Australia Lesson Activities - Environmental Studies

THEME: Victoria River District
SUBJECT AREAS: Environmental Studies
TOPIC: Fish!

2001 October 1, East bank of the Victoria River, Kalkaringi.

bel: “there are lots of little fishies in there . . .”
josh: “where there’s fish the water can’t be too bad . . .”
jason: “but the fish are trying to jump out . . .”

Both chemically and physically, the naturally occurring watercourses of inland Australia are an extremely unstable part of the ecosystem. Only the most adaptable fish species are capable of survival in the unpredictable conditions. The fish we saw ‘trying to jump out’ of the water at Gordy Creek, (six kilometres from Kalkaringi on the road to the Western Australian border) were possibly using evaporation to cool themselves in the heat of the late morning.

This is just one of the many adaptations which fish species such as the Goby, Eel-tailed Catfish, Hardyhead, Grunter, and Rainbow Fish, may have developed to cope with the many variable factors which regularly influence the watery environments of Central Australia. The major variables are:

* Salinity: The amount of salt in the water.
For comparison, seawater contains, on average, 35 parts salt per thousand. Salinities of inland waters can range from fresh, at one part per thousand, to hyper-saline, at 350 parts per thousand. Salinity can vary over this range in just two to six months.

* Water Level: Partial or complete drying up of rivers and pools.
Due to the infrequent and erratic rainfall of the central deserts, the vast majority of standing water holes and rivers are dry for several months each year. Fish need to be able to reproduce in a very short and unpredictable season, and sometimes must survive in shallow and crowded water.

* Temperature: How hot the water is, and how fast it changes temperature.
Water temperature can vary between three degrees Celsius overnight in winter, to thirty-five degrees Celsius in the middle of a summer day. Fish use the layered temperatures in a pool, congregating in the cooler vegetated side-shallows, or lying buried in the sediments, which line the bottom.

* Oxygen Saturation: How much air there is in the water.
Dissolved oxygen ranges from stagnant, at 0 per cent, to super-saturation at 192 per cent. The percentage of oxygen in a single body of water can regularly fluctuate from fifteen to eighty in a single day.

* Inundation: Flooding of land, which is usually completely dry, and of mostly dry watercourses.
While flooding benefits many species of fish and other flora and fauna, it also means the greatest times of change in each of the variables listed here, most especially salinity.

* Pollution: The amount of human waste dumped in waterways.
Especially in mining areas and around the larger towns and communities, pollution exhausts reserves of dissolved oxygen, and dumped toxins poison fish.

But it seems to us that the greatest mystery is how they all came to be here. When rivers are dry for half a year or more, how do fish suddenly appear with the first rains? During flood, fish travel large distances over land between rivers. It is also speculated that birds, such as pelicans, distribute them, but the chances of a live fish being able to travel by this method are slim.

Another theory which seems a little fantastic, is that of fish being transported through the air during storms:
- In 1909, in Caloundra, Queensland, there was a report of small fish rattling on a tin roof during a storm.
- Hundreds of gudgeons were seen in 1920 in the streets of Gulargambone, New South Wales.
- Small fish were observed in ponds in Marble Bar in Western Australia after severe storms in 1942.
- In 1971, on the airstrip at Hughendan, Queensland, numerous grunters fell between three and six a.m.
Too absurd? Who knows? – Truth is stranger than fiction after all . . .

bel

Suggested learning activities:

Choose one of the * points above (Salinity, Water Level, Temperature, Oxygen Saturation, Inundation, or Pollution) and explore it further. Look for its affect upon water reserves, and upon fish.

Explore a waterway or lake near your home. How do the features of the water change over the course of a year? What fish inhabit the water system? How do humans utilise the water? Comment on the pollution level of the water. Find out how far its catchment area extends, and where the water flows to.

THEME: Gregory National Park
SUBJECT AREA: Environmental Studies
TOPIC: The Boab Tree

2001 October 4, Thursday. Gunbunbu Waterhole, Humbert River, Humbert Track, Gregory National Park.

Famed as Australia’s most grotesque tree, the Boab (Adansonia gregorii) is only found from the south-western Kimberley to the Northern Territory’s Victoria River. This is the area within Gregory National Park, which we are currently passing through. Augustus Gregory explored this area in the mid 1850s, and both the park and the tree are named in his honour. (see today’s history update)

The Boab grows on flood plains and in rocky areas. The one in our photograph is on the bank of the Humbert River. Its huge, grey swollen trunk topped by a mass of contorted branches make it a fascinating sight, particularly during the dry season when it loses its leaves and becomes “the tree that was planted upside-down”.

Although Boabs rarely grow higher than twenty metres, their trunks can be over twenty-five metres around. These giant bottle-like trunks store the moisture these trees need to survive in the hot tropical environment, and can be an emergency source of moisture to someone lost in the bush.

Suggested activities:
Using our photograph as a guide, draw a picture of a Boab tree, and compare it to a tree which grows near your home. Around your picture, write each difference you can think of, and also any similarities.

bel

THEME: Limestone Gorge
SUBJECT AREA: Environment
TOPIC: Flora of the Tropical Karst Landscape

2001 October 8, Monday. Timber Creek.

The beautiful Kapok Bush Cochlospermum fraseri is one of the rare deciduous plants of Australia. Deciduous is the antonym of Evergreen, and means that the tree loses its leaves each year. Most Australian trees are Evergreen. Its lack of leaves makes the Kapok an easy place for birds to land, and entices them with unobstructed views of the surrounding gorge. They will not, however, rest for long, as the rugged skeletal form offers no shelter from the fierce rays of the sun.

The Kapok is native to the Top End, and thrives amazingly well in the heat and humidity. Throughout the dry season, the dormant Kapok appears as a dry twig. As we have visited later than the usual tourist season, we have been lucky enough to see the bursts of large, bright yellow flowers which greet the first of the summer rains. Despite fragile appearances, these fantastic flowers are hardy enough to last on the tree for several weeks.

Beside its beauty, the Kapok is both ingenious and useful. The name Kapok derives from a closely related tree found in Africa, Asia, and Latin America. Mattresses, pillows, and soft toys have been made from the cotton wool– like fibre, which is harvested from the ripe seed-pods. This soft, light fibre surrounds each seed and is released with them as the pods open. This resourceful system allows both the wind and river currents to carry the gene pool over wide distances. Many animals eat Kapok seeds, and shelter amongst the lush wet season foliage.

Some of the other special plants we’ve seen in the Limestone Gorge area include the Plains Bloodwood Eucalyptus, which supports the handsome flights of parrots inhabiting the park, and whose wood is valued for its resistance to termite damage. The Bauhinia, has dainty rounded leaves which resemble butterflies as they turn yellow in patches; Nutwood trees are conspicuous as their bark contrasts like a checkerboard, and species of gnarled Hakea and gummy Spinifex keep company with the ubiquitous Boab.

Suggested learning activities:
Identify plants which have adapted to use the wind to spread their seed-stock. Many grasses have long, light wings to do this. Bright yellow Dandelion flowers develop a white pom pom which can be released with a puff of breath. What advantages do these plants have over others you can find?
Collect seeding plants, native and otherwise, from your local area, and see how many you can identify. If possible, find someone who knows about these shrubs and grasses (like a farmer) and ask him some questions. You;ll be surprised at what you can learn about the resourcefulness of seed spreading plants.

bel

THEME: Creepy Crawlies
SUBJECT: Environment
TOPIC: Termites

2001 October 11, Thursday. Innesvale Station.

While ecosystems and their inhabitants have come and gone, one feature of the landscape has been our constant companion since we left the beach at the Starcke eighty days ago. From big enough to climb upon for a 360 degree view, to dainty enough to be knocked over by a wayward cyclist (cheap imported rubbish, falling apart . . .); from the red of the Tanami, to the grey of the ranges; from lumpy and dumpy, to tall and fluted – they have been ever-present and infinitely fascinating.

In fact, the more we learn about termite mounds and their bite-size inhabitants, the more enraptured we become. More so perhaps than Verna Kruckow, our unimpeachable hostess back at Pinnacle Springs Station, who has to share her house with them. We haven’t yet tired of their presence, however, as they keep mostly to themselves, and we’re too busy dealing with blow flies. Here are some terrific facts you mightn’t know about the tincy little things which cover most of the Northern Territory:

*It is unusual for termites to be active in the daytime. This is because their soft bodies cannot prevent water loss enough to survive in the sun’s heat.

*Sometimes, geckos lay their eggs inside termite mounds.

*Golden-shouldered Parrots, Hooded Parrots and the extinct Paradise Parrot build their nests in the mounds, and feed on the seeds of native grasses.

*The fact that there are millions of termites has allowed lizards to become very abundant. More lizards eat termites than anything else.

*Soldier termites have armoured heads and large jaws ready to attack anything which threatens the colony.

*Tens of thousands, and sometimes millions of termites inhabit each nest. There are so many that of you weighed all of the termites in one area they would weigh more than all the kangaroos in the same area.

*All the members of a colony continually exchange food and saliva with one another. These substances have chemicals in them which communicate messages to the whole colony. Each termite colony has a distinctive odour.

*Somewhere in the termite nets is a queen ant, gigantic in comparison with the other termite workers who feed and tend to her needs.

*All of the three genera of ants are found in Australia.

*The Tanami Desert has eight hundred termite mounds per hectare.

*Termites collect water from the soil, tunnelling to depths of up to one hundred metres, to raise the humidity within the mounds. The galleries of most termite mounds have relative humidities of close to ninety-five per cent.

*The pregnant abdomen of the queen is swollen to many times the size of one of her attendants. She is the only mother amongst the thousands of termites and her sole job is to lay eggs, which she does continually.

*Termites eat cellulose – the hard part of plants, such as the trunks of trees and the hard spiky leaves of spinifex. Because hardly any other animal can eat this, termites have an abundant supply of food. They also eat animal dung.

*Ants are one of the most diverse genus of multi-celled organisms in the world, along with Acacia Trees, and Dung Beetles.

*There are often openings in the ground at the base of a spinifex clump. These are entrances to the termite nest, highways leading into an underground metropolis of ants, and are the reason termites are rarely seen around the mounds.

*Ants survive in Arid Australia at ground temperatures of over sixty-five degrees centigrade.

Suggested learning activities:
Try to find answers to as many of the following questions as you are able. Be creative – visit the school library, ask your teachers and parents, check the internet – you might even find some of the answers in this update . . .
How do termites differ from ants?
Who are the termites main predator?
How big can an ant grow?
How far does termite mound covered land extend in the Northern Territory and Queensland?
Where else in the world are termite mounds found?
What type of animal is a termite?
How many eggs can a queen ant lay and how long do they take to hatch?
What similarities does a termite colony have to a bee hive?
What adaptations have termites developed to cope with desiccation?
. . . and anything else you can think of.

THEME: Road Trains
SUBJECT: Environmental Studies
TOPIC: CROCS!

Of all the creatures team members were most concerned about when they first started this trip, saltwater crocodiles had to be the most talked about. “What do you do if you get taken by a croc” was one question I remember hearing more than a couple of times at our first day’s campsite on the Starcke River, a well known hangout for crocs. According to our Bush Bible ‘The Worst-Case Scenario Survival Handbook’ by Joshua Piven and David Borgenicht, the way to prevent an attack or to get a croc to release something (i.e. you) from its mouth is to “tap it on the snout”. Reassuring words? We think not!

This morning we were told by one of the contract musterers (they gather cattle together for stations on a contract basis) camped on the river beside the mangled wreckage of the road train that they’d seen a 14ft crocodile the previous evening just upstream of the accident site. “He’ll be attracted to the smell in the water of the dead cattle” he continued. “Give it another week and this whole area will be stiff with crocs I reckon”. This gave us little reassurance for crossing the river this morning with our bikes, expecting some giant monster to come lunging out of the deep at us any time. But putting our emotions aside for a minute, lets take a slightly closer look at the biology of crocodiles and what makes them one of the more extraordinary animals we’ve come across on the trip so far.

The Latin name for the salt-water variety is Crocodylus porosus. One big difference from their freshwater cousins (see yesterday’s general update) is the stubby snout and considerably stouter frame. Saltwater crocs can also grow up to 7m in length as opposed a maximum of around 3m for the ‘freshies’ and are quite capable of attacking and eating humans, whereas ‘freshies’ won’t unless seriously provoked.

Being a reptile, crocodiles are ‘cold-blooded’ relying upon the heat of the sun for their body warmth. This is why you can very often see them basking on riverbanks in the daytime. If they get too hot, they can slip into the water to cool off. They do not have any of the sophisticated body temperature regulation systems that mammals have for example (see suggested learning activities below). At this time of year many crocs are hibernating. Their main time for feeding and activity in general is during the wet season.

They have a keen sense of smell, as displayed by the 14ft one the musterer saw last night, and can be attracted from several miles downstream by a wounded animal. (The musterer also told us how when the centre of the town of Katherine was flooded last year, a 20ft croc was seen heading down the main street in the direction of the butcher’s shop!)

As well as rivers, like the Daly River on which the road train disaster happened, saltwater crocodiles inhabit coastal estuaries, swamps and may be seen swimming out to sea, but also dwell in billabongs (a large pool of water) and pools well inland, which they reach by river systems during periods of flood and also by limited overland excursions.

In the spring, females will lay 30-80 hard-shelled eggs in a nest created from soil, vegetation and debris located on a riverbank or side of a billabong. She will defend the nest aggressively until such time as the babies hatch, at which point she will carry the hatchlings to the water in her mouth, trying not to swallow any along the way of course!

As with snakes, crocodiles have a ‘bad rap’ with people due to the ferocious ‘monster’ image we have fixed in our psyche and which is reinforced in films and by the media in general. But statistically, one is far more likely to come foul of an automobile accident. In 1986, for example, 2, 873 Australians died in automobile related accidents. Four people died as a result of attacks by crocodiles during the 4-year period between 1982-86.

Suggested learning activities: find out more about the how reptiles, and crocodiles in particular, regulate their body heat. Compare and contrast their body cooling system to that of a warm-blooded animal, like humans for example. List the main differences. Find out more about a particular physiological feature of crocodiles that interest you most.

THEME: Pine Creek
SUBJECT AREA: Environment
TOPIC: Furphy’s

2001 October 15, Monday. North of Pine Creek.

You should have seen us the first time we saw natural running water after the Tanami Desert, near Kalkaringi. Hooting like fools we wallowed in the ankle-depth water, fully clothed, socked, and shoed; sliding on the slimy stone bed, frolicking like children.

Since that time, we have seen water more and more frequently, and almost expect to be camped beside some each evening – but not TOO close. Watercourses in the Top End are almost invariably hazardous to swimmers, and while camping reasonably close by for a one-nighter is considered to be safe, if one was to live alongside one, they could be assured of a visit, sooner or later, from an ever watching and waiting crocodile.

So as a pioneer, how could you avoid this natural environmental hazard? By storing your water away from its source. The Furphy brothers Farm Water Cart, manufactured and used in South Eastern Australia for filling troughs for livestock and watering gardens, was used throughout the country for various agricultural and domestic purposes. The typical example shown in our photograph was manufactured in Shepparton, Victoria, in 1942, and brought to Pine Creek perhaps via the Ghan train line.

The overland transportation of such large pieces of iron is yet another amazing colonial exploit, akin to that of the flywheel we saw at the historic Mount Molloy timber mill, Cape York, which had been cast in Illinois, USA, around the turn of the century. See today’s LITERACY update for details on the cast iron ends and their hidden message.

Suggested learning activities: Identify a natural hazard in your home area, either current or historical. How have people learned to live with it, or adapted to it? Identify places where the natural dangers are too great for humans to inhabit them. What makes these places dangerous? How could humans learn to cope with the dangers by using technology? Are the hazardous places functioning eco-systems without human habitation, or are they desertified places, uninhabitable because of pollution, or previous human misuse?

bel