|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.
|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.
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.
|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.
|A Quenda or Southern Brown Bandicoot (Isoodon obesulus) - one of the few native marsupials which still lives in Perth.|
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.
|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!
|'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:
- 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 email@example.com or on 9461 7160 for more information.