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Rocky shores, reefs and caves

Context

Rocky shores, reefs and caves are widely distributed habitats around the UK and consist of both littoral and sub littoral rock features. This reporting category contains data for both intertidal and subtidal hard substrata features (rocky shores, reefs, caves) as well as biogenic reefs associated with soft substrates (such as Sabellaria or Serpula reefs).

SSSIs can be notified if they qualify under criteria outlined in the intertidal marine habitats and saline lagoons chapter of the Guidelines for Selection of Biological SSSIs. In Northern Ireland, ASSIs are selected on a very similar basis – the Guidelines for the Selection of Biological ASSIs in Northern Ireland is an addendum to the SSSI guidelines rather than an alternative

Littoral rock

The geology and wave exposure of the shore influence the form of the habitat, which can include vertical rock, shore platforms, boulder shores, or rocky reefs surrounded by areas of sediment. These two factors are also major influences on the associated marine communities. In general, littoral rock tends to be colonised by algae in wave-sheltered conditions, and by limpets, barnacles and mussels as wave-exposure increases. Relatively soft rock such as chalk and limestone can support boring species, whereas colonisation of basalt and granite is limited to the rock surfaces. In all cases there is a distinct zonation of species down the shore, which principally reflects the degree of immersion by the tide. Biogeographic differences are also apparent, with the littoral rock areas of South-west England tending to be richer in species than similar rocky habitats in the North and East.

Inshore sublittoral rock

The seabed of inshore areas (defined as within six nautical miles of the shoreline) is dominated by soft sediment. Where sublittoral rock habitats occur they tend to be immediately adjacent to the shore, fringing islands, headlands, open coast and rocky inlets such as rias and sea lochs. Further offshore, rocky sublittoral habitats may be present as submerged reefs, pinnacles and ledges, and are often surrounded by areas of soft sediment.

Most sublittoral rocky habitats are in areas exposed to water movement, which keeps the rock surface free of sediment. Rocky areas in sheltered situations are not as common, but do occur in Scottish sea lochs as well as the rias of South-west Britain.

Chalk reefs, which occur in parts of southern Britain and off the East coast, support a diversity of flora and fauna. This includes foliose red algae and small brown algae on upward facing surfaces, turfs of hydroids and bryozoans, and an abundance of sponges and animals which bore into the soft rock.

Sabellaria alveolata reefs are formed by the honeycomb worm S. alveolata, a polychaete which constructs tubes in tightly packed masses with a distinctive honeycomb-like appearance. Reefs are mainly found on the bottom third of the shore, but may reach mean high water of neap tides and extend into the shallow subtidal in places. They form on a variety of hard substrata, from pebbles to bedrock, in areas with a good supply of suspended sand grains from which the animals form their tubes, and include areas of sediment when an attachment has been established. The British Isles represent the northern extremity of the range in the North-east Atlantic.

Sabellaria spinulosa reefs comprise dense subtidal aggregations of this small, tube-building polychaete worm. S. spinulosa can act to stabilise cobble, pebble and gravel habitats, providing a consolidated habitat for epibenthic species. They provide a biogenic habitat that allows many other associated species to become established.

Summary statistics

	SAC	A/SSSI	Total
Favourable condition	74%	85%	80%
Main monitoring coverage	E, S	E, S
Reported assessments	19	27	46
Completeness of assessments	38%	unknown
Distribution of features			UK

Number of assessments reported by country and site type

Country	SAC	SSSI/ASSI
England	13	21
Scotland	6	5
Wales	0	0
Northern Ireland	0	1
United Kingdom	19	27

Natura features

List of Natura 2000 interest features within this reporting category

Interest feature name
Formal name	Informal name	No. of assessments reported	Total no. of features	% assessed
Reefs	Reefs	14	35	40%
Submerged or partially submerged sea caves	Sea caves	5	15	33%

Natura 2000 comprises Special Protection Areas (under the Birds Directive) and Special Areas for Conservation (under the Habitats and Species Directive). The list presented here includes all of the qualifying interest features under these Directives, and shows the proportion of these features for which a condition assessment has been made.

SSSI features

List of SSSI and ASSI interest features in this reporting category

Interest feature name
Formal name	Informal name	No. of assessments reported
Littoral rock	Littoral rock	21
Reefs	Reefs	2
Submerged or partially submerged sea caves	Sea caves	1
Subtidal reefs	Reefs	1
Tidal rapids	Tidal rapids	2

This list has not been fully standardised at a UK level yet. It is intended to show the principal constituent "feature types" for this reporting category.

Maps - distribution

Distribution of reported interest features.

Map showing the locations of the 10km squares in which at least one condition assessment has been reported. It does not show features that have not yet been assessed.

Maps - Natura

Current condition of SAC features
Distribution of SAC features showing assessments of favourability (where unfavourable-recovering is counted as unfavourable).

Condition of SAC features, with those currently reported as unfavourable-recovering shown as favourable
The implication of the unfavourable-recovering condition assessments is that at some point in the future these features should become favourable. This map shows the effect of that recovery by counting the favourable and unfavourable-recovering assessments together.

IMPORTANT NOTE: we do not have information on the timescale of the predicted recovery, which may be influenced by many past, natural and human related factors. A sustained sympathetic management regime is more likely to result in favourable condition being attained.

Key: Proportion of assessed features on 10km squares that are favourable:

Details of how these maps were produced

Maps - SSSI

Current condition of SSSI/ASSI features
Distribution of SSSI/ASSI features showing assessments of favourability (where unfavourable-recovering is counted as unfavourable).

Condition of SSSI/ASSI features, with those currently reported as unfavourable-recovering shown as favourable
The implication of the unfavourable-recovering condition assessments is that at some point in the future these features should become favourable. This map shows the effect of that recovery by counting the favourable and unfavourable-recovering assessments together.

Key: Proportion of assessed features on 10km squares that are favourable:

Details of how these maps were produced

Condition summary

This lists the 10 different condition assessments and presents a bar chart showing the number of features within the SSSI series and the Natura 2000 series (either SPA for bird features or SAC for features other than birds). Note that for Natura 2000 we are able to estimate the number of features that have not been assessed during the 6 year reporting period - we are unable to do this for SSSI/ASSI because we do not have an overall list of notified interest features for these designations.

NB favourable unclassified and unfavourable unclassified have been used in this first six year cycle to get around difficulties in identifying trends in condition as common standards monitoring is implemented. It is expected that these categories will not be used for subsequent assessments of a feature.

Condition assessment - Natura 2000 features

The number and proportion of assessments for Natura 2000 (SAC and SPA) interest features falling into each of the condition categories. Note that the �unfavourable� category includes all reports of unfavourable condition except �unfavourable recovering� which is shown as a separate segment.

Condition assessment - SSSI features

The number and proportion of assessments for SSSI/ASSI interest features falling into each of the condition categories. Note that the �unfavourable� category includes all reports of unfavourable condition except �unfavourable recovering� which is shown as a separate segment.

Adverse activities

The number of interest features where an activity has been reported as being implicated in the "unfavourable" condition of a feature. More than one adverse activity may be reported for each feature.

Management measures

For each "measure" the chart shows the number of interest features where that measure has been taken on a site to improve or maintain the condition of an interest feature. More than one measure may be reported for each feature assessed.

Interpretation

80% of rocky shore, reef and sea cave features reported are in favourable condition. This is above the average for marine and coastal features, for all habitats features and for all features combined together. Of the 20 SAC features that have been reported, 74% are in favourable condition with 5% unfavourable-recovering. 85% of A/SSSI features reported are in favourable condition.

All of the sea caves reported are in favourable condition. Five reefs are reported as being in unfavourable condition. Detrimental activities identified for reefs include coastal squeeze, extraction, sea fisheries, recreation and inappropriate management.