M1 AM Delaware River/Bay
Monday, 14 November 2005: 8:00 AM - 11:40 AM in Ballroom 1

(LAU-1117-822850) Organic contaminant and trace element trends in Delaware Bay oysters, 1986-2004.

Lauenstein, G.¹, Christensen, J.¹, ¹ National Oceanic and Atmospheric Administration, Silver Spring, MD, USA

ABSTRACT- NOAA's National Status and Trends (NS&T) Mussel Watch Project has established eight sites in Delaware Bay. Two of those sites are located on the headlands of Cape May and Cape Henlopen where the mussel Mytilus edulis is collected. Two main stem sites only provided oysters for one sampling year. The remaining main stem sites all have 10 or more years of oyster monitoring data that cover the time span of 1986 to 2004. In 1992, the Mussel Watch Project began biennial sampling so half of the core Mussel Watch sites were sampled in any given year, since that time. While 2004 was the most recent biennial sampling year for Delaware Bay, samples were again collected during 2005 because of the Athos 1 oil spill. Using the Spearman Rank Correlation Coefficient, trends were determined for both the Capes and the main stem sites. Because of the large number of analytes quantified by the Project only the following trace elements and organic compounds were analyzed for trends: Ag, As, Cd, Cu, Hg, Ni, Pb, Sn, Zn, hexachlorbenzene, lindane, Mirex, total-DDT, total-PAHs, total-chlordane, total-dieldrin, total-butyltin, and total-PCBs. Trends for Delaware Bay are generally consistent with National findings from the Mussel Watch Project. For most organic compounds and trace elements at most sites, no trends were found. When trends exist, decreasing trends are much more prevalent than increasing trends. All six sites for which trends could be determined had decreasing lindane concentrations and all but one site (Cape May) exhibited decreasing total-chlordane concentrations. Three sites had decreasing concentrations of total-DDT. The remaining analytes considered had decreasing trends at two or fewer sites. The only multi-site increasing trend was found for silver, at three sites, two of which are the cape sites.

Key words: Delaware Bay, oysters, contaminant trends, trace elements