Outer Bristol Channel Marine Habitat Survey

Exploring the sea bed in our local area

The Outer Bristol Channel Marine Habitat Study

An Aggregate Levy Sustainability Fund (ALSF) project

Bristle worm
A bristle worm found commonly in the Bristol Channel.
Hermit crab (Pagurus prideaux) with commensal Cloak Anemone (Adamsia carciniopados)
A Seabed image from the Bristol Channel showing some animals (Dead Man's fingers Alcyonium digitatum, a sponge, a prawn, an edible crab Cancer pagurus, a coral and a bryozoan Flustra foliacea)
The photosled (UW Bangor) used to video and take photos of the seabed.

The Marine Biodiversity section has been involved in a large project looking at the animals living on and in the sea bed of the Outer Bristol Channel. The project was in partnership with the British Geological Survey (BGS).

We use a variety of techniques to discover the secrets of the sea bed. To study the animals we use a grab. This mechanical device removes a sample from the sea floor and enables us to count and identify the animals within once it has been brought aboard ship. The geologists use several pieces of equipment, including sonar, to map the seafloor below. We have also taken video footage and photographs that show exactly what the sea bed looks like, showing the larger animals living on the sea bed together with the tracks and burrows of other creatures.

The BGS geologists have produced maps that show the physical nature of the sea bed in greater detail than has been previously possible. Sandy, muddy and gravelly areas have been identified, as well as rock outcrops, sand waves, and even some wrecks. The northern area of the Outer Bristol Channel is largely covered with large sand wave fields that can be up to 19 m in height. The southern sector is a more gravelly habitat with isolated sand waves. The study area is a complex environment with a variety of habitats that are home to hundreds of different animal species — including worms, shells, crabs, starfish and many more. The biological and geological information has been combined to form an extensive idea of habitats of the area. This shows that the animals and biotopes of the area largely agree with the sea bed types and physical nature of the sea bed. One interesting find was a small bivalve shell (‘Mysella’ obliquata), originally described from Northern Ireland, but not recorded in UK waters for over 100 years.

The Bristol Channel is used for many different activities, ranging from recreation to the dredging of sand. A good knowledge of the sea bed is therefore essential to ensure the sustainability and conservation of our natural resources.

The study has provided 'baseline information', detailing the habitats, and biotopes and species present in the Outer Bristol Channel. This information is being disseminated to everyone from schoolchildren through to those involved in marine science, conservation, planning, and use of natural resources. This will contribute toward achieving the sustainable use of these resources.

This has been a unique project for us, in that outreach has been included from the start of the project. We have developed an extensive and successful outreach program including workshops, an educational CD-ROM and an interactive multimedia exhibition.

If you are interested in seeing the summary report then click here to download the pdf. The full report will be available shortly, please click here to download further information and an order form, or contact Andrew Mackie.

A project website is under development and will be available shortly

The British Geological Survey:

The education and outreach activities (Explore the Sea Floor) are continuing through 2006-2008 as part of a new project Marine aggregates — Science, Industry, Stewardship and People Networks sponsored by the Welsh Assembly Government, English Nature, National Museum Wales and The Crown Estate. For more information, contact

If you are interested in learning more about marine life and habitats:

Other sea bed mapping projects include:

HabMAP (Habitat mapping for conservation and management of the Southern Irish Sea)

MESH (Mapping European Seabed Habitats):

sonar image
A multibeam sonar image showing the profile of the seabed.