ACS Monterey Bay Program for September 2005
Mercury Concentrations in the Pacific Harbor Seal in
- 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
||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
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:
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Last updated October 4, 2005.