MP9 Metals and Bioaccumulation
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(KAM-1117-753951) Bioaccumulation of Mercury in Sea Turtles in Baja California Sur.

Kampalath, R¹, Gardner, S², Mendez, L², Jay, J¹, ¹ University of California - Los Angeles, Los Angeles, CA, USA² Centro de Investigaciones Biologicas del Noroeste, La Paz, Baja California Sur, Mexico

ABSTRACT- Because all sea turtle species are either endangered or threatened with extinction, it is important to document and understand any factors that might affect their survival or reproduction. Mercury contaminates aquatic food webs worldwide through point sources as well as long-range atmospheric transport, and its ecological impact is determined by the factors affecting its methylation and bioaccumulation. We have studied the bioaccumulation of mercury in sea turtles of Bahia Magdalena, a coastal lagoon in Baja California Sur, Mexico that provides habitat for three species of sea turtle. We analyzed sea turtle tissue samples (liver, muscle, adipose, and kidney) as well as stomach content samples from Baja California Sur to determine baseline Hg concentrations in healthy turtles. In all species tested, mercury concentrations generally increased in the following order: adipose<muscle<kidney<liver. Loggerhead turtles, which are carnivorous, had the highest concentrations of mercury (up to 0.285 ppm in liver), Olive Ridleys (omnivores) tended to have the next highest concentration, while the herbivorous Green turtle had the lowest concentrations. We also measured Hg levels in water, sediments, and various species of algae, which are important in the diet of omnivorous and herbivorous sea turtles. Bioconcentration factors for mercury were calculated for each tissue by species. This data set represents a valuable addition to the small data set available worldwide for levels of this contaminant in sea turtles.

Key words: sea turtles, mercury, bioaccumulation