Health of Herring Gulls (Larus argentatus) in Relation to Breeding Location in the Early 1990s. I. Biochemical Measures

Abstract

Tissues of 156 adult herring gulls (Larus argentatus) were sampled in the early 1990s from 11 colonies throughout the Laurentian Great Lakes and 2 reference colonies in Lake Winnipeg and the Bay of Fundy. Gulls from 1 or more Great Lakes differed from Lake Winnipeg or the Bay of Fundy for 17 of 19 clinical biochemical measures, whereas the freshwater and marine reference sites differed in only 3. Three differed with sex. There was little evidence to suggest that these differences reflect genotypic differences. Plasma thyroxine, albumin, calcium, magnesium, inorganic phosphorus, triglyceride, bile acids, total protein, uric acid, and urea nitrogen concentrations and aspartate aminotransferase (AST) activity were lower in gulls from one or more Great Lakes than for gulls from one or both reference sites, while those for globulins and glucose were higher. Highly carboxylated porphyrins accumulated in the livers of Great Lakes gulls and ethoxyresorufin O-deethylase (EROD) activity was induced. There was resistance to PCB/TCDD-induced EROD induction in the Lake Erie colonies. Gulls from five colonies were unable to obtain adequate food to maintain average body condition. Body condition was associated with seven biochemical measures. Colonies in designated Areas of Concern as well as those with high liver polychlorinated biphenyl (PCB) concentrations both differed for 50% of the biochemical measures. Associations between biochemical measures and δ15N-derived trophic position and/or contaminant levels in tissues suggest the effects may be toxicopathic responses. Associations were most frequently with PCBs and dioxin-like contaminants. The health of adult herring gulls varied with breeding location and “lifestyle” in the early 1990s, and Great Lakes gulls suffered from chemical and nutritional stressors that modulated physiological processes and endocrine function.