Overview

Comprehensive Description

Description

 Grass-like flowering plant with grass green, long, narrow, ribbon shaped leaves 6-22 cm in length and 0.5-1.5 mm wide with 3 irregularly spaced veins. The tips of the leaves are blunt, notched, often asymmetric, and become indented in older leaves. Leaves shoot from a creeping rhizome, 0.5-2 cm thick, with 1-4 roots per node, which binds the sediment. Leaves shoot in groups of 2-5, encased in a short, open, sheath 0.54 cm long. Several flowers (4-5 male and 4-5 female) occur on a spear-shaped reproductive shoot 2 -25 cm long (usually 10cm). Seeds are smooth, white, and 1.5-2 mm in length (excluding the style). Leaves and rhizomes contain air spaces, lacunae, that aid buoyancy and keep the leaves upright when immersed.Like most of Zostera sp. this species may exhibit morphological variation depending on location, tidal zone and age of plant (Phillips & Menez, 1988).
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Distribution

Range Description

Zostera noltii occurs in the eastern Atlantic as well as the Baltic, Mediterranean, Black, Caspian and Aral Seas. Zostera noltii also occurs in western Africa in Mauritania and in the Canary and Cape Verde Islands.
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Distribution in Egypt

Mareotic Sector, North Sinai , 

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Global Distribution

Mediterranean Sea, Black Sea, Caspian Sea, Aral Sea, European and North African coasts of the Atlantic Ocean.

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Zostera noltii is a small seagrass species occurring in intertidal and subtidal areas (den Hartog 1970). This species can occur in areas of low salinity and co-occurs with Ruppia spp. at the inner edges (0.5-1.5 m depth) of Zostera marina beds. It is found in coastal and estuarine areas with soft sedimentation to a maximum depth of 10 m. This species can also live under permanent subtidal conditions in small brackish streams and coastal lagoons with euryhaline conditions. It is never found below the low-tide mark. Highest salinity level tolerated is 25-51 psu (Green and Short 2003).

The critical level of burial or erosion tolerated by this species is extremely low (between 4 and 8 cm) due to the small size of the species and the lack of vertical rhizomes (Cabaco and Santos 2007).

This species forms single species meadows in the Mediterranean Bioregion (Short et al. 2007). In the Black Sea, Z. noltii is found in pure and mixed stands from 0.2-10 m depth on sandy substrates. It has 62 species of macroalgae associated with it (Milchakova 1999).

Systems
  • Freshwater
  • Marine
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Muddy tidal zone and shallow saline coastal waters.

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 Grows in scattered clumps, dense beds or meadows on intertidal mud or detritus rich fine sand in the intertidal. It is particularly abundant between mean high water neaps and mean low water neaps, often forming a dense belt. Its upper and lower limits shift down shore with decreasing salinity, and in brackish waters (e.g. lagoons, étangs), it may become permanently submerged.
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Life History and Behavior

Life Expectancy

Perennial

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Zostera noltii

The following is a representative barcode sequence, the centroid of all available sequences for this species.


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Statistics of barcoding coverage: Zostera noltii

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
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Barcode data: Zostera noltei

The following is a representative barcode sequence, the centroid of all available sequences for this species.


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Statistics of barcoding coverage: Zostera noltei

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 4
Specimens with Barcodes: 4
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2010

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.

Contributor/s

Justification
Zostera noltii is widespread in the northern Atlantic. It is a fast growing species. There have been local declines in some regions due to loss of water clarity from sedimentation, coastal development and wasting disease. However the declines are not significant enough to trigger any of the threatened categories. This species is listed as Least Concern.
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Population

Population
This species is known to be declining in the Black, Caspian and Aral Seas. There is little available information on the population status in other regions, but the overall status is most likely decreasing.

Population Trend
Decreasing
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Threats

Major Threats
There are no major threats to Zostera noltii. However there have been local declines in some regions due to loss of water clarity from sedimentation, coastal development and wasting disease. Zostera noltii is sensitive to eutrophication (Short and Burdick 1995) and is highly affected by shading (Van Lent et al. 1991). Nutrient loading from runoff has resulted in some local declines. Seagrass beds of Z. noltii can recover from the stress of eutrophication when measures are put in place to manage the system (Marques et al. 2003). Zostera noltii is outcompeted by macroalgae in nutrient-enriched waters (Verdelhos et al. 2005).

The invasive species Caulerpa racemosa may interfere with the interaction between C. nodosa and Z. noltii when they occur in the same habitat (Ceccherelli et al. 2001).
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Management

Conservation Actions

Conservation Actions
There are no specific conservation measures for Zostera noltii.

This species is Listed in the Rio Declaration as diverse habitats in need of protection and monitoring.

This species is found in two national nature reserves in Caspian Sea (Green and Short 2003), and may be found in other Marine Protected Areas (MPAs).
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Wikipedia

Zostera noltei

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 estuaries, bays and lagoons.

Description[edit]

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 22 cm (9 in) 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 2 mm (0.08 in) long.[3]

Distribution and habitat[edit]

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.[1] Around the British Isles it grows extensively in the Firths of Moray and Cromarty, the Wash and the Thames Estuary. In Ireland substantial quantities are found in Strangford Lough, 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.[4] It also grows in Morocco, Mauritania, the Canary Islands and Cape Verde. It grows intertidally on fine sandy or muddy 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 estuaries and lagoons. It is adversely affected by high nutrient levels and cloudy water.[1]

Biology[edit]

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.[5]

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 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.[6]

Ecology[edit]

Zostera noltii stabilises the seabed

Seagrass beds are highly productive and form the basis of important coastal ecosystems. 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 parasite, Plasmodiophora bicaudata, attacks eel grasses, including Zostera noltii.[7] It prevents further growth between the nodes and damages clumps with the leaves growing in tufts, causing what is known as wasting disease.[3] 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.[8]

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 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.[9] Wigeon numbers have also declined.[9] They are shy birds and only resort to feeding on Zostera noltii when the seagrass beds lower down the beach are exhausted.[8] 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.[5]

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 biodiverse assortment of animal species, these are more numerous in subtidal beds.[3] Although Zostera noltii populations may be declining slowly, the IUCN Red List of Threatened Species lists it as being of "Least concern".[1]

References[edit]

  1. ^ a b c d 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 noltii". IUCN Red List of Threatened Species. Version 2012.2. International Union for Conservation of Nature. Retrieved May 26, 2013. 
  2. ^ Guiry, Michael D. (2013). "Zostera (Zosterella) noltii Hornemann". World Register of Marine Species. Retrieved 2013-05-26. 
  3. ^ a b c Tyler-Walters, Harvey (2005). "Dwarf eelgrass - Zostera noltii". Marine Life Information Network (MarLIN). The Marine Biological Association of the UK. Retrieved 2013-05-26. 
  4. ^ Tyler-Walters, Harvey (2005). "Dwarf eelgrass - Zostera noltii - Habitat preferences and distribution". Marine Life Information Network (MarLIN). The Marine Biological Association of the UK. Retrieved 2013-07-02. 
  5. ^ a b Tyler-Walters, Harvey (2005). "Dwarf eelgrass - Zostera noltii - General biology". Marine Life Information Network (MarLIN). The Marine Biological Association of the UK. Retrieved 2013-07-02. 
  6. ^ Tyler-Walters, Harvey (2005). "Dwarf eelgrass - Zostera noltii - Reproduction and longevity". Marine Life Information Network (MarLIN). The Marine Biological Association of the UK. Retrieved 2013-05-26. 
  7. ^ Tyler-Walters, Harvey (2008). "Common eelgrass - Zostera marina". Marine Life Information Network (MarLIN). The Marine Biological Association of the UK. Retrieved 2013-07-02. 
  8. ^ a b "Elgrass beds: Ecological relationships". UK Marine Special Areas of Conservation. Retrieved 2013-05-26. 
  9. ^ a b Tyler-Walters, Harvey (2005). "Dwarf eelgrass - Zostera noltii - Importance". Marine Life Information Network (MarLIN). The Marine Biological Association of the UK. Retrieved 2013-07-02. 
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