Australian Ramsar Sites - Site 36
NAME:
Peel-Yalgorup System, Western Australia
DESIGNATED:
7 June 1990
GEOGRAPHICAL COORDINATES:
Latitude (approx) 320 32'S to 330 06'S
Longitude (approx) 1150 38'E to 1150 46'E
GENERAL LOCATION:
Mandurah, south-western Australia.
AREA:
Approximately 21,000
WETLAND TYPE:
Dominant:
- Marine and Coastal Wetland - 6
Inland Wetland - 7
Others:
ELEVATION:
OVERVIEW:
A large system of estuary and saline lakes. Up to 150 000 waterbirds
have been recorded in the estuary, and the saline lakes have an
interesting hydrology.
PHYSICAL FEATURES:
Peel Inlet and Harvey Estuary form a shallow estuarine system
connected to the sea via a narrow channel at the northern end
of the Inlet. The Murray and Serpentine Rivers drain into the
north-eastern corner of the Inlet; the Harvey River enters the
Estuary at its southern end. Several major drains from agricultural
land empty into the eastern side of the Estuary and Inlet.
A large proportion of the Peel Inlet and southern end of the Harvey
Estuary contains water less than 0.5 m deep; the maximum depth
of the water is only about 2 metres. Salinity varies according
to season and location in the system but, in general terms, varies
from 10 ppt in winter to 45 ppt TDS in summer. Tidal flushing
in summer is not great enough to prevent evaporation making the
water slightly more concentrated than seawater.
The Yalgorup lakes vary from about 1-4 metres in depth and are
saline (although they are principally supplied by fresh groundwater
and precipitation) because of long-term concentration of salt
by evaporation; they never overflow. The salinity regime in particular
lakes varies according to their hydrology. Lake Clifton has very
extensive areas of groundwater seepage, which result in pronounced
horizontal salinity gradients; away from the shoreline the water
varies from about 10 ppt in winter to 40 ppt TDS in summer. Large
quantities of calcium carbonate precipitate out of seepage water
as it enters Lake Clifton and Lake Pollard. Lake Hayward reaches
about 200 ppt TDS in summer but is remarkable for exhibiting vertical
stratification of salinity in winter when it is only about 2 metres
deep. Surface water contains about 70 ppt, that on the bottom
contains 180 ppt. This results in an inverse thermal stratification
with water at the bottom of the lake reaching 350 C and, because
of prolific growth of cyanophyta, being about 2 000% saturated
with oxygen.
Parts of Peel Inlet and Harvey Estuary and some of the lakes in
the Yalgorup chain are fringed by samphire flats. Behind the samphire,
or sometimes adjacent to the water where samphire is absent, rushes
and sedges occur. Outside this is a zone of trees tolerant of
water-logging while the higher ground away from the lake supports
open forest. Large parts of the shoreline throughout the Peel-Yalgorup
system have been cleared, usually for agriculture, thus altering
or eliminating the tree zones.
Samphire vegetation around Peel Inlet and Harvey Estuary is dominated
by Halosarcia Halocnemoides. The dominant species of sedge
is Bolboschoenus caldwellii, which grows both being samphire
and to the water's edge where low trees of Melaleuca rhaphiophylla
and M. hamulosa around the eastern side of the Inlet or
M. cuticularis and M. rhaphiophylla along
the Estuary. Melaleuca is sometimes replaced by Acacia
saligna and Eucalyptus rudis farther from the water.
As the ground begins to rise the vegetation changes to open forest
dominated by Eucalyptus gomphocephala and Agonis
flexuosa on the western side of the system or E. marginata
and E. calophylla on the eastern side.
The vegetation around the Yalgorup lake is virtually the same.
Around hypersaline lakes there is a narrow belt of samphire, behind
which clumps of Juncus kraussii and Gahnia trifida
occur. Hyposaline lakes lack samphire but have a dense belt of
Melaleuca cuticularis and M. rhapiophylla
in the cast of hyposaline lakes; samphire and rushes are replaced
by M. cuticularis and Acacia cyclops in the
case of hypoersaline ones. The surrounding woodland is dominated
by Eucalyptus gomphocephala and Agonis flexuosa.
ECOLOGICAL FEATURES:
In terms of total number, Peel Inlet and Harvey Estuary comprise
the most important area for waterbirds in south-western Australia:
over 150 000 were recorded in February 1977. It was conservatively
estimated that 12 000-15 000 ducks and swans used the area each
year between 1981-85; much higher usage occurred in 1976-77. Particularly
abundant species of duck are:
Black Swan Cygnus atratus 5 422 Aug 1976
Australian Shelduck Tadorna tadornoides 5 644 Dec 1984
Pacific Black Duck Anas superciliosus 3 000 Feb 1982
Grey Teal A. gibberifrons > 20 000 Dec 1976
Australasian Shoveler A. rhynchotis 500 Feb 1982
Blue-billed Duck Oxyura australis 1 200 Jul 1983
Highest numbers of many species in southwestern Australia have
been recorded in the Inlet and Estuary system, including the Little
Egret Egretta garzetta and Royal Spoonbill Platalea
regia, which are uncommon in the region. Species recorded
in large numbers include:
Hoary-headed Grebe Poliocephalus poliocephalus 1 000s Jun 1977
Australian Pelican Pelecanus conspicillatus 2 102 Dec 1976
Black-winged Stilt Himantopus himantopus 2 703 Nov 1977
Banded Stilt Cladorhynchus leucocephalus > 60000 Feb '77
Red-necked Avocet Recurvirostra novaehollandiae > l 100 Apr 1977
Red Knot Calidris canutus > 1 000 Oct 1976
Sharp-tailed Sandpiper C. acuminata 2 119 Jan 1983
Red-necked Stint C. ruficollis 8 063 Mar 1985
Curlew Sandpiper C. ferruginea 1 000s Dec 1976
A total of 67 species of waterbird has been recorded in Peel Inlet
and Harvey Estuary. Many species also occur in the Yalgorup lakes,
including large numbers of ducks, swans and waders. Over 2 200
Musk Duck (Biziura lobata) were counted in Lake Clifton
in March 1986 and 11 000 Australian Shelduck were recorded there
in November 1986.
Peel Inlet and Harvey Estuary contain large numbers of fish, Blue
Manna Crabs (Portunus pelagicus) and Greasy-back Prawns
(Metapeneas dalli). The area supports the biggest
professional and amateur estuarine fishery in Western Australia.
Lake Clifton is one of only two sites known in the world where
"stromatolite-like" structures occur in hyposaline water.
They are formed by calcium carbonate precipitating out of freshwater
seepage and being incorporated in the mucilage secreted by the
cyanophyta growing on the bottom of the lake. The hydrology of
the Yalgorup lakes is extremely interesting: several types of
salinity regime occur in lakes with similar physiognomy that are
supplied by the same underground aquifer.
LAND TENURE:
The wetlands area in Peel Inlet and Harvey Estuary extends to
high water mark and mostly falls within the Shire of Murray; the
southern tip of Harvey Estuary is in the Shire of Waroona. Various
State Governments agencies, including the Peel Inlet Management
Authority, Waterways Commission and Marine and Harbours Department,
have statutory powers in the waters of Peel Inlet and Harvey Estuary.
There is a series of small Nature Reserves at the southern end
of Harvey Estuary and Inlet (t2990, t23756, t24739, t2738, t2707,
t2436, t4990), some of which are included in the wetland area.
There is also an aquatic Nature Reserve (t28087) in the south-
eastern corner of the Inlet. Yunderup National Park is located
in the delta where the Murray River enters Peel Inlet.
Lake McLarty is a proposed Nature Reserve. Most of Lake Mealup
is either Nature Reserve or is owned by the Lake Mealup Preservation
Society. There areas are included in the proposed Wetland of International
Importance.
The Yalgorup lakes are contained in Yalgorup National Park but
in many cases only a very thin band of riparian land has been
included in the Park. All Nature Reserves in the wetlands area
and Yalgorup National Parks are vested in the National Parks and
Nature Conservation Authority of Western Australia; Yalgorup National
Park is vested in the Murray Shire. The reserves and Yalgorup
National Parks are managed by the Department of Conservation and
Land Management; Yunderup National Park is managed by the Murray
Shire.
CONSERVATION MEASURES TAKEN: There are a series of Nature
Reserves around Harvey Estuary and Peel Inlet (2990, 23756, 24739,
2738, 2707, 2436, 4990, 28087) and there is a National Park where
the Murray River enters Peel Inlet. Yalgorup lakes are all within
Yalgorup National Park. A management plan was prepared for Peel
Inlet and Harvey Estuary in 1982.
CONSERVATION MEASURES PROPOSED BUT NOT YET IMPLEMENTED:
There is a proposal to create another connection with the sea
(the 'Dawesville Cut') on the western side of Peel Inlet to improve
tidal flushing and reduce the build up nutrients (draining in
from the catchment) in the system.
CURRENT LAND USE:
Peel Inlet and Harvey Estuary are used extensively for public
recreation, especially fishing. The town of Mandurah is on the
northern edge of the Inlet and there are several small housing
developments along the shores of the Inlet and the north-western
part of the Estuary. The area to the east is used principally
for cattle farming and there are many farmlets and holiday homes
on the western side of the Estuary.
The Yalgorup lakes are in a National Park and are used only for
passive recreation associated with their natural values. However,
much of the surrounding land has been cleared for cattle farming
and an area on the north-eastern shore of Lake Clifton has recently
been sub-divided for housing.
DISTURBANCES/THREATS:
A major management problem exists in Peel Inlet and Harvey Estuary.
Large amounts of phosphate leached from surrounding agricultural
land into the estuarine system have caused it to become eutrophic
and there is massive production of benthic and planktonic algae,
which causes a variety of biological problems. There has been
intensive investigation into ways of managing the system and the
Peel Inlet Management Authority is implementing a management plan
produced in 1982. As far as waterbirds are concerned, any further
development around the deltas where rivers enter the Inlet and
Estuary should be carefully controlled. Similarly, urban development
around the Yalgorup lakes should be approached cautiously, especially
in the case of Lake Clifton where it may interfere with the groundwater
seepages producing the "stromatolites". Furthermore,
intensive human activity on the shore of Lake Clifton would result
in severe damage to these comparatively delicate structures.
HYDROLOGICAL AND PHYSICAL VALUES:
SOCIAL AND CULTURAL VALUES:
The major social values of Peel Inlet and Harvey Estuary are fishing,
both commercial and recreational, and other aquatic activities.
There is extensive residential development on the shores of the
Inlet and Estuary; there is also residential development on the
eastern shore of Lake Clifton. Farming occurs adjacent to Lakes
Clifton and Preston and parts of Peel Inlet and Harvey Estuary.
NOTEWORTHY FAUNA:
See ECOLOGICAL FEATURES.
NOTEWORTHY FLORA:
See ECOLOGICAL FEATURES.
CURRENT SCIENTIFIC RESEARCH AND FACILITIES:
Extensive research has been, and currently is being, conducted
by the Environmental Protection Authority and universities on
management of Peel Inlet and Harvey Estuary. Limited research
has been conducted on the lakes of the Yalgorup system, where
the University of Western Australia operates the Neville Stanley
Research Station.
CURRENT CONSERVATION EDUCATION:
An education program is being developed by Department of Conservation
and Land Management.
CURRENT RECREATION AND TOURISM: Peel Inlet and Harvey Estuary
are used extensively for recreational fishing and boating. There
is limited use of Yalgorup National Park for passive recreation.
MANAGEMENT AUTHORITY:
- Peel Inlet Management Authority
- Department of Conservation and Land Management,
PO Box 104,
Como WA 6152.
JURISDICTION:
Government of Western Australia
REFERENCES:
Backshall, D.J. and Bridgewater, P.B. (1981). Peripheral vegetation
of Peel Inlet and Harvey Estuary, Western Australia. Journal of
the Royal Society of Western Australia 63, 5-11.
Black, R.E. and Hodgkin, E.P. (1984). Management of Peel Inlet
and Harvey Estuary. Bulletin 170. Department of Conservation and
Environment, Perth.
Burke, C.M. and Knott, B. (1989). Limnology of four groundwater-fed
saline lakes in south-western Australia. Australian Journal of
Marine and Freshwater Research 40, 55-68.
Jaensch, R.P., Vervest, R.M. and Hewish, M.J. (1988). Waterbirds
in nature reserves of south-western Australia, 1981-1985: reserve
accounts. Royal Australasian Ornithologists Union Report 30, 1-290.
Moore, L.S. (1987). Water chemistry of the coastal saline lakes
of the Clifton-Preston Lakeland System, south-western Australia,
and its influence on stromatolite formation. Australian Journal
of Marine and Freshwater Research 38, 647- 660.
Moore, L., Knott, B. and Stnaley, N.F. (1984). The stromatolites
of Lake Clifton, Western Australia. Search 14, 309-314.
REASONS FOR INCLUSION:
1, 2(d), 3(a) and 3(c).
