Mercury in its organic and inorganic forms is a persistent pollutant in the marine environment, and is increasing in the ocean surface. This study seeks to increase our understanding of how mercury enters the environment and becomes integrated into the food web. To do so we have selected giant brown kelp (<i>Macrocystis pyrifera</i>), a fast-growing producer that is both widespread and abundant, as a biosentinel. This species may serve as an indicator of current levels of mercury in the ocean surface and the contributions of non-point and point source mercury pollution. The study area includes kelp beds off the coast of Southern California from Santa Barbara, Ventura, and Los Angeles, as well as the Port of Long Beach and Santa Rosa Island. We quantified mercury in kelp samples by thermal decomposition, amalgamation and atomic absorption spectroscopy. Results show high levels of mercury near the Port of Long Beach (avg 125.5 ppb, standard deviation 25.1) and low levels in Ventura County (average 0.36 ppb, standard deviation 0.2). Santa Rosa Island kelp had moderate levels of mercury (average 46.1 ppb, standard deviation 9.8), which may be a result of upwelling and unique ocean currents surrounding waters. The implications of this will be discussed.

Establishing giant brown kelp as biosentinel of environmental mercury

251st National Meeting (2016)

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