Species identified on the Birkenfels wreck

The dominant species on vertical and horizontal surfaces were Sarsia eximia and Jassa herdmanni associated with Tubularia indivisa. They represent more than 80% of the covering. Sea anemonies (particularly Diadumene cincta and Metridium senile) represent more or less 10% of the covering. Locally they are more abundant, particularly on overhangs.

On some spots Ophiothrix fragilis represents up to 30% of the covering. These ophiurians aggregate, forming several layers with population densities varying from 288 to 1,440 specimens/m². All the body size were observed from early juveniles (4 vertebral ossicles/arm) to adults. Psammechinus miliaris is represented by juveniles (maximum 10 mm across) only with densities varying from 32 to 256 specimens/m².

Living specimens of Nassarius incrasatus and Epithonium clathratulum were observed. Their population density reaches up to 80 specimens/m² and 96 specimens/m², respectively.

With at least 120 species identified since the start of the study in 2001, the biodiversity of the Birkenfels's macrofauna is much higher than the one of nearly all the prospected soft bottom communities on the Belgian Continental Shelf. CATTRIJSSE & DEGRAER (2001) mention an average of 8 to 30 macrobenthos species per prospected zone, the number of observations per zone varying between 13 and 209. Regarding the epibenthos species, CATTRIJSSE (2001) mentions an average of 12 to 18 species per prospected zone, the number of observations per zone varying between 3 and 67.

References:

Cattrijsse, A. 2001. Epifauna of the Belgian Continental Shelf. In Biodiversity of the benthos and the avifauna of the Belgian Coastal waters, pp 21-23, Federal Office for Scientific, Technical and Cultural Affairs, Brussels, 48 pp.

Cattrijsse, A. & M. Vincx. 2001. Biodiversity of the benthos and the avifauna of the Belgian Coastal waters. Federal Office for Scientific, Technical and Cultural Affairs, Brussels, 48 pp.

Cattrijsse, A. & S. Degraer. 2001. Macrofauna biodiversity patterns of the Belgian waters. In Biodiversity of the benthos and the avifauna of the Belgian Coastal waters, pp17-20, Federal Office for Scientific, Technical and Cultural Affairs, Brussels, 48 pp.

Massin, C., J.Mallefet & A.Norro. 2002. Scientific diving, a new tool for monitoring in situ North Sea biodiversity: preliminary results. RBINS Bulletin, Biology, 72-suppl., 17-18.

Massin, C., J.Mallefet & A.Norro. 2002. Biodiversity of a wreck from the Belgian Continental Shelf: monitoring using scientific diving. Preliminary results. RBINS Bulletin, Biology, 72-suppl., 67-72.