Photophilic communities without canopy-forming algae in Mediterranean infralittoral and upper circalittoral rock
.jpg "European Red List of Habitats 2016")
.jpg "European Red List of Habitats 2016")
Quick facts
| Red List habitat type | code MEDA3.1x |
|---|---|
| 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 habitat is present from the upper infralittoral zone to the upper circalittoral zone. Assemblages are always algal-dominated, although some invertebrates can be common in the understory and growing as epiphytes. It consists of rocky bottoms covered by erect macroalgae that do not form canopies. The structure includes bush-forming or 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).
Species composition differs greatly depending on environmental conditions. Factors accounting for the variability on the assemblages include light availability, hydrodynamism, nutrient concentration in the seawater, substrate type, sedimentation, temperature, salinity, grazing intensity, predation, and 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. The habitat can be present both in good environmental conditions, and in rather degraded situations.
Several associated biotopes have been described, distinguished according to the dominant species. They include; Padina pavonica and similar species growing on well-lit shallow sheltered areas subjected to a moderate grazing by sea urchins; Pterothamnion crispum and Compsothamnion thuyoides growing on shallow, shaded sheltered to moderately exposed rocks; Corallina elongata growing on shallow exposed shores; Halopteris scoparia growing on well-lit sheltered areas down to 25 meters depth, mainly on northern areas, sometimes associated to the brown algae Cladostephus spongiosus; and Codium bursa on moderately lit infralittoral rock.
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 spp., Cladophora spp., Acinetospora spp., 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.
Threat status
Synthesis of Red List assessment
The habitat has a large Extent of Occurrence (EOO) and AOO, and therefore it could potentially qualify as Least Concern under Criterion B but there is no information on any trends. However it has been assessed as Data Deficient for both the EU 28 and EU 28+ because of the lack of information on any 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
Pressures and threats
- Urbanisation, residential and commercial development
- Urbanised areas, human habitation
- Pollution
- Pollution to surface waters (limnic, terrestrial, marine & brackish)
- Marine water pollution
- Invasive, other problematic species and genes
- Invasive non-native species
- Natural biotic and abiotic processes (without catastrophes)
- Species composition change (succession)
- Accumulation of organic material
- Eutrophication (natural)
- Climate change
- Temperature changes (e.g. rise of temperature & extremes)
Habitat restoration potential
Trends in extent |
|
Average current trend in quantity |
|
Unknown  |
Unknown |
| EU28 | EU28+ |
Trends in quality |
|
Average current trend in quality |
|
| Unknown |
Unknown |
| EU28 | EU28+ |
Conservation and management needs
List of conservation and management needs
- Measures related to wetland, freshwater and coastal habitats
- Restoring/Improving water quality
- Measures related to spatial planning
- Establish protected areas/sites
- Measures related to hunting, taking and fishing and species management
- Regulation/Management of fishery in marine and brackish systems
- Measures related to special resouce use
- Regulating/Managing exploitation of natural resources on sea
Distribution
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 | Unknown |
| 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 | 1,779,665 | 704 | 1,219 | 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+ | >704 | >1,219 | 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. |
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).
