Gravel bottoms with Ophelia species

Compiled by: Dieter Boedeker and Fritz Gosselck, Germany

1. Description of the habitat in the Baltic Sea

Sea bottoms consisting of gravel or gravel and mollusc shells or small shell fragments, often building small patches inside other sediments. Due to the large variety of interstitial space, inhabited by species of often very specialised fauna, e.g., of the polychaets Ophelia limacina, O. rathkei, Travisia forbesii. This fauna is restricted to the Belt Sea (sandbanks) and parts of the “submerged belt" of the Arkona Basin.  Gravel bottoms are generally exposed to currents and they are mainly found permanently at the same location (Similary to EUNIS classification A 5.111-5.113; A 5.143, A 5.144).

2. Distribution (past and present)

The biotope occurs mainly in the southern and western parts of the Baltic Sea area, but is very rare. They are found in exposed abrasion areas (sandbanks, near-shore wave exposed shallow sublittoral).

3. Importance (sub-regional, Baltic-wide, global)

The Baltic Sea shell gravel bottoms in the southern Baltic Sea and in the Belt Sea are considered to be of Baltic-wide importance in the HELCOM area.

4. Status of threat/decline

From a Baltic-wide perspective the status of threat and/or decline is not exactly known, however the biotope is considered to be rare and only small in area, and therefore “potentially endangered”.  

5. Threat/decline factors

Sand and gravel extraction, bottom trawling, oil and gas exploration and exploitation, pollution, offshore installations.

6. Options for improvement

A Baltic-wide biotope inventory and a threat assessment is needed, for the time being this biotops should be considered as highly sensitive and worthy of protection.

7. References

HELCOM (1998). Red List of Marine and Coastal Biotopes and Biotope Complexes of the Baltic Sea, Belt Sea and Kattegat - Including a comprehensive description and classification system for all Baltic Marine and Coastal Biotopes. HELCOM-Baltic Sea Environment Proceedings 75, Helsinki Commission. 115 pp.