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Directory of Important Wetlands

Directory of Important Wetlands in Australia - Information sheet

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Port Gawler & Buckland Park Lake - SA015

Level of importance: National - Directory
Location: 34 degrees 40' S, 138 degrees 26' E; Fleurieu Peninsula, situated on the estuary of the Gawler River on the east coast of Gulf St Vincent, approximately 30 km north of Adelaide. Includes the mangrove and samphire habitats of Port Gawler and the freshwater habitats of Buckland Park Lake 34 degrees 40' S, 138 degrees 28' E.
Biogeographic region: Eyre and Yorke Blocks.
Shire:
Area: Port Gawler: 434 ha.
Elevation: 0-10 m ASL.
Other listed wetlands in same aggregation: SA005.
Wetland type: A1, A2, A6, B6, A8, A9, C4, A7
Criteria for inclusion: 1, 3, 5, 6,
Site description:
Port Gawler consists of vast tidal flats and fringing mangrove forests that are crossed by a multitude of tidal channels. Shell-grit ridges occur along a well-defined belt within the mangrove forest. To the east, within 500 m of the area, lie extensive shallow salt evaporation ponds which are a part of the salt-extraction system which extends from the Barker Inlet/St Kilda region. A saltmarsh samphire community occupies the area between the mangroves and the evaporation ponds. Adjacent to the ponds lies Buckland Park Lake which was formed by damming the deltaic mouth of the Gawler River. The Lake is a shallow, ephemeral freshwater lake and is divided into a southern and northern basin. When full, the Lake consists of a relatively long (2 km) and narrow (0.4 km) stretch of open water. Several channels radiate from the Lake and penetrate into the surrounding lignum swamps. The Gawler River, which has its source over 40 km to the east, flows through both sites and forms a long, narrow estuary at Port Gawler.
Physical features:
Landform: Mangrove forest, tidal flats, samphire swamp, intermittent sand (shell-grit) dunes, salt evaporation ponds, estuarine habitats, seasonal freshwater lake. Geology: Port Gawler occupies the St Kilda Formation (shelly stranded beach deposits and shelly silts, clays and sands, modern swamp deposits). Buckand Park Lake occupies the Pooraka Formation (red-brown sandy clay with some carbonate). Climate: Average annual rainfall is c. 420 mm, mostly falling during winter; evaporation is estimated to be 1800 mm.
Hydrological features:
Water supply: Port Gawler - Southern Ocean; tidal range of 2.3 m (spring tides). Buckland Park Lake - fills in winter from flows along the Gawler River which enters the lake via a channel from the south east corner. Water depth: Buckland Park Lake is relatively shallow and does not exceed 0.9 m when full; maximum depths in channels exceed 1.5 m. As the water level rises and the Lake overflows, water leaves the Lake via spillways and is channelled through the mangroves and out to sea. Water levels drop during spring (Sept.-Dec.) and rapidly dries up in summer once the Lake is pumped to remove saline water from the southern basin. Water salinity: Buckland Park Lake - 1-4 ppt TDS, in winter after the Lake has filled; 40-60 ppt TDS, in the Lake's southern basin in late summer (Paton et al. 1991).
Ecological features:
Ecological role: Port Gawler provides an important nursery area for commercial fish and crustacean species. Buckland Park attracts an extremely wide variety of waterbirds, in particular waterfowl, that use the lake and associated swamps for feeding, breeding and roosting. Plant structural formations: Mangrove low forest, samphire shrubland and chenopod shrubland mainly occur at Port Gawler; lignum shrubland, samphire shrubland and low woodland occur at Buckland Park Lake.
Significance:
Buckland Park Lake is the only substantial freshwater habitat on the Adelaide Plains and is also the single most important breeding habitat for a range of waterfowl within the Adelaide region.
Notable flora:
Threatened species: Halosarcia flabelliformis (Nv, Sv). Composition: The sub-littoral zone at Port Gawler supports seagrass meadows of Zostera mucronata, Heterozostera tasmanica and Posidonia australis; Avicennia marina low forest occupies almost the entire upper-littoral zone and extends over 1.4 km inland at its widest point; samphire communities of Sclerostegia arbuscula and Sarcocornia quinqueflora occupy the flats behind the mangroves; on slightly higher ground Halosarcia halocnemoides and H. flabelliformis occur; the slopes of the low shell-grit ridges support a low shrubland of Maireana oppositifolia and Atriplex paludosa with some Halosarcia halocnemoides; the crests of stranded beach dunes are mainly vegetated with Myoporum insulare, Acacia ligulata, Olearia axillaris, Alyxia buxifolia and Nitraria billardierei. Buckland Park Lake is flanked by extensive areas of lignum Muehlenbeckia florulenta, samphire Halosarcia spp. and Typha sp. swamps; several dense patches of planted Casuarina pauper occur on the western shores; stands of Eucalyptus camaldulensis occur along the Gawler River (SANPWS 1983; Paton et al. 1991).
Notable fauna:
Threatened species: White-bellied Sea-Eagle Haliaeetus leucogaster (Sv), Cape Barren Goose Cereopsis novaehollandiae (Sv), Freckled Duck Stictonetta naevosa (Sv), Musk Duck Biziura lobata (Sv), Little Egret Egretta garzetta (Sv), Eastern Curlew Numenius madagascariensis (Sv), Fairy Tern Sterna nereis (Sv), Slender-billed Thornbill Acanthiza iredalei rosinae (Sv), Australasian Shoveler Anas rhynchotis (Sr), Baillon's Crake Porzana pusilla (Sr) and Spotless Crake Porzana tabuensis (Sr). Composition: 65 waterbird species recorded; 16 listed under treaties. Resident treaty birds include the White-bellied Sea-Eagle, Great Egret Ardea alba, Glossy Ibis Plegadis falcinellus, and Caspian Tern Sterna caspia. The majority of species occur at Buckland Park Lake, and amongst these are 11 species that are rarely encountered in the Adelaide region, including the Blue-billed Duck Oxyura australis, Freckled Duck, Australasian Shoveler, Spotless Crake, Baillon's Crake, Buff-banded Rail Gallirallus philippensis, Long-toed Stint Calidris subminuta and Pectoral Sandpiper C. melanotos. Breeding: 21 species found breeding at Buckland Park Lake; 11 being waterfowl - Freckled Duck, Hardhead Aythya australis, Australasian Shoveler, Blue-billed Duck, Chestnut Teal Anas castanea and Australian Shelduck Tadorna tadornoides. At Port Gawler, there are well-established nesting colonies of Pied Cormorants Phalacrocorax varius. Migration stop-over: 12 species of migrant shorebird occur, including the Common Greenshank Tringa nebularia, Marsh Sandpiper T. stagnatilis, Wood Sandpiper T. glareola, Common Sandpiper Actitis hypoleucos, Black-tailed Godwit Limosa limosa, Curlew Sandpiper Calidris ferruginea and Pacific Golden Plover Pluvialis fulva. Numbers: During 1989-1991, 5200 Grey Teals Anas gracilis, 1100 Red-necked Stints Calidris ruficollis, 1000 Black Swans Cygnus atratus, 300 Sharp-tailed Sandpipers Calidris acuminata, 200 Pacific Black Ducks Anas superciliosa, 180 Chestnut Teals, and 100 Australian Shelducks were recorded at Buckland Park Lake (SANPWS 1983; Paton et al. 1991; Matthew 1994).
Other Fauna:
Fishes: 13 species of marine fish recorded at Port Gawler; six species of fish recorded from the freshwaters of the Gawler River and Buckland Park Lake. Amphibians: Four species of frog recorded at Buckland Park Lake, including the Brown Froglet Crinia signifera, juvenile Spotted Marsh Frog Limnodynastes tasmaniensis, Eastern Banjo Frog L. dumerilii and Painted Frog Neobatrachus pictus. Reptiles: A Eastern Long-necked Tortoise Chelodina longicollis carapace and disturbed nest site found at Buckland Park Lake (SANPWS 1983; Paton et al. 1991; Goonan 1993).
Social and Cultural values:
Land tenure:
Crown land - Port Gawler is a Conservation Park (434 ha), Buckland Park Lake is privately owned. Crown land with salt mining leases.
Current land use:
Nature conservation, recreation and stock grazing. Port Gawler and its surrounds are intensely used for recreation, particularly boating, fishing, crabbing and various off road vehicle sports.
Disturbance or threat:
Past/present: The Bolivar Sewage Treatment Works is located south of Port Gawler and discharges secondarily treated effluent and sludge, seepage of saline water into Buckland Park Lake from nearby salt evaporation ponds, displayment of the Lake's fringing wetland vegetation by an expanding Casuarina woodland and predation by foxes and cats.

Potential: Continual seepage of salt into the Lake.
Conservation measures taken:
Draft management plan for Port Gawler Conservation Park prepared in 1983. Port Gawler is listed on the Register of the National Estate.
Management authority and jurisdiction:
The park is managed by DENR. District office located at Salisbury. Penrice Soda Products Pty. Ltd. manage the salt fields and hold the salt mining leases.
References:
See SA Reference List
Compiler & date:
J. Morelli, S.A. Department of Environment and Natural Resources, 1995.
Drainage:  
AWRC Division: South Australian Gulf
AWRC Region:
AWRC Basin:
Catchment:
Sub-catchment: