The purpose of this investigation was to examine the relationships between sublittoral sediments and their associated macro-infaunas in a coastal embayment. Samples of a fine-grained surficial deposit were collected at monthly intervals from Swansea Bay, located in the northern Bristol Channel. The area is one of high tidal and wave energy. Mean spring and mean neap tidal ranges are 8.6 and 4.1 m respectively, and the area is subjected to wave action from locally-generated winds and swell from the Atlantic Ocean. Maximum near-bed tidally- or wave-induced currents are of the order of 1 ms-1.
The surveys have provided the factual basis for a model to explain the presence in a sublittoral deposit of allochthonous bivalves of an inshore, muddy-sand Abra community and an offshore Spisula subcommunity of the Venus communtiy. Further, a mechanism is advanced to explain the rapid burial of the allochthonous bivalves by coarse-grained sediment influx during storms and the subsequent localized deposition of mud.