Red List habitat classification > RL - Marine habitats > RLMED - Mediterranean > MEDA5.53 Seagrass beds (other than Posidonia) on Mediterranean infralittoral sand

Seagrass beds (other than Posidonia) on Mediterranean infralittoral sand

Quick facts

Red List habitat type code MEDA5.53
Threat status
Europe Least Concern
EU Least Concern
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

Mediterranean seagrasses form dense and highly productive meadows or beds, between the surface to 15 m depth in coastal lagoons and down to 50 m depth in the open-sea, in clear water conditions. Besides the seagrass Posidonia oceanica, these meadows are built by several submerged magnoliophytes, such as: Cymodocea nodosa, Zostera marinaZostera noltei or the introduced species Halophila stipulacea, and, in transitional waters and coastal lagoons by Ruppia sp. All these species can be found alone or combined among them to form mixed meadows. The basic physical requirements of seagrass meadows habitats are sufficient light, a suitable substratum (muddy or sandy bottom) and moderate levels of wave exposure. Their tolerance to variation of environmental factors (e.g. salinity, temperature, nutrient concentration) and their geographical distribution differ depending on the dominant seagrass species.

Seagrasses provide habitat for a large set of organisms. The leaf canopy and the network of rhizomes and roots provide substratum for attachment, and creates hiding places to avoid predation. As a result, the abundance and diversity of the fauna and flora living in seagrass meadows are consistently higher than those of adjacent unvegetated areas. In addition seagrass meadows play an important role as spawning zone and hatchery for several species of fishes and are wintering areas of several species of birds

Several sub-habitat can be distinguished. Cymodocea nodosa beds are widely distributed throughout the Mediterranean, and outside, around the Canary Islands and down the North African coast, and are usually frequent in areas with salinity fluctuations from 26 to 44%. These meadows are observed in coastal lagoons and in the open-sea. Eelgrass beds (Z. marina) are rare in the Mediterranean and it is found mostly as small isolated stands, down to 10-15 meters depth depending on water clarity. Dense meadows can however occur, especially, in coastal lagoons and transitional waters. They are distributed from the Arctic waters until the Mediterranean and are very abundant in the Baltic Sea, the North Sea and along the Atlantic coasts down to northern Spain. Ruppia beds grow in brackish waters, in permanent pools of mud or sand flats, as well as in inlets or estuaries. Mixed beds of Zostera and Ruppia can be observed in shallow sublittoral sediments. These communities are generally found in extremely sheltered bays and coastal lagoons, with very weak tidal currents.

Indicators of quality:

Extended seagrass beds with a good penetration to deep waters are characteristic of coastal waters with minimal anthropogenic impact. Since seagrasses are mostly perennial organisms, they reflect the temporally integrated environmental conditions, and, therefore, seagrasses are very good indicator on which environmental monitoring and management of coastal waters can focus. Cymodocea nodosa is considered at the Mediterranean level, as a biological quality element for the implementation of the Water Framework Directive and several indicators have been proposed for this assessment.

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

Threat status

Synthesis of Red List assessment

The habitat is known to occur along most of the Mediterranean coast. It has a large EOO >50,000km2 and AOO >50, which exceeds the thresholds for a threatened category on the basis of restricted geographic distribution. There is increasing anthropogenic pressure on this habitat from pollution, aquaculture and fishing gear and some declines in quality have been reported but trends in quantity are currently unknown. This habitat displays adaptive plasticity and successful colonisation after periods of pressure and can recover naturally in relatively short time periods. Based on the above and the knowledge of experts, this habitat assessed as Least Concern for both the EU 28 and EU 28+.
EU
Red List Category Red List Criteria
Least Concern -
Europe
Red List Category Red List Criteria
Least Concern -

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
  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
    • Professional active fishing
    • Benthic or demersal trawling
  • 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

The predicted recovery times is particularly short for fast-recovering species (e.g. Cymodocea nodosa – within 1 year) however the capacity for the habitat to recover its functionality would be longer.

Trends in extent

Average current trend in quantity

Stable Stable
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Unknown
EU28 EU28+

Conservation and management needs

Cymodocea nodosa is considered at the Mediterranean level, as a biological quality element for the implementation of the Water Framework Directive and several indicators have been proposed for this assessment. Both Zosteras and Cymodocea are included in the Annex II of the Barcelona Conventions and some national legislations. Besides, the habitat formed by these seagrasses is also protected in various marine protected areas in the countries along the Mediterranean Sea.
To prevent physical damage caused by fishing trawling on the meadows, different measures should be considered such as placing artificial reefs along certain stretches of the coast, develop effective surveillance programmes and enforcing existint regulations to prevent illegal trawling. Awareness programmes with different sectors such as recreational boats and local councils will help to manage better coastal activities and identify areas where cost-effective schemes for threats reduction could be implemented.
Mapping and monitoring efforts are still much needed for most of its range of distribution.

List of conservation and management needs

  • Measures related to marine habitats
    • Restoring marine habitats
  • 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

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 274,000 Decreasing Stable
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 2,528,443 3,701 195,700 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+ 4,082 >195,700 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

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
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