Geographic variation in blood plasma protein concentrations of young herring gulls (Larus argentatus) and Caspian terns (Sterna caspia) from the Great Lakes and Lake Winnipeg

Relative and total amounts of plasma protein fractions are affected by infections, inflammation, and nutritional and physiological status, and are therefore important health indicators in free-living animals. Our objectives were: (1) to examine intercolony differences in plasma protein fractions in prefledgling gulls and terns; (2) to investigate relationships between plasma proteins and other physiological measures such as weight loss, growth, and immune function; and (3) to examine potential associations between organochlorine exposure and plasma proteins. During 1992, blood was collected from 3-week-old herring gull (Larus argentatus) chicks from six sites on Lakes Superior, Huron, Michigan, Erie, and Winnipeg and from 3-week-old Caspian tern (Sterna caspia) chicks from five sites on Lakes Huron, Michigan, and Ontario. These sites provided a wide gradient of organochlorine contamination. Plasma proteins were separated by high-resolution agarose gel electrophoresis and stained with Coomassie brilliant blue dye. Six major fractions were quantified: prealbumin, albumin, α-globulins, β₁-globulins, β₂-globulins, and γ-globulins. Total protein, prealbumin, albumin, and γ-globulin concentrations and the albumin/globulin ratio did not differ among sites. Total protein, albumin, and the albumin/globulin ratio were not decreased in birds experiencing food stress or weight loss. Intersite differences were found in α- and β-globulins. In gulls, β₂-globulins were positively associated with polychlorinated biphenyls (PCBs) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ether (DDE). In terns, PCBs were negatively associated with α-globulins and positively associated with β₁-globulins. Additional research is needed to identify individual proteins and elucidate causal relationships between the particular protein concentrations and factors such as contaminants, growth, and condition.