Natural England Conservation Advice for Marine Protected Areas
Mounts Bay MCZ

Natural England guidance

This site collection contains Natural England’s conservation advice for this site. It fulfils Natural England’s responsibility under the Marine and Coastal Access Act 2009, to give advice on how to further the conservation objectives for the site, identify the activities that are capable of affecting the designated 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

Site name: Mounts Bay MCZ
Designation type: MCZ
Site identification: UKMCZ0036
Latest designation date: 29 January 2016
Designated features
(click to see site specific description):

General information on the site features:
The general information on the designated features from the MCZ features catalogue is useful for understanding the designated features, and should be used in conjunction with the site specific information.
Designated area (ha): 1183
Component Sites of Special Scientific Interest (SSSI):
Overlapping Protected Areas:

Last updated: 13th September 2019

Background information and geography

Mounts Bay MCZ is an inshore site located on the south-west coast of Cornwall, in the south-west of England. The landward boundary follows the mean high water mark from Cudden Point in the east, to a point between Long Rock and Cressars in the west. The seaward boundary extends south from this point for 2.8km towards Cudden Point. The site covers almost 12km2 and is approximately 27m at its deepest point. It is centred on the village of Marazion, approximately 3 miles east of Penzance and includes the area surrounding the iconic tidal island St Michael’s Mount.

The site protects a range of different habitats, including rocky reefs, both along the shoreline and under the sea, and sandy sediments that span both intertidal and subtidal areas. Seagrass beds can also be found within the site and these can sometimes be seen on the shore on extreme low tides. Seagrass beds are known to stabilise sediments and can provide a foraging and nursery habitat for a number of species, including species that are caught commercially.

The range of habitats support a variety of marine life including marine worms and bivalve molluscs in the soft sediments and a high diversity of seaweeds on the rocky shores, as well as sea snails, crabs, anemones, starfish and sea squirts.

This site is important in protecting stalked jellyfish and giant goby. Stalked jellyfish typically spend their life attached to seagrass or on seaweed in intertidal pools. The giant goby is a fish that lives in rockpools and is a rare find in Britain.

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.

Conservation objectives

The site’s conservation objectives apply to the Marine Conservation Zone and the individual species and/or habitat for which the site has been designated (the ‘Designated features’ listed below). The conservation objective of each of the zones is that the protected habitats:

  1. are maintained in favourable condition if they are already in favourable condition
  2. be brought into favourable condition if they are not already in favourable condition

For each protected feature, favourable condition means that, within a zone:

  1. its extent is stable or increasing
  2. its structure and functions, its quality, and the composition of its characteristic biological communities (including diversity and abundance of species forming part or inhabiting the habitat) are sufficient to ensure that its condition remains healthy and does not deteriorate

Any temporary deterioration in condition is to be disregarded if the habitat is sufficiently healthy and resilient to enable its recovery. For each species of marine fauna, favourable condition means that the population within a zone is supported in numbers which enable it to thrive, by maintaining:

  1. the quality and quantity of its habitat
  2. the number, age and sex ratio of its population

Any temporary reduction of numbers of a species is to be disregarded if the population is sufficiently thriving and resilient to enable its recovery. Any alteration to a feature brought about entirely by natural processes is to be disregarded when determining whether a protected feature is in favourable condition. This should be read in conjunction with the accompanying supplementary advice section, which provides more detailed advice and information to help achieve the objectives set out above.

Designated features:

  • High energy infralittoral rock
  • High energy intertidal rock
  • Intertidal coarse sediment
  • Intertidal sand and muddy sand
  • Moderate energy infralittoral rock
  • Moderate energy intertidal rock
  • Subtidal sand
  • Seagrass beds
  • Giant goby (Gobius cobitus)
  • Stalked jellyfish (Haliclystus spp.)
  • Stalked jellyfish (Calvadosia campanulata)
  • Stalked jellyfish (Calvadosia cruxmelitensis)



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 September 2019


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 September 2019


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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