The creation of a seamless habitat map in St Austell Bay using LIDAR point cloud intensity data and high-resolution MBES data

Supervisor: Veerle Huvenne (National Oceanography Centre, Southampton)
The ability to create accurate and reliable coastal habitat maps has increased dramatically over the past decade, but very few map the intertidal zone, the area of the seashore that will be most affected by global sea level change. Benthic habitat mapping is traditionally carried out using multibeam data in the form of bathymetry and backscatter and is combined with ground-truthing to create an overview of the seafloor. However in order to map the intertidal zone successfully it is necessary to use data which covers the terrestrial realm as well. LIDAR is an emerging technology in habitat mapping as it provides high-resolution data of wide areas in a relatively quick period of time. The purpose of this study is to combine two high resolution datasets and to create a seamless habitat map of the upper shore, inter-tidal zone and shallow waters. The study then uses the resulting map as a basis for management recommendations, including the establishment of an MPA. St Austell Bay, in Cornwall, was chosen as the site to explore the technique due to the overlapping of both LIDAR intensity data and high-resolution multibeam data. As well as this, there was also ground-truthing data present from the Bay in the form of grab samples, aerial photography and high definition video and photography of the seabed from a series of research tows. A multi-method approach was used to define both the morphology and composition of the seabed and terrestrial environments. Through the use of ArcGISTM software the morphology of the region was split into five groups; flat and sloping zones, crests and depressions and breaks of slope. Individual habitat maps using bathymetry and backscatter data and then LIDAR data were created before combining the two to achieve a seamless habitat map. The seamless map identified eight classes in St Austell Bay, ranging from flat and smooth, sandy silt to unvegetated cliff faces. The map indicated that certain habitats extended continuously from above the mean low water out into the shallow water of the Bay. This habitat, located at Par Sands to the North of the Bay, is of particular interest as it is protected as a Country Wildlife Site (CWS). However under the current protection the continuous habitat is only protected to mean low water and not out into the shallow waters of the Bay. The seamless habitat map can be used as a basis for recommending the extension of this CWS to incorporate the benthic marine habitat as well.