Survey run by Dr Ken Collins of the NOC (Southampton) on behalf of Dorset Wildlife Trust. These records all relate to 'Collins, K., Johnson, M., Mallinson, J. and Markey, M. (2000) Seagrass (Zostera marina) and Sea Pen (Virgularia mirabilis) surveys, Portland Harbour to Ringstead, Dorset' A copy of the report is held at Dorset Environmental Records Centre.
The main focus of this work was a video sledge survey of Portland Harbour. A colour video camera was towed at 1-2 knots over the seabed of the Harbour. Tracks at 200m spacing were followed through the whole of the Harbour with the exception of the port exclusion zone and around a very large vessel moored in the centre of the harbour. In the shallow, western part of the harbour, the survey was extended to the extent of the low water springs. Differential GPS positions were continuously recorded against the video time code. A detailed study of the Portland Harbour video records has been made by Mike Johnson as part of his BSc dissertation - see references for full title.
The survey vessel is based in Poole Harbour and en route to Portland Harbour tows were made from off Ringstead to Weymouth Bay. In the very shallow waters off Ringstead, a small 4m inflatable was used to tow a sledge with a self contained camcorder in underwater housing. Here, positions were recorded using a handheld GPS unit. Please note, these records have also been incorporated into subsequent reports written by the same author.
The survey data entered into this database has been supplied electronically by Dr. Ken Collins.
