|Researched by||Dr Harvey Tyler-Walters||Refereed by||Dr Leigh Jones|
|Other common names||-||Synonyms||Zostera nana Roth, Zostera noltii|
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).
|Phylum||Tracheophyta||Vascular plants (seagrasses, pondweeds, and reeds)|
|Recent Synonyms||Zostera nana RothZostera noltii|
|Typical abundance||High density|
|Male size range||Male size at maturity|
|Female size range||Medium-large(21-50cm)||Female size at maturity|
|Growth form||Foliose||Growth rate||See additional text|
|Body flexibility||High (greater than 45 degrees)||Mobility||Sessile|
|Characteristic feeding method||Autotroph|
|Typically feeds on||Not relevant|
|Sociability||Not relevant||Environmental position||Epifaunal, Infaunal|
Numerous epiphytes, some specific to seagrasses and the parasitic fungus Plasmodiophora bicaudata Feldm.
|Is the species harmful?||No|
No text entered
Growth in seagrasses is generally limited by light and affected by temperature (Philliparts, 1995a & b; Marta et al., 1996). Zostera noltei is more tolerant of high light intensities, available at low tide, than Zostera marina, presumably an adaptation to life higher on the shore and the more turbid environment of intertidal flats (Vermaat et al., 1996; Davison & Hughes, 1998). New leaves appear in spring and eelgrass meadows develop over intertidal flats in summer, due to vegetative growth. Increase in shoot density resulting from continuous branching of the rhizome (Vermaat & Verhagen, 1996). A shoot density of 1000-23000 /m was reported in the Zandkreek estuary, Netherlands (Vermaat & Verhagen, 1996). Leaf growth stops in September/October and leaves are shed although Zostera noltei keeps its leaves longer than Zostera marina in winter. In the intertidal the combined action of grazing and wave action causes leaves to be lost over winter, and the plant reduced to its rhizomes within the sediment. For example, Nacken & Reise (2000) reported that 50% of leaves fell off while the rest were taken by birds (see importance) in the Wadden Sea. In the following season, regrowth occurs from the remaining rhizomes.
The rhizome of Zostera noltei is thinner than that of the longer lived Zostera marina and its growth is rapid and ephemeral in nature, taking advantage of seasonal increases in light and nutrients rather than metabolites stored in the rhizome (Marta et al., 1996; Dawes & Guiry, 1992). Marta et al. (1996) reported shoot growth rates of ca 0.2 cm/day (winter minimum) to ca 0.8-0.9 cm/day (summer maximum) in the Mediterranean (with winter temperature of 12 °C and summer maximum temperature of 23.2 °C). They also stated that the rhizomes were short lived, <1 year, presumably from one growing season to the next, however given the 'life-span' of vegetative clones of Zostera marina, the plants and seagrass bed of Zostera noltei may be much older.
The following algal species have been recorded only from seagrass leaves: Halothrix lumbricalis; Leblondiella densa; Myrionema magnusii; Cladosiphon zosterae; Punctaria crispata and Cladosiphon contortus, which is larger and found primarily on Zostera sp. rhizomes. Other species of algae are host specific for Zostera marina. The parasitic fungus Plasmodiophora bicaudata Feldm. prevented growth form rhizome internodes and gives the diseased plant a tufted appearance (den Hartog, 1970).
Plus et al. (2001) reported the gross production rates of Zostera noltei beds in the Thau lagoon, France, to be between 97.5 - 1001.3 mg oxygen /m /h which was within the range reported for other temperate seagrass beds.
|Physiographic preferences||Strait / sound, Sea loch / Sea lough, Ria / Voe, Estuary, Isolated saline water (Lagoon), Enclosed coast / Embayment|
|Biological zone preferences||Lower eulittoral, Mid eulittoral, Sublittoral fringe, Upper eulittoral|
|Substratum / habitat preferences||Mud, Muddy sand, Sandy mud|
|Tidal strength preferences||Moderately Strong 1 to 3 knots (0.5-1.5 m/sec.), Very Weak (negligible), Weak < 1 knot (<0.5 m/sec.)|
|Wave exposure preferences||Extremely sheltered, Sheltered, Very sheltered|
|Salinity preferences||Full (30-40 psu), Low (<18 psu), Reduced (18-30 psu), Variable (18-40 psu)|
|Other preferences||No text entered|
|Migration Pattern||Non-migratory / resident|
The distribution of Zostera noltei in the intertidal may be affected by infaunal deposit feeders. For example, Philliparts (1994a) noted an abrupt cut off between a Zostera noltei bed and an area dominated by Arenicola marina. Zostera noltei was excluded from sediment dominated by Arenicola marina, while the lug worm itself was excluded from the Zostera noltei bed by the presence of a clay layer (Philippart, 1994a). Similar separation has been noted between areas dominated by Zostera noltei or Hediste diversicolor (Hughes et al., 2000).
|Reproductive type||Vegetative||Reproductive frequency||Annual protracted|
|Fecundity (number of eggs)||No information||Generation time||1-2 years|
|Age at maturity||1-2 years||Season||May - September|
|Life span||See additional information|
|Larval/propagule type||-||Larval/juvenile development||Oviparous|
|Duration of larval stage||Not relevant||Larval dispersal potential||100 -1000 m|
|Larval settlement period||Not relevant|
This MarLIN sensitivity assessment has been superseded by the MarESA approach to sensitivity assessment. MarLIN assessments used an approach that has now been modified to reflect the most recent conservation imperatives and terminology and are due to be updated by 2016/17.
The rhizome occupies the top 20cm of the substratum. Substratum loss will result in the loss of the shoots, rhizome and probably the seed bank. Recoverability will depend on recruitment from other populations. Although Zostera sp. seed dispersal may occur over large distances, high seedling mortality and seed predation may significantly reduce effective recruitment. Holt et al. (1997) suggested that recovery would take between 5-10 years, but in many cases longer. The slow recovery of Zostera populations since the 1920s - 30s outbreak of wasting disease and the continued decline of Zostera noltei beds suggests that, once lost, eelgrass beds take considerable time to re-establish.
Sediment disturbance, siltation, erosion and turbidity resulting from coastal engineering and dredging activities have been implicated in the decline of seagrass beds world wide (Davison & Hughes, 1998; Holt et al., 1997). Seagrasses are intolerant of smothering and typically bend over with addition of sediment and are buried in a few centimetres of sediment (Fonseca, 1992). Zostera sp. are highly intolerant of smothering by epiphytes or algal mats (see nutrients). Recoverability will depend on recruitment from other populations. Although Zostera sp. seed dispersal may occur over large distances, high seedling mortality and seed predation may significantly reduce effective recruitment. Holt et al. (1997) suggested that recovery would take between 5-10 years, but in many cases longer. The slow recovery of Zostera populations since the 1920s - 30s outbreak of wasting disease and the continued decline of Zostera noltei beds suggests that, once lost, eelgrass beds take considerable time to re-establish.
Increased sediment availability may result in raised eelgrass beds or smothering of the leaves. Decreased sedimentation is likely to result in erosion and loss of the eelgrass beds. Sediment deposited during summer months may be lost again due to winter storms, resuspension by grazing wildfowl, and increased erosion due to die back of leaves and shoots in autumn and winter.
However, increased sediment erosion or accretion have been associated with loss of seagrass beds in the Australia, the Mediterranean, the Wadden Sea, and USA. Sediment dynamics and hydrodynamics are key factors in seagrass systems (Asmus & Asmus, 2000a; Davison & Hughes, 1998; Holt et al., 1997). Overall, therefore, seagrass beds are probably intolerant of any activity that changes the sediment regime where the change is greater than expected due to natural events in magnitude or duration and an intolerance of intermediate has been reported. The slow recovery of Zostera populations since the 1920s - 30s outbreak of wasting disease and the continuing decline of Zostera noltii beds suggests that, once lost, eelgrass beds take considerable time to re-establish. However, evidence from grazing studies suggest that Zostera noltii beds can recover within a year after removal of 63% of plant biomass (Nacken & Reise, 2000). Similarly, Dawes & Guiry (1992) regarded Zostera noltei as ephemeral in nature. However, where a bed is stressed by other factors, recovery may be delayed (Holt et al. 1997; Davison & Hughes 1998).
|Low||Very high||Very Low|
Zostera noltei is more tolerant of desiccation than other Zostera species, indicated by its intertidal position and ability to colonize well draining sediment. In well -drained areas Zostera noltei may dry out completely between tides (Davison & Hughes, 1998). However, little information on desiccation tolerance was found.
Zostera noltei is abundant between mean high water neaps and mean low water neaps. It can survive higher on the shore than Zostera angustifolia although they are often sympatric. Intertidal seagrasses are adapted to leaf and sediment loss due to wave action, grazing and the re-suspension of sediment resulting in high turbidities (Vermaat et al., 1996). Although the intertidal is likely to be affected by high turbidity, Zostera noltei probably makes up for this lack of light by utilising the high levels of light availability when emmersed. It can tolerate higher light intensities than other seagrasses (Vermaat et al., 1996; Davison & Hughes, 1998). Philippart (1995b) noted that although tolerant of high light intensities, its upper shore extent was limited by desiccation tolerance, and the optimal intertidal position of Zostera noltei on a tidal flat near Terschelling, Wadden Sea, was 50% emersion.
A long term change in the emergence regime is likely to increase or reduce the extent of the population in the intertidal. An increase in emergence is likely to reduce its upper extent although this may be compensated for increased growth lower on the shore. Decreased emergence is likely to enable to seagrass bed to expand further up the shore. However, expansion depends on available habitat and competition in infaunal dominated sediments (e.g. Hediste diversicolor or Arenicola marina(Hughes et al., 2000; Philippart, 1994a).
The slow recovery of Zostera populations since the 1920s - 30s outbreak of wasting disease and the continuing decline of Zostera noltei beds suggests that, once lost, eelgrass beds take considerable time to re-establish. However, evidence from grazing studies suggest that Zostera noltii beds can recover within a year after removal of 63% of plant biomass (Nacken & Reise, 2000). Similarly, Dawes & Guiry (1992) regarded Zostera noltei as ephemeral in nature. However, where a bed is stressed by other factors, recovery may be delayed (Holt et al. 1997; Davison & Hughes 1998).
Zostera noltei beds typically occur where water flow rates are weak or negligible. Increased flow rates are likely to erode sediment, expose rhizomes and lead to loss of the plants. Increased water flow rates deposit coarser sediments and erode fine sediments resulting in loss of suitable substrata for this species.
The slow recovery of Zostera populations since the 1920s - 30s outbreak of wasting disease and the continuing decline of Zostera noltii beds suggests that, once lost, eelgrass beds take considerable time to re-establish. However, evidence from grazing studies suggest that Zostera noltei beds can recover within a year after removal of 63% of plant biomass (Nacken & Reise, 2000). Similarly, Dawes & Guiry (1992) regarded Zostera noltei as ephemeral in nature. However, where a bed is stressed by other factors, recovery may be delayed (Holt et al. 1997; Davison & Hughes 1998).
|Tolerant||Not relevant||Not sensitive||Not relevant|
Populations of Zostera noltei occur from the Mediterranean to southern Norway and Zostera sp. are regarded as tolerant of temperatures between about 5 - 30°C. Therefore, they may tolerate the range of temperatures likely in the British Isles (Davison & Hughes, 1998). Intertidal populations may be damaged by frost (Hartog, 1987) and Covey & Hocking (1987) reported defoliation of Zostera noltii in the upper reaches of mudflats in Helford River due to ice formation in the exceptionally cold winter of 1987. However, the rhizomes survived and leaves are usually lost at this time of year due to shedding, storms or grazing with little apparent effect (Nacken & Reise, 2000). Populations at the edge of the range are likely to be more intolerant of temperature change. Phillips & Menez (1988) reported death of seagrass as the result of a thermal plume in Biscayn Bay, Florida that raised ambient temperature by 5°C, however, the species concerned were not cited. Long term temperature increase may increase the relative contribution of sexual reproduction and seed germination to population structure.
Increased turbidity due to suspended sediment, humic substances, riverine discharges or phytoplankton growth reduces the light reaching submerged plants. Increase turbidity has been associated with the continued decline of seagrass beds world-wide (Philippart, 1994; Davison & Hughes, 1998; Asmus & Asmus, 2000). However, intertidal Zostera noltei 'escapes' this turbidity since it is able to take advantage of the high light intensities available at low tide (Vermaat et al., 1996). Furthermore, Zostera noltei can store and mobilize carbohydrates and has been reported to be able to tolerate acute light reductions (below 2% of surface irradiance for two weeks) (Peralta et al., 2002). However, Zostera noltei are likely to be more intolerant to chronic increases in turbidity. Philippart (1994b) suggested that the declines in Zostera noltei beds in the Wadden Sea probably occurred at low water level. Permanently submerged population in brackish conditions may be more intolerant of increased turbidity. The slow recovery of Zostera populations since the 1920s - 30s outbreak of wasting disease and the continuing decline of Zostera noltei beds suggests that, once lost, eelgrass beds take considerable time to re-establish. However, evidence from grazing studies suggest that Zostera noltei beds can recover within a year after removal of 63% of plant biomass (Nacken & Reise, 2000). Similarly, Dawes & Guiry (1992) regarded Zostera noltii as ephemeral in nature. However, where a bed is stressed by other factors, recovery may be delayed (Holt et al. 1997; Davison & Hughes, 1998).
Seagrasses require sheltered environments, with gentle longshore currents and tidal flux. Increased wave exposure may increase sediment erosion (see siltation above). Populations present in moderately strong currents may benefit from decreased water flow rates. Small patchy populations or recently established population and seedling may be highly intolerant of increased wave action since they lack an extensive rhizome system.
Recoverability will depend on recruitment from other populations. Although Zostera sp. seed dispersal may occur over large distances, high seedling mortality and seed predation may significantly reduce effective recruitment. Holt et al. (1997) suggested that recovery would take between 5-10 years, but in many cases longer. The slow recovery of Zostera populations since the 1920s - 30s outbreak of wasting disease and the continued decline of Zostera noltei beds suggests that, once lost, eelgrass beds take considerable time to re-establish.
|Tolerant||Not relevant||Not sensitive|
The effect of sound waves and vibration on plants is poorly studied. It is likely that sound waves will have little effect at the benchmark levels suggested. Wildfowl are intolerant of disturbance by noise, which may reduce grazing pressure on intertidal Zostera noltei. However, Naken & Reise (2000) suggested that grazing was important for the persistence of Zostera noltei beds, at least in their study area.
|Tolerant||Not relevant||Not sensitive||High|
Plants have no known visual receptors and are therefore, not sensitive to this factor. Wildfowl are intolerant of disturbance by visual presence of activities, which may reduce grazing pressure on intertidal Zostera noltei. However, Naken & Reise (2000) suggested that grazing was important for the persistence of Zostera noltei beds, at least in their study area.
Seagrass rhizomes are easily damaged by trampling, anchoring, dredging and other activities that disturb the sediment (Holt et al., 1997; Davison & Hughes, 1998). Small scale sediment disturbance may actually stimulate growth and small patches of sediment allow recolonization by seedlings. Rhizomes are likely to be damaged, leaf blades removed and seeds buried too deep to germinate, by activities such as trampling, anchoring, digging, dredging, power boat and jet-ski wash. For example, damage after the Sea Empress oil spill was reported as limited to the ruts left by clean up vehicles (Jones et al., 2000). Brent geese feed on shoots, rhizomes, and roots, reworking the top centimetre of sediment (8 times in 3 months), and in the process dig pits 3-10cm deep by trampling. As a result, in the Wadden Sea from Sept-Dec (the over-wintering period) Brent geese removed 63% of the plant biomass and pitted 12% of the seagrass bed. However, the bed of Zostera noltii recovered by the following year, and the authors suggested that grazing and bioturbation was necessary for the persistence of the intertidal seagrass beds (Nacken & Reise, 2000). Similarly, several authors have suggested that Zostera sp. can recover from 'normal' levels of wildfowl grazing (Davison & Hughes, 1998). However, suction dredging for cockles in Solway Firth removed Zostera in affected areas while Zostera was abundant in un-dredged areas (Perkins, 1988). Therefore, the passage of a scallop dredge through the seagrass bed (see benchmark) will probably remove a proportion of the seagrass population and intolerance has been assessed as intermediate. Recoverability is likely to be high (see additional information below). However, seagrass beds are likely to be of higher intolerance to repeated scallop dredging or suction dredging.
Seagrass rhizomes are easily damaged by trampling, anchoring, dredging and other activities that disturb the sediment (Holt et al., 1997; Davison & Hughes, 1998). The seagrass bed is unlikely to survive displacement. Evidence from grazing studies suggest that Zostera noltei beds can recover within a year after removal of 63% of plant biomass (Nacken & Reise, 2000). Similarly, Dawes & Guiry (1992) regarded Zostera noltii as ephemeral in nature. However, where a bed is stressed by other factors, recovery may be delayed (Holt et al. 1997; Davison & Hughes 1998).
There was little information on the effects of chemical contaminants on Zostera noltei and what little was found mainly refers to Zostera marina. Zostera marina is known to accumulate TBT but no damage was observable in the field (Williams et al.,1994). Naphthalene, pentachlorophenol, Aldicarb and Kepone reduce nitrogen fixation and may affect Zostera marina viability. Triazine herbicides (e.g. Irgarol) inhibit photosynthesis and sublethal effects have been detected. Terrestrial herbicides may damage eelgrass beds in the marine environment. For example, the herbicide Atrazine is reported to cause growth inhibition and 50% mortality in Zostera marina exposed to 100 ppb (ng/ l) Atrazine for 21 days (Davison & Hughes 1998). Bester (2000) noted a correlation between raised concentrations of 4 triazine herbicides and areas where Zostera sp. had been lost.
|Low||Very high||Very Low||Low|
Little information was found regarding heavy metal concentrations in Zostera noltei however, the following information was found for Zostera marina. The concentration and toxicity of heavy metals in salt marsh plants, including Zostera marina was reviewed by Williams et al., 1994. Growth of Zostera marina is inhibited by 0.32 mg/l Cu and 10 mg/l Hg, but Cd, Zn, Cr and Pb had measurable but less toxic effects (Williams et al., (1994). Davison & Hughes (1998) report that Hg, Ni and Pb reduce nitrogen fixation which may affect viability. However, leaves and rhizomes accumulate heavy metals, especially in winter. Williams et al. (1994) did not observe any damage to Zostera marina in the field. Williams et al. (1994) noted that the major route for uptake of heavy metals was through the leaves and suggested that intertidal populations would accumulate less heavy metals due to their reduced exposure.
The effects of hydrocarbon contamination on Zostera noltii will depend on the type of oil spilled (L. Jones, pers. comm.). Removal of oil intolerant grazers, e.g. gastropods or amphipods, may result in smothering of eelgrasses by epiphytes or algal mats (see nutrients below and LMS.Znol).
|No information||Not relevant||No information||Not relevant|
Increased nutrient concentrations (nitrates and phosphates) have been implicated in the continued decline of seagrass beds world-wide, either directly or due to eutrophication (Phillips & Menez, 1988; Davison & Hughes, 1998; Philippart, 1994b; Philippart, 1995a, b; Vermaat et al., 1994; Asmus & Asmus, 2000). The following effects on Zostera sp. have been attributed to nutrients and eutrophication.
Long-term increases in nutrients or eutrophication may result in loss of the intertidal eelgrass beds.
|Low||Very high||Very Low||Low|
Zostera sp. have a wide tolerance of salinity from 10 - 39 ppt (Davison & Hughes 1998), although den Hartog (1970) suggested a lower salinity tolerance of 5 psu for Zostera sp. Den Hartog (1970) stated that Zostera noltii was a euryhaline species, penetrating estuaries and the Baltic Sea to the average annual isohaline of 9-10 psu. Zostera noltei is probably more tolerant of extremes of salinity than its congeners due to its intertidal habit and Zostera sp. occupy a wide range of salinities, therefore 'low' intolerance has been recorded.
|Low||Very high||Very Low||Low|
The effects of oxygen concentration on the growth and survivability of Zostera noltei are not reported in the literature. Zostera sp. leaves contain air spaces (lacunae) and oxygen is transported to the roots where it permeates into the sediment, resulting in a oxygenated microzone. This enhances the uptake of nitrogen. The presence of air spaces suggests that seagrass may be tolerant of low oxygen levels in the short term, however, prolonged deoxygenation, especially if combined with low light penetration and hence reduced photosynthesis may have an effect.
A major outbreak of wasting disease resulted in significant declines of Zostera beds on both sides of the Atlantic in 1920s to 1930s, primarily Zostera marina in the subtidal. Wasting disease is thought to be caused by the marine fungus, Labyrinthula macrocystis. The disease causes death of leaves and after 2-3 seasons death of regenerative shoots, rhizomes and loss of up to 90 percent of the population. The disease is less likely at low salinities however, and Zostera noltei was little affected (Rasmussen, 1977; Davison & Hughes, 1998). Decline of intertidal Zostera marina and Zostera noltei beds in the Wadden Sea began in the 1960s and a marked decline in Zostera noltei occurred between 1965 and 1975, presumably due to anthropogenic change (Philippart, 1994b).
Spartina anglica (a cord grass) is an invasive pioneer species, a hybrid of introduced and native cord grass species. Its rapid growth consolidates sediment, raises mudflats and reduces sediment availability elsewhere. It has been implicated in the reduction of common eelgrass cover in Lindisfarne, Northumberland due to encroachment and changes in sediment dynamics. Wire weed (Sargassum muticum) invades open substratum and may prevent recolonization of areas of eelgrass beds left open by disturbance (Davison & Hughes 1998). Zostera marina and Sargassum muticum may compete for space in the lower shore lagoons of the Solent. However, evidence for competition is conflicting and requires further research. If the invasive species prevents recolonization then recoverability from other factors will be reduced. Intertidal Zostera noltei may be more vulnerable to competition from Spartina sp.
Wildfowl grazing can consume significant amounts of seagrass and reduce cover mainly in autumn and winter. Tubbs & Tubbs (1983) reported that Brent geese reduced the cover of Zostera marina and Zostera noltei from 60-100% to 5-10% in mid October to mid January in the Solent. Grazing is probably part of the natural seasonal fluctuation in seagrass cover and Zostera sp. can recover from normal grazing (Naken & Reise, 2000; Davison & Hughes, 1998). Zostera noltei is the preferred food of the dark-bellied Brent goose (Branta bernicla). Brent geese feed on shoots, rhizomes and roots, reworking the top centimetre of sediment (8 times in 3 months), and in the process dig pits 3-10cm deep by trampling. As a result, in the Wadden Sea from Sept-Dec (the over-wintering period) Brent geese removed 63% of the plant biomass and pitted 12% of the seagrass bed. However, the bed of Zostera noltei recovered by the following year, and the authors suggested that grazing and bioturbation was necessary for the persistence of the intertidal seagrass beds (Nacken & Reise, 2000). However, where a bed is stressed by other factors it may not be able to withstand grazing (Holt et al. 1997; Davison & Hughes 1998). For example, seagrass rhizomes are easily damaged by trampling, anchoring, dredging and other activities that disturb the sediment. A seagrass bed is unlikely to survive displacement or extraction, although Phillips & Menez (1988) reported that rhizomes and shoots can root and re-establish themselves if they settle on sediment long enough. Therefore, Zostera noltei beds have been considered to be of 'intermediate' intolerance to extraction.
Zostera sp. are regarded as very intolerant of hydraulic bivalve fishing in the UK and Wadden Sea (Holt et al., 1997; Davison & Hughes, 1998; Philippart, 1994b). Cockles and Zostera noltei are frequently associated and intertidal beds may be more vulnerable (Holt et al., 1997). Hydraulic dredging is likely to break up and remove rhizomes. It was suggested that hydraulic harvesting of cockles in the Solway Firth could cause widespread damage or eradicate Zostera sp. from the bay (Perkins, 1988). Digging and dredging for the American hard-shell clam (Mercenaria mercenaria had a significant effect on the eelgrass beds (Cox, 1991; Eno et al., 1997). In the Dutch Wadden Sea, seagrass is hardly found where cockles are normally fished (Dankers & de Vlas, 1992). Recovery was severely restricted especially where no rhizomes and roots were left in the sediment (De Jong & de Jong, 1992; Philippart, 1994b).
No text entered.
|IUCN Red List||Least Concern (LC)|
|National (GB) importance||Nationally scarce||Global red list (IUCN) category||Least Concern (LC)|
|Origin||-||Date Arrived||Not relevant|
Sea grasses have been put to a number of uses in the past for example, sound-proofing, insulation, roofing thatch, binding soil, packaging, basket weaving and in the manufacture of 'coir' matting (see Kuelan, 1999 for review).
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Last Updated: 14/10/2005