Invertebrate-dominated Pontic circalittoral rock

Circalittoral rock starts at the lower limit of distribution of photophilic plants and ends where the circalittoral rocky substrate gives way to sediments. On the Northwestern Black Sea shelf the habitat occurs on rocky coasts in depths between 10-15 m (depending on local conditions of light penetration, the upper limit of the habitat is defined as the lower limit of photophilic plants) down to 30-70m (depending on how deep rocky reefs occur at the location). The fauna is highly diverse, including many invertebrate and fish species which occur only in this habitat, some of them rare or protected. The habitat is very important due to the crucial ecological role of mussels in the self-cleansing capacity of the ecosystem and in benthic- pelagic coupling. One square meter of mussel-covered circalittoral rock has a clearance rate of 1.3 to 7.1 m3 m-2  h-1  and is able to filter 31-170 m3 of seawater per day. Biological production of this habitat is usually around 6 kg m-2  but can exceed 10 kg m-2  in favourable conditions, with complex foodweb linking it to other habitats. Also, it is an important feeding ground, nursery and refuge for many commercially valuable fish species and it provides the biofiltering capacity essential for maintaining the quality of nearshore waters.

Indicators of quality:

The following parameters and thresholds have been established for Romania:

1. Cover of Mytilus galloprovincialis (in the habitat subtype where it is dominant) ≥ 50%

2. Cover of invertebrate crusts, turfs and canopies (in the habitat subtype where they dominate) ≥ 80%

3. Median shell length of Mytilus galloprovincialis ≥ 50 mm SL

4. Live biomass of Mytilus galloprovincialis where dominant ≥ 6kg m-2

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats