SEDIMENT CHEMISTRY, TOXICITY, AND FORAMINIFERAL DISTRIBUTIONS AT CONTAMINATED SITES OFF SOUTHERN CALIFORNIA (Invited Presentation)

In 2008, a special study of the Southern California Bight (SCB) Regional Marine Monitoring Program (Bight'08) was undertaken to assess the extent and magnitude of altered foraminiferal communities in the SCB at 386 locations in embayments (estuaries, marinas, ports, and bays) and offshore (shelf to lower slope) and to compare those distributions to benthic macrofaunal communities (undisturbed to highly disturbed based on the Benthic Response Index and the Sediment Quality Objectives Benthic Line of Evidence), sediment chemistry (the concentrations above which adverse biological effects are possible [10%; ERL=effects range-low] and probable [50%; ERM=effects range-median] for organisms living in the sediment), and sediment toxicity (nontoxic to high toxicity based on amphipod survival and mussel embryo development). Although the benthic macrofauna and sediment toxicity showed no evidence of disturbance on the mainland or island shelves, heavy metals and/or organic compounds were found in the sediments in concentrations exceeding accepted sediment quality guidelines (above ERL levels at 125 offshore sites, 49 of which also exeeded ERM levels). In the foraminiferal assemblage, Bulimina denudata thrives where mercury, silver, the pesticide DDT, and polychlorinated biphenyls (PCBs) are prevalent, Eggerella advena appears to tolerate most of the trace metal and organic contaminants, Trochammina pacifica is less abundant where the highest number of ERL exceedences occur but best tolerates silver among all the contaminants, and Buliminella elegantissima, Nonionella stella and N. basispinata appear to be negatively affected by most contaminants except polycyclic aromatic hydrocarbons (PAHs). In contrast, the benthic macrofaunal communities at embayments sites occurred in poor condition more than half of the area of the estuaries and a third of the marinas, and toxicity was moderate to high in the sediment of about a fourth of these sites. The ERL values were exceeded at 145 sites, 32 of which also exceeded ERM levels. Of the 16 highly disturbed macrofaunal embayment sites, three were devoid of foraminifera and diversity dropped to nearly half in several other moderately to highly disturbed sites compared to the reference sites. It appears that foraminifera are useful bio-indicators of contaminated sites.