Petroleum Hydrocarbons
An examination
of past records regarding oil spills in the Sanctuary region reveals
only one very small release and suggests the likelihood of a significant
spill is quite remote (Dept. of Comm. 1991). Yet on an annual basis
approximately 2,700 vessels (about 225 trips per month) cross Stellwagen
Bank and roughly one-half of these are carrying liquid petroleum cargo
(Ibid). Thus the risk of contamination from petroleum hydrocarbons,
albeit small, does exist.
Evidence
which documents background petroleum hydrocarbon concentrations in marine
mammals is limited. Most of the available literature deals with the
acute toxicological and behavioral effects of exposures to various types
of petroleum products. However, studies of stranded cetaceans have shown
the presence of petroleum hydrocarbons in the blubber (National Research
Council, 1985).
Dietary
routes are important pathways for the absorption of petroleum hydrocarbons
in seals, and presumably for other species as well (Englehardt, 1977).
Most marine mammals are potential accumulators of petroleum residues
(e.g., naphalene) transferred through the food chain. Blubber residue
concentrations tend to reflect trophic status, with odontocetes having
higher concentrations than mysticetes which feed at lower trophic levels
(Geraci and St. Aubin, 1985).
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