Persistent organochlorine pollutants in eggs of colonial waterbirds from Galveston Bay and East Texas, USA

Eggs of neotropic cormorants (Phalacrocorax brasilianus), black-crowned nig ht herons (Nycticorax nycticorax), and great egrets (Ardea alba) nesting on several locations in Galveston Bay (TX, USA) and at two control sites outs ide the bay were collected during April-May 1996 and analyzed for chlorinat ed pesticides, PCBs, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans. Additionally, concentrations of 2,3,7,8-tetrachlorodibenzo- p-dioxin equivalents (TCDD-EQs) were determined by use of relative potency factors (TEQs) or the H4IIE-luc bioassay TCDD-EQs. Concentrations of 1,1,-d ichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) were greater in eggs of neotr opic cormorants from Alexander Island (mean = 1,040 ng/g wet wt) in the Hou ston Ship Channel (Houston, TX, USA) and in those from Telfair Island (mean = 1,460 ng/g wet wt), a reference location outside the bay, than in most l ocations inside the bay (mean range = 119-453 ng/g wet wt). Mean PCB concen trations were greater in eggs of neotropic cormorants from Alexander Island (mean = 5,720 ng/g wet wt) than in eggs of cormorants from areas farther a way from the ship channel, including two reference sites outside the bay (m ean range = 404-3,140 ng/g wet wt). The TCDD was the main dioxin congener d etected in eggs from all locations within Galveston Bay. Instrumental TEQs in eggs ranged from 67 pg/g wet weight at control sites to 452 pg/g wet wei ght at Alexander Island. Concentrations of TCDD-EQs determined in the H4IIE assay were correlated with instrumental TEQs and were greater in eggs of c ormorants from islands within the bay, although these were farther away fro m the ship channel. Overall, concentrations of DDE, PCBs, TCDD, and TODD-EQ s were less than the threshold levels known to affect reproduction. However , some eggs contained concentrations of total PCBs or DDE greater than what would elicit adverse effects on birds. No identifiable deformities or abno rmalities were detected in embryos collected from all sites.