Red List habitat classification > RL - Marine habitats > RLMED - Mediterranean > MEDA3.13 Photophilic communities with canopy-forming algae in Mediterranean infralittoral and upper circalittoral rock

Photophilic communities with canopy-forming algae in Mediterranean infralittoral and upper circalittoral rock

Quick facts

Red List habitat type	code MEDA3.13
Threat status
Europe	Data Deficient
EU	Endangered
Relation to	Annex I habitat types (EU Habitats Directive)
Source	European Red List habitat factsheet
	European Red List of habitats reports
	European Red List of habitats (Excel table)

Summary

This habitat occurs on rocky bottoms and is characterised by communities macroalgae that form canopies. The structure includes bush-forming, turf forming algae, encrusting fauna and epiphytes. The coverage of the “bush” and turf strata is usually higher than in an assemblage dominated by canopy algae. Assemblages are also highly miniaturized (less than 20 cm high) and very rich in species (up to 110 species in a 400 cm² area).

This habitat is present from the upper infalittoral zone (0 m) to the upper circalittoral zone. Assemblages are always algal-dominated, although some invertebrates can be common in the understory and growing as epiphytes. Species composition greatly differs according to the environmental conditions. Factors accounting for the variability on the assemblages include light availability, hydrodynamism, nutrient concentration in seawater, substrate, sedimentation, temperature, salinity, grazing intensity, predation, frequency of disturbances. High densities of sea urchins (Paracentrotus lividus) can graze the algae, producing structurally less complex assemblages and even barren areas. Grazing by other fish species (Sarpa salpa or the exotic Siganus rivulatus, S. luridus) can modify the species composition.

Several associated biotopes have been described and are distinguished according to the dominant species. They include; Corallina elongata on shallow exposed shores; the red algae Haliptilon virgatum, growing on well-lit, shallow exposed shores in central and southern shores, usually accompanied by Laurencia obtusa, Laurencia majuscula and Dictyota fasciola; Colpomenia sinuosa growing on shallow sheltered rocks in nutrient-rich environments; Cladophoropsis membranacea growing on extremely sheltered zones in bays and lagoons; and Arthrocladia villosa and Sporochnus pedunculatus on moderately lit lower infralittoral to upper circalittoral rock, in places with strong unidirectional currents.

Indicators of quality:

This habitat is very variable according to the degree of anthropogenic disturbance. Indicators of quality can be measured by examining trends. The first signs of decline imply substitution of species, a decrease on diversity, an increase on invasive exotic species, and an increase in opportunistic, fast-growing species like some Ulva, Cladophora, Acinetospora, or stress resistant like Corallina elongata or Lithophyllum incrustans. Mussels can also replace the dominant algae in shallow waters when the charge of particulate organic matter is very high.

Characteristic species

Characteristic species:

This community is characterised by the presence of many photophilic algae covering hard bottoms. The number of species is very large, and can be completely different according to the bathymetric level, exposure and geographical region. They include:

Rhodophyta (red algae) - Liagora viscida, Liagora distenta, Amphiroa rigida, Corallina elongata, Haliptilon virgatum, Tricleocarpa fragilis, Ceramium virgatum, Wrangelia penicillata, Chylocladia verticillata, Chrysymenia ventricosa, Halymenia floresii, Gelidium spinosum, Predaea ollivieri, Chondracanthus acicularis, Jania rubens, Lithophyllum incrustans, Neogoniolithon brassica-florida, Mesophyllum alternans, Halopithys incurva, Lophocladia lallemandii, Peyssonnelia squamaria, Asparagopsis armata, Asparagopsis taxiformis, Sphaerococcus coronopifolius, Laurencia obtusa, Laurencia majuscula, Digenea simplex, Rytiphlaea tinctoria, Alsidium corallinum, Pterothamnion crispum, Compsothamnion thuyoides, Plocamium cartilagineum, Schottera nicaeensis, Pterocladiella capillacea, Botryocladia botryoides, Peyssonnelia squamaria, Palisada patentiramea

Phaeophyta - Dictyota fasciola, Colpomenia sinuosa, Taonia atomaria, Dictyota cf. dichotoma, Dictyota mediterranea, Stypopodium schimperi, Lobophora variegata, Dictyota spiralis, Zonaria tournefortii, Padina pavonicoides, Padina ditristromatica, Arthrocladia villosa, Sporochnus pedunculatus, Carpomitra costata, Acinetospora crinita, Hydroclathus clathratus, Dictyota dichotoma v. intricata, Sphacelaria cirrosa, Halopteris scoparia, Halopteris filicina, Padina pavonica, Cladostephus spongiosus, Dictyopteris polypodioides.

Chlorophyta (green algae )- Ulva rigida, Umbraulva olivascens, Dasycladus vermicularis, Flabellia petiolata, Acetabularia acetabulum, Parvocaulis parvulus, Caulerpa prolifera, Caulerpa cylindracea, Codium bursa, Anadyomene stellata, Cladophoropsis membranacea, Cladophora prolifera.

Porifera - Crambe crambe, Phorbas topsentii, Sarcotragus fasciculatus, Sarcotragus spinosulus, Hemimycale columella.

Mollusca - Bittium reticulatum, Conus ventricosus, Columbella rustica, Rissoa guerinii.

Crustacea - Macropodia longirostris, Maja crispata.

Echinodermata - Echinaster sepositus, Marthasterias glacialis, Paracentrotus lividus, Arbacia lixula, Holothuria tubulosa, Ophidiaster ophidianus, Ophiothrix fragilis.

Fish - Labrus merula, Coris julis, Serranus cabrilla, Serranus scriba, Symphodus ocellatus, Symphodus tinca, Scorpaena porcus, Epinephelus marginatus, Sciaena umbra, Diplodus sargus, Diplodus vulgaris, Diplodus cervinus, Diplodus puntazzo, Siganus rivulatus, Parablennius pilicornis, Trypterygion delaisi, Symphodus mediterraneus, Siganus luridus, Epinephelus costae, Sarpa salpa, Chromis chromis, Mullus surmuletus, Dentex dentex, Symphodus roissali, Sparisoma cretense.

For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

Although territorial data was not provided for all countries, there is an overall consensus in the expert opinion that this habitat has declined in quantity and quality in the EU 28 in the past 50 years. There is a lack of quantitative data for countries outside the EU 28 to infer the situation for the EU 28+.
Expert opinion that there has been a 77% reduction in the quantity of this habitat. and a substantial reduction in quality . This habitat is therefore assessed as Endangered under Criteria A. Due to the lack of quantitative data for countries outside the EU 28, the habitat is assessed as Data Deficient at the EU 28+ level.

EU
Red List Category	Red List Criteria
Endangered	A1, A2b

Europe
Red List Category	Red List Criteria
Data Deficient	-

Confidence in the assessment

medium

Red List of habitat categories and criteria descriptions

European Red List of Habitats categories

Based on Scientific Foundations for an IUCN Red List of Ecosystems

European Red List of Habitats criteria

Reduction in quantity (area of distribution)	A	A1 Present decline (over last 50 years) A2a Future decline (over the next 50 years) A2b Future/present decline (over a 50-year period inclunding present and future) A3 Historic decline
Restricted geographic distribution	B	B1 Restricted Extent of Occurrence (EOO) B2 Restricted Area of Occupancy (AOO) B3 Present at few locations
Reduction in abiotic quality	C	C/D1 Reduction in quality over the last 50 years C/D2 Reduction in quality in the future or in a period including present and future C/D3 Historic reduction in quality
Reduction in biotic quality	D
Quantitative analysis of probability of collapse	E

From Scientific Foundations for an IUCN Red List of Ecosystems

Pressures and threats

Biological resource use other than agriculture & forestry

Suspension culture
Fishing and harvesting aquatic resources
Benthic or demersal trawling

Human intrusions and disturbances

Penetration/ Disturbance below surface of the seabed

Pollution

Pollution to surface waters (limnic, terrestrial, marine & brackish)
Marine water pollution

Invasive, other problematic species and genes

Invasive non-native species

Habitat restoration potential

Little information exist about the recovery potential of this habitat over a certain degree of deterioration. The low dispersal capacity of most Cystoseira species makes natural recovery unlikely, so artificial reforestation may be an extremely valuable solution for lost forest .
In the case of Sargassum canopy but also species like C. barbarta, C. compressa and C. foeniculacea, the presence of aericysts facilitates dispersion and the recovery of populations from distant areas.

Trends in extent
Average current trend in quantity
Decreasing	Decreasing
EU28	EU28+

Trends in quality
Average current trend in quality
Decreasing	Decreasing
EU28	EU28+

Conservation and management needs

Some of these canopy-forming algae habitats are in protected areas and several Natura 2000 sites (e.g. Scandola, Bouches de Bonifacio, Cerbères-Banyuls, Calanque and Port-Cros in France, Formentera- Espardell and Dragonera in Spain; Kimolos in Greece; St Peter´s Island and Maratea in Italy). The declaration of other MPAs and the effective management of the existing ones where dense Cystoseira and other large brown algae forests thrive could favour the conservation of this habitat and its recovery when the herbivore pressure is not too high. Nonetheless, the protection of existing forests formed by Cystoseira and other subhabitats of canopy forming communities should complement regular monitoring programs in order to highlight potential threats and early signs of regression. Restoration of this habitat in priority areas with re-forestation methods has been suggested as a potential solution to assist fragmented/lost forests to recover and stimulate natural restoration of lost populations assisted at the same time with other measures such as improving sewage treatment or limitation of excessive herbivory at specific sites. An ecosystem-based management applied to a network of MPAs with long-term monitoring programs and restoration actions, where necessary, is probably the best perspective for the preservation of this habitat in the Mediterranean Sea.

List of conservation and management needs

Measures related to marine habitats

Restoring marine habitats

Measures related to spatial planning

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	60,808	Decreasing	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	2,011,255	765	> 60,808	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+	1,032		> 60,808	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

Not available

Legal status

Relation to other habitat types mentioned in legal instruments

Legal text	Annex	Name in legal text	Code in legal text	Habitat type relationship	More information
Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora - consolidated version 01/01/2007	Annex I: natural habitat types of community interest whose conservation requires the designation of special areas of conservation	Coastal lagoons	1150	Narrower	http://ec.europa.eu/environm...rective/index_en.htm
Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora - consolidated version 01/01/2007	Annex I: natural habitat types of community interest whose conservation requires the designation of special areas of conservation	Large shallow inlets and bays	1160	Overlap
Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora - consolidated version 01/01/2007	Annex I: natural habitat types of community interest whose conservation requires the designation of special areas of conservation	Reefs	1170	Narrower

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Photophilic communities with canopy-forming algae in Mediterranean infralittoral and upper circalittoral rock

Quick facts

Summary

Threat status

Synthesis of Red List assessment

Confidence in the assessment

European Red List of Habitats categories

European Red List of Habitats criteria

Pressures and threats

Habitat restoration potential

Trends in extent

Average current trend in quantity

Trends in quality

Average current trend in quality

Conservation and management needs

List of conservation and management needs

Distribution

Geographic occurrence and trends

Extent of Occurrence, Area of Occupancy and habitat area

Characteristic species

Legal status

Relation to other habitat types mentioned in legal instruments

Vegetation types

Relation to vegetation types (syntaxa)

Other classifications