This report is a compilation of 22 habitat reviews, covering many of the significant marine habitats found around the UK’s coastline and in particular within the network of marine Special Areas of Conservation (SACs).

The purpose of these reviews is to provide a technical summary of the key characteristics of each habitat, to assist in their management and conservation. As such the reviews are primarily aimed at marine specialists involved in the conservation management of the habitats, both in the UK and in other European countries.

The information in this report is based upon nine more detailed studies undertaken through the UK Marine SACs Project and upon the earlier work on habitat classification provided by JNCC’s Marine Nature Conservation Review and BioMar. The reviews were originally conceived to support the work of OSPAR and in particular to contribute to our understanding of the ecological functioning of certain marine habitats in the north-east Atlantic. Recognising their value in underpinning Special Areas of Conservation, the series of reviews has been extended as part of the UK Marine SACs Project.

The understanding contained in these reviews continues to evolve, both in terms of the knowledge of the ecology of the features themselves and in the most effective and practical means of categorising and interpreting this knowledge. The work will continue to be taken forward through the MarLIN programme.

The 22 habitat reviews in this report provide a summary of key information, contained in the nine studies noted above and other key references, in terms of more specific features. The selection of these features and the information presented in the reviews builds upon the habitat classification system developed for Britain and Ireland under the EC Life-funded BioMar Project. This system defines and describes seabed habitats (biotopes) at a variety of hierarchical scales as an aid to the management and conservation of marine habitats.

Each habitat is described in a standard way, under the following headings:

• Biotope code and name
• Habitat classification
• Biotope description
• Similar biotopes
• Characterising species
• Distribution
• Frequency of occurrence

The reviews presented here provide the following key additional information on each habitat:

• A correlation with other national and international classifications
• A description of the ecological role of the habitat or its key component species
• An assessment of the sensitivity of the habitat to various human activities
• An assessment of the present conservation status (degree of threat) of the habitat, its current level of protection, and an outline of the management measures that are required to improve its status.

The reviews provide a model for the development of a key information system on marine habitats, designed to provide essential information to underpin management and conservation of the marine ecosystem. They have a standard format to assist the user in quickly locating the relevant information and lead the user to more detailed information in supporting references if required. This standard approach lends itself to display on electronic media such as the Internet (some reviews are now available on JNCC’s web site: www.jncc.gov.uk), where inclusion of photographic images or other graphics and hypertext links can greatly enhance the user’s ability to access the information. The categories used in each review are defined below.

The habitats included here are mostly at the habitat complex level in the MNCR BioMar classification, that is they each comprise a number of more specifically defined biotopes which occur in broadly similar habitat conditions. In a few cases the habitat reviews are at a lower level in the classification, for example the habitats dominated by single species such as mussels, maerl, eelgrass and honeycomb worms.

Each habitat review is laid out in a standard format. The main sources of information, criteria and terminology used are given below:

The habitat unit described is correlated to the following habitat classifications:

The habitat description is taken from the MNCR BioMar classification (Connor et al. 1997a, b).

The habitat distribution maps are generated from the JNCC’s Marine Nature Conservation Review database, providing information on the known distribution of the habitat, including all relevant sub-types, at the date given.

Information relating to each habitat is derived from Connor et al. (1997a, b) and the relevant UK Marine SACs Project review.

The terms used for each of the habitat factors (e.g. moderately strong tidal streams) are given in a linked document, as defined in Connor et al. (1997a, b).

The tables listing characterising species are taken from marine biotopes classification for Britain and Ireland (Connor et al. 1997a, b). Data on characterising species not contained within these reports were derived from the JNCC’s Marine Nature Conservation Review database. The tables are explained in a linked document.

Information relating to each habitat is derived mainly from the relevant UK Marine SACs Project review.

The measures of sensitivity are based on definitions developed for the MarLIN programme, and assessed using information derived mainly from the relevant UK Marine SACs Project review. The sensitivity ranks are the maximum likely for each activity assessed against the benchmarks given (i.e. a given amount of activity over a particular period). Tyler-Walters & Jackson (2000) describe the MarLIN programme’s methodology, definitions and procedures for assessing sensitivity of habitats and species.

Note: Whilst this methodology is now well advanced, it is likely that both the methodology and subsequent ratings will need to be modified in the light of their practical application and as new information becomes available. Also management of human activities needs to take account of site-specific conditions, such as the local extent and frequency of the activity, as these will have a strong bearing on whether the activity is having a significant damaging effect on the habitat.

The availability of conservation status information is very limited at present; assessment criteria are currently being developed by OSPAR, but are subject to change in the light of their practical application. The ‘status of decline’ criterion, as currently defined in the OSPAR ‘Faial’ criteria (most recent version: IMPACT 99/15/1, Annex 6), has been applied at a UK level. For the Wadden Sea, similar status criteria (Wadden Sea biotope red list categories: Completely destroyed, threatened by complete destruction, heavily endangered, endangered, potentially endangered, presumably not endangered at present) have been used, as defined by Von Nordheim, Andersen & Thissen (1996)).

If the habitat has some specific protected status in the EC Habitats Directive or the UK Biodiversity Action Plan, the corresponding habitat is given (UK Biodiversity Group 1999).

The terms used for each of the habitat factors

Explanatory table for the species composition and biodiversity tables

Explanatory table for the information given on sensitivity to human activities

Explanatory notes for information given on the conservation status of a biotope

References