Lagoons

Context

Lagoons in the UK are essentially bodies of saline water partially separated from the adjacent sea.  They may be natural or artificial.  Lagoons retain a proportion of their seawater at low tide and may develop as brackish, fully saline or hyper-saline water bodies.  The largest lagoon in the UK is in excess of 800ha (Loch of Stenness) although the rest are much smaller and some are less than 1ha.  Lagoons can contain a variety of substrata, often soft sediments which in turn may support tasselweeds and stoneworts as well as filamentous green and brown algae.  In addition lagoons contain invertebrates rarely found elsewhere.  They also provide important habitat for waterfowl, marshland birds and seabirds. The flora and invertebrate fauna present can be divided into three main components: those that are essentially freshwater in origin, those that are marine/brackish species and those that are more specialist lagoonal species.  The presence of certain specialist plants and animals make this habitat important to the UK's overall biodiversity.
 
There are several different types of lagoons, ranging from those separated from the adjacent sea by a barrier of sand or shingle (typical lagoons), to those arising as ponded waters in depressions on soft sedimentary shores, to those separated by a rocky sill or artificial construction such as a sea wall.  Sea water exchange in lagoons occurs through a natural or man-modified channel or by percolation through, or overtopping of, the barrier.  The salinity of the systems is determined by various levels of freshwater input from ground or surface waters.  The degree of separation and the nature of the material separating the lagoon from the sea are the basis for distinguishing several different physiographic types of lagoon.
 
SSSIs can be notified if they qualify under criteria outlined in the intertidal marine habitats and saline lagoons chapter and Section 9 of Chapter 1 Coastlands 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. 
 
Although they can be  of conservation value and are eligible for designation as SSSIs, artifical lagoons are excluded from SAC selection.
 

Summary statistics

  SAC A/SSSI Total
Favourable condition 64% 69% 68%
Main monitoring coverage E, S E, S  
Reported assessments 11 36 47
Completeness of assessments 58% unknown  
Distribution of features     UK
 

Number of assessments reported by country and site type

Country SAC SSSI/ASSI
England 8 30
Scotland 3 6
Wales 0 0
Northern Ireland 0 0
United Kingdom 11 36
 

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
Coastal lagoons Lagoons 11 19 58%
 
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
Coastal lagoons Lagoons 30
Saline lagoon Saline lagoon 6
 
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

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

 

Maps - SSSI

Current condition of SSSI/ASSI features Condition of SSSI/ASSI features, with those currently reported as unfavourable-recovering shown as favourable
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.

 

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:

SSSI map legend - Proportion of assessed features on 10km squares that are favourable

 

Details of how these maps were produced

 

Condition summary

Reporting category condition summary on Natura 2000 sites and SSSI

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
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
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
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

82% of the lagoon features have been reported; 68% of them are in favourable condition.  This is above average for marine and coastal features, for all habitat features, and for all features considered together.  69% of the A/SSSI features reported are in favourable condition with 14% unfavourable-recovering.  64% of the SAC features reported are in favourable condition with 18% unfavourable-recovering.
 
Water quality, coastal squeeze and coastal management were all listed as factors influencing the condition of lagoon features.  All of the features reported in unfavourable condition (either declining or recovering) have management in place.