1994 Purbeck Marine Research Unit Canford School, Swanage Dorset, Ross Coral Mapping Drift dive transect surveys

All these records relate to "Powell (ed) (1994) - Ross Coral Mapping Project (Preliminary Report) 1994" A copy of the report is held at English Nature (Dorset Team). This survey aimed to map the distribution and record the abundance of Ross coral (Pentapora foliacea) in the area off Swanage between Handfast Point and Ballard Point. The survey confirmed that Ross coral occurs much further east along the English Channel than previously recorded. Due to strong tidal flows in the area, drift dives were used to make transects of the area. 12 dives were undertaken, 10 of which recorded Pentapora, and have been entered on this database. The largest colonies were 30cm or more in diameter and occurred on outcrops of chalk and large boulders in the south western part of the survey area. Within the area investigated, several thousand colonies were recorded, making Ross Coral locally abundant. GPS/Decca navigation was used to pinpoint the position of the dive support boat at the start, during (following the diver's surface marker buoy) and at the end of the dive allowing a habitat map along the line of the dive to be constructed. The survey also highlighted an area of significant marine interest with a species rich animal turf on the chalk and rubble sea floor off Ballard Point. Underwater photography was used to supplement written records and to aid identification of other species. Reference was made to two records further east, off the Isle of Wight, one occurring in water 65-70m deep.