Yolk PCB and Plasma Retinol Concentrations in Shag ( Phalacrocorax aristotelis ) Hatchlings

Abstract

To evaluate the possibilities of applying plasma retinol as a biomarker of response in seabirds exposed to chronic low levels of organochlorines, the relationship between yolk content of polychlorinated biphenyls (PCBs) and plasma retinol levels were studied in newly hatched shag chicks (Phalacrocorax aristotelis) from the coast of central Norway. The mean concentration of 29 PCB-congeners (SigmaPCB) in the yolk sac was 1.22 microgram/g ww (wet weight basis) (SD = 0.57, n = 10), or 17.99 ng/g lw (lipid weight basis) (SD = 6.26, n = 10). Expressed as TCDD-equivalents (SigmaTEQ), the exposure in the yolk sac was 43.9 pg/g ww (SD = 19.5, n = 10), or 637.1 pg/g lw (SD = 240.8, n = 10), considerably lower than the levels that have been associated with clear-cut lethal and sublethal effects such as egg mortality, hatchability, or live deformity in Phalacrocoracidae species. There were significant negative correlations between SigmaPCB ww and the variables egg volume, yolk mass, and hatchling mass. We suggest that these relationships are passive causes of a higher lipid concentration in small eggs, rather than the PCB affecting the variables. Analyses showed that there was a borderline significant positive correlation between SigmaPCB lw in yolk and plasma retinol concentration. Although the results indicate that plasma retinol level alone is a poor indicator of PCB exposure in shag hatchlings, the result may be related to the low level of contaminant exposure and the low sample size of the study.

Contamination and Biomarkers in the Great Blue Heron, an Indicator of the State of the St. Lawrence River

“…A decrease in T3 and T4 was observed after treatment of chicken embryos with Aroclor 1242 and Aroclor 1254, but not after treatment with PCB congeners # 54, 77 and 80 (Gould et al, 1999). As reported by many authors, various mechanisms, sometimes contradictory, control the levels of retinol and thyroid hormones and contaminants such as PCBs, PCDDs and organochlorines may interfere in many ways in these processes (Brouwer and Van den Berg, 1986;Brouwer et al, 1990;Peakall, 1992;Fairbrother, 1993;Murvoll et al, 1999). Other non-measured contaminants such as coplanar PCB congeners and PCB metabolites may also interfere with the regulation of these systems.…”

“…Previous studies on effects of dioxin-like contaminants in plasma retinol levels have shown contradictory results (Spear and Bourbonnais, 2000). Murvoll et al (1999) found a borderline significant positive correlation between PCBs in lipid weight and plasma retinol in shag (Phalacrocorax aristotelis) hatchlings, at PCB levels lower than levels in the great blue heron from the St. Lawrence. Murk et al (1994) found increased plasma retinol levels with increasing PCB burden in common tern (Sterna hirundo) hatchlings, while Elliott et al (1996) found no difference in 1-day-old bald eagle chick's plasma retinol among colonies with various levels of dioxin and furan contamination.…”

Assessment of biological effects of chlorinated hydrocarbons in osprey chicks

“…Lipid content and mass of yolk sacs in these ospreys also correlated with egg volume and hatchling mass. Murvoll et al [39] reported that lipid content of yolk sac regressed significantly with egg volume and hatchling weight and therefore PCBs and body weight in Norwegian shags ( Phalacrocorax aristotelis ). They argued that their results and a number of the previously reported relationships between embryonic body weight and contaminants were the result of covariation between body weight and lipid content rather than being cause and effect.…”

“…It is not clear why we found only weak positive relationships for a few contaminants, e.g., TEQs and some PCB congeners, with egg volume and yolk‐free body weight. However, the studies of Custer et al [31] and Murvoll et al [39] focused on single colonies, whereas we collected from seven widely separated sites.…”

“…In wild birds, there are reports of associations between PCBs and plasma retinol concentrations, although the regressions are generally of a positive form. Mur‐voll et al [39] recently reported a positive relationship between plasma retinol and total PCBs in shags. Murk et al [46] reported a positive relationship between plasma retinol and hepatic EROD in common tern chicks.…”