Subtidal sandbanks

Context

Subtidal sandbanks which are slightly covered by sea water all the time consist of sandy sediments that are permanently covered by shallow sea water, typically at depths of less than 20m below chart datum (but sometimes including channels or other areas greater than 20m deep).  The habitat comprises distinct banks (i.e. elongated, rounded or irregular 'mound' shapes) which may arise from horizontal or sloping plains of sandy sediment.  Where the areas of horizontal or sloping sandy habitat are closely associated with the banks, they are included within the habitat.
 
The diversity and types of community associated with this habitat are determined particularly by sediment type together with a variety of other physical, chemical and hydrographic factors.  These include geographical location (which influences water temperature), the relative exposure of the coast (from wave-exposed open coasts to tide-swept coasts or sheltered inlets and estuaries), the topographical structure of the habitat, and differences in the depth, turbidity and salinity of the surrounding water.  Within the UK's inshore waters sandbanks which are slightly covered by sea water all the time can be categorised into four main sub-types:
  1. gravelly and clean sands;
  2. muddy sands;
  3. eelgrass Zostera marina beds;
  4. maerl beds (composed of free-living Corallinaceae).
 
The latter two sub-types are particularly distinctive and are of high conservation value because of the diversity of species they may support and their general scarcity in UK waters.
 
'Sandbanks which are slightly covered by sea water all the time' is a habitat listed on Annex I of the EC Habitats Directive, qualifying as a feature for the selection of a Special Area of Conservation (SACs).
 
 

Summary statistics

  SAC Total
Favourable condition 67% 67%
Main monitoring coverage E, S  
Reported assessments 9 9
Completeness of assessments 39%  
Distribution of features   UK
 

Number of assessments reported by country and site type

Country SAC
England 5
Scotland 4
Wales 0
Northern Ireland 0
United Kingdom 9
 

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
Sandbanks which are slightly covered by sea water all the time Subtidal sandbanks 9 23 39%
 
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.
 

Maps - distribution

UK distibution of reported interest features

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

Distribution of SAC features showing assessments of favourability Condition of SAC features, with those currently reported as unfavourable-recovering shown as favourable
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:

Natura map legend - Key: proportion of assessed features on 10km squares that are favourable

 

Details of how these maps were produced

 

Condition summary

Reporting category condition summary on SAC sites

This lists the 10 different condition assessments and presents a bar chart showing the number of features reported within 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.

 

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
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.
 

Adverse activities

The number of interest features where an activity has been reported as being implicated in the "unfavourable" condition of a feature
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

The measures summary bar chart lists the management measures relevant to the reporting category
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

 
10 of the 23 SAC subtidal sandbank features have been reported; 67% are in favourable condition.  This is just above the average for marine and coastal features, and well above the averages for all habitat features and all features combined. 
 
For the three features reported as unfavourable-declining, detrimental activities identified include coastal squeeze, sea fisheries, recreation/disturbance, and water quality issues.  Management is in place for one of these features.