Moerella spp. with venerid bivalves in infralittoral gravelly sand

Description (English)

Infralittoral medium to coarse sand and gravelly sand which is subject to moderately strong water movement from tidal streams may be characterised by Moerella spp. with the polychaete Glycera lapidum (agg.) and venerid bivalves. Typical species include Moerella pygmaea or M. donacina with other robust bivalves such as Dosinia lupinus, Timoclea ovata, Goodallia triangularis and Chamelea gallina. Other infauna include nephtyd and spionid polychaetes and amphipod crustacea. Another important component of this biotope in some areas is the bivalve Spisula solida (see Khne & Rachnor 1996) which may be common or abundant. In conjunction with unit A5.242 this biotope may form part of the 'Shallow Venus Community', the 'Boreal Off-shore Sand Association' and the 'Goniadella-Spisula association' of previous workers (see Petersen 1918; Jones 1951; Thorson 1957; Salzwedel, Rachor & Gerdes 1985). Epifaunal communities may be reduced in this biotope when compared to A5.242; both types may have surface sand waves which may be indicative of the presence of venerid bivalves (Warwick & Davies 1977). This hypothesis, however, requires testing. Remote grab sampling is likely to under-estimate venerid bivalves and other deep-burrowing and more dispersed species such as Paphia, Ensis and Spatangus. In southern areas of the UK and the North Sea, in slightly siltier sand and shelly sand, A5.133 may give way to the other Spisula biotope A5.244.
Situation: This biotope is found on the exposed open coast and in estuaries with moderately strong tidal currents.

Source: EUNIS habitat classification