Effects of polyhalogenated aromatic hydrocarbons and related contaminants on common tern reproduction: Integration of biological, biochemical, and chemical data

Abstract

In eight Dutch or Belgian common tern (Sterna hirundo) colonies, breeding biology and food choice were determined, and 15 second eggs were collected from three-egg clutches for artificial incubation, biochemical analysis and analysis of yolk-sac polyhalogenated hydrocarbon (PHAH) levels. Results from these analyses were combined with biological data from the eggs remaining in each clutch. In some breeding colonies severe flooding, rainy and cold weather, and extreme predation caused extensive losses of eggs and chicks. A relationship was found between yolksac mono-ortho polychlorinated biphenyl (mo-PCB) levels and main food species (fish or insects) of the adult terns before egg-laying. Colony average breeding data differed only slightly, and were difficult to relate to PHAH-levels. When the colonies were grouped after yolksac PHAH-patterns and main food species, significant differences in average egg laying date, incubation period, egg volume and chick weight could be related to differences in yolksac PHAH and retinoid levels, and hepatic ethoxyresorufin-O-deethylase (EROD) activity. The data from all colonies also were combined into one data-set and correlated with the biochemical parameters and PHAH levels. In summary higher yolksac PHAH levels or hepatic EROD-activity correlated with and later egg laying, prolonged incubation period and smaller eggs and chicks. Lower yolksac retinoid- and plasma thyroid hormone levels, and a higher ratio of plasma retinol over yolksac retinoids correlated with later egg laying, prolonged incubation periods and smaller chicks and eggs. The dynamic environment of the terns had more obvious detrimental effects on breeding success than PHAHs. However, the more subtle effects observed for PHAHs could still be of importance during specific stress circumstances. To monitor site-specific reproduction effects, tree-nesting birds feeding on relatively big and non-migrating fishes would be most suitable. The use of specific biomarkers for exposure and effect is recommended to establish a causal relationship between a certain class of pollutants and an adverse biological effect.

Feminization in common terns (Sterna hirunda) : relationship to persistent organic contaminants

“…Common tern colonies in the Netherlands have shown several effects correlating to increasing levels of PCBs and "TCDD equivalents" (defined later). These effects included delayed egg laying, prolonged incubation periods, smaller chicks and eggs, and elevated hepatic ethoxyresorufin-0-deethylase (EROD) and pentoxyresoufin-0-dealkylase (PROD) activites (Murk, Boudewijn et al 1996). These elevated contaminant levels or EROD or PROD activities also were associated with increased plasma thyroid hormones, hepatic T4-glucuronyltransferase activity, and plasma retinol and yolk sac retinoid levels (Murk, Bosveld et al 1994).…”

“…Elevated levels of deformities, decreases in body weights and egg volumes, and changes in organ weights have been associated with elevated organochlorine contaminant levels (Kubiak, Harris et al 1989;Ludwig, Kurita-Matsuba et al 1996;Murk, Boudewijn et al 1996). Liver fluorescence was used as an indicator of porphyria since exposure to PCBs and dioxins has been correlated with elevated porphyrin levels in livers of birds (Kennedy, Fox et al 1998).…”

“…Reproductive tracts were examined for abnormalities, and male gonads were examined histologically for feminization. Hepatic mixed function oxidase activities (EROD and PROD) and protein levels (CYP1A) were examined as they may indicate contaminant induced cytochrome P450 proteins (Murk, Bosveld et al 1994;Murk, Boudewijn et al 1996). Induction of EROD and PROD can indicate exposure to dioxinlike compounds and phenobarbital-like compounds, respectively, and we hoped to use these activities as biomarkers of exposure to the respective groups of chemicals.…”

“…As the embryo utilizes the yolk for nutrition, it is exposed to contaminants deposited in the yolk by the female. (Gilbertson, Kubiak et al 1991;Giesy, Ludwig et al 1994;Sanderson, Norstrom et al 1994;Murk, Boudewijn et al 1996). Cormorants, blackcrowned night-herons, gulls, great blue herons, and terns all have been affected.…”

“…Cormorants, blackcrowned night-herons, gulls, great blue herons, and terns all have been affected. Terns on the Great Lakes and in the Netherlands have shown impaired reproduction, reduced body weight and femur length, increased liver to body weight ratios, increases in monooxygenase activities, and impaired behavior, all of which were associated with high levels of PCBs (Kubiak, Harris et al 1989;Hoffman, Smith et al 1993;Ludwig, KuritaMatsuba et al 1996;Murk, Boudewijn et al 1996). High levels of DDT, PCBs and other contaminants also have been associated with a sex ratio skewed toward females, femalefemale pairing, and supernormal clutches.…”