Communities of Mediterranean mediolittoral rockpools

Rockpools occur where the topography of the shore allows seawater to be retained within depressions in the bedrock. As the associated communities are permanently submerged they are not directly affected by height on the shore and normal rocky shore zonation patterns do not apply. Factors such as pool depth, surface area, volume, orientation to sunlight, shading, internal topography, sediment content and type, together with wave exposure, shore height, and hence flushing rate, and the presence of absence of freshwater runoff, results in large spatial variation in community structure, even between adjacent pools at
the same shore height. 

The provision of seawater to this habitat can be completely interrupted during long periods of calm sea conditions. In these cases, the habitat may face important changes in temperature, pH, salinity and oxygen concentration. Nitrogen concentration is very often high and seasonal changes more abrupt than
in the adjacent, regularly swashed communities. In these conditions, the development of macroalgal communities is hindered and green algae can dominate. Large numbers of benthic species and juvenile stages of some commercial species of fish may be present in rockpools.

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. Most of the associated species are opportunistic and show high turnover however changes in species richness and percent algae cover could indicate changes in the quality of the environment.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats