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| Wetlands are VITAL... in so many ways. |
Today's issue of the
West Australian's Ed! Magazine featured a double page spread I wrote on the importance of our unique, local wetlands here in Perth. The article tells a story, which begins like this...
Long ago in the dreaming, a giant serpent, the Wagyl, slithered across
the land, twisting across the surface on a magical journey. It moved over the
south-west of Western Australia, pushing up the ground to form mountains, and
carving great channels into the earth. These soon filled with water and created
the many rivers, lakes and swamps that the Noongar people, traditional
custodians of this ancient land of the south-west, became familiar with. As the
Noongar culture continues its 40 000 year journey and lives on in modern times,
the wetlands continue to hold special cultural significance for those people
strongly bonded to the earth.
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| Pacific Black Duck (Anas superciliosa), known as 'Yet' in Noongar, is still a very common waterbird seen that can be seen on many of Perth's wetlands. |
Unfortunately the European explorers, who in 1697 would paddle a longboat up the greatest of these
wetlands, Derbal Yerrigan (later dubbed the Swan River), and the subsequent
settlers who arrived in the early 1800s, did not value the Perth regions'
wetlands as strongly. Their attitude of controlling and conquering nature soon
lead to about 80% of wetlands on the Swan Coastal Plain being drained,
flattened and turned into rubbish tips. It is only in relatively recent decades
that our modern society has come to learn what the Noongar people had known all
along: wetland ecosystems are a vital source of life-giving water, provide
habitat for a diverse range of wildlife, and perform important environmental
jobs which cleanse the air and water. In this way they directly benefit all
living things which reside on this land today, including humans.
But what are wetlands? Which types of animals and plants call them home?
And what can we do to ensure those we have left are conserved for the future?
Come with me on a journey of discovery to find out!
What is a Wetland?
The term wetland is used to
describe any ecosystem which is covered with water at any time during the year.
Wetlands can be either freshwater, saltwater or a mix of both. Here we will
focus mostly on freshwater wetlands of the Perth region, which include lakes, swamps,
rivers and creeks.
The
Swan – Perth’s Iconic River
From the air, Derbal Yerrigan is
the most prominent wetland in Perth. It drains water from the Darling Range
(Perth Hills) and further inland west towards the ocean. A large rock bar once
permanently blocked the river mouth (where Fremantle is today), limiting
seawater from coming upstream and keeping this giant estuary fresh water. When
the Fremantle Harbour was constructed in the 1890s, the rock bar was blown up
and now much of the river is part saltwater. But the Swan River still supports
a huge range of wildlife, particularly waterbirds, including the Black Swan (‘marli’
or ‘koltjak’ in Noongar), which nests along the banks, and many ducks, terns
and cormorants. Below the surface, fish like Black Bream and Flathead are
common and a popular target for keen fishers. And if you are super lucky, you
might even observe some of the resident Bottlenose Dolphins which call our
river home. At Bull Creek, a tributary of the Swan River Estuary which flows
into the Canning River, freshwater crayfish known as Gilgies can still be
found. These have declined in parts of their range, sometimes because of
invasive ‘Yabbies’ (introduced from over east) which take over their habitat.
Flooded Gums and Swamp Sheoaks, so named because of their water-loving
habitats, represent the river’s original trees and today they provide shade at
grassy picnic sites along the riverbank.
Freshwater
Chains
Large chains of freshwater lakes
and swamps stretch parallel to the coast, both north and south of the Swan
River. The two main ones are the Perth Great Lakes and the Beeliar chain. They
have formed over thousands of years by water courses flowing west from the
hills, which are slow-moving and become obstructed by one of the three Coastal
Plain sand dune systems (Bassendean, Spearwood and Quindilup), so have had to
divert their courses north or south. Eventually the flow of water moves
underground, leaving a scattering of wet areas across the land’s surface,
distinguishable by their different vegetation. Some of the plants found here include:
- Modong/Moonah
(Paperbark, Melaleuca preissiana) –
large trees often growing in damp areas with underground freshwater. They
provide shade and habitat for many small birds and frogs.
- Yandjet
(Bulrush, Typha species) – tall
rushes that grow in dense clumps at the edge of larger lakes. Place names like
Yanchep and Yangebup are derived from the Noongar word for this plant.
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| Swamp Paperbark (Melaleuca rhaphiophylla) thrives in fresh water. |
Wetland chains have seen the
most impact with urban development of the Perth region, and most lakes and
swamps have been filled, drained and concreted. Two of the larger wetlands in
the once extensive chain north of the river (close to Perth’s city centre)
remain: Herdsman Lake and Lake Monger. Both sites provide important habitat for
rarer birds like the Crested Grebe and occasionally Freckled Ducks, and contain
high numbers of Oblong Turtles (Booyi in Noongar) which are nocturnal hunters
of small fish and a range of macro-invertebrates (small animals living in the
water). Swamp Harriers rear chicks on their flat, hidden nests among the
Bulrush thickets, at Herdsman.
The bigger lakes contain water
all year, but smaller swamps and creeks may only fill with water after rain.
Some species of frog (like the very camouflaged Squelching Froglet) need
sufficient winter rainfall to breed. Their activities are prompted by the first
rains, which set the waterways flowing and send the frogs into a very loud chorus,
an impressive sound considering they are only 2cm long! Digging into the moist
earth to feed on frogs, as well as other tasty treats like earthworms and
beetle larvae, is the Quenda or Southern Brown Bandicoot. This marsupial is one
of the few remaining native mammals clinging on near Perth, and dense
vegetation preserved in Regional Parks gives it suitable habitat.
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| A Quenda or Southern Brown Bandicoot (Isoodon obesulus) - one of the few native marsupials which still lives in Perth. |
Beautiful
Beeliar
The Beeliar chain, named after
the Noongar word for the area, is found south of Fremantle and includes Bibra,
Thomson’s and Forrestdale Lakes. Some of these sites are listed as Wetlands of
International Importance (known as RAMSAR wetlands) because they provide
important resources for migratory waterbirds.
- Birds
like the Red Knot (pictured below) travel thousands of kilometres from breeding
grounds in the northern hemisphere to fatten up on the rich food source of
worms found on muddy wetland edges.
- Large
colonies of White and Straw-necked Ibis build their nests in the lower
paperbark shrubs each spring. These breeding sites can have hundreds of chicks
and are a hive of activity!
All wetland chains were highly
important for Noongar people who used them for ceremonies, and relied on them
as sources of fresh water and places for hunting. Animals like waterfowl (ducks
and swans) were hunted in summer when many species move to coastal wetlands to
moult their flight feathers, making them easy to catch. Chains of wetlands were
also important as trade routes between different tribes moving up and down the
Swan Coastal Plain.
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| Red Knot (Calidris canutus) are migratory waders that travel from Australia to Siberia to breed. |
Keep
Wetlands Clean
Collecting litter is a regular
activity when I visit Perth’s wetlands. I feel it vitally important to take
away rubbish and help clean the environment, both for the creatures who live
there, and other people who want to enjoy it. On one walk south of Perth I
picked up an aluminium can which rattled. My curiosity had me cutting the can
open when I got home and finding inside, to my horror, the head of a Tiger
Snake! This poor creature’s scaly neck had got stuck in the can opening while
trying to get inside, leading to its death.
On another visit I collected
enough plastic bottles, cans, bike tyres and other plastic waste to fill my small
kayak. I even pulled in two illegally set Gilgie nets which are often known to
kill (by drowning) Oblong Turtles.
Nurturing our wetlands by
removing polluting items that affect their health has been a practice people of
the Perth region have felt important for thousands of years. You wouldn’t leave
a dead rat in your drink bottle, would you!? Removing litter items, or
reporting those people who illegally discard waste, is a great way to
contribute to a healthy wetland environment, and ultimately, a healthy you!
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| 'Booyi' is the Noongar word for the Oblong Turtle (Chelodina oblonga). |
How
can YOU experience wetlands?
Many of the large remaining
wetlands have been set aside as natural reserves for the protection of plants,
animals and water. These are places where fantastic trails and boardwalks often
allow you to meander among the shady paperbarks and experience the beauty of
our freshwater lakes and swamps, learning about them while doing so. A simple
walk on a sunny afternoon at Herdsman Lake, Yangebup or along the upper reaches
of the Canning River will almost certainly guarantee a sighting of a native
waterbird. Experiencing nature through wetland walks, runs or rides is good for
your fitness, and keeps your mind refreshed and healthy.
Hobbies that you might like to
adopt that can take you on a journey exploring the wetlands in Perth, and
beyond, include:
- Birdwatching
- Cycling
- Painting
or Drawing
- Nature
Walks
- Wildflower
Photography
- Canoeing
or Kayaking
Sometimes its nice to start with
a guided tour and fortunately there are some brilliant environmental education
centres to help you and your school. The Herdsman Lake Wildlife Centre runs
educational activities . More information can be found at http://www.wagouldleague.com.au/.
If you are south of the river, a
visit to the CREEC (Canning River Eco Education Centre) is a must! The entrance
is adorned with beautiful paintings, photos and videos of wetlands and
wildlife, examples of birds nests, and a ‘touch try’ where you can get up close
to some wetland show-and-tell. Contact CREEC at creec@canning.wa.gov.au or on 9461
7160 for more information.
