BIOTIC

BIOTIC Species Information for Atrina fragilis
All Taxonomy Biology Distribution Reproduction

Researched by	Dr Harvey Tyler-Walters	Data supplied by	MarLIN
Refereed by	Dr Dan Minchin
Distribution and Habitat
Distribution in Britain & Ireland	Predominantly southern and western shores of the UK from North Scotland to the Iberian Peninsula, including the Channel Isles (see additional information below). Recorded at Milford Haven.
Global distribution	Northern UK to Iberian Peninsula and the Adriatic Sea.
Biogeographic range	Not researched	Depth range	LWS to 400m
Migratory	Non-migratory / Resident
Distribution Additional Information	Distribution Specimens occur as solitary individuals or localized patches of small groups of individuals. Records for Ireland were supplied by Julia Nunn and the Centre for Environmental Data and Recording (CEDaR). Records of fan mussel shells, and records before 1950, are more widespread than shown in the above map, which only shows live records after 1950. Atrina fragilis was recorded in Zostera sp. beds in the Isles of Scilly, however specimens have not been found since the Zostera sp. beds were lost (Turk 1982; Turk & Seaward 1997). This species was more common in scallop areas in the early 1900s. Presumably trawling and dredging of theses formerly populated regions is the reason for the decline of this species (Minchin pers. comm.). Dredging of a Pecten maximus bed off Glengad Head, Ireland, after 1975, removed many live specimens of Atrina fragilis in scallop dredges and the population of fan mussels is thought to have been destroyed by subsequent dredging (Anon 1999c). The species is known from weak to moderately strong currents, for example in Knightstown, Valentia Island the population is exposed to >2 knots on spring tides (Dan Minchin pers. comm.). Although usually found at full salinities it may be exposed to reduced or variable salinities for brief periods (Dan Minchin pers. comm.).

Substratum preferences	Gravel / shingle Mixed Muddy gravel Muddy sand Mud Fine clean sand Sandy mud Coarse clean sand	Physiographic preferences	Offshore seabed Ria / Voe Enclosed coast / Embayment
Biological zone	Sublittoral Fringe Upper Infralittoral Lower Infralittoral Upper Circalittoral Lower Circalittoral	Wave exposure	Sheltered Very Sheltered
Tidal stream strength/Water flow	Moderately Strong (1-3 kn) Weak (<1 kn)	Salinity	Full (30-40 psu)
Habitat Preferences Additional Information
Distribution References	Tebble, 1976, Woodward, 1985, Anonymous, 1999(c), Seaward, 1990, Seaward, 1982, Turk, 1982, Turk & Seaward, 1997, Moore, 2002, Simunovic et al., 2001,