The 2018 surveying of Runnel Stone Marine Conservation Zone (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 targeted designated subtidal sedimentary Broadscale Habitats (BSHs). A third undesignated BSH, 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 several discrepancies which are discussed.
The drop camera survey recorded areas of rock habitats extending from the shallow to deeper subtidal (infralittoral to circalittoral) including areas characterised by high wave energy and moderate wave energy. Although all 170 of the successfully captured 2018 video samples were of good quality, all biological abundances within these data were only provided as presence or 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 designated habitat, High energy circalittoral rock, 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 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 commonly interspersed with patches of sediment habitats.
Overall, Infaunal Quality Index (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 Features of Conservation Importance (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.