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Zostera marina

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Taxonomy [top]

Kingdom Phylum Class Order Family
PLANTAE TRACHEOPHYTA LILIOPSIDA NAJADALES ZOSTERACEAE

Scientific Name: Zostera marina
Species Authority: L.
Common Name/s:
English Eelgrass, Species code: Zm

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: 2007-10-23
Assessor/s: Short, F.T., Carruthers, T.J.R., Waycott, M., Kendrick, G.A., Fourqurean, J.W., Callabine, A., Kenworthy, W.J. & Dennison, W.C.
Reviewer/s: Livingstone, S., Harwell, H. & Carpenter, K.E.
Justification:
This species is widespread, circumglobal in the Northern hemisphere. There have been documented localized declines in parts of the range, but not sufficient to warrant placement in a threatened category. Zostera marina is listed as Least Concern.

Geographic Range [top]

Range Description: Zostera marina is widespread and circumglobal in northern latitudes, found throughout the north Atlantic and north Pacific and in the Mediterranean and Black Seas. Zostera marina extends into the Arctic in Alaska, Canada, Greenland, and northern Europe and to the tropics in Baja California, Mexico.
Countries:
Native:
Algeria; Bulgaria; Canada; China; Denmark; Estonia; Finland; France; Germany; Greece; Greenland; Iceland; Ireland; Italy; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Latvia; Libya; Lithuania; Mexico; Morocco; Netherlands; Norway; Poland; Portugal; Romania; Russian Federation; Spain; Sweden; Tunisia; Turkey; Ukraine; United Kingdom; United States
FAO Marine Fishing Areas:
Native:
Arctic Sea; Atlantic – eastern central; Atlantic – northeast; Atlantic – northwest; Atlantic – western central; Mediterranean and Black Sea; Pacific – eastern central; Pacific – northeast; Pacific – northwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There are regions of large scale decline for Zostera marina (wasting disease and major pollution threats), areas where there has been no decline and the population is thriving, and areas of complete disappearance. This species is a widespread and dominant species, usually monospecific meadows. It has declines mostly in developed and populated areas in Europe and North America.

Ongoing restoration efforts since the 1940s in Europe and North America transplanted to re-establish populations of eelgrass in part of their former range from which they had been extirpated.

There has been a global decline of area covered by Zostera marina by 1.4% per year based on 126 documented changes in area that have been conducted over a 10 year period from 1990-2000.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: In Scandinavia and UK, this is the most widely distributed seagrass, dominates sandy and muddy sediments in coastal areas of low to moderate wave exposure. In southernmost Sweden it flourishes on stony and sandy bottoms at 2-4 m depth. It has a wide salinity tolerance of 5-35 ppt. In the western Baltic Sea it occurs along exposed sandy shores and in long bays and shallow lagoons with reduced water exchange and muddy substrate. Has a facultative mutualism with blue mussels (Mytilus edulis) in shallow waters (1-3 m depth).

This species is commonly grazed by isopods (Idotea spp.) and snails (Hydrophobia spp., Littorina spp.). It is also consumed by birds, especially Mute Swans (Cygnus olor) in shallow lagoons.

This is a relict species in the Mediterranean, where it forms perennial meadows distributed from the intertidal to a few meters deep. In the Black Sea, Z. marina is found in pure and mixed stands from 0.5-15 m depth on silty-sandy substrates. It has 80-100% cover in its beds and shoot density of 988/m². It has 115 species of macroalgae associated with it (Milchakova 1999). Zostera marina occurs regularly in coastal lagoons of the western Mediterranean (Laugier et al. 1999) where it is often found with Z. noltii.

In Japan, occurs in the shallowest parts of subtidal beds, mostly between 1-5 m deep, but in some places down to 10 m. Flowering and fruiting seasons vary by 2-4 months across Japan, with early flowering and fruiting observed at lower latitudes. In South Korea, appears at the intertidal and subtidal zones, where the water depth is usually less than 5 m, and forms relatively large meadows and can be observed in both muddy and sandy sediments. It accounts for about 90% of total seagrass coverage in Republic of Korea.

Zostera marina is the dominant species in terms of biomass and habitats in the Pacific coast of North America, where it grows in the shallow waters of the continental shelf, the Gulf of California, coastal lagoons, estuaries and coastal fjords. Can co-mingle with Zostera japonica in the Pacific Northwest and Ruppia maritima in Baja California. Overwhelmingly dominant seagrass in coastal and estuarine areas of the western North Atlantic, found in both intertidal and subtidal areas, from a depth of +2 m to -12 m mean sea level. Distribution ranges from the protected low-salinity (5 ppt) waters of inner estuaries and coastal ponds to high-energy locations fully exposed to the Gulf of Maine and the North Atlantic with salinity of 36 psu (Green and Short 2003).
Systems: Marine

Threats [top]

Major Threat(s): There have been local declines in many regions due to loss of water clarity from sedimentation, coastal development and wasting disease. Nutrient loading from runoff has also resulted in some local declines.

Conservation Actions [top]

Conservation Actions: There are no specific conservation measures in place for this species, but it has general protection under coastal habitat conservation laws and where it occurs in protected areas.
Citation: Short, F.T., Carruthers, T.J.R., Waycott, M., Kendrick, G.A., Fourqurean, J.W., Callabine, A., Kenworthy, W.J. & Dennison, W.C. 2010. Zostera marina. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 19 April 2014.
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