Yolk PCB and plasma retinol concentrations in shag (Phalacrocorax aristotelis) hatchlings

evaluate the possibilities of applying plasma retinol as a biomarker of res ponse in seabirds exposed to chronic low levels of organochlorines, the rel ationship between yolk content of polychlorinated biphenyls (PCBs) and plas ma retinol levels were studied in newly hatched shag chicks (Phalacrocorax aristotelis) from the coast of central Norway. The mean concentration of 29 PCB-congeners (Sigma PCB) in the yolk sac was 1.22 mu g/g ww (wet weight b asis) (SD = 0.57, n = 10), or 17.99 ng/g lw (lipid weight basis) (SD = 6.26 , 10). Expressed as TCDD-equivalents (Sigma TEQ), 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 cle ar-cut lethal and sublethal effects such as egg mortality, hatchability, or live deformity in Phalacrocoracidae species. There were significant negati ve correlations between Sigma PCB ww and the variables egg volume, yolk mas s, and hatchling mass. We suggest that these relationships are passive caus es of a higher lipid concentration in small eggs, rather than the PCB affec ting the variables. Analyses showed that there was a borderline significant positive correlation between Sigma PCB lw in yolk and plasma retinol conce ntration. Although the results indicate that plasma retinol level alone is a poor indicator of PCB exposure in shag hatchlings, the result may be rela ted to the low level of contaminant exposure and the low sample size of the study.