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Zostera
In the British Isles, three species of eelgrass of the genus Zostera
occur, common eelgrass Z. marina, narrow-leaved
eelgrass Z. angustifolia, and dwarf eelgrass
Z. noltii. It is not clear if Z.
angustifolia is a variety of Z. marina
as it is usually regarded by authorities outside the British Isles. Most of
the UK literature distinguishes between Z. marina
and Z. angustifolia and this is applied in
this guide. All three 'species' were once abundant and widespread around the
British coasts, but as a result of a ‘wasting
disease’ in the early 1930s populations are now depleted in
many areas. This resulted in attempts to restoring
Zostera species in some areas.
There has been some recovery since but the species are still nationally scarce
in the UK.
 Zostera
beds are an important source of food and shelter for the young stages of many
fish and crustacean species, some of which are themselves food for commercially-valuable
fishery species. They are also important feeding grounds for ducks and geese.
Caption:
The dense network of rhizomes formed by the eelgrass plants (shown in picture
opposite) binds the sediment and reduces erosion in shallow waters, helping
to maintain the stability of the shoreline.
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Guidance on further information: More information on the species
and their value in relation to the conservation management of marine SACs
can be found in a report prepared for the UK
Marine SAC Project. Research Report No 234 "Sensitivity
and vulnerability to man induced change of selected communities: Intertidal
brown algal shrubs Zostera beds and Sabellaria spinulosa reefs" (Davison
& Hughes 1998), which can be downloaded in pdf format @ http://www.english-nature.org.uk
under project publications.
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References
Davison, D.M. & Hughes, D.J.
1998.
Zostera Biotypes (Volume 1): an Overview of Dynamics and Sensitivity Characteristics for Conservation Management of Marine SACs.
Scottish Association for Marine Science (UK Marine SACs Project), 1
UK Marine SACs Project.
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