Based on 12 years of sampling in Liverpool Bay a number of spatial and temporal variants of the Abra community can be recognised: a) species poor localities that are consistently dominated by Pectinaria koreni or Abra alba ; b) unstable fluid muds with ephemeral recruitments of Pectinaria ; c) species rich localities with a range of alternative dominants; d) heterogeneous offshore localities that are temporarily colonised by Abra community species. General colonisation events occurred in 1972 and 1978 which may be synchronised with events elsewhere in the North Sea.