Site details

Ophiothrix fragilis beds of the Dover Strait
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Flag of France
1 star - Not protected
Normal Focal Site

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The Blanc-Nez (in the foreground) and Gris-Nez capes area. Photo: Service Maritime de Boulogne sur mer

Synoptic description of site:

Site belonging the pebbles community withe sessile epifauna and Ophiothrix fragilis , located in a strong current area. 300 species, mean density of macrobenthos : about 1700 /m2. Mean biomass (AFDW) 320g/m2

Extensive description of site:

This site is located in a strong current area in front of Gris-Nez and Blanc-Nez Capes between 20 to 40 m depth. It comprises Ophiothirx fragilis beds on pebbles with a sessile epifauna community. This kind of community is found in only three locations in the English Channel. The substratum consists of clean pebbles and heterogeneous sands.

Habitats present:
Sublittoral XX
Seagrass beds 

Description of fauna and flora:

The benthic macrofauna is well developed, but mainly dominated (in terms of density and of biomass) by three species : Ophiothrix fragilis, Alcyonium digitatum and Urticina felina. 300 macrobenthic species have been recorded, most of the species being suspension feeders. The mean density of the macrobenthos is 1700.m-2 and the mean biomass is 320 g.m-2.

Human impact:

Despite its location in a coastal area, this site is subjected to only moderate levels of pollution of the water masses coming from the English Channel and from the Southern Bight of the North Sea;


All facilities for marine biodiversity research are available at the Marine Station of Wimereux: research vessels, scientific divers, fully equipped laboratories and accommodation.

Available database and website:

The global species inventory ("Faune et Flore du littoral du Pas de Calais et de la Manche Orientale") is currently updated, and is available as hard copy and will be soon available on-line on the website of the Marine Station. An inventory of the benthic macrofauna of the Ophiothrix fragilis bed of the Dover Strait is only available as hard copy (Davoult D. PhD).

Dataset covering this area:

Commitment and ongoing research:

The Marine Station, the "Unite Mixte de Recherche ELICO" from CNRS and the Lille 1 University are based in Wimereux and undertake biodiversity-related research in the area in collaboration with the Biological Station of Roscoff for this project.

Additional Information:

Some references: Dewarumez J.-M., Davoult D. & S. Frontier, 1991. Examples of responses of benthic communities to environmental stress (Strait of Dover-France). Oceanol. Acta, N° Sp 11 : 191-196. Dewarumez J.-M., Davoult D., Sanvicente Anorve L.E. & S. Frontier, 1992. Is the « muddy heterogeneous sediment community » an ecotone between the « pebbles community » and the « Abra alba community » in the Southern Bight of the North Sea . Neth. J. Sea Res., 30 : 229-238. Davoult D., Dewarumez J.-M. & S. Frontier, 1993. Long term changes (1979-1990) in three benthic communities (English Channel): use of factor analysis and rank frequency diagrams for studying structural development. Neth.J. Aquat. Ecol., 27 : 415-426. Davoult D., Dewarumez J.-M. & A. Migné. 1998. Long-term changes (1979-1994) in two coastal benthic communities (English Channel).Oceanol. Acta, 21 : 609-617.