First report of chlorinated and brominated hydrocarbon pollutants in marine bird eggs from an oceanic Indian Ocean island

Abstract

We report for the first time levels of persistent organic pollutants in marine bird eggs from an oceanic island in the Indian Ocean, the world's third largest ocean. Ten eggs each of the Common Noddy, also known as the Brown Noddy (Anous stolidus), and Sooty Tern (Sterna fuscata) were collected from Ile Cocos off the coast of the island of Rodrigues, located 560km east of the island of Mauritius. ΣPCBs had the highest levels (2.2 and 2.6ng/gwm, wet mass; 20 and 19ng/glm, lipid mass) for common Noddy and Sooty Tern, respectively (and following), then ΣDDT (1.9 and 3.1ng/gwm; 17 and 23ng/glm), and mirex (0.96 and 0.69 ng/g wm; 8.7 and 5.0ng/glm). ΣChlordanes (0.094 and 0.15ng/gwm; 0.48 and 0.73ng/glm) and Σtoxaphenes (0.26 and 0.61ng/gwm; 2.4 and 5.9ng/glm) are rare data for these compounds from this ocean. Brominated flame retardants were low (0.08 and 0.07ng/gwm; 0.7 and 0.7ng/glm). Multivariate analyses indicated different contamination patterns in the prey items as Sooty Terns had significantly higher levels of mean Σchlordanes and Σtoxaphenes, as well as CB105, -108 and -157. p,p′-DDE had an association with thinner eggshells in the Sooty Tern. Although the contaminant levels were in all respects low, industrialisation, development on the periphery, commercial exploitation of the marine environment, and pollutants transferred over long distances by marine debris is likely to add to chemical pressure in this region. Monitoring changes in background levels of pollutants in remote regions will indicate such trends, and marine bird eggs from Rodrigues would be an excellent site.