Ma. Mora, ORGANOCHLORINES AND TRACE-ELEMENTS IN 4 COLONIAL WATERBIRD SPECIES NESTING IN THE LOWER LAGUNA-MADRE, TEXAS, Archives of environmental contamination and toxicology, 31(4), 1996, pp. 533-537
Eggs from four aquatic bird species nesting on the National Audubon Sa
nctuary Islands of the lower Laguna Madre were collected during 1993 a
nd 1994 to determine concentrations of organochlorine compounds and tr
ace metals and to evaluate their possible detrimental effects on birds
nesting in this aquatic ecosystem. The only chlorinated hydrocarbons
found above detection limits were p,p'-DDE (DDE), p,p'-DDT (DDT), HCB,
HCH, chlordane, and polychlorinated biphenyls (PCBs). Median DDE and
PCB levels in eggs of four species were below 1 mu g/g ww. Concentrati
ons of DDE were much greater (6-70 fold) than the concentrations of ot
her chlorinated pesticides which were present at or near detection lim
its. One egg from a snowy egret contained 9.65 mu g/g DDE, 0.056 mu g/
g DDD, and 1.75 mu g/g DDT. Ten heavy metals and trace elements (Hg, S
e, B, Cr, Cu, Fe, Mg, Mn, Sr, and Zn) were detected in 90% of the samp
les but at levels that were not of concern. In 1993-1994, concentratio
ns of DDE in eggs of aquatic birds of the lower Laguna Madre were much
lower than levels detected in this area during the late 1970s and ear
ly 1980s. Concentrations of DDE, PCBs, and trace metals in eggs detect
ed in this study could not be associated with deformities or other det
rimental effects on birds.