After the oil pollution from Fu Shan Hai
A two-year study of the impact of the oil pollution on the breeding birds of Ertholmene, Denmark.
In June 2003, the archipelago of Ertholmene in the Baltic Sea north of Bornholm was hit by oil from the wrecked bulkcarrier Fu Shan Hai. The oil pollution lasted for a month, and an estimated 1100-1600 seabirds, mainly auks and eiders, were killed.
Ertholmene is designated as a EU habitat area (DK H210), EU bird protection area (DK F79) and Natura 2000 area (DK SPA79). The archipelago has a breeding population of 2000 pairs of eiders (Somateria mollissima), 2500 pairs of common guillemots (Uria aalge), 850 pairs of razorbills (Alca torda) and 10,000 pairs of gulls (mainly herring gull Larus argentatus).
In 2004-05 the private organisation Christiansøs Naturvidenskabelige Feltstation (Christiansø Biological Research Station) undertook a detailed investigation of the impact of the oil pollution on the breeding birds of Ertholmene.
For duck species the impact was significant. The breeding population of red-breasted mergansers (Mergus serrator) was halved (from 20 to 10 pairs), and the approx. 250 eiders killed clearly intensified the alarming decrease in the breeding eider population that has occurred since 1998. In just seven years the breeding population has decreased by 40%.
For the auks, a small decrease was expected but the breeding population actually increased during 2004-05, the razorbill breeding population alone by 11% in 2004. The investigations on Ertholmene showed that a large part of the auks killed were visiting young non-breeding birds from other colonies in the Baltic. Contrary to the female duck populations, the Baltic auk-colonies are not closed systems, and some interchange between the colonies do occur. Many young auks visit other colonies before they start breeding at an age of four years. The proportion of young birds that breed in other colonies than their natal are low, but even so emigration from large colonies can have significant influence on the population development in small colonies. Large auk colonies are found less than 300 km north of Ertholmene, and some years - as e.g. 2004 - the number of birds immigrating to Ertholmene can be relatively high.
In summary, the oil pollution had the highest impact on local duck populations, the lowest on the auk populations where the impact was divided between several Baltic colonies.
In both 2004 and 2005 the condition, breeding success and breeding schedule of auks and eiders were normal, compared to the years before 2003. As the auks feed on sprats and the eiders on mussels, the oil pollution does not appear to have affected the marine environment adversely. However, no analyses of toxic components in the marine environment were undertaken.
The report - in Danish - is available from Christiansø Biological Research Station, email: feltstation@chnf.dk, price: 100 DKR. An earlier report from Christiansø Biological Research Station about the oil pollution on Ertholmene on a day-to-day basis can be downloaded at: http://www.chnf.dk/artik_pdfs/olieforurening_2003_ertholmene_chroe_feltstation_bog.pdf
Peter Lyngs
Christiansøs Naturvidenskabelige Feltstation
Christiansø 97, 3760 pr Gudhjem
Tlf: 56462047,
email: feltstation@chnf.dk,