Red List habitat classification > RL - Marine habitats > RLMED - Mediterranean > MEDA1.23 Communities of moderately exposed Mediterranean lower mediolittoral rock

Communities of moderately exposed Mediterranean lower mediolittoral rock

Quick facts

Red List habitat type code MEDA1.23
Threat status
Europe Data Deficient
EU Data Deficient
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

This is an intertidal habitat which occurs on rocky and boulder shores, just above the mid tide levels. It is present in locations that are moderately exposed to wave action and may be subject to strong or moderate currents. The associated biotopes are dominated by the red alga Corallina elongata in the most exposed conditions, and Gelidium pusillum and G.crinale where there are elevated nutrient levels. In some situation the habitat is almost devoid of erect macroalgae, grazed by Patella spp., and characterised by crusts of the Lithophyllum spp. In the inner parts of bays or close to the beaches, other red algae species (mainly Laurencia pyramidalis, Laurencia glandulifera, Palisada perforata and Osmundea verlaquei) but also Hypnea musciformis and Ceramium ciliatum may dominate. There is also an associated biotope dominated by Palisada tenerrima which forms dense, almost monospecific turfs that completely cover the rock in the central and southern part of the Mediterranean and a dominance by Haliptilon virgatum in several Mediterranean regions characterised by warm waters and relatively high light irradiances.

Indicators of quality
An increase in the abundance of many organisms: green algae, Gelidium spp., Scytosiphon lomentaria, Petalonia fascia, Mytilus galloprovincialis and, occasionally, Corallina elongata can be indicators of poor quality. Conversely species of the genus Osmundea, Laurencia and Palisada seem to avoid polluted waters. Their absence may therefore also be a potential indicator of changes in quality of the habitat. 

A "Quality of Rocky Bottoms index" (CFR by its Spanish acronym) used in Spanish Atlantic waters for the assessment of macroalgae communities on rocky shores may have some potentially application in assessment of quality of this habitat.

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

This is a widespread habitat in the Mediterranean Sea, however there is very little information on its detailed distribution. Expert opinion is that it has suffered some declines in extent and this is likely to continue as the pressures and threats remain although past and future reductions in quantity and quality cannot be quantified. The habitat has a large EOO and AOO, and its distribution is such that the identified threats are unlikely to affect all localities at once. It therefore qualifies as Least Concern under Criterion B but the overall assessment is Data Deficient both at the EU 28 and the EU 28+ levels because of the lack of information on its trends in quantity and quality.
EU
Red List Category Red List Criteria
Data Deficient -
Europe
Red List Category Red List Criteria
Data Deficient -

Confidence in the assessment

low
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Urbanisation, residential and commercial development
    • Urbanised areas, human habitation
    • Discharges
  • Pollution
    • Pollution to surface waters by industrial plants
    • Other point source pollution to surface water
    • Diffuse pollution to surface waters due to household sewage and waste waters
    • Nutrient enrichment (N, P, organic matter)
    • Input of contaminants (synthetic substances, non-synthetic substances, radionuclides) - diffuse sources, point sources, acute events
    • Oil spills in the sea
    • Toxic chemical discharge from material dumped at sea

Habitat restoration potential

Some of the dominant species of this habitat such as Corallina elongata turfs show greater capacity to some disturbance and recovery. Overall it is considered capable of recovering if suitable substrate is present and the environmental conditions (including water quality) are beneficial.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

This habitat is widespread and common and therefore likely to be present within some protected areas although it may not be subject to specific conservation measures. Beneficial actions include those which improve water quality and the regulation of coastal development in order to avoid both direct and indirect damage. Further work is needed to identify management measures to support the conservation of this habitat.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to spatial planning
    • Other marine-related measures
    • Establish protected areas/sites

Distribution

For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

Seas Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Adriatic Sea Present Unknown Unknown Decreasing
Aegian-Levantine Sea
Ionian Sea and the Central Mediterranean Sea
Western Mediterranean Sea

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 2,000,004 367 Unknown EOO and AOO have been calculated on the available data. Although this data set is known to be incomplete the figures exceed the thresholds for threatened status.
EU28+ >367 Unknown EOO and AOO have been calculated on the available data. Although this data set is known to be incomplete the figures exceed the thresholds for threatened status.
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Algae Anadyomene stellata
Algae Antithamnionella elegans
Algae Asparagopsis armata
Algae Boergeseniella fruticulosa
Algae Callithamnion granulatum
Algae Ceramium ciliatum
Algae Ceramium echionotum
Algae Chaetomorpha aerea
Algae Chondria boryana
Algae Cladophora laetevirens
Algae Corallina elongata
Algae Cystoseira compressa
Algae Cystoseira mediterranea
Algae Gastroclonium clavatum
Algae Gelidium crinale
Algae Gelidium pusillum
Algae Grateloupia filicina
Algae Haliptilon virgatum
Algae Hypnea musciformis
Algae Jania rubens
Algae Laurencia glandulifera
Algae Laurencia pyramidalis
Algae Liagora viscida
Algae Lithophyllum byssoides
Algae Lithophyllum incrustans
Algae Lophosiphonia obscura
Algae Osmundea verlaquei
Algae Padina pavonica
Algae Petalonia fascia
Algae Polysiphonia sertularioides
Algae Pseudolithoderma adriaticum
Algae Scytosiphon lomentaria
Algae Sphacelaria cirrosa
Algae Ulva fasciata
Algae Ulva rigida
Invertebrates Actinia equina
Invertebrates Anemonia viridis
Invertebrates Mytilaster minimus
Invertebrates Mytilus galloprovincialis
Invertebrates Pachygrapsus marmoratus
Invertebrates Patella rustica
Invertebrates Patella ulyssiponensis
Species scientific name English common name Species group
Anadyomene stellata Algae
Antithamnionella elegans Algae
Asparagopsis armata Algae
Boergeseniella fruticulosa Algae
Callithamnion granulatum Algae
Ceramium ciliatum Algae
Ceramium echionotum Algae
Chaetomorpha aerea Algae
Chondria boryana Algae
Cladophora laetevirens Algae
Corallina elongata Algae
Cystoseira compressa Algae
Cystoseira mediterranea Algae
Gastroclonium clavatum Algae
Gelidium crinale Algae
Gelidium pusillum Algae
Grateloupia filicina Algae
Haliptilon virgatum Algae
Hypnea musciformis Algae
Jania rubens Algae
Laurencia glandulifera Algae
Laurencia pyramidalis Algae
Liagora viscida Algae
Lithophyllum byssoides Algae
Lithophyllum incrustans Algae
Lophosiphonia obscura Algae
Osmundea verlaquei Algae
Padina pavonica Algae
Petalonia fascia Algae
Polysiphonia sertularioides Algae
Pseudolithoderma adriaticum Algae
Scytosiphon lomentaria Algae
Sphacelaria cirrosa Algae
Ulva fasciata Algae
Ulva rigida Algae
Actinia equina Invertebrates
Anemonia viridis Invertebrates
Mytilaster minimus Invertebrates
Mytilus galloprovincialis Invertebrates
Pachygrapsus marmoratus Invertebrates
Patella rustica Invertebrates
Patella ulyssiponensis Invertebrates

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
European Environment Agency (EEA)
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