Ephemeral green or red seaweeds (freshwater or sand-influenced) on Atlantic littoral non-mobile substrata

This habitat type occurs across the intertidal zone and sometimes in the splash zone, including on cliff faces in such locations. It may also be present on upper shore hard substrata that is relatively unstable (e.g. soft rock), or which is subject to considerable freshwater runoff. A dense mat of green filamentous algae, often together with some red algae, is a characteristic feature.

On moderately exposed shores, the biotopes 'Enteromorpha spp. on freshwater-influenced or unstable upper shore rock ' or 'P. purpurea and/or Enteromorpha spp. on sand-scoured mid- to lower-eulittoral rock'  may be present, both of which tend to support a low species diversity.

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