (PAHs), are readily metabolized by mammals and do not accumulate in their tissues. Assessing the exposure of marine mammals to these compounds is not as straightforward as is the case for lower vertebrates (e.g. fish) and invertebrates. The latter have little capacity for metabolizing this class of aromatic compounds; therefore PAHs will accumulate in their tissues (Livingstone et al., 1992). Although specific cases of marine mammal response to benzo[a]pyrene exposure will be discussed, we will not address PAHs or petroleum effects in this review. Concentrations of contaminants provided in this chapter are on a wet weight basis, except when noted otherwise.
