Heavy metal biomonitoring by seaweeds on the Delmarva Peninsula, east coast of the USA

Metal pollution in aquatic ecosystems can pose a major environmental concern impacting various life-forms. The usefulness, of seaweeds as biomonitors or indicators of metals in the coastal bays of the Delmarva Peninsula is highlighted in this study, conducted in early spring 2006. Lack of any preexisting data on metal loads in Delmarva seaweeds and in the ambient medium (water and sediments) led to this pilot study for preliminary investigations on the ecological health of these coastal bays. The seaweed species collected from three different sites of the Delmarva Peninsula were: phaeophytes Fucus vesiculosus, and Fucus distichus, chlorophytes Ulva lactuca, and Enteromorpha intestinalis, and rhoclophyte Gracilaria tikvahiae. The sampled seaweeds, seawater, and sediments were subsequently analyzed for chromium, manganese, cobalt, nickel, copper, lead, arsenic, and zinc. The results showed high concentrations of Mn, and low concentrations of Cu in almost all the species. Bioconcentration factors (BCFs) in Ulva lactuca and Fucus vesiculosus, across sites, were similar (though the orders of magnitude varied) for Cu, Zn, and Ni. Calculation of metal pollution index (MPI) and Tomlinson pollution load index (PLI) showed that all three sites had low contamination with the metals investigated.