Accumulation of trace elements and persistent organochlorines in resident and migratory waders from Calatagan Bay, Philippines

Abstract

Concentrations of V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl and Pb were determined in the liver of six species of resident and migratory waders collected in December 1997 from Calatagan Bay, Philippines. Renal Cd concentrations in these species were also determined. Trace element levels were observed to have either decreased or remained intact in the winter, suggestive that trace element burdens for migratory waders could be minimal during wintering. It seems that the migration distance of waders is a dominant factor in the accumulation of toxic elements such as Cd, Hg and Pb. Hepatic Cd concentrations of pintail snipe are likely to be incritical levels. While concentrations of persistent organochlorines such as PCBs, DDTs, HCHs, CHLs and HCB were determined in the whole bodies and adipose tissues of migratory and resident waders collected in April and December 1994. Accumulation patterns of OCs found in resident birds suggested that PCBs and CHLs were the predominant contents. Among the OCs, It was noted that migratory birds retained mostly high concentrations of DDTs. This finding could be reflective of the presence of these contaminants in the stopover and breeding/wintering ground of these waders in China and Russia. Whereas residual concentrations found in resident birds reflect the pollution status of the sampling area, those found in migratory waders reflect both the pollution status of the sampling area and their migratory routes. Waders are therefore useful bioindicators to elucidate the contamination status of toxic metals and organochlorines in breeding grounds, stopover sites and wintering grounds