Natural England Conservation Advice for Marine Protected Areas
Chesil and the Fleet SAC

Natural England guidance

This site collection contains Natural England's conservation advice for this site. It fulfils Natural England’s responsibility under the Conservation of Habitats and Species Regulations 2017 (as amended), to give advice on how to further the conservation objectives for the site, identify the activities that are capable of affecting the qualifying features and the processes which they are dependent upon.

Natural England's conservation advice for this site is made up of a number of components. You will need to consider: Additional information for consideration:

Site information

Overarching site: Chesil Beach and The Fleet EMS
Site name: Chesil and the Fleet SAC
Designation type: SAC
Site identification: UK0017076
Latest designation date: 01 April 2005
Qualifying features
(click to see site specific description):

General information on the site features:
The generic information on the qualifying features is useful for understanding the qualifying features, and should be used in conjunction with the site specific information.
Designated area (ha): 1634.91
Component Sites of Special Scientific Interest (SSSI):
Overlapping Protected Areas:

Last updated: 13th March 2020

Background information and geography

The Chesil Bank is situated on the West Dorset coast, stretching 29 km from West Bay to Portland, and is one of the five largest shingle beaches in Britain. Due to longshore drift and other contributing factors, the beach material is precisely graded from pea-gravels at West Bay to cobbles at Chiswell, Portland (although there are local variations) (May and Hansom, 2003).

The Fleet is the largest example of a lagoonal habitat in England, covering approximately 495 ha, supporting the greatest diversity of habitats and species of any lagoon in the UK (Bamber, 1997). It is very shallow, with a minimum depth of approximately 30 cm at its western extreme, deepening to 5 m under Ferrybridge (Foote, 1998). It is illustrative of two of the five lagoonal types found in the UK as it is predominantly a lagoonal inlet but also has features of percolation lagoons. It is bordered by the fossil shingle barrier structure of Chesil Beach, through which seawater is proposed to percolate into the lagoon, certainly during the development of ‘canns’ under particular conditions, but most of its water exchange occurs through the narrow channel that links it to Portland Harbour. A low freshwater input produces fully saline conditions throughout most of the Fleet, with reduced salinity occurring only in the west. The lagoon is extremely sheltered from wave action and has weak tidal streams, except in the eastern Narrows and entrance channel at Ferrybridge. The tidal range is much smaller and temperature range far greater than on the open coast. This suite of environmental conditions is rarely found in the UK in a single lagoon and influences the diversity and composition of its biological communities (Copley, 1999).

The Fleet can be divided into three zones; the lower Fleet or lagoonal inlet channel which is a typical estuarine lagoon, and the mid- and west Fleet which is a classic lagoon and also includes the third, smaller, reduced salinity zone at the far western end at Abbotsbury (Whittaker, 1978), (Bamber et al., 1992), (Dyrynda, 1997). Much of the seabed of the Fleet is composed of fine mud and sands to coarse cobbles and pebbles but there are also areas of bedrock within the tide-swept Narrows (Dyrynda and Cleator, 1995). Where the sediment is coarser and consists more of gravels, pebbles and cobbles in the eastern section of the lagoon between Smallmouth and the Narrows, the snakelocks anemone Anemonia viridis occurs in unusually high densities with the starfish Asterina gibbosa. The pebble habitat, adjacent to Chesil Bank, is surprisingly stable and is encrusted with low growing algae whilst a number of invertebrates live in the gaps amongst the pebbles themselves. Extensive seagrass communities are found in the lower, mid- and west Fleet but are absent from Abbotsbury embayment and the fast-flowing Narrows eastward.

Where seawater percolates through Chesil Bank at the low shore level, small saline springs occur and flow into the lagoon. These springs support an unusual assemblage of molluscs including DeFolin’s lagoon snail Caecum armoricum, which is known only from two other sites in the UK (Seaward, 1987), (Pain et al., 2009), (Wilkinson and Baldock, 2013). Where the fast flowing water in the Narrows scours the only subtidal bedrock in the Fleet, large conspicuous species, particularly sponges and large seaweeds, survive in the strong water flow carrying nutrients from the western Fleet (Dyrynda, 1984). Notable species include the rare sponge Suberites massa and the sponge Halichondria bowerbankii.

The Fleet is an important nursery ground for a number of fish species and is a designated sea bass nursery. Over 25 different species of fish have been recorded, including grey mullet, Couch’s, sand and common gobies, and two species of pipefish; 17 species of fish occur predominantly in the eastern section of the Fleet (Dyrynda, 1997), (Baldock and Kay, 2012), (Baldock, 2016 Pers Comm).

Site maps

Use the MAGIC website to see site maps, including habitats, species and other marine designations.

These maps are based on best available evidence, there are some caveats associated with the maps on MAGIC.

There are some instances where the feature, subfeature or supporting habitat name varies on MAGIC from the conservation advice. The alternative names are listed on gov.uk.

Annual vegetation of drift lines (H1210) and Perennial vegetation of stony banks (H1220) are collectively referred to as Coastal Vegetated Shingle on MAGIC; Atlantic salt meadows (Glauco-puccinellietalia maritimae) (H1330) and Mediterranean and thermo-Atlantic halophilous scrubs (Sarcocornetea fruticosi) (H1420) are collectively referred to as Saltmarsh; and Coastal lagoons (H1150) as Saline lagoons.

Conservation objectives

The site’s conservation objectives apply to the site and the individual species and/or assemblage of species for which the site has been classified (the "Qualifying features" listed above).

The objectives are to ensure that, subject to natural change, the integrity of the site is maintained or restored as appropriate, and that the site contributes to achieving the Favourable Conservation Status of its qualifying features, by maintaining or restoring:
  • the extent and distribution of qualifying natural habitats and habitats of the qualifying species
  • the structure and function (including typical species) of qualifying natural habitats
  • the structure and function of the habitats of the qualifying species
  • the supporting processes on which qualifying natural habitats and the habitats of qualifying species rely
  • the populations of each of the qualifying species
  • the distribution of qualifying species within the site

Qualifying features

Refer to the site information table above for the list of features within this site.

This should be read in conjunction with the accompanying supplementary advice section, which provides more detailed information to help achieve the objectives set out above, including which attributes should be maintained and which restored.

The conservation objectives apply under the Habitats Regulations, and must be considered during a Habitats Regulation Assessment, including an Appropriate Assessment.

The conservation objectives and accompanying supplementary advice provide a framework to inform the management and measures needed to conserve or restore the European site, and the prevention of deterioration and significant disturbance of its qualifying features.

Where the objectives are met, the site will be considered to show a high level of integrity, and to be contributing to achieving the aims of the Habitats Regulations.

Supplementary Advice on Conservation Objectives

See supplementary advice on conservation objectives for this site, which aim to describe the range of ecological attributes that are most likely to contribute to a site’s overall integrity.

Last updated: 13th March 2020


Advice on Operations

See the advice on operations for this site to view information on the sensitivity of features in this site to the pressures exerted by different activities.

Last updated: 13th March 2020


Feature Condition

In 2016, Natural England trialled and rolled out a new Marine Protected Area (MPA) condition assessment methodology that provides robust results and information on the condition of marine features designated within MPAs in England. With guidance from National teams and using all available evidence and condition monitoring data, Area Teams conduct these assessments following a standardised approach that assesses if the feature and sub feature conservation targets set for each MPA have been met.

To date, condition assessments have been completed for a number of features in a range of marine Special Areas of Conservation (SACs) by the National and Area Teams. Further marine habitat features in SACs and other MPAs will continue to be assessed in the future. The new method can now also be applied to complete habitat and species condition assessments for other MPAs in England, whilst still meeting the different processes in place to report on the results of condition of features in Marine Conservation Zones (MCZs) and Special Protection Areas (SPAs). Different processes are currently in place to decide and report on the condition of non-marine habitat and species features of SACs.

The main part of the assessment process is directly undertaken and stored here on Natural England’s Designated Sites View. The details for the most recent assessments of this site can be found here.

Management measures

If you are carrying out an environmental assessment, planning an operation or assessing an operation or proposal, it is important to consult with the following organisations where applicable. To find out if any management measures, byelaws or other restrictions apply to your activity see the management measure page or you can use the following links for more information.

The Marine Management Organisation license, regulate and plan marine activities in the seas around England and Wales so that they’re carried out in a sustainable way.
Environment Agency are responsible for regulating major industry and waste, water quality and resources, fisheries, inland river, estuary and harbour navigations, conservation and ecology.
Offshore Petroleum Regulator for the Environment and Decommissioning (OPRED) regulates oil and gas, CCS and gas storage activities in the marine environment.

Further information

For further information relating to this designated site you can refer to the following resources:
Site specific information: Other information:
For further information about this site contact: Natural England enquiries Telephone: 0300 060 3900. Email: enquiries@naturalengland.org.uk


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