ACS Monterey Bay Program for September 2005

Mercury Concentrations in the Pacific Harbor Seal in Central California

	Thursday, September 29, 2005 7 p.m. Refreshments, 7:30 p.m. Program Lecture Hall, Monterey Boatworks, Hopkins Marine Station, Pacific Grove (Across from American Tin Cannery Outlet Stores)
	Speaker: Tiffini Brookens, M.S. Candidate, Moss Landing Marine Laboratories

The Pacific harbor seal, Phoca vitulina richardii, generally inhabits nearshore areas associated with productive waters that provide an adequate source of prey. Harbor seals, situated at the top of the marine food web, consume a considerable amount of fish, thereby accumulating significant amounts of mercury, Hg. Because of their fish and invertebrate diet, mercury levels in marine mammals often are orders of magnitude greater than levels found in terrestrial carnivorous mammals. Harbor seals, therefore, are useful mammalian biomonitors for Hg because they feed, reproduce, and rest near or on shore, and are high-level trophic consumers.

Increasing concern about environmental pollution has led to many studies regarding heavy metal burdens in animals. Harbor seals are endemic to marine and estuarine habitats near urban or industrialized regions; therefore, they are vulnerable to contaminated runoff. Since the industrial revolution atmospheric Mercury levels have increased by three- to five-fold and caused corresponding increases in aquatic ecosystems.

Once mercury is transported into nearby bays, it is incorporated into aquatic flora and fauna as it is cycled throughout the ecosystem. Nearly all Hg in fish muscle and whole fish is methylmercury (MeHg), a highly neurotoxic form that increases to high concentrations in aquatic food webs, and consumption of fish is the primary route of MeHg exposure to mammals with harmful effects on reproductive success and the central nervous system. This also, of course, relates to effects on humans who consume these fish. To determine total mercury and methylmercury concentrations, live capture and dead seals were sampled throughout central California from March 2003-January 2005.

Please join us to learn at first hand the impacts of this dangerous organometallic compound to our environment.

Related web pages:

• Moss Landing Marine Labs

• Back to list of previous meetings.