Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA5.53A Seagrass beds on Atlantic infralittoral sand (Macaronesian)

Seagrass beds on Atlantic infralittoral sand (Macaronesian)

Quick facts

Red List habitat type code NEAA5.53A
Threat status
Europe Vulnerable
EU Vulnerable
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

This habitat consists of beds of submerged marine angiosperms in the genera Cymodocea, Halophila, Ruppia, Thalassia and Zostera in the southern islands of Macaronesia (it does not occur in the Azores). Seagrass beds are present mainly off the sheltered eastern coasts of the Canary Islands (Spain), on the wide subtidal platforms with sandy substrata and gently sloping coastlines which are sheltered from the Trade Winds. They may occur in patches or form extensive meadows reaching depths of over 30m where light levels are sufficient to support growth. C. nodosa has also been reported in scattered locations along the southern coast of Madeira Island (Portugal). In the Canary Islands, C.nodosa can be found forming unispecific meadows, but also mixed with Halophila decipiens on muddy bottoms or with the green macroalga Caulerpa prolifera on sandy bottoms.

Marine seagrass meadows are very important in providing several ecological services, such as primary production, habitats, nurseries and coastal protection. Primary productivity may vary, depending on many factors such as the density of the meadow, geographic area or hydrologic factors. These ecosystems are one of the most important habitats for several marine organisms, which depend on them in different phases of their life cycle, not only to feed but also to take shelter from predators.

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. Total area covered, density of the intertidal beds and species composition is, for example, used as a Water Framework Directive parameter for assessing ecological status.

The overall quality and continued occurrence of this habitat is dependent on the presence of seagrass species which create the biogenic structural complexity on which the characteristic associated species depend. The density and the maintenance of a viable population of seagrass is therefore a key indicator of habitat quality, together with the visual evidence of presence or absence of physical damage. Shoot density and leaf length have both been examined as potential indicators of quality of this habitat.

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

Threat status

Synthesis of Red List assessment

This habitat does not have a restricted geographical distribution but it has suffered declines in both quantity and quality over the last 50 years. The dense meadows of C.nodosa in the bay of Machico last recorded in 2000, are now absent with C.nodosa currently only present in a few areas on the south coast of Madeira covering a total area less than 1km2. Subtidal Zostera beds have always had a very restricted occurrence in the Canarian Archipelago with just three small patches in a single harbour in Lanzarote. They did occur in Grand Canaria in the 1970s but this is no longer the case. There has also been an overall decline in quality of this habitat as indicated by four metrics of the seagrass; shoot density, biomass, leaf length and coverage.
Expert opinion is that over the last 50 years the decline in quantity is estimated to have been over 30% and that the decline in quality has been substantial with a severe decline affecting more than 30% of the extent of this habitat. The Red List assessment is therefore that this is a Vulnerable habitat for both the EU 28 and EU 28+.
EU
Red List Category Red List Criteria
Vulnerable A1, C/D1
Europe
Red List Category Red List Criteria
Vulnerable A1, C/D1

Confidence in the assessment

medium
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Transportation and service corridors
    • Shipping lanes, ports, marine constructions
  • Biological resource use other than agriculture & forestry
    • Marine and Freshwater Aquaculture
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Nutrient enrichment (N, P, organic matter)
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Removal of sediments (mud...)

Habitat restoration potential

Recovery can occur if conditions are suitable but will depend on depth, substratum and the scale of the damage. If damage is minor natural recovery may be possible but if there is more extensive damage or loss, intervention may be needed. A small scale pilot project to transplant healthy C.nodosa affected by port expansion in Fuerteventura was considered unsuccessful and recent work suggests that there may be a critical mass of transplants needed for recovery and that proxmity of the area selected for transplantation to donor beds is also beneficial.

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

Regulation of activities (such as coastal development, dredging, waste disposal) and zoning to ensure that aquaculture facilities are located away from this habitat are useful management measures.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
    • Restoring/Improving the hydrological regime
  • Measures related to marine habitats
    • Restoring marine habitats
  • Measures related to spatial planning
    • Establish protected areas/sites
    • Legal protection of habitats and species
  • Measures related to hunting, taking and fishing and species management
    • Regulation/Management of fishery in marine and brackish systems
  • Measures related to urban areas, industry, energy and transport
    • Urban and industrial waste management

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)
Macaronesia Present unknown Decreasing Decreasing

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 153,446 59 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+ 59 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 Caulerpa prolifera
Flowering Plants Zostera marina
Species scientific name English common name Species group
Caulerpa prolifera Algae
Zostera marina Flowering Plants

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
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