While sites were located to survey hard substratum, pebbly sand habitats that occurred between the reefs were also recorded but not analysed as
they were not considered a designated part of the reef feature. During analysis of rocky habitats, observations were made that sessile RAS were occurring on pebbly sand, which therefore must be overlying bedrock that the species could attach to (Keough and Downes, 1982). This observation became of critical importance as fishers were seeking permission to scallop dredge sediments between the reef www.selleckchem.com/products/birinapant-tl32711.html features within the MPA. By returning to the video archive we could formally enumerate pebbly sand Reef Associated Species (RAS) assemblages, which had previously been ignored for the reef species recovery analysis, and compare them over time from 2008,
when the exclusion was enforced, to 3 years later in 2011. Here we test the hypothesis that, if protected from fishing, inter-reef pebbly sand habitats can support significantly more sessile RAS than similar habitats in areas that remain open to fishing. If pebbly sand habitats were found to support sessile RAS, this would provide evidence to broaden the definition of ‘reef’ as a feature, with consequences for how lines are drawn around such protected features in MPAs. We measured the following response variables for sessile RAS: Species Richness, Fluorouracil Overall Abundance, Assemblage Composition, and a subset of sessile RAS indicator species that were preselected (ross coral Pentapora fascialis, sea squirt Phallusia mammillata, dead man’s fingers Alcyonium digitatum, branching sponges, pink sea fans Eunicella verrucosa and hydroids ( Jackson et al., 2008)). The case study site is in Lyme Bay (Fig. 1), located on the south west coast of the UK. Lyme Bay comprises a mosaic
of rocky reefs with boulders, cobbles and mixed sediments, known to support some fragile biogenic reef species of national importance (Hiscock and Breckels, 2007 and Vanstaen and Eggleston, 2011). This study focused on pebbly sand habitats (particle size ⩽64 mm diameter (Irving, 2009)), which occurred between areas of rock, boulders and cobbles. All identifiable species were enumerated; however, only the sessile Reef Associated Species (sessile RAS = structure forming species Phospholipase D1 that are attached to the seabed and are associated with hard substratum) were analysed as it was considered that it was only the sessile RAS that could truly indicate the ‘reef’ feature. To determine whether sessile RAS can occur on pebbly sand if fishing pressure is relieved, the seabed was surveyed across Lyme Bay at the point when towed demersal trawling was excluded from the proposed MPA (2008), which is considered here as the ‘Before’ baseline data. Samples were taken inside the MPA or outside the MPA, which remained open to fishing (‘Open Controls; OC’). The survey was then repeated three years later. The design is effectively a Before After Control Impact (BACI) design (Underwood, 1994).