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{{italic title}}
{{taxobox
| name = Dwarf eelgrass
| image = Zostera noltii.jpg
| status = LC
| status_system = IUCN3.1
| status_ref =  <ref name=iucn>{{IUCN |id=173361 |title=''Zostera noltii'' |assessor=Short, F.T. |assessor2=Carruthers, T.J.R. |assessor3=Waycott, M. |assessor4=Kendrick, G.A. |assessor5=Fourqurean, J.W. |assessor6=Callabine, A. |assessor7=Kenworthy, W.J. |assessor8=Dennison, W.C. |year=2010 |version=2012.2 |accessdate=May 26, 2013}}</ref>
| regnum = [[Plant]]ae
| unranked_divisio = [[Angiosperms]]
| unranked_classis = [[Monocots]]
| ordo = [[Alismatales]]
| familia = [[Zosteraceae]]
| genus = ''[[Zostera]]''
| species = '''''Z. noltii'''''
| binomial = ''Zostera noltii''
| binomial_authority = [[Jens Wilken Hornemann|Hornem.]]<ref name=WoRMS>{{cite WoRMS |author=Guiry, Michael D. |year=2013 |title=''Zostera (Zosterella) noltii'' Hornemann |id=145796 |accessdate=2013-05-26 |db=}}</ref>
| synonyms = ''Zostera noltii''
}}
'''''Zostera noltii''''' is a species of [[seagrass]] known by the common name '''dwarf eelgrass'''. It is found in shallow coastal waters in north western [[Europe]], the [[Mediterranean Sea]], [[Black Sea]], [[Caspian Sea]] and [[Aral Sea]] and on islands in the Atlantic off the coast of northwest Africa. It is an important part of the intertidal and shallow subtidal ecosystems of [[Estuary|estuaries]], bays and [[lagoon]]s.

==Description==
''Zostera noltii'' has a creeping [[rhizome]] that runs along under the surface of the seabed. Groups of two to five strap-shaped leaves grow out of nodes on the rhizome and each node also bears a tuft of up to four short roots that anchor the plant in the sediment. The leaves have three irregular, longitudinal veins and blunt, notched ends. They are up to {{convert|22|cm|0|abbr=on}} long and contain air spaces which make them buoyant. Several separate male and female flowers grow on a short, spear-shaped lateral stem. The smooth white seeds develop inside a green capsule with membranous walls and are about {{convert|2|mm|2|abbr=on}} long.<ref name=MarLIN>{{cite web |url=http://www.marlin.ac.uk/speciesfullreview.php?speciesID=4601 |title=Dwarf eelgrass - ''Zostera noltii'' |author=Tyler-Walters, Harvey |year=2005 |work=[[Marine Life Information Network]] (MarLIN) |publisher=[[The Marine Biological Association of the UK]] |accessdate=2013-05-26}}</ref>

==Distribution and habitat==
[[File:Banquettes de Zostera noltii.JPG|thumb|left|Beds of dwarf eelgrass on the beach at [[Port-Saint-Louis-du-Rhône]], France]]
''Zostera noltii'' is found in the eastern [[Atlantic Ocean]] along the coasts of Europe as far north as [[Norway]], [[Sweden]] and the [[Baltic Sea]].<ref name=iucn/> Around the [[British Isles]] it grows extensively in the Firths of [[Moray Firth|Moray]] and [[Cromarty Firth|Cromarty]], the [[The Wash|Wash]] and the [[Thames Estuary]]. In [[Ireland]] substantial quantities are found in [[Strangford Lough]],<ref>Hackney, P.(Ed) 1992. ''Stewart & Corry's Flora of the North-east of Ireland,'' Third Edition. Institute of Irish Studies. The Queen's University of Belfast. ISBA 0 85389 446 9
</ref> [[Dungarvan|Dungarvan Harbour]] and [[Dublin Bay]]. In the [[Mediterranean Sea]] and the [[Black Sea]], it is restricted to the brackish conditions found in lagoons and estuaries. It is the only species of seagrass found in the [[Caspian Sea]] and the [[Aral Sea]].<ref>{{cite web |url=http://www.marlin.ac.uk/specieshabitats.php?speciesID=4601 |title=Dwarf eelgrass - ''Zostera noltii'' - Habitat preferences and distribution |author=Tyler-Walters, Harvey |year=2005 |work=Marine Life Information Network (MarLIN) |publisher=The Marine Biological Association of the UK |accessdate=2013-07-02}}</ref> It also grows in [[Morocco]], [[Mauritania]], the [[Canary Islands]] and [[Cape Verde]]. It grows intertidally on fine sandy or muddy [[Substrate (biology)|substrates]] and can tolerate various levels of [[salinity]]. It tends to grow in a band higher up the beach than ''[[Zostera marina]]'' beds and is often mixed with other seagrasses (''[[Ruppia]]'' spp.). It grows subtidally in deeper water when it is in low salinity or brackish water in [[Estuary|estuaries]] and [[lagoon]]s. It is adversely affected by [[Eutrophication|high nutrient levels]] and [[Turbidity|cloudy water]].<ref name=iucn/>

==Biology==
Growth of ''Zostera noltii'' starts in the spring with the appearance of new leaves and the lengthening and branching of the rhizome. Dense beds of shoots appear with seagrass meadows covering the intertidal flats during the summer, and at this time, flowering takes place. By autumn growth has stopped and over the winter most of the leaves either get broken off or are eaten by birds so that the only parts left are the submerged rhizomes. A clump of rhizomes may live for many years.<ref name=Gen>{{cite web |url=http://www.marlin.ac.uk/generalbiology.php?speciesID=4601 |title=Dwarf eelgrass - ''Zostera noltii'' - General biology |author=Tyler-Walters, Harvey |year=2005 |work=Marine Life Information Network (MarLIN) |publisher=The Marine Biological Association of the UK |accessdate=2013-07-02}}</ref>

The male flowers release strands of pollen which are of about the same density as the surrounding water and which remain capable of fertilising female flowers for several days. The seed capsules are [[photosynthesis|photosynthetic]] and contain a bubble of air. After some weeks they split open and the seed sink to the bottom. Alternatively, the capsules may become detached from the plant and float away, releasing the seed elsewhere. The seeds are dispersed by waves and currents, or sometimes on the feet or in the gut of a bird.<ref>{{cite web |url=http://www.marlin.ac.uk/reproduction.php?speciesID=4601 |title=Dwarf eelgrass - ''Zostera noltii'' - Reproduction and longevity |author=Tyler-Walters, Harvey |year=2005 |work=Marine Life Information Network (MarLIN) |publisher=The Marine Biological Association of the UK |accessdate=2013-05-26}}</ref>

==Ecology==
[[File:Fig. 03 Zostera noltii.jpg|thumb|left|''Zostera noltii'' stabilises the seabed]]
Seagrass beds are highly productive and form the basis of important coastal [[ecosystem]]s. Many different species of algae grow epiphytically on ''Zostera noltii''. These include the [[brown algae]] species ''[[Cladosiphon zosterae]]'', ''[[Halothrix lumbricalis]]'', ''[[Leblondiella densa]]'', ''[[Myrionema magnusii]]'' and ''[[Punctaria crispata]]''. These also grow on other seagrasses such as ''Zostera marina''. A [[Parasitism|parasite]], ''[[Plasmodiophora bicaudata]]'', attacks eel grasses, including ''Zostera noltii''.<ref>{{cite web |url=http://www.marlin.ac.uk/speciesfullreview.php?speciesID=4600 |title=Common eelgrass - ''Zostera marina'' |author=Tyler-Walters, Harvey |year=2008 |work=Marine Life Information Network (MarLIN) |publisher=The Marine Biological Association of the UK |accessdate=2013-07-02}}</ref> It prevents further growth between the nodes and damages clumps with the leaves growing in tufts, causing what is known as wasting disease.<ref name=MarLIN/> Eel grass beds provide a refuge for many invertebrates and a safe haven for developing juvenile fish. The [[detritus]] produced when the leaves decay in winter enriches the sediment. The decomposing tissues are the basis for a [[food chain]] and large numbers of protists are found in the water column nearby feeding on leached organic compounds and the [[bacteria]] that break down the tissues.<ref name=UKMSAC>{{cite web |url=http://www.ukmarinesac.org.uk/communities/habitats-review/hr10_3.htm |title=Elgrass beds: Ecological relationships |publisher=UK Marine Special Areas of Conservation |accessdate=2013-05-26}}</ref>

''Zostera noltii'' plays an important part in the winter diet of the [[whooper swan]] (''Cygnus cygnus''), the [[mute swan]] (''Cygnus olor''), the [[brent goose]] (''Branta bernicla'') and the [[Eurasian wigeon|wigeon]] (''Anas penelope'') and in fact, overwinting populations of brent goose in Europe have declined since wasting disease has become established and reduced the quantity of eel grass available.<ref name=imp/> Wigeon numbers have also declined.<ref name=imp>{{cite web |url=http://www.marlin.ac.uk/speciesimportance.php?speciesID=4601 |title=Dwarf eelgrass - ''Zostera noltii'' - Importance |author=Tyler-Walters, Harvey |year=2005 |work=Marine Life Information Network (MarLIN) |publisher=The Marine Biological Association of the UK |accessdate=2013-07-02}}</ref> They are shy birds and only resort to feeding on ''Zostera noltii'' when the seagrass beds lower down the beach are exhausted.<ref name=UKMSAC/> At least some of the seeds of eel grass have been found to germinate freely after they have passed through the gut of [[wildfowl]] and this provides a means by which the eel grass may travel dozens of kilometres (miles) and increase its range. However, seedlings of ''Zostera noltii'' are seldom encountered and vegetative reproduction, in which sections of rhizome become detached from the parent plant, is probably the most common means of spread.<ref name=Gen/>

''Zostera noltii'' and other seagrasses are important in stabilising sediments and reducing wave energy and may provide a coastal defence against erosion. It is however sensitive to being smothered by shifting sediment and has a low capacity to recover when buried. This may be due to its relatively short leaves and its lack of vertical rhizomes. It is regularly exposed on the foreshore at low tide and is resistant to desiccation. Although it supports a [[Biodiversity|biodiverse]] assortment of animal species, these are more numerous in subtidal beds.<ref name=MarLIN/> Although ''Zostera noltii'' populations may be declining slowly, the [[IUCN Red List of Threatened Species]] lists it as being of "[[least concern]]".<ref name=iucn/>

==References==
{{reflist}}

[[Category:Zosteraceae]]
[[Category:Plants described in 1832]]
[[Category:Flora of Uzbekistan]]
[[Category:Flora of Kazakhstan]]
[[Category:Flora of Russia]]
[[Category:Flora of Azerbaijan]]
[[Category:Flora of Iran]]
[[Category:Flora of Greece]]
[[Category:Flora of Bulgaria]]
[[Category:Flora of Turkey]]
[[Category:Flora of Italy]]
[[Category:Flora of Croatia]]
[[Category:Flora of Spain]]
[[Category:Flora of France]]
[[Category:Flora of Corsica]]
[[Category:Flora of Sardinia]]
[[Category:Flora of Romania]]
[[Category:Flora of Sicily]]
[[Category:Flora of the Balearic Islands]]
[[Category:Flora of Cape Verde]]
[[Category:Flora of Ireland]]
[[Category:Flora of Great Britain]]
[[Category:Flora of Denmark]]
[[Category:Flora of Norway]]
[[Category:Flora of Sweden]]
[[Category:Flora of Belgium]]
[[Category:Flora of the Netherlands]]
[[Category:Flora of Germany]]
[[Category:Flora of Poland]]
[[Category:Flora of Algeria]]
[[Category:Flora of Morocco]]
[[Category:Flora of Tunisia]]
[[Category:Flora of Libya]]
[[Category:Flora of Egypt]]
[[Category:Flora of the Canary Islands]]
[[Category:Flora of Mauritania]]
[[Category:Biota of the Atlantic Ocean]]
[[Category:Biota of the Mediterranean Sea]]
[[Category:Biota of the Black Sea]]
[[Category:Biota of the Caspian Sea]]

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Tom.Reding: /* top */Fix :Category:CS1 maint: Uses authors parameter: vauthors/veditors or enumerate multiple authors/editors/assessors; WP:GenFixes on using AWB