Marine Protected Area (MPA) Monitoring Programme: Lundy Special Area of Conservation (SAC) Monitoring Report 2017.
Abstract
This monitoring report contains data acquired during a dedicated survey carried out at the Lundy Special Area of Conservation (SAC), a marine protected area (MPA) located off the northern coast of Devon and Cornwall, in 2017. The survey collected infaunal, sediment particle size and sediment contaminants data from grab samples and epibiotic data using a drop-down video approach, with chemical, physical and biological characteristics of the habitats present within the SAC. The grab samples revealed that four sediment EUNIS Level 3 habitat classes (A5.1 Sublittoral coarse sediment and A5.2 Sublittoral sand, both of which equate to Annex I Sandbank feature habitats, and A5.3 Sublittoral mud and A5.4 Sublittoral mixed sediments) were observed across the 98 grab samples. The Annex I Sandbank feature habitat A5.1 Sublittoral coarse sediment was significantly more species rich than the other three habitats and possessed high infaunal abundances. In contrast, A5.2 Sublittoral sand, which is also an Annex I Sandbank feature habitat, was the least speciose sedimentary habitat within the SAC. In general, Annex I Sandbanks feature habitats were distinguished from non-Sandbank habitats by greater numbers of the Ross worm Sabellaria spinulosa and the pea urchin Echinocyamus pusillus, and fewer numbers of annelid worms more commonly associated with finer sediments such as Mediomastus fragilis and Scalibregma inflatum. Infaunal multivariate structure was related to EUNIS habitat class, with the largest differences being observed between A5.1 Sublittoral coarse sediment and A5.4 Sublittoral mixed sediments. Eight biotopes were assigned across the 98 grab samples: 95% at the EUNIS Level 5. The two most prevalent biotope classifications were A5.132 (Mediomastus fragilis, Lumbrineris spp. and venerid bivalves in circalittoral coarse sand or gravel) and A5.611 (S. spinulosa on stable circalittoral mixed sediment). Epibiotic data acquired from the imagery approaches revealed three habitat classes present within the Lundy SAC; A3.1 Atlantic and Mediterranean high energy infralittoral rock, A4.1 Atlantic and Mediterranean high energy circalittoral rock and A4.2 Atlantic and Mediterranean moderate energy circalittoral rock. These hard substrate habitats presented a clear geographical separation, primarily associated with depth, tidal flow and east-west shore of Lundy. Although a full investigation of Annex I Reef or Stony Reef subtypes was not possible, examples of Annex I Reef Page 18 of 195 NECR482 Lundy Special Area of Conservation (SAC) Monitoring Report 2017 features bedrock reef, stony reef and bedrock and/or stony (potential) habitats were observed based on the camera still images. The 2017 sediment data were used to groundtruth previously acquired acoustic data (2015) from a region to the east of Lundy, to produce a geomorphological and sediment map. The data revealed a low (~10 m high), broad (more than 1.2 km) sandbank which occupies most of the area surveyed, apart from the southern section where bedrock is observed. The three fisheries management zones within the Lundy SAC were compared based on their sediment particle size distributions and infaunal assemblages. This comparison was based on two contrasting sampling designs: 38 single replicate samples and 12 intensively sampled boxes (five replicates within each). Both sediment particle size and associated infaunal communities displayed large spatial variability within each of the three zones. Recommendations are presented for improving data quality and refining target metrics for future monitoring of the Lundy SAC based on the findings in the report. Key recommendations include ensuring sampling location consistency between surveys, the acquisition of acoustic data for the whole SAC (to augment the relatively small area collected hitherto), and greater efforts to acquire better quality video and stills photography data to aid the assessment of reef quality. Additionally, the observed small-scale (within some intensively sampled boxes) variability in sediment particle size analysis (PSA) and infaunal assemblages, implies that stations vary with respect to their suitability for monitoring changes associated with any fisheries management approaches.