NERI Technical report No. 529: Mejlgrund and Lillegrund. An investigation of biological diversity on shallow waters reefs in Samsø Belt, Denmark. Dahl, K., Lundsteen, S. & Secher Tendal, O. 2005. 87 pp.
Summary
The investigation included quantitative measurements of the benthic vegetation and fauna on two neighbouring stony reefs in the Danish Belt Sea. Sampling was done with a suction sampler on two different substrates, a mixed substrate including sand and gravel as well as on larger stones covering approximately 0.1 m2 of the seabed. The biodiversity on the reefs was high. A total number of 218 species were identified from water depths ranging from 3.9 to 8.6 m. The average biomasses on stones were high ranging from 112 to 191 g ashfree dry weight per 0.1 m2 at the different depth intervals with the majority consisting of macroalgae. The biomasses on the mixed substrates were much less, 24 to 83 g ashfree dry weight per 0.1 m2 with a relatively high proportion of macrofauna. Newly settled Mytilus edulis were extremely abundant in the algal vegetation as well as on the seabed of mixed substrate. The algal vegetation on the deepest investigated station at 8.6 m was heavily grassed by the sea urchin Psammechinus miliaris.
Notes on some of the species are included with new observations on habitat utilisation and comments about species determination. This includes a new variety of the species Lacuna pallidula (Gastropoda) and a species related to Parvicardium ovale (Bivalvia), which has not previously been described.
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