The Marine Chemistry Branch focuses on a wide range of research themes related to the health and well being of marine resource species, and the extent to which human activities affects fisheries sustainability and utilization. The Branch characterizes water, sediment, and tissues of a variety of fish and invertebrate species to determine how biogeochemical energy, carbon, elements and compounds are distributed in nearshore and estuarine systems, and how they are transferred through the food web. Chemical characterization by complimentary techniques address a variety of fisheries management issues concerning resource species, such as, stock identification, the functional utilization of habitat by fish, and the identification of critical habitats during their various life stages.