The 2018 surveying of Runnel Stone MCZ was delivered by both the Environment Agency and the Cornwall Inshore Fisheries and Conservation Authority (CIFCA).
The grabbing survey identified and successfully sampled both of the targeted designated subtidal sedimentary BSHs. A third undesignated BSH, A5.4 Subtidal mixed sediments, was also recorded. The distribution of BSHs recorded in 2018 was in reasonable agreement with the predicted distribution of habitats estimated from previous surveys and the Marine Evidence modelling; however, there are a number of discrepancies which are discussed.
The drop camera survey recorded areas characterised by high and moderate energy infralittoral and circalittoral rock habitats. Although all 170 of the successfully captured 2018 video samples were considered to be of good quality, all biological abundances within these data were only provided as presence-absence data. This was linked to the strong tidal streams affecting the surveyor’s ability to gather imagery data at sufficiently low tow speeds.
The A4.1 High energy circalittoral rock designated habitat FOCI was not recorded in either the still or the video imagery. This is despite the interpreted broadscale habitat map predicting a large area of this habitat to be present in the north-west of the MCZ.
The 2012 and 2018 surveys focussed on different geographical areas, making direct comparison of habitat extents difficult. Despite this, the distribution of A4.2 Moderate energy circalittoral rock was similarly widespread between 2012 and 2018, suggesting a similar distribution of this habitat within the two surveys.
The data show that areas predicted by the habitat map to be dominated by circalittoral rock habitats were actually commonly interspersed with patches of sediment habitats.
Overall, IQI values were indicative of “Good” status under the Water Framework Directive. This indicates that the benthic assemblages showed minimal impacts from anthropogenic activity.
- Recommendations for Future Monitoring
- Update habitat maps.
- Consider image capture methods for high energy benthic habitats and species FOCI.
- Consider image capture methods for species FOCI.
- Identification of key structural and functional taxa.
- Incorporation of biological traits analyses.
- Data analysis 1: analysis of different data types.
- Data analysis 2: appropriate indictors of change.
- Continue monitoring of contaminants.