2013 Natural England Fal and Helford SAC Maerl Drop-down Video and Dive Survey

notPlanned

"Background Seastar Survey Ltd. was contracted by Natural England (NE) to undertake a survey of the Fal and Helford Special Area of Conservation (SAC) in the summer of 2013. The survey was intended to gather data to inform condition monitoring of the maerl bed sub-feature of the Fal and Helford SAC. Three attributes were to be assessed during the survey: Extent of maerl bed communitiesof maerl bed communitiescomposition of maerl bed communitiesIn order to achieve these objectives, a two phase survey was planned, comprising of a drop-down camera survey and a scientific diving survey. The drop-down video survey was designed to investigate the extent and distribution of the maerl bed communities within the SAC. The main aim of the scientific diving survey was to assess the species composition of the maerl beds within the SAC, supporting the data gathered during the drop-down video survey. ConclusionsThe survey was successful in gathering sufficient data to assess the extent, distribution and species composition of maerl bed communities within the Fal and Helford SAC. There was no evidence from the current survey data to suggest that condition of the live maerl beds have deteriorated compared to the known data at the time of sampling. The extent and distribution of the live maerl beds does not appear to have altered. Although there were some differences in the species composition compared to previous surveys, the community present was largely the same. The differences in species presence / absence may be due to different survey sampling times, or varying levels of taxonomic experience of the dive team involved during the survey. Multivariate analysis of the scientific dive data showed that there were distinct differences in the communities present on areas dominated by Phymatolithon calcareum compared to those dominated by Lithothamnion corallioides. In addition, the community present on the L. corallioides beds showed some differences based on geographical location, with dive sites within St. Mawes Bank having different communities to those from Castle Point and Helford River. These differences should be considered when assessing future condition monitoring of the species composition attribute of the maerl beds. d"