Communities of Mediterranean mediolittoral coarse sediment

Littoral coarse sediments are found along relatively exposed open shores, where wave action prevents finer sediments from settling. This habitat include shores of mobile pebbles, cobbles and gravel, sometimes with varying amounts of coarse sand. The sediment is highly mobile and subject to high degrees of drying between tides, while sediment particle size structure may vary seasonally, with relatively finer sediments able to settle during calmer conditions in summer. As a result, few species are able to survive in this environment. It is occupied by scavengers species that feed on various plant debris and waste material retained between the pebbles and gravel. Beaches of mobile cobbles and pebbles tend to be devoid of macroinfauna, while gravelly shores may support limited numbers of crustaceans, polychaetes and holothurians. These communities are exposed to alternating water submersion and emersion because of variations in the water level. 

One of associated biotopes consist mainly of detritus-feeding species which draw their nourishment from decaying vegetation and miscellaneous debris caught up in the shingle. It is characterised by two crustaceans, the amphipod Gammarus olivii and the isopod Sphaeroma serratum. 

Indicators of quality:

Both biotic and abiotic indicators have been used to describe marine habitat quality. These include: the presence of characteristic species as well as those which are sensitive to the pressures the habitat may face; water quality parameters; levels of exposure to particular pressure, and more integrated indices which describe habitat structure and function, such as trophic index, or successional stages of development in habitats that have a natural cycle of change over time.

There are no commonly agreed indicators of quality for this habitat, although particular parameters may have been set in certain situations, e.g. protected features within Natura 2000 sites, where reference values have been determined and applied on a location-specific basis. 

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats