Organochlorine Contaminants, Immunocompetence and Vitellogenin in Herring Gulls (Larus argentatus) and Great Black-Backed Gulls (Larus marinus) Nesting on Lake Ontario in 2001–2002

Abstract

Abstract. In 2001–2002, Great Black-backed Gull (Larus marinus) eggs from Lake Ontario had significantly higher concentrations of organochlorine contaminants than Herring Gull (L. argentatus) eggs. This study investigated whether higher contaminants in Great Black-backed Gulls affected immunocompetence, packed cell volume (PCV) and body condition in chicks, endocrine disruption and body condition in adults, and reproductive success. Variables were compared between species at two Lake Ontario sites (one in Ontario, Canada, and one in New York, USA), and with a control site in the Bay of Fundy, Canada. For Herring Gull chicks, body condition and total antibody titers to sheep red blood cells were greater at one contaminated site; PCV, phytohemagglutinin-P stimulation and reproductive output did not differ among sites. For Great Black-backed Gull chicks, PCV was significantly lower at one contaminated site; there were no other significant differences among sites. Between species, Herring Gull chicks had sign...