SITE SYNOPSIS

SITE NAME: TACUMSHIN LAKE

SITE CODE: 000709

Tacumshin Lake is a shallow coastal lagoon situated on the south Co. Wexford coast
about half way between Kilmore Quay and Carnsore Point and 15 km south of
Wexford town. The lagoon was formerly a shallow sea bay which over time has been
separated from the sea by a gravel/sand spit that has extended across the mouth of the
bay from east to west, due to long-shore drift.

At times in the past this spit completely land-locked the lagoon, and at the end of the
19th century when this situation prevailed for some time the lake was drained by
means of a large bore pipe set through the gravel/sand bar. Some of the drained lake
bed was used by growing cereal crops. In the mid-1970s the spit again closed off the
lagoon from the sea. The water level rose after exceptionally heavy rainfall and
flooded several hundred hectares of low lying surrounding farmland. To relieve
flooding the farmers reactivated the old drainage pipe and installed a second pipe at a
lower level. The capacity of these two pipes is insufficient to prevent the lagoon
filling up in winter when inflow from streams is greater than the outflow through the
pipes. Thus, from about November to May the water level normally reaches the
HWM as shown on the 6" O.S. maps, while from May to November the water level
approximates to that of LWM as shown on the 6" O.S. maps. To speed the drainage
from the lagoon two main drains were excavated leading to the landward end of the
pipes.

The spit separating the lagoon from the sea has been built up by tide-borne gravels
and wind-blown sand. The patches were formed from water and wind-borne silts and
sands, consolidated by salt marsh vegetation. The lake bed is composed of silt and
sand deposited by incoming tides and feeder streams. The surrounding lands are
composed of glacial till.

The lagoon bed sediments support extensive areas of Glasswort (Salicornia spp.)
where conditions remain brackish in summer. Other areas support Lesser Sea-spurrey
(Spergularia marina). The permanent water bodies (including the excavated
channels) and the marshy areas associated with stream inlets are colonised by
Common Reed (Phragmites australis), Sea Club-rush (Scirpus maritimus) and
Common Club-rush (Scirpus lacustris). Tasselweed (Ruppia maritima) forms dense
stands in the permanent brackish water in the centre of the lagoon bed. Other typical
lagoonal plants present include Horned Pondweed (Zanichellia palustris) and the rare
charophyte (Chara canescens). The patches have dense Fescue (Festuca sp.) swards
and patches of Sea Purslane (Halimione portulacoides) and Sea Rush (Juncus
maritimus).

The gravel/sand barrier is in two parts, the eastern one being a mature dune system
with low-growing herbs and grasses, such as Lady's Bedstraw (Galium verum) and
Kidney Vetch (Anthyllis vulneraria); the western one has a developing dune
vegetation with the pioneering Sea Couch (Elymus farctus) dominating. Marram
(Ammophila arenaria) is found throughout. Lyme Grass (Leymus arenarius) is found
here at the western edge of its range, while the endangered and legally protected
Cottonweed (Otanthus maritimus) has been recorded.

The waterfowl population of the lagoon is exceptionally diverse and the area supports
large numbers of birds through the whole year, which is unusual among Irish
wetlands. In summer the restricted area of water remaining in the lagoon supports a
moulting flock of 300-400 Mute Swans, one of the largest concentrations in Ireland.
The area is also an important summering site for non-breeding Black-tailed Godwits.
During spring and autumn migration large numbers of waders use the lagoon as a
resting and feeding area before continuing on to breeding or wintering grounds. Large
numbers of Lesser Black-backed Gulls (up to 1,000) gather at the lagoon for some
weeks prior to their autumn migration to Iberia. The lagoon is particularly attractive
to vagrant North American and Eurasian waterfowl, especially in the autumn.
As water levels gradually rise in early winter large numbers of waterfowl – Mallard
(104), Teal (663), Gadwall (51), Wigeon (3608), Pintail (278), Shoveler (118), Tufted
Duck (122), Pochard (86), Coot (690), Brent Goose (45), Lapwing (5043), Blacktailed
Godwit (131) and Curlew (268) congregate at the lagoon to feed on its rich food
resources. The lagoon was formerly used by a large colony of Herring Gull and in
1975 90 pairs of the rare Roseate Tern attempted to nest on the Little Patch. In
autumn the abundant insect life of the dry lake bed and Sea-spurrey (Spergularia)
stands provide food for large numbers of migrating Swallows and Martins which also
use the reed beds as a night roosting area, with up to 10,000 individuals being
recorded in recent years.

The site is of particular conservation significance for its lagoon, which is an excellent
example of a sedimentary lagoon with a gravel/sand barrier, that supports a wide
variety of plants and animals, including many lagoonal specialist species. It is one of
the largest examples of a lagoon in the country. This habitat, which is both threatened
and declining throughout Europe, is listed on Annex I of the E.U. Habitats Directive
with priority status. Good examples of four other habitats that are listed on Annex I
of this directive occur within the site, i.e. drift lines, perennial vegetation of stony
banks, embryonic shifting dunes and Marram dunes. Tacumshin Lake is also an
important ornithological site and has been designated a Special Protection Area under
the E.U. Birds Directive. It is nationally important for nine bird species, especially
Gadwall and Pintail. The presence of a number of rare or scarce plant species adds
additional interest to the site.

30.11.1999