Community Description & Details

• Freshwater Wetlands on Coastal Floodplains of the NSW North Coast, Sydney Basin and South-east Bioregions is an Endangered Ecological Community associated with periodic or semi-permanent inundation by freshwater. These wetlands are often associated with ephemeral or semi-permanent standing water.¹
• The structure of the community may vary from sedgelands and reedlands to herbfields. Woody species of plants (e.g. large shrubs and trees) are generally scarce.¹
• This community typically occurs on silts, muds or humic loams in depressions, flats, drainage lines, backswamps, lagoons and lakes associated with coastal floodplains.¹
• The plant composition of these communities is primarily determined by the frequency, duration and depth of waterlogging and may also be influenced by the level of nutrients and salinity in the water and substrate.¹
• Commonly occurring plants within this community include; Paspalum distichum (Water Couch), Pseudoraphis spinescens (Mud Grass), Carex appressa (Tussock Sedge), Baumea articulata, Lepironia articulata, Philydrum lanuginosum (Woolly Frogsmouth), Ludwigia peploides subsp. montevidensis (Water Primrose), Myriophyllum spp. (Milfoils), Azolla filiculoides var. rubra, Lemna spp. (Duckweeds), Nymphaea gigantea (Giant Waterlily), Nymphoides indica (Water Snowflake), Ottelia ovalifolia (Swamp Lily) and Potamogeton spp. (Pondweeds).¹
• The composition and structure of the vegetation is also influenced by grazing history, changes to hydrology and soil salinity, catchment runoff, disturbance, and weed invasion.¹

Habitat Requirements

Landform: River flats, terraces and coastal flood plains.¹

Distribution: This community occurs throughout coastal areas of NSW.¹

Elevation: Generally occurs below 20m elevation.¹

Soil: The soils where this community occurs are usually silts, muds or humic loams in depressions, flats, drainage lines, backswamps, lagoons and lakes associated with coastal floodplains. Locally this community is most commonly found on alluvial soils associated with the Wyong, Yarramalong, Oxford Falls and Hawkesbury River Soil Landscapes.²

Hydrology: Generally associated with periodic or semi-permanent inundation by freshwater, although there may be minor saline influence in some wetlands.

Where this community can be found

Gosford: Ettalong Creek near Umina, Near Lisarow Railway Station and Iluka Lagoon at Umina.

Wyong: To the west of Ourimbah picnic area on the F3 Freeway, Tuggerah Wetland.

Lake Macquarie: Jewells Swamp and South-east of Belmont Park.

Where this Community is Protected

Small areas of freshwater wetlands are contained within local conservation reserves, including Awabakal Nature Reserve near Belmont, and Munmorah State Recreation Area.

Threats to Survival

• Alteration to natural hydrological regimes.
• Vegetation clearing.
• Fragmentation.
• Land filling and earthworks associated with development.
• Flood mitigation and drainage works.
• Pollution from urban and agricultural runoff.
• Weed invasion.
• Overgrazing and soil disturbances by livestock.
• Activation/exposure of acid sulphate soils.
• Altered fire regimes.
• Predation of native wetland fauna, particularly by mosquito fish and cane toads.
• Rubbish dumping.

Freshwater Wetlands on Coastal Floodplains has been identified as being affected by the following Key Threatening Processes:

• Clearing of native vegetation.
• Invasion of native plant communities by exotic perennial grasses.
• Alteration to the natural flow regimes of rivers, streams, floodplains and wetlands.

Management Issues

• Decreasing water flows may result in the expansion of some drier communities at the expense of freshwater wetlands. This may also affect local animal populations.
• Disturbance and activation of acid sulphate soils may result in changes to the extent and composition of this community.
• Coordinating planning and management practices across whole catchments is required to conserve, manage and improve freshwater wetlands.
• Urban expansion may result in the increase of human impacts such as clearing, altered hydrological regimes, rubbish dumping, urban pollution and fires.

Useful Web links:

• Department of Environment and Climate Change - www.dec.nsw.gov.au

Further Reading:

• Bell, S.A.J. (2002) The Natural Vegetation of the Wyong Local Government Area, Central Coast, New South Wales.      Vegetation Community Profiles. Final Report to Wyong Shire Council.
• Bell, S.A.J. (2004) The natural vegetation of the Gosford Local Government Area, Central Coast, New South Wales:    Vegetation Community Profiles. Final Report to Gosford City Council.
• Keith, D. (2004) Ocean Shores to Desert Dunes: The Native Vegetation of New South Wales and ACT. Dept of Environment and Conservation (NSW).
• National Parks and Wildlife Service (2003), Lower Hunter and Central Coast Regional Environment Management
  Strategy Vegetation Survey, Classification and Mapping: Lower Hunter and Central Coast Region. CRA Unit, National Parks and Wildlife Service, Hurstville.

Bibliography:

1. NSW Scientific Committee (December 2004) – Final determination to list Freshwater Wetlands on Coastal Floodplains of the NSW North Coast, Sydney Basin and South East Corner bioregions as an Endangered Ecological Community.
2. C.L. Murphy Ed. (1993) Soil Landscapes of the Gosford/Lake Macquarie 1:100,000 sheet, Soil Conservation Service of NSW.