Organochlorine contaminants in northern royal albatross from Taiaroa Head, Otago Peninsula

Abstract

Northern royal albatross (Diomedea sanfordi) eggs and chicks were collected at Taiaroa Head from 1995 to 1998 by Department of Conservation staff. Frozen whole eggs and chicks were submitted to ESR for chemical analysis. The analysis quantified the levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and a range of persistent organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT) group compounds. The total international dioxin equivalents (I-TEQ) ranged from 3.2 to 15.4 pg/g wet weight, while PCB concentrations (sum of 32 congeners) ranged from 15.7 to 89.2 ng/g wet weight. These values are very similar to the levels reported in northern royal albatross eggs collected from the Chatham Islands over the 1995 - 1996 period. Certain organochlorine pesticide residues were detected in all samples. The most prevalent were tachlor epoxide, which had mean concentrations in eggs of 58 ng/g, 6.2 ng/g, 5.0 ng/g and 1.2 ng/g wet weight, respectively. The profile of PCDD/F and PCB congeners was consistent with previous analysis conducted on northern royal albatross eggs from the Chatham Island. The profiles were also similar to those reported in albatross species from the North Pacific ocean. There was no apparent effect on the measured levels of sampling season (95/ 96 versus 97/98) or whether analysis was on eggs or chicks. The mean (range) I-TEQ values for eggs 1995/96, eggs 1997/98 and chicks 1997/98 were 8.14 (4.79 - 12.88), 9.91 (6.57-13.79) and 9.91 (3.20-15.37) pg/g wet weight, respectively. As all egg samples were from females of known age, the relationship between the age of females and the concentration of organochlorine residues in eggs was examined. No significant relationships were established. As an example, the regression between female age and egg concentration p,p'-DDE (y= -1.98x + 112.57) had a very weak r2 value of 0.155. The mean value and range for egg shell thickness was 0.57 min (0.53 - 0.63) indicating no egg shell thinning in the samples collected. The lack of egg shell effects and the similarity between residues in this study and samples previously collected from the Chatham Islands, suggests apparent reproductive impairment in Chatham Island albatross is not caused by the analysed organochlorine contaminants. The similarity of the organochlorine levels between Taiaroa Head and Chatham Island albatross suggests that previous conclusions regarding risk still apply: namely, that while the greatest risk of adverse effects to albatross are attributable to the I-TEQ, the residues are below the exposure levels where adverse effects would be expected to occur.