Forrestdale Lake
Encyclopedia
Forrestdale Lake is a lake
nature reserve
in the City of Armadale
, Western Australia
, approximately 25 km south of the central business district
of Perth
, the state capital, and on the southern fringes of the Perth metropolitan area. It lies immediately south of the suburb of Forrestdale
, and 8 km south-east of Jandakot Airport
. It is a still largely natural wetland, with some adjoining native vegetation, surrounded by land developed for housing and agriculture, that regularly supports large numbers of shorebirds
and other waterbirds.
as an important site for tortoise hunting, with campsites occupied for long periods. It is associated with the Waugal
, a powerful and important water serpent in Noongar
mythology
that created rivers and lakes, and maintains the flow of waters to its resting places.
and poultry farming
. By 1898, the area around the lake had been set aside for a township with recommendations made for its subdivision. The Jandakot region started producing vegetables, apiary
products and dairy produce for the Fremantle markets.
From the 1920s agriculture gave way to sheep and cattle grazing, which continued through the next 50 years. During the 1940s the west side of the lake was heavily grazed by livestock, particularly during the drier summers when the lake’s fringing vegetation served as supplementary fodder. As a result, the land on the west side of the lake lacks native understorey plants and is infested with introduced plants such as arum lilies.
The lake was gazetted as an A-class Nature Reserve in 1957 for the protection of flora and fauna, as well as for recreation, particularly sailing
. The population in the Forrestdale area increased rapidly in the late 1960s as the townsite blocks to the north-west of the lake were taken up. Since then the population has gradually increased to about 1350.
Register of the National Estate
in March 1978. With the similar Thomsons Lake
10 km to the west, it forms the Forrestdale and Thomsons Lakes Ramsar Site
, designated under the Ramsar Convention
on 7 June 1990 and recognising it as a wetland of international importance. In 1998 the purpose of the reserve was changed to simply “Conservation of Flora and Fauna”. It is registered as Nature Reserve 24781, vested in the Conservation Commission of Western Australia and managed by the Department of Conservation and Land Management. It is mainly used for birdwatching, nature walks, horse riding
and general recreation by surrounding residents.
, and is a major breeding site, migration stop-over and semi-permanent drought refuge
area for waterbirds. It usually dries out by mid-summer. The area to the north-east is suburban with houses only 50 m from the lake. Land to the west has been developed for agriculture or housing to about 100 m from the shoreline. There is a large area of natural open woodland
on the eastern side.
grey-white siliceous
sand
s. It is a deflation basin bordered by low sand ridges up to five metres high. On the north-eastern edge of the lake there is a rocky sandstone
outcrop. The lake bed sediments are up to two metres thick and include clay
, silt
, peat
, diatomite, marl
and freshwater limestone
.
It also lies on the eastern margin of the Jandakot Mound
, a region of elevated water table beneath the Swan Coastal Plain, where the mound intersects the Perth Groundwater Area. Water levels in the lake were much higher in the 1970s and 80s, and have been declining steadily since 1992. Groundwater levels have also decreased since records began in 1996 and are about 1.5 to 2.5 m below the levels of the 1970s and 1980s. The lake is now drying out earlier than in previous wetter years.
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There is often a dense mat of Fennel Pondweed, stoneworts, and ditch grasses in the water of the lake. Surrounding the open water is an almost continuous belt of the introduced bulrush Typha orientalis, behind which various sedges, rushes and reeds grow. Beyond these is a belt of trees, mainly paperbarks
and Swamp Banksia
backed by Orange Wattle
and Flooded Gum
. The higher sandy ground on the eastern side supports open woodland dominated by Candlestick Banksia
. Some 351 vascular plant
s from 77 families
have been recorded from the nature reserve, of which 99 are introduced
weed
s. Twenty six species of algae have also been recorded.
More than 20,000 waterbirds have been recorded on Forrestdale Lake. It regularly supports more than 1% of the national population of five shorebirds
: Red-capped Plover
(with up to 1,300 recorded at any one time), Black-winged Stilt
(3,840), Red-necked Avocet
(1,113), Long-toed Stint
(up to 80), and Curlew Sandpiper
(2,000). In some years it supports more than 10,000 duck
s, including Australian Shelduck (up to 1,650 counted), Pacific Black Duck
(5,500), Grey Teal
(9,000), Australasian Shoveler
(2,000), and Hardhead
(1,053). The lake is one of the few sites in Western Australia where Little Ringed Plover
and Little Stint
have been recorded more than once, and it is the only location in the state where White-rumped Sandpiper
has been recorded.
As well as the uncommon skink
Lerista lineata, Forrestdale Lake supports six frog species and at least 62 aquatic invertebrate
taxa. The Long-necked Tortoise
is present. The critically endangered
Australian native bee
, Neopasiphae simplicior
, is thought to occur only as a single population within the bushland of the Forrestdale Lake Nature Reserve adjacent to the lake and the Armadale Golf Course.
s to control chironomids (non-biting midges) is a potential threat to aquatic invertebrate and bird life; in 1984 about 220 shorebirds were killed at the lake as a result of such spraying. Increased groundwater abstraction may exacerbate already declining water levels. The area of bulrushes
in the fringing vegetation has increased and threatens its ecological character by changing its floristics
, reducing the amount of open water, and reducing the area of mudflat
available to migratory
shorebirds. Disturbance of waterbirds by humans and dogs may occur, especially in late summer and autumn when the lake is drying out. Increasing urbanisation of the catchment may change the water balance or increase the already high nutrient level.
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
nature reserve
Nature reserve
A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...
in the City of Armadale
City of Armadale
The City of Armadale is a Local Government Area in the south-eastern suburbs of the Western Australian capital city of Perth, located about southeast of Perth's central business district...
, Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, approximately 25 km south of the central business district
Central business district
A central business district is the commercial and often geographic heart of a city. In North America this part of a city is commonly referred to as "downtown" or "city center"...
of Perth
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
, the state capital, and on the southern fringes of the Perth metropolitan area. It lies immediately south of the suburb of Forrestdale
Forrestdale, Western Australia
Forrestdale is a suburb of Perth, Western Australia, located within the City of Armadale.- Natural history :Forrestdale is home to Forrestdale Lake, a nature reserve important for waterbirds, many of which breed there. It usually fills in winter and dries out in summer...
, and 8 km south-east of Jandakot Airport
Jandakot Airport
Jandakot Airport is an Australian general aviation airport located in Jandakot, Western Australia. Jandakot airport opened in 1963. From 1 July 1998, Jandakot Airport Holdings purchased a 50-year lease with a 49-year option to operate and maintain the airport including its conservation...
. It is a still largely natural wetland, with some adjoining native vegetation, surrounded by land developed for housing and agriculture, that regularly supports large numbers of shorebirds
Wader
Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...
and other waterbirds.
Traditional usage
Before European settlement the lake was used by Abroriginal peopleIndigenous Australians
Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....
as an important site for tortoise hunting, with campsites occupied for long periods. It is associated with the Waugal
Wagyl
The Wagyl is, according to Noongar culture, a snakelike dreamtime creature responsible for the creation of the Swan and Canning Rivers and other waterways and landforms around present day Perth and the south-west of Western AustraliaA superior being, the Rainbow Serpent created the universe and...
, a powerful and important water serpent in Noongar
Noongar
The Noongar are an indigenous Australian people who live in the south-west corner of Western Australia from Geraldton on the west coast to Esperance on the south coast...
mythology
Mythology
The term mythology can refer either to the study of myths, or to a body or collection of myths. As examples, comparative mythology is the study of connections between myths from different cultures, whereas Greek mythology is the body of myths from ancient Greece...
that created rivers and lakes, and maintains the flow of waters to its resting places.
European settlement
The first non-Aboriginal settlement occurred in 1885, when William and Alfred Skeet were granted a ‘Special Occupation’ license for 100 acre (0.404686 km²) adjoining the lake, as well as licences to cut and sell timber. Farming around the lake began in 1893; much of the land was cleared, crops were trialled along with dairyDairy farming
Dairy farming is a class of agricultural, or an animal husbandry, enterprise, for long-term production of milk, usually from dairy cows but also from goats and sheep, which may be either processed on-site or transported to a dairy factory for processing and eventual retail sale.Most dairy farms...
and poultry farming
Poultry farming
Poultry farming is the raising of domesticated birds such as chickens, turkeys, ducks, and geese, for the purpose of farming meat or eggs for food. According to the Worldwatch Institute, 74 percent of the world's poultry meat, and 68 percent of eggs are produced in ways that are described as...
. By 1898, the area around the lake had been set aside for a township with recommendations made for its subdivision. The Jandakot region started producing vegetables, apiary
Apiary
An apiary is a place where beehives of honey bees are kept. Traditionally beekeepers paid land rent in honey for the use of small parcels. Some farmers will provide free apiary sites, because they need pollination, and farmers who need many hives often pay for them to be moved to the crops when...
products and dairy produce for the Fremantle markets.
From the 1920s agriculture gave way to sheep and cattle grazing, which continued through the next 50 years. During the 1940s the west side of the lake was heavily grazed by livestock, particularly during the drier summers when the lake’s fringing vegetation served as supplementary fodder. As a result, the land on the west side of the lake lacks native understorey plants and is infested with introduced plants such as arum lilies.
The lake was gazetted as an A-class Nature Reserve in 1957 for the protection of flora and fauna, as well as for recreation, particularly sailing
Boating
Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether powerboats, sailboats, or man-powered vessels , focused on the travel itself, as well as sports activities, such as fishing or water skiing...
. The population in the Forrestdale area increased rapidly in the late 1960s as the townsite blocks to the north-west of the lake were taken up. Since then the population has gradually increased to about 1350.
Protection
Originally Lake Jandakot, it was renamed Forrestdale in 1973. It was listed on the CommonwealthGovernment of Australia
The Commonwealth of Australia is a federal constitutional monarchy under a parliamentary democracy. The Commonwealth of Australia was formed in 1901 as a result of an agreement among six self-governing British colonies, which became the six states...
Register of the National Estate
Register of the National Estate
The Register of the National Estate is a listing of natural and cultural heritage places in Australia. The listing was initially compiled between 1976 and 2003 by the Australian Heritage Commission. The register is now maintained by the Australian Heritage Council...
in March 1978. With the similar Thomsons Lake
Thomsons Lake
Thomsons Lake is a lake nature reserve in the City of Cockburn, Western Australia, approximately 25 km south of the central business district of Perth, the state capital, and on the southern fringes of the Perth metropolitan area. It in the suburb of Beeliar, 7 km south-west of Jandakot Airport...
10 km to the west, it forms the Forrestdale and Thomsons Lakes Ramsar Site
Forrestdale and Thomsons Lakes Ramsar Site
The Forrestdale and Thomsons Lakes Ramsar Site comprises two separate nature reserves, totaling 754 ha in area, protecting two shallow fresh to brackish, seasonal lakes in a suburban and agricultural landscape in south-western Western Australia. It is used mainly for birdwatching and walking. It...
, designated under the Ramsar Convention
Ramsar Convention
The Ramsar Convention is an international treaty for the conservation and sustainable utilization of wetlands, i.e., to stem the progressive encroachment on and loss of wetlands now and in the future, recognizing the fundamental ecological functions of wetlands and their economic, cultural,...
on 7 June 1990 and recognising it as a wetland of international importance. In 1998 the purpose of the reserve was changed to simply “Conservation of Flora and Fauna”. It is registered as Nature Reserve 24781, vested in the Conservation Commission of Western Australia and managed by the Department of Conservation and Land Management. It is mainly used for birdwatching, nature walks, horse riding
Pleasure riding
Pleasure riding is a form of equestrianism that encompasses many forms of recreational riding for personal enjoyment, absent elements of competition. Pleasure riding is called "hacking" in British English, and in parts of the eastern United States and Canada...
and general recreation by surrounding residents.
Description
Forrestdale Lake is a shallow, brackish, seasonal lake with a large area 220 hectares (543.6 acre) of open water when full. It has extensive fringing sedgeland typical of the Swan Coastal PlainSwan Coastal Plain
The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geological and biological zone, one of Western Australia's...
, and is a major breeding site, migration stop-over and semi-permanent drought refuge
Drought refuge
A drought refuge is a site that provides permanent fresh water or moist conditions for plants and animals, acting as a refuge habitat when surrounding areas are affected by drought and allowing ecosystems and core species populations to survive until the drought breaks...
area for waterbirds. It usually dries out by mid-summer. The area to the north-east is suburban with houses only 50 m from the lake. Land to the west has been developed for agriculture or housing to about 100 m from the shoreline. There is a large area of natural open woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...
on the eastern side.
Geology and hydrology
The lake lies on the eastern edge of the gently undulating Bassendean Dune System, which is formed mainly of leachedLeaching (pedology)
In pedology, leaching is the loss of mineral and organic solutes due to percolation. It is a mechanism of soil formation. It is distinct from the soil forming process of eluviation, which is the loss of mineral and organic colloids. Leached and elluviated materials tend to be lost from topsoil and...
grey-white siliceous
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...
sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
s. It is a deflation basin bordered by low sand ridges up to five metres high. On the north-eastern edge of the lake there is a rocky sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
outcrop. The lake bed sediments are up to two metres thick and include clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
, silt
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...
, peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...
, diatomite, marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
and freshwater limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
.
It also lies on the eastern margin of the Jandakot Mound
Jandakot Mound
The Jandakot Mound, or Jandakot Groundwater Mound, is an unconfined aquifer in south-western Western Australia. It is the smaller of the two main shallow aquifers near Perth that together supply about 40% of Perth's drinking water. Its highest point lies about 18 km south of Perth’s central...
, a region of elevated water table beneath the Swan Coastal Plain, where the mound intersects the Perth Groundwater Area. Water levels in the lake were much higher in the 1970s and 80s, and have been declining steadily since 1992. Groundwater levels have also decreased since records began in 1996 and are about 1.5 to 2.5 m below the levels of the 1970s and 1980s. The lake is now drying out earlier than in previous wetter years.
Flora and fauna
Melaleuca
Melaleuca is a genus of plants in the myrtle family Myrtaceae known for its natural soothing and cleansing properties. There are well over 200 recognised species, most of which are endemic to Australia...
and Swamp Banksia
Banksia littoralis
Banksia littoralis, commonly known as the Swamp Banksia, Swamp Oak, Pungura and the Western Swamp Banksia, is a tree in the plant genus Banksia. It is found in south west Western Australia from the south eastern metropolitan area of Perth to the Stirling Range and Albany...
backed by Orange Wattle
Acacia saligna
Acacia saligna, commonly known by various names including coojong, golden wreath wattle, orange wattle, blue-leafed wattle, Western Australian golden wattle, and, in Africa, Port Jackson willow, is a small tree in the family Fabaceae...
and Flooded Gum
Eucalyptus rudis
Eucalyptus rudis, Flooded gum, is a medium sized tree with rough, dark and light grey bark, however north of Perth its bark is smooth and very similar to Eucalyptus camaldulensis. Leaves are stalked, alternate, ovate to orbicular 12 x 7 cm, slightly discolourous and dull grey-green...
. The higher sandy ground on the eastern side supports open woodland dominated by Candlestick Banksia
Banksia attenuata
Banksia attenuata, commonly known as the candlestick banksia or slender banksia, is a species of plant in the proteaceae family. Commonly a tree, it reaches 10 m high, but is often a shrub in dryer areas 0.4 to 2 m high...
. Some 351 vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...
s from 77 families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
have been recorded from the nature reserve, of which 99 are introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
s. Twenty six species of algae have also been recorded.
More than 20,000 waterbirds have been recorded on Forrestdale Lake. It regularly supports more than 1% of the national population of five shorebirds
Wader
Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...
: Red-capped Plover
Red-capped Plover
The Red-capped Plover , also known as the Red-capped Dotterel, is a small plover. It breeds in Australia. The species is closely related to the Kentish Plover, Javan Plover and White-fronted Plover.-Description:Red-capped Plovers have white underparts and forehead...
(with up to 1,300 recorded at any one time), Black-winged Stilt
Black-winged Stilt
The Black-winged Stilt or Common Stilt is a widely distributed very long-legged wader in the avocet and stilt family . Opinions differ as to whether the birds treated under the scientific name H. himantopus ought to be treated as a single species and if not, how many species to recognize...
(3,840), Red-necked Avocet
Red-necked Avocet
The Red-necked Avocet is a water bird found throughout Australia, except for the northern parts of the Northern Territory....
(1,113), Long-toed Stint
Long-toed Stint
The Long-toed Stint, Calidris or Erolia subminuta, is a small wader bird. It breeds across northern Asia and is strongly migratory, wintering in south and south east Asia and Australasia...
(up to 80), and Curlew Sandpiper
Curlew Sandpiper
The Curlew Sandpiper is a small wader that breeds on the tundra of Arctic Siberia. It is strongly migratory, wintering mainly in Africa, but also in south and southeast Asia and in Australasia...
(2,000). In some years it supports more than 10,000 duck
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
s, including Australian Shelduck (up to 1,650 counted), Pacific Black Duck
Pacific Black Duck
The Pacific Black Duck is a dabbling duck found in much of Indonesia, New Guinea, Australia, New Zealand, and many islands in the southwestern Pacific, reaching to the Caroline Islands in the north and French Polynesia in the east. It is usually called the Grey Duck in New Zealand...
(5,500), Grey Teal
Grey Teal
The Grey Teal, Anas gracilis is a dabbling duck found in open wetlands in New Guinea, Australia, New Zealand, Vanuatu and Solomon Islands....
(9,000), Australasian Shoveler
Australasian Shoveler
The Australasian Shoveler is a species of dabbling duck in the genus Anas. It ranges from 46–53 cm. It lives in heavily vegetated swamps. In Australia it is protected under the National Parks and Wildlife Act, 1974...
(2,000), and Hardhead
Hardhead
The Hardhead, Aythya australis, is the only true diving duck found in Australia. Hardheads are common in the south-east of Australia, particularly in the Murray-Darling Basin, but also in the wetter country near the coasts. They are moderately nomadic in normal years, but disperse widely in times...
(1,053). The lake is one of the few sites in Western Australia where Little Ringed Plover
Little Ringed Plover
The Little Ringed Plover is a small plover. Adults have a grey-brown back and wings, a white belly, and a white breast with one black neckband. They have a brown cap, a white forehead, a black mask around the eyes with white above and a short dark bill...
and Little Stint
Little Stint
The Little Stint, Calidris minuta , is a very small wader. It breeds in arctic Europe and Asia, and is a long-distance migrant, wintering south to Africa and south Asia...
have been recorded more than once, and it is the only location in the state where White-rumped Sandpiper
White-rumped Sandpiper
The White-rumped Sandpiper is a small shorebird.Adults have black legs and a small thin dark bill. The body is dark brown on top and mainly white underneath, with brown streaks on the breast and a white rump. They have a white stripe over their eyes. This bird shows long wings in flight. In winter...
has been recorded.
As well as the uncommon skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...
Lerista lineata, Forrestdale Lake supports six frog species and at least 62 aquatic invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
taxa. The Long-necked Tortoise
Narrow-breasted Snake-necked Turtle
The narrow-breasted snake-necked turtle or long necked tortoise is a species of turtle in the Chelidae family.It is endemic to the southwestern part of Western Australia....
is present. The critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
Australian native bee
Australian native bees
Australia has over 1,500 species of native bee. Bees can be distinguished from flies in that bees have four wings, where flies have only two. Bees collect pollen, from flowers, to feed their young...
, Neopasiphae simplicior
Neopasiphae simplicior
Neopasiphae simplicior, a native bee, is an endangered species found near Perth, Western Australia. Body is creamy yellow and brown, 7 mm long and wings up to 5 mm long. The Swan Coastal Plain has undergone agricultural and suburban development which has reduced the range and threatens...
, is thought to occur only as a single population within the bushland of the Forrestdale Lake Nature Reserve adjacent to the lake and the Armadale Golf Course.
Threats
The use of pesticidePesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s to control chironomids (non-biting midges) is a potential threat to aquatic invertebrate and bird life; in 1984 about 220 shorebirds were killed at the lake as a result of such spraying. Increased groundwater abstraction may exacerbate already declining water levels. The area of bulrushes
Typha
Typha is a genus of about eleven species of monocotyledonous flowering plants in the family Typhaceae. The genus has a largely Northern Hemisphere distribution, but is essentially cosmopolitan, being found in a variety of wetland habitats...
in the fringing vegetation has increased and threatens its ecological character by changing its floristics
Floristics
Floristics is a subdomain of botany and biogeography that studies distribution and relationships of plant species over geographic areas.The term is not to be confused with floristry....
, reducing the amount of open water, and reducing the area of mudflat
Mudflat
Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of...
available to migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
shorebirds. Disturbance of waterbirds by humans and dogs may occur, especially in late summer and autumn when the lake is drying out. Increasing urbanisation of the catchment may change the water balance or increase the already high nutrient level.