Zostera angustifolia

Ecology

Z. angustifolia is a perennial which grows on sheltered tidal mudflats, in estuaries and in coastal lagoons, usually in shallower, more turbid water than Z. marina. It is usually found on mud or muddy sands, between the half-tide and low-tide marks. Lowland.

Status

Native

World Distribution

Z. angustifolia is also recorded from Denmark and Sweden; it is difficult to distinguish from narrow-leaved variants of Z. marina and is not regarded as specifically distinct by Hartog (1970).

Broad Habitats

Littoral sediment (includes saltmarsh and saltmarsh pools)

Light (Ellenberg): 7

Moisture (Ellenberg): 12

Reaction (Ellenberg): 8

Nitrogen (Ellenberg): 5

8

Salt Tolerance (Ellenberg): 8

January Mean Temperature (Celsius): 4.3

July Mean Temperature (Celsius): 15

Annual Precipitation (mm): 926

Length: 30

Perennation - primary

Perennial

Life Form - primary

Perennial hydrophyte (perennial water plant)

Woodiness

Herbaceous

Clonality - primary

Rhizome far-creeping

Count of 10km squares in Great Britain: 131

Count of 10km squares in Ireland: 27

Count of 10km squares in the Channel Isles: 6

Atlas Change Index: -0.68

Distribution information

JNCC Designations

NHMSYS0000465248

Scarce Atlas Account

Scarce Atlas Account: 

Zostera angustifolia (Hornem.) Reichb.

Narrow-leaved eelgrass

Status: scarce

 

This is a marine species of mudflats and estuaries which are always well sheltered from violent waves. It is recorded from half-tide to low-tide mark, and more rarely down to 4 metres, generally in shallower but more turbid water than Z. marina (Tutin 1942), especially on muds and muddy sands (Gubbay 1988). It grows in waters of variable salinity, often about 25 g dm-3 (i.e. fairly brackish (Turin 1942)), although it has been recorded in salinities up to 42 g dm-3 (highly saline (Clapham, Tutin & Moore 1987)). It is usually found in pure stands (although rarely as extensive as Z. marina), or sometimes with the green seaweed Chaetomorpha spp. It also grows in some coastal lagoons, including The Fleet where it is accompanied by Ruppia cirrhosa, R. maritima and Zostera noltii and the charophyte Lamprothamnium papulosum

The rhizome is perennial and long-lived, although the flowering shoots are annual. Short lengths of rhizome readily break off and are dispersed by the tide, providing the main means for establishing new colonies. It flowers in sea temperatures above 15 °C (usually around July), shedding its seeds in August and September. Germination occurs in autumn and early winter, but seedlings are always scarce, and absent in some years.

No major declines have been noted in this species, which did not suffer the wasting disease reported for Z. marina. Changes in salinity and substrate distribution as a result of estuarine ‘reclamation’ is the most serious threat at some sites.

Z. angustifolia is recorded in Europe from Denmark, Ireland and Sweden, but its distribution is imperfectly known because of confusion with Z. noltii and narrow-leaved variants of Z. marina.

Some of the mapped records for this species may well be a confusion with narrow-leaved forms of Z. marina, which can, in exposed habitats or turbulent waters, have leaves as narrow as 2 mm (Evans 1985). Stace (1991) suggests that this plant may only be a variety (var. angustifolia Hornem.) of Z. marina.

 

M. Scott

PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.

Atlas text references

Atlas (304c)
Scarce plants in Britain,
Stewart, A., Pearman D. A., and Preston C. D.
, Peterborough, (1994)

Biological Flora of the British Isles. No. 7. Zostera genus L. (pp. 217), Zostera marina L. (pp. 217-224), Zostera hornemanniana Tutin (pp. 224-226),
Tutin, T. G.
, Journal of Ecology, Volume 30, p.217-226, (1942)