n.t. waterwatch

N.T. WATERWATCHEDUCATION KIT

Part 3

Aquatic Ecosystems

and Habitats

NT WATERWATCHEDUCATION KIT

PART 3:AQUATIC ECOSYSTEMS AND

HABITATS

NT Waterwatch Education Kit - Part 3: Aquatic Ecosystems and Habitats

ii

NT Waterwatch Education Kit. Part 3: Aquatic Ecosystems and Aquatic Habitats. Edited by SueBellette and Geraldine Lee.

Published by Department of Infrastructure, Planning and Environment (DIPE)PO Box 30Palmerston NT 0831Tel: 08 8999 4456Fax: 08 8999 4445Website: www.lpe.nt.gov.au/waterwatch

Northern Territory Government

All rights reserved. No part of this publication may be reproduced, stored in any retrieval system ortransmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwisefor commercial purposes without the prior written permission of the publisher.

The information in this publication has been published by DIPE to assist public knowledge anddiscussion and to help improve the sustainable management of water.

Publication dataBellette, S., and Lee, G. (eds) 2003, NT Waterwatch Education Kit. Part 3: Aquatic Ecosystems andAquatic Habitats, Department of Infrastructure, Planning and Environment, Darwin.

ISBN 1 920772 09 X (set of 7 vols)ISBN 1920772 03 0 (Vol. 4)

Cover by Geraldine Lee

Funding provided by The Natural Heritage Trust and Department of Infrastructure, Planning andEnvironment.


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TABLE OF CONTENTSPART 3: AQUATIC ECOSYSTEMS AND HABITATS___________________________________1

INTRODUCTION 1RATIONALE 1

ABORIGINAL CULTURE__________________________________________________________2

WHAT IS A WETLAND? __________________________________________________________3WHAT IS AN ECOSYSTEM? 3WHAT IS AN AQUATIC HABITAT? 3

AQUATIC ECOSYSTEMS OF THE NT _______________________________________________4

Billabongs and Floodplains 4Creeks and Streams 6Springs 7Sinkholes 8Paperbark Swamps 9Estuaries and Coastal Lagoons 10Salt water crocodiles 11Rivers 12Flood-outs 14Claypans and Saltpans 14

AQUATIC HABITATS____________________________________________________________15PLANTS 15RIPARIAN VEGETATION 16

Bank Vegetation 16Aquatic Vegetation 16

HABITAT TYPES _______________________________________________________________18RIVER BANKS 18WHY IS RIPARIAN VEGETATION IMPORTANT? 19

Food and shelter 19Woody debris 19Shading 20Bank Stabilisation 20Water quality 20

ANIMALS 22

MACROINVERTEBRATE ECOLOGY ______________________________________________22THE AQUATIC FOOD CHAIN 23METAMORPHOSIS 23MACRO-INVERTEBRATES HABITATS 24

Riffles 24Runs 24Pools 24

MACROINVERTEBRATE ADAPTATIONS 25Adaptations for life in fast-moving water 25Adaptations for life in slow-moving or still water 25


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LIST OF FIGURESFIGURE 1 TYPES OF AQUATIC PLANTS .............................................................................................................. 16FIGURE 2 PLAIN VIEW/CROSS SECTION OF A POOL, RIFFLE AND RUN. ............................................................... 18FIGURE 3 STREAM BANK SHAPES . .................................................................................................................... 18FIGURE 4 THE RIPARIAN ENVIRONMENT........................................................................................................... 19FIGURE 5 COMPARISON OF VEGETATED AND UNVEGETATED RIVER BANK........................................................ 20FIGURE 6 EFFECT OF RIPARIAN VEGETATION ON RUNOFF AND WATER QUALITY. ............................................. 21FIGURE 7 DRAGONFLY LARVAE........................................................................................................................ 22FIGURE 8 FEEDING RELATIONSHIPS OF MACRO-INVERTEBRATES...................................................................... 23FIGURE 9 CADDIS FLY LARVAE......................................................................................................................... 23FIGURE 10 RIVER HABITATS............................................................................................................................... 41

LIST OF PLATESPLATE 1 SUNSET UPPER KATHERINE RIVER ..................................................................................................... 1PLATE 2 KATHERINE GORGE ............................................................................................................................ 3PLATE 3 Nelumbo LILIES .................................................................................................................................. 4PLATE 4 SATELLITE IMAGE OF MARY RIVER FLOODPLAINS ............................................................................. 4PLATE 5 MAGPIE GOOSE (Anseranas semipalmata) ......................................................................................... 5PLATE 6 LOTUS LILY (Nelumbo nucifera)......................................................................................................... 5PLATE 7 RAPID CREEK...................................................................................................................................... 6PLATE 8 ARCHERFISH (Toxotes chatareus)....................................................................................................... 6PLATE 9 RIVER PANDANUS (Pandanus aquaticus), BERRY CREEK................................................................... 6PLATE 10 BERRY SPRINGS.................................................................................................................................. 7PLATE 11 MATARANKA SPRINGS........................................................................................................................ 7PLATE 12 DAMSELFLY ADULTS (MATING) .......................................................................................................... 7PLATE 13 SINKHOLE, KATHERINE ...................................................................................................................... 8PLATE 14 LIMESTONE CAVE, KATHERINE .......................................................................................................... 8PLATE 15 GREEN TREE FROG (Littoria carulea)................................................................................................. 8PLATE 16 GIRRAWEEN LAGOON (CLOSE UP OF ‘PAPER’ BARK)........................................................................... 9PLATE 17 SCREW PALM (Pandanus spiralis) FRUIT AND TREE ........................................................................... 9PLATE 18 AMAKWULA RIVER........................................................................................................................... 10PLATE 19 MANGROVE APPLE (Sonneratia alba) .............................................................................................. 10PLATE 20 STILT ROOTED MANGROVE (Rhizophora stylosa) ............................................................................ 10PLATE 21 CROCODILES ON THE MARY RIVER FLOODPLAINS (NOTICE THE FISHING LURE). .............................. 11PLATE 22 FLORA RIVER, KATHERINE............................................................................................................... 12PLATE 23 KING RIVER ...................................................................................................................................... 12PLATE 24 GOYDER RIVER................................................................................................................................. 12PLATE 25 TODD RIVER, ALICE SPRINGS ........................................................................................................... 13PLATE 26 WATER HOLDING FROG (Cyclorana platycephalus).......................................................................... 13PLATE 27 AERIAL PHOTOGRAPH OF A FLOOD-OUT, ANDADO STATION, NT. .................................................... 14PLATE 28 CLAY-PAN (DRY), CENTRAL AUSTRALIA.......................................................................................... 14PLATE 29 AERIAL PHOTOGRAPH OF A SALT PAN IN CENTRAL AUSTRALIA ....................................................... 14PLATE 30 MANGROVE APPLE (Sonneratia alba) FLOWERS............................................................................... 15PLATE 31 PANDANUS (Pandanus aquaticus) AT BERRY SPRINGS .................................................................... 15PLATE 32 Eriocaulon setaceum........................................................................................................................ 17PLATE 33 Nymphaea violacea .......................................................................................................................... 17PLATE 34 MELALEUCA (PAPERBARK) TREES AT GIRRAWEEN LAGOON ............................................................ 17PLATE 35 KATYDID .......................................................................................................................................... 22

LIST OF TABLESTABLE 1 COMPARISON BETWEEN COMPLETE AND INCOMPLETE METAMORPHOSIS. ......................................... 24TABLE 2 FRESHWATER MACRO-INVERTEBRATE HABITATS.............................................................................. 25TABLE 3 ESTUARINE MACRO-INVERTEBRATE HABITATS ................................................................................. 26


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ACTIVITIES1. LOCAL SURFACE WATER INVESTIGATION (B1-B5) _____________________________27

2. LIFECYCLE OF THE BARRAMUNDI (B3-B5) ____________________________________28

3. FISH KILLS (B3-B5) __________________________________________________________30

4. KATHERINE REGION SINKHOLES (B3-B5) _____________________________________31

5. CROCODILE ECOLOGY (B3-B5) _______________________________________________34

6. AQUATIC ADAPTATIONS TO ARID ECOSYSTEMS? (B3-B5) ______________________35

7. PLANT RECOGNITION TRAIL (B3-B5)__________________________________________36

8. RIPARIAN VEGETATION STUDY (B1-B3)_______________________________________37

9. AQUATIC PLANTS (B1-B3) ___________________________________________________38

10. FIELD EXCURSION TO IDENTIFY LOCAL HABITATS (B1-B3)_____________________39

11. THE FRESH WATER AQUARIUM (B1-B3) _______________________________________42

12. SURVIVING IN EPHEMERAL AQUATIC HABITATS (B3-B5)_______________________43

13. LIFE IN OUR WATERWAYS (B3-B5) ___________________________________________47

14. ADAPTATIONS FOR SEASONAL CHANGES (B3) ________________________________49

15. ADAPTATIONS OF MACROINVERTEBRATES (B3) ______________________________50

16. TAKE HOME MESSAGES (B1-B3) ______________________________________________51

STUDENT SHEETS3.1 BARRAMUNDI ______________________________________________________________293.2 SINKHOLES _________________________________________________________________323.3 STREAM HABITAT TERMS ___________________________________________________403.4 WHAT AM I? ________________________________________________________________48


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PART 3: Aquatic Ecosystems and Habitats

IntroductionThe diverse aquatic ecosystems of the NT range from the clay pans, rock holes and ephemeralrivers of Central Australia to the lagoons and permanent river systems of the Top End. Eachaquatic ecosystem provides different resources that make up the habitats within them.

In order to understand what impact human activity has on the environment we first need tounderstand what makes up the environment and what natural processes are taking place thatmay be altered.

Plate 1 Sunset Upper Katherine River

RationaleThe Northern Territory (NT) has many varied wetlands,which are extremely important to Territorians from cultural,spiritual, economic and ecological viewpoints.

This section gives examples of the many wetland types in theNT. Examples are also given of the diverse range of flora,fauna and cultural uses associated with these waterways.

Students should be encouraged to determine the range ofvalues which are placed on wetlands by using local examples.


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Aboriginal CultureAboriginal communities have a rich tradition of environmental knowledge.Highlighted within this education kit is the Rirratjinu Language of NorthEast Arnhem Land. Working together and sharing knowledge is how theNhulunbuy Waterwatch Program and Yirrkala School has enriched thiseducation kit (Schenkel pers. com).

Rirratjinu Language has been, where possible, incorporated into theactivities and learning outcomes. We encourage teachers and schools inother areas to work closely with traditional owners and incorporate thelocal language and culture when learning about water resource monitoringand management (Schenkel pers. com.)

This is just one language group within an area which has many and bytaking this first step we are able to keep culture alive, understand eachother better and have a great time learning about our waterways (SchenkelPers. com.)

Among Aboriginal people there is a belief of a special period of creationoften referred to as ‘Dreamtime’. During this time ancestral spirit beings,sometimes in the form of people or animals, roamed the featureless, flatearth creating everything that exists today including plants and animals,features in the landscape including waterways, language, law and tradition.Sometimes the activities of these creator beings are linked into ‘Dreamingtrails’. Special places where spirit beings were active or now reside are ofgreat significance to Aboriginal people.


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What is a Wetland?

One of the broadest definitions for ‘wetlands’is that adopted by the Ramsar Convention,this being:

“Areas of marsh, fen, peatland or water,whether natural or artificial, permanent or

temporary, with water that is static orflowing, fresh, brackish or salt, including

areas of marine water to a depth which at lowtide does not exceed six metres”

(http://www.ramsar.org).Plate 2 Katherine Gorge

Wetland habitats include billabongs, floodplains, creeks and streams, springs, sinkholes,swamps, estuaries, rivers, mangroves, flood-outs, salt pans and clay pans. These are richecosystems and show great biodiversity.

What is an Ecosystem?The terms ecosystem and habitat can become confused. An ecosystem is the combination of acommunity (biota) and its abiotic environment. Ecosystems are characterised by ecologicalprocesses such as the flow of energy and nutrients through food webs. The ecotone is theregion lying between two ecosystems, often sharing some ecological features of both theecosystems it is in between. A riparian zone, ie the land immediately adjacent to a river thatmay from time to time become submerged, represents an ecotone between water bodies andtheir catchments.

What is an Aquatic Habitat?A habitat is a place that provides food, water and shelter for plants and/or animals that areoccupying and using the space and resources. An aquatic habitat is one that an animal or plantuses to live or reproduce in, where water is the medium in/on which the organism lives. Thewater may be permanent or seasonal, fresh or saline water.

The habitat of a species may cross several ecosystems depending on resourceavailability. However an ecosystem can consist of a variety of habitats, for example a

portion of a river may contain a riffle, pool, run, sand bed and riverbank.

See Activity 1 (p 27)


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Aquatic Ecosystems of the NTBillabongs and Floodplains(gu`un').

Billabongs are waterholes which may form in thebeds of drying ephemeral waterways, or when ariver bend becomes cut off from the mainwaterway, or as seasonal floodplains recede toform discrete aquatic environments (Boulton &Brock 1999).

Plate 3 Nelumbo Lilies

The coastal floodplains of the NT contain Australia’s largest areas of relatively unmodifiedwetlands, covering an area of approximately 10 000 km 2. The floodplains provide feedingand breeding grounds for a large number of waterbirds, and provide crucial dry-season refuge.The mudflats and coastal flats associated with the wetlands support thousands of shorebirdsduring annual migrations. The floodplains are also important habitats for crocodiles(Crocodylus porosus) and barramundi (Lates calcarifer), the premier target fish species of therecreational fishing industry.

The Mary River wetlands areamongst some of the largest coastalwetlands in the NT, covering anarea of approximately 1,300 km2.NT floodplains are underincreasing pressure from a range ofthreats including saltwaterintrusion, weeds, improvedpastures, grazing and feral animals.

Plate 4 Satellite Image of Mary River Floodplains

See Activity 2 (p 28-29)


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Magpie geese (gurrumattji) are easy tofind on the floodplains as they group inflocks of hundreds, sometimes thousands.Magpie Geese mate for life, although amale may choose two females. Thefamily unit will share a nest and theresponsibilities of tending the eggs. Thenests are built of mats of floatingvegetation on the floodplains (Serventy1985).

Plate 5 Magpie Goose (Anseranas semipalmata)

Eleocharis dulcis and Oryza spp (wild rice). grass are important food sources for magpiegeese. Adult geese feed on the bulbs of the Eleocharis , while fledgling geese are dependenton the seeds of Oryza for growth and development. Aboriginal people have traditionallyhunted magpie geese for food (Serventy 1985).

The Lotus lily (dhatam') has large pink flowersup to 25 cm across and giant leaves up to 75 cmacross. The seeds and tubers (burpu) of this lilyare edible raw. The seeds are also ground byAboriginal people to make flour for bush bread(Brock 1988).

Plate 6 Lotus lily (Nelumbo nucifera)

Fish KillsFish kills are a regular occurrence in billabongs and receding floodplains in the NT. Thetiming of these kills generally correlate to the Build-Up Season (the season preceding the WetSeason) and are a result of natural occurrences. As water evaporates large numbers of fishbecome concentrated in small areas of water. Dissolved oxygen levels lower and temperaturesincrease. Fish deaths may also be attributed to naturally occurring toxins, which are morelikely to concentrate as a result of run-off from the first rains(http://www.nt.gov.au/dbird/dpif/pubcat/newsletters/ahnnt.shtml)



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Creeks and Streams (Riyala)

Creeks and streams are waterways of various sizeswhich feed into larger water bodies. Streams can beidentified by order in relation to the number oftributaries. Higher order streams have moretributaries (Boulton and Brock 1999).

Plate 7 Rapid Creek

Common archerfish (nyinganyinga) occur in manyvaried aquatic habitats of the NT, including marineand fresh water environments. These fish cangenerally be found patrolling areas shaded byriverine vegetation. The archerfish is not onlycapable of jumping out of the water to catchunsuspecting prey, usually terrestrial insects, but itcan also spit jets of water, which knock insects intothe water (Larson & Martin 1989).

Plate 8 Archerfish (Toxotes chatareus)

This distinctive, water-loving tree with spiky leavesis a common feature around Top End waterways(Brock 1988).

Although the fruit of this Pandanus species isinedible Aboriginal people can use the plant bycreating paint brushes and rope from the roots(Brock 1988).

Plate 9 River pandanus (Pandanus aquaticus), Berry Creek


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Springs

Springs are formed by water which flowsnaturally from underground, as a result of thewater table intersecting the ground surface. BerryCreek starts from a number of springs, forms asmall creek, then reaches Darwin Harbour througha mangrove lined estuary(http://www.nt.gov.au/paw/parks/berry.htm).

Plate 10 Berry Springs

Locally referred to as "thermal springs" the waterat Mataranka Hot Springs emerges at 32 °C, anaverage temperature for groundwater in theregion. The Springs are found at the point wherethe river bed is deep enough to intersect thewatertable, allowing the aquifer to overflow.

Plate 11 Mataranka Springs

Damselflies (mili mili) are closely related to dragonflies.Because damselflies undergo metamorphosis, with an aquaticphase they are dependent on wetlands (Williams & Feltmate1992).

Adult damselflies lay their eggs in the stems of aquatic plants.Once the eggs hatch the first part of a damselfly’s life is spentas an aquatic nymph, which breathes using the pointed gillseasily visible on the diagram below (Williams &Feltmate 1992).

Plate 12 Damselfly adults (mating)

The presence of damselfly nymphs is an indication of good water quality. It iscommon for Waterwatch volunteers to catch and identify damselfly nymphs whiledoing macroinvertebrate surveys (Waterwatch Aust. 2000).


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SinkholesA sinkhole is a localised sinking of the landsurface, which may be shallow or deep andmay occur either rapidly or gradually.Sinkholes may be formed if:• changes occur in surface or sub-surface

flow or drainage regimes;• the water table is lowered;• a major storm occurs; and/or• a major drought occurs (Karp 2002).

Plate 13 Sinkhole, KatherineThe development of sinkholes requires alandscape underlain by soluble rock such aslimestone or dolomite. While the formationof sinkholes can be naturally induced, theycan also be induced by humans (Karp 2002).

Plate 14 Limestone Cave, Katherine

Sinkholes have significant cultural value, somebeing sacred sites. Sinkholes can also provideecologically valuable temporary and permanentwater sources.

Frogs (garkman) undergo a process calledmetamorphosis which means many frogs,including the Green Tree Frog (Littoria carulea)are dependent on water for breeding (Tyler &Davies 1986).

Plate 15 Green Tree Frog (Littoria carulea)

See Activity 4 (p 31-33)


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Paperbark Swamps

Ephemeral paperbark swamps form vast wetlandareas during the Top End’s wet season.

Plate 16 Girraween Lagoon (close up of ‘paper’ bark)

The papery bark of Melaleuca trees is used by Aboriginal people in the creation of shelter,bedding, fish traps, watercraft and containers. It is also used when cooking food. Medicinallythe infusion from the leaves of certain species can be inhaled or drunk to treat coughs, colds,congestion, fever and other ailments (Brock 1988).

Pandanus spiralis iscommonly referred to as thescrew palm. This distinctivetree with the bright orangefruits can be found in manydifferent habitats, where wateris a common factor. Habitatsinclude swamps, creeks,billabongs, lagoons andfloodplains (Brock 1988).

There are many cultural uses for Pandanus. The fruit iseaten raw or roasted. Medicinally the core of the stem isused in the treatment of diarrhoea, sores, ulcers andtoothache. Pandanus leaves are used for weaving mats,baskets and dilly bags (Brock 1988).

Plate 17 Screw Palm (Pandanus spiralis) fruit and tree


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Estuaries and Coastal Lagoons (Dhulupun)

An estuary is an area where saltwater from the seamixes with freshwater from the land, examples includethe mouths of a rivers, salt marshes and coastallagoons. A lagoon is a broad, shallow estuarine systemseparated from the ocean by a physical barrier,generally close to the shore line (Mastaller 1997).

Both estuaries and coastal lagoons have water which isdescribed as brackish, meaning it is salty. Brackishwater ecosystems provide important habitats which areimportant to marine and terrestrial flora and fauna forshelter, food and reproduction (Mastaller 1997).

Plate 18 Amakwula River

Coastal wetlands support valuable mangrove orgathul’ ecosystems. Mangroves in the NT coverapproximately 4120km2 of coast and river systems.This represents a third of the area covered bymangroves in Australia (Brocklehurst & Edmedes1995).

Plate 19 Mangrove Apple (Sonneratia alba)

Mangroves are important ecologically and economically in the NT. Many marine species,including those which commercially valuable, such as the barramundi (ratjuk) and mudcrab(nyoka), are dependent on mangrove ecosystems for food and for breeding habitats (Mastaller1997).

Rhizophora mangroves are easily recognised by theirarching prop roots. These roots enable Rhizophoratrees to colonise the seaward edge of mangrovecommunities, despite constant tidal inundation andwave action. Rhizophora is used by Aboriginal peoplein the treatment of medical conditions, includingchicken pox (Brock 1988).

Plate 20 Stilt Rooted Mangrove (Rhizophora stylosa)


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Salt water crocodiles (bäru)Salt water crocodiles (Crocodylus porosus) can be found in manycoastal areas and river systems of the NT. It is very important to realisethat these potentially dangerous animals also live in freshwater rivers,billabongs and swamps. Movement between habitats frequently occursbetween seasons (http://www.flmnh.ufl.edu/cnhc/csp_cpor.htm).

Adult crocodiles represent the highest point of the food chain. Theyfeed on animals including mudcrabs, turtles, goannas, snakes and shoreand wading birds. Large adults occasionally take much larger preyinclude buffalo and cattle.

Breeding territories are established in freshwaterareas. 40 to 60 eggs are usually laid in nests madefrom plant matter and mud. Nests are constructedbetween November and March and haltchlingsemerge after around 90 days(http://www.flmnh.ufl.edu/cnhc/csp_cpor.htm).

Plate 21 Crocodiles on the Mary River Floodplains (notice the fishing lure).

Unregulated hunting, mainly between 1945 and 1970,dramatically reduced Australian crocodile populations.Conservation measures, including hunting bans, have beensuccessful in protecting crocodiles, for this reasoncrocodiles should be viewed as dangerous. However tragicsituations can be avoided with increased awareness and bytaking care, whilst you are visiting crocodile habitats(http://www.flmnh.ufl.edu/cnhc/csp_cpor.htm).



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Rivers (Gapu maya)

A river is a large flowing water body which is often afinal collection point for water within a catchment.Many tributaries, such as creeks, may flow into a riverand contribute to its volume (Boulton and Brock 1999).

Plate 22 Flora River, Katherine

Plate 23 King River

Situated in north-eastern Arnhem Land the GoyderRiver is fed by spring discharge from an extensivedolomite aquifer. In November more than sixmonths after the last rains, the upper section of theriver maintains a flow of 1000 litres per second.This supports narrow patches of rainforest alongthe banks.

Plate 24 Goyder River

(http://www.lpe.nt.gov.au/advis/water/ground/Goyder.htm)


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In contrast to Northern rivers the majorrivers in arid Australia only flow afterabundant rains. However the vegetationcorridors which line the riverbanks provideessential shelter for the animals which livein arid environments (Davey 1983).

Plate 25 Todd River, Alice Springs

Arid AdaptationsArid adapted animals have developed many strategies which enable them to cope with theharsh, arid conditions in which they live. These include (Davey 1983):

• sheltering above or below ground to reduce the time spent in the sun/wind;• reducing water requirements, through lowered metabolic rates and aestivation;• reduced excretion of water in sweat/urine;• tolerance relatively high levels of dehydration;• ability to absorb large amounts of water in short time periods;• increased storage of water in body tissues;• utilising water from plant and animal tissues when digested;• utilising water from night dews;• fabricating water from metabolic processes, including carbohydrate breakdown;• life cycles suited for infrequent and short duration water supply; and• tolerance of highly saline waters.

The water holding frog, native to Central Australia,appears above ground only after rain. During dryperiods the frog burrows into the soil, where itcreates an underground chamber. A waterprooflining is then produced, which together with thefrog's bladder is filled with water, which acts as areserve until the next rains(http://www.frogwatch.org.au).

Plate 26 Water holding frog (Cyclorana platycephalus)



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Flood-outs

Inland rivers obviously do not haveopportunity to drain to the ocean. Insteadriver channels move towards landformscalled flood-outs.

The geological features of an area willinfluence whether a flood-out may reform tobecome a concentrated channel of water.Flood-outs are flats which radially dispersewater away from the end of a stream channel,across vast tracts of land (McDonald et al1998).

Plate 27 Aerial photograph of a flood-out, Andado Station, NT.

Claypans and Saltpans

Pans, or playas are large, shallow, level-flooreddepressions. These basins flood after storms to formtemporary lakes, which then rapidly dry out due toevaporation and infiltration of the water into thesurrounding soil and groundwater aquifers. (McDonald etal 1998).

Plate 28 Clay-pan (dry), Central Australia

Salt pans form when trapped floodwatersevaporate, leaving a crust of salt. The highsalt content of the soil limits plant growthto a few halophytic (salt tolerant) plants.http://www.lib.ttu.edu/playa/hydroact.htm

Plate 29 Aerial Photograph of a salt pan in Central Australia


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Aquatic Habitats

Plants

Plate 30 Mangrove Apple (Sonneratia alba) flowers

Plants are an important part of the water cycle. Plants produce carbohydrates needed forgrowth and reproduction through a process called photosynthesis. This series of chemicalreactions requires water in addition to light and carbon dioxide. Water molecules are absorbedfrom the soil into roots by the plant. Transpiration is the loss of water by evaporation from theleaves of plants. The water leaves plants as water vapour through the leaf surfaces (Knox etal. 1994).

Plants also influence the amount of water which isabsorbed into the soil. Plant structures decrease thevelocity (and therefore erosive potential) of raindroplets and channel them gently towards theground. Stabilising root structures of plants furtherreduce the erosive potential of rain. Shade created byplants reduces evaporation levels (Knox et al. 1994).

Plate 31 Pandanus (Pandanus aquaticus) at Berry Springs


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Riparian VegetationVegetation that grows on the riverbanks is known as the riparian zone. This vegetationprovides essential habitats for the animals living in and along the waterway. Riparianvegetation influences stream health by slowing overland run-off and trapping soil particlesthereby reducing soil erosion. Riparian vegetation is often composed of plants which prefermoist conditions and are adapted to occasional flooding. Riparian vegetation includes nativeand introduced species which tend to form a corridor (riparian zone) along the edge of awaterbody (Waterwatch Aust. 2000).

Fringing vegetation is important in maintaining a healthy river system and preventing erosionof the river banks. It provides food and shelter for a variety of animals and acts as a filter tomaintain the quality of water that enters the waterway. Fringing vegetation strips out sedimentand takes up nutrients; it also stabilises (traps) and aerates sediments, and so preventsmurkiness (Waterwatch Aust. 2000).

There is a variety of fringing and aquatic plants, different types of trees, shrubs, sedges andgrasses can be found in salty, brackish and freshwater conditions.

Bank Vegetation

Bank vegetation provides much of the protection from erosion because its roots hold the soiltogether. Trees overhanging the stream keep the water cool. Leaves and branches can fall intothe stream, as well as insects and other animals, and these provide food and protection forriver animals. Examples of bank vegetation in the NT include freshwater mangroves(Barringtonia acutangula), Paperbark species (Melaleuca sp.), Pandanus (Pandanusaquaticus and Pandanus spiralis) and River red gums (Eucalyptus camaldulensis) (Brock1988).

Aquatic Vegetation

Aquatic vegetation native to the NT has many diverse forms, all of are important inmaintaining healthy aquatic habitats.

Figure 1 Types of aquatic plants


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Free floating plant species which are generally notrooted into any substrate, but rather float on thewater surface (Sainty & Jacobs 1988).

Plate 32 Eriocaulon setaceum

Floating attached plants species include the water lilyNymphaea violacea (Plate 33). Floating attachedplants are rooted in the waterway substrate, but haveat least the mature leaves floating on the watersurface. These plants provide an important source ofenergy and play a significant role in the cycling ofnutrients. They provide shelter and refuge for aquaticanimals and a place for algae and invertebrates toattach themselves (Sainty & Jacobs 1988).

Plate 33 Nymphaea violacea

Emergent plant species, such as the water chestnut (Eleocharis dulcis) are rooted in thesubstrate of the waterway, however their leaves protrude above the water surface (Cowie et al2000). Trees and shrubs can also be considered emergents when they grow in seasonallyinundated areas such as floodplains or swamps (Sainty & Jacobs 1988). Submerged plantsremain below the surface.

Plate 34 Melaleuca (paperbark) trees at Girraween Lagoon


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Habitat Types

Water flowing through a riverpasses through three physicallydifferent environments, thesebeing riffles, runs and pools.Varying flows and depths createa variety of habitats for aquaticflora and fauna. Riffles areshallow, rocky and well aerateddue to fast flowing turbulentwater. Runs are deeper, slowerand not as rocky as riffles andhave some mud or silt amongtheir rocks Pools are deep andhave silt or mud bottoms(Waterwatch Aust. 2000).

Figure 2 Plain view/cross section of a pool, riffle and run (Waterwatch Aust. 2000).

River BanksVertical or undercut - a bank that rises verticallyor overhangs the stream generally gives goodcover for macro-invertebrates and fish and isresistant to erosion. The banks may be composedof solid rock or very fine sediment which is moreresistant to erosion.

Steeply sloping - a bank that slopes at more than a30 degree angle. This type of bank is veryvulnerable to erosion if composed of sand orgravel.

Gradual sloping - a bank that has a slope of 30degrees or less. Although this type of bank ishighly resistant to erosion, it does not give muchstreamside cover.

Artificial changes to banks including the use ofconcrete or rock can stabilise eroding banks,however significant reductions in vegetation cannegatively impact stream fauna. Concrete banksmay also cause erosion upstream or downstreamdue to changed water velocity.

(Waterwatch Aust. 2000).

Figure 3 Stream bank shapes (Waterwatch Aust. 2000).


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Why is Riparian Vegetation Important?

Figure 4 The riparian environment (Munks 1996 cited in Waterwatch Aust. 2000)

Riparian vegetation contributes to the quality of the aquatic environment as a source of food,shelter, habitat and shade: it stabilises stream banks and protects water quality (WaterwatchAust. 2000).

Food and shelter

Riparian plants are a valuable source of food and shelter for birds, amphibians, reptiles andother animals. Leaf litter, insects, fruit and fallen branches from overhanging trees, give year-round food and shelter for native fish, invertebrates and turtles. Riparian vegetation canprovide valuable refuges for rare and threatened plants and animals (Waterwatch Aust. 2000).

Woody debris

Riparian vegetation is a source of woody debris (fallen trees, logs and branches) which fallsinto the water and becomes a vital habitat for stream life. Logs and branches trap passingleaves and twigs so they can be used as food by aquatic animals. The rough surface ofsubmerged native logs and branches forms micro-habitats for animals lower in the food chain.Woody debris creates valuable breeding places for macro-invertebrates and fish. Large piecesof woody debris slow the flow of small streams and help to form pools. De-snagging streams(removing woody debris) removes important habitats and should be avoided except where thestream is choked with debris and serious erosion is likely (Waterwatch Aust. 2000).


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Figure 5 Comparison of vegetated and unvegetated river bank (Munks 1996, citedin Waterwatch Aust. 2000)

Shading

Riparian vegetation shades waterways and protects life from high temperatures which can belethal to many aquatic plants and animals. Shaded parts of the stream are necessary forsuccessful breeding by some aquatic animals, including fish (Waterwatch Aust. 2000).

Bank Stabilisation

Roots of riparian plants bind soil particles together and prevent erosion, undercutting andbank collapse. Many Australian streams have highly variable flows which allow vegetation topersist on the toe of the bank. This helps to prevent scouring of the bank (Waterwatch Aust.2000).

Water quality

Vegetation holding the bank together lowers the amount of sediment entering the water andcan also trap silt and sand present in flood flows before it enters the waterway. The deep rootsof shrubs and trees on the banks help to keep the water table low through extraction of groundwater by evapotranspiration. This delays the onset of saturation of the river bank during heavyrainfall and reduces the incidence of bank collapse (Waterwatch Aust. 2000).


21

Vegetation within 40m of the waterway buffers the stream from activities on the land, eg:clearing and cropping is the most important part of the habitat to examine. It slows theoverland movement of water into streams and traps sediment, nutrients, pesticides andherbicides from up-slope areas. Land is often cleared for agriculture, housing, roads andduring forest harvesting, but this has led to large amounts of sediment (gravel, sand and silt)washing into our waterways. When streamside vegetation is removed there is less protectionagainst soil loss, bank collapse and pollution, leading to poorer water quality and degradedconditions for aquatic plants and animals, both at the site and downstream (Waterwatch Aust.2000).

Excessive nutrients enteringstreams encourage prolific growthof water weeds, particularly indisturbed areas. Dense aquaticweeds slow waterway flowcausing sediment to settle, whichin turn leads to a broadening ofthe channel and increased erosionof the banks. Additionallydecomposition of large amountsof aquatic weeds by bacteria canlead to lower oxygen levels in thewater (Waterwatch Aust. 2000).

Figure 6 Effect of riparian vegetation on runoff and water quality (Munks 1996 ,cited in Waterwatch Aust. 2000).

See Activities 7 to 10 (p 36-41)


22

Animals

Plate 35 Katydid

Riparian ecosystems support a much higher abundance and diversity of animal species than insurrounding areas. Aquatic habitats and the associated vegetation of the riparian zonesprovide animals with food, standing water, nesting and roosting sites and shelter frompredators. Water is also often a requirement for reproduction in both aquatic and terrestrialspecies (LWRRDC 1999).

Macroinvertebrate EcologyAn aquatic macroinvertebrate is an animal without a backbone, that spends allor part of its life in water. The word ‘macro’ indicates these animals are largeenough to be seen with the unaided eye (Waterwatch Aust. 2000).

Figure 7 Dragonfly larvae

There are many kinds of macro-invertebrates in our waterways, including worms, snails,mites, bugs, beetles, dragonflies and freshwater crayfish. Our understanding ofmacroinvertebrates, in combination their abundance, the fact that they are easy to catch andrelatively easy to identify at various levels either in the filed or later in a lab, are all factorwhich mean they make excellent biological indicators. A biological indicator is a livingindication of how healthy a waterway is! (Waterwatch Aust. 2000).

See Activities 11 to 13 (p 42-48)


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The Aquatic Food ChainAquatic macro-invertebrates occupy a major role in the food chains of aquatic ecosystems.Macro-invertebrates consumers include herbivores (who eat algae and other aquatic plants)and carnivores (who eat other invertebrates) while macro-invertebrate decomposers aremostly detrivores (who eat dead plant and animal material). All these macro-invertebrates arein turn an important food source for fish, waterbirds and other fauna (Waterwatch Aust.2000).

Macro-invertebrates can be grouped according to their eating habits:

• grazers - feed on algaeattached to rocks or logs inthe water, eg snails andmayflies;

• shredders- eat largerpieces of food (> 1 mm)such as wood and leavesthat fall into the water, egdragonfly larvae;

• collectors - feed onsmall bits of food (<1 mm)either by filtering thepassing water or gatheringit from the bottom, egcaddis fly larvae;

• predators- capture andeat other animals, eg waterstriders and damselflylarvae.

Figure 8 Feeding relationships of macro-invertebrates (Odum 1959, cited inWaterwatch Aust. 2000).

Other aquatic animals like fish, frogs and birds depend on macro-invertebrates as their mainsource of food. The greater the variety of waterbugs in a stream, the more chance that animalshigher up the food chain will also be living there (Waterwatch Aust. 2000).

MetamorphosisSome insects spend only a part of their life in fresh water. Insects such as mayflies, caddisflies and midges undergo a process called metamorphosis. This process dramatically changesbody shape as the invertebrate grows from an egg to an adult. The transformation may take aslittle as two weeks, eg: mosquitoes, or up to four years for some dragonflies (WaterwatchAust. 2000).

Figure 9 Caddis fly larvae


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There are two types of metamorphosis, these being incomplete and complete. Incompletemetamorphosis is characterised by a nymph phase. Nymphs, such as a mayfly nymph, looksimilar to the adult, progressively becoming more similar with each moulting. Completemetamorphosis begins with a larval stage. The larva then pupates emerging as an adult withwings. True flies, beetles and caddis flies all undergo complete metamorphosis (WaterwatchAust. 2000).

Other invertebrates spend all their life in water, eg: back-swimmers, water scorpions andwater striders (Waterwatch Aust. 2000).

Table 1 Comparison between complete and incomplete metamorphosis(Waterwatch Aust. 2000).

Incomplete metamorphosis Complete metamorphosisegg eggearly nymph larvalate nymph pupaadult adult

Macro-invertebrates habitatsAnimals survive best in places that provide protection, camouflage, and food sources.Whatever your waterway, it will probably have several different habitats suitable forinvertebrates. Macro-invertebrates are found in still water, riffles, runs and in pools of flowingwaters such as creeks (Waterwatch Aust. 2000).

RifflesWithin faster flowing riffles rocks provide a variety of living places and a large surface areafor macro-invertebrates to hold onto. Food is continually swept down in the current fromupstream. Since riffles provide a variety of living places, current conditions and food, theyoften support a diversity of macro-invertebrates (Waterwatch Aust. 2000).

RunsRuns are generally deeper and slower than riffles. Smaller particles like sand and gravel tendto settle on the bottom; limiting the variety of living places for macro-invertebrates. Inaddition, occasional floods will wash sand and gravel and any animals downstream. Food issuspended in the water, deposited on the bottom or may grow on the stream bed. This type ofphysical habitat limits the variety of macro-invertebrates (Waterwatch Aust. 2000).

PoolsPools usually have sandy or muddy bottoms with fewer types of macro-invertebrates present.The habitat is less suitable so macro-invertebrates will attach to plant stems, roots, logs andother submerged items (Waterwatch Aust. 2000).


25

Macroinvertebrate AdaptationsAdaptations for life in fast-moving waterAnimals living in moving water must be able to ‘hang-on’ and catch their food. You can oftenfind examples of the following adaptations in Waterwatch macroinvertebrate samples(Waterwatch Aust. 2000):• streamlined bodies (water pennies);

• special hooks on legs(mayflies and stoneflies);

• suction body parts (black flies and snails);

• sticky secretions to attach themselves to the bottom (caddis flies and midges);

• structures to keep themselves in place (caddis flies); and

• specialised front legs and mouth-parts to filter the water or catch food moving past (blackflies).

Adaptations for life in slow-moving or still waterIn contrast to fast moving water, animals in still or slow-moving water don’t have to hang onand food is not brought to them in the current. They tend to have a wider range of sizes andshapes and be more mobile. Some have special adaptations to live on the surface, such aswater striders, while others burrow into the soft sediments (Waterwatch Aust. 2000).

Table 2 Freshwater macro-invertebrate habitats (Waterwatch Aust. 2000).

Habitats Macro-invertebrates that may be living there.

Edgewater includes overhangingvegetation from banks.

Fast moving bugs and beetles, freshwater shrimp.

Bottom - mud, sand, silt, gravel,rocks.

Worms, fly larvae, bivalve mussels.

Aquatic plants - plants under thesurface as well as those growingthrough the water and floating.

Gripping insects, caddis flies, damselflies, shrimp,snails.

Flowing water - riffles, pools andruns.

Gripping insects, caddis flies, and beetle larvae thathave burrowed into logs and under rocks.


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Table 3 Estuarine macro-invertebrate habitats (Waterwatch Aust. 2000).

Estuarine (salt water) habitats Macro-invertebrates that may be living there.

Seagrass and mudflats. Whelks, cockles, shrimp, periwinkles, crabs, snails,amphipods, polychaete & squirt worms.

Seagrasses are sensitive, slow growing and used bymany fish as a breeding ground.

Saltmarsh. Crabs, slugs, isopods, mosquito and midge larvae.

Mangroves. Crabs, amphipods, isopods, prawns, shrimp, oysters,whelks, worms, barnacles and mussels.

See Activities 14 and 16 (p 49-52)


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Local Surface WaterLocal Surface WaterLocal Surface WaterLocal Surface WaterInvestigationInvestigationInvestigationInvestigation

Activity 1

Curriculum Links:Science Concepts and Context / Life and Living CC1.2, CC 2.2, CC 3.2, CC 4.2, CC 5.2

SOSE Environments / Natural Systems Env 1.3,Env 2.3, Env 3.3, Env 4.3, Env 5.3

Focus Question:

What are some different typesof surface water in the NT?

Aims:1. To build on student’s understanding of

the aquatic ecosystems in the NT.

2. To examine how different ecosystemssupport different plant and animalcommunities.

Main Ideas:

Surface water is freshwater that isvisible above ground in waterholes,rivers wetlands, lakes, dams etc.

Surface waters may be man-made,natural, permanent and ephemeral.

Need:

Internet access and local maps.

Consider:

Students research some actual examples ofsurface water bodies in their local regionand label them man-made or natural,permanent or ephemeral.

Analysis:

Research animals and plants which arespecific to the various water bodies whichyou have identified.

Analyse the various challenges which theseanimals and plants may face during thecourse of one year.

When do the different surface water bodiesdry out (if at all) and for how long do theydry out?

Does the region flood?

Is the waterbody inundated with saline orbrackish waters?

Extension:

Map these local water bodies on aphotocopy of a local map of the region.Use the map determine where the flow intothese water bodies has come from andwhere it goes.

Reflection:

How does the presence of a range ofdifferent surface water bodies in a regionsupport biodiversity? (Biodiversity is thevariety of living things that can besupported in a given area).


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Lifecycle of theLifecycle of theLifecycle of theLifecycle of theBarramundiBarramundiBarramundiBarramundi

Activity 2

Curriculum Links:Science Concepts and Context / Life and Living CC3.2, CC 4.2, CC 5.2

SOSE Environments / Natural Systems Env 3.3,Env 4.3, Env 5.3

Focus Question:

What adaptations enableanimals to live in aquaticenvironments?

Aim:

To understand the concept that lifecyclestrategies are a form of adaptation to aparticular environment.

Main Idea:The barramundi (Lates calcarifer),is the premier target fish species ofthe recreational fishing industry.

Barramundi spawn around rivermouths early in the Wet Season.High tides wash the eggs and larvaeinto adjoining coastal swamps.

Juvenile barramundi migrateupstream at the end of the WetSeason while mature males andfemales live mostly in tidal areas.

Need:Student Sheet 3.1: Barramundi (below).

Consider:Read the Barramundi student sheet. Youmay choose to do additional research onthe barramundi’s lifecycle.

Analysis:

What specific needs do the Barramundirequire for a complete breeding cycle?

Draw a diagram which labels the variousstages in the barramundi life cycle.

Investigate the reasons for the complicatedlife cycle of the barramundi.

Investigate your local area for suitablehabitats.

Reflection:

Given the Barramundi is a popular fish tocatch and eat, what is being done aboutprotecting this fish from being overfishedto the point that the population is beingreduced?

Who is monitoring the fish numbers?


29

Student Sheet 3.1: Barramundi

Many fish species inhabit the protected waterways of Top End parks andreserves, most of them freshwater species. The Barramundi (Lates calcarifer), isby far the most prized target of recreational fishermen.

Barramundi thrive in both salt and fresh water. Barramundi spawn around rivermouths early in the wet season and high tides wash the eggs and larvae intoadjoining coastal swamps. Juvenile barramundi migrate upstream at the end ofthe Wet Season while mature males and females live mostly in tidal areas. Oneof the most fascinating biological aspects of this fish is that adult males turn intofemales to breed.

Fishing Controls

The Department of Business, Industry and Resource Development (DBIRD) hasintroduced a series of special controls to help minimise the impact ofrecreational and commercial fishing on the Territory's Barramundi resource.These controls cover fish size limits, bag limits, seasonal closures, gearrestrictions in specified areas, and a ban on tethering of fish.

It is illegal to catch and keep Barramundi which measure less than 55 cm inlength.

People fishing in the designated Mary River Zone are not permitted to take morethan two Barramundi in one day nor to have more than two Barramundi in theirpossession at any one time. In other Territory waterways, the bag limits are fiveBarramundi in one day and five at any one time.

Tethering of fish is illegal in the Northern Territory.

Always release any fish that is not needed

Give released fish the best chance to survive by:� removing the hook while the fish is still in the water;� using a net to land, de-hook and weigh a fish before release;� gripping the lower jaw, rather than placing fingers under the gill cover, when

measuring a fish; and� not leaving live fish on a hot deck or seat.

Design a poster which communicates some or all ofthese messages to fishermen


30

Fish KillsFish KillsFish KillsFish Kills

Activity 3

Curriculum Links:Science Concepts and Context / Life and Living CC3.2, CC 4.2, CC 5.2

SOSE Environments / Natural Systems Env 3.3, Env4.3, Env 5.3

Focus Question:What factors can affect thehealth of aquatic habitats?

Aim:To gain a better understanding of thecomplexities surrounding the reasons forfish kills in the NT.

Main Idea:

Fish kills may be natural or a resultof pollution.

Naturally occurring fish kills canoccur as floodplains in the NTrecede. As water evaporates largenumbers of fish become concentratedin small areas of water. Dissolvedoxygen levels lower andtemperatures increase. Fish deathsmay also be attributed to naturallyoccurring toxins.

The timing of these kills generallycorrelate to the Build-Up Season.

Fills kills can also occur as a resultof toxic pollutants which have beenintroduced into waterways byhumans, such as pesticides and toxicchemicals.

Need:

Research fish kills by contactingGovernment Departments such as theDepartment of Industry and ResourceDevelopment (DBIRD) and theDepartment of Infrastructure, Planningand Environment or the Internet.

Consider:

At what time of year are fish kills mostlikely to occur?

What are the mechanisms which causeseasonal changes in dissolved oxygenlevels?

Analysis:

Write a detective story about twochildren who discover a major fish kill inthe river and follow clues to find theculprit who had flushed old engine oilinto a stormwater drain. Create a positiveending to the story.

Alternatively research and write a storyabout a fishy expedition where poisonwas used to stun and catch the fish to eat(indigenous methods).

Extension:

Discuss some of the naturally occurringtoxins which can be found in thewaterways of the Top End?

Research the precautions taken whenusing this method of fishing.


31

Katherine RegionKatherine RegionKatherine RegionKatherine RegionSinkholesSinkholesSinkholesSinkholes

Activity 4

Curriculum Links:

SOSE Environments / Environmental Awarenessand Care Env, 3.2, Env 4.2, Env 5.2

SOSE Environments / Natural Systems Env 3.3,Env 4.3, Env 5.3

Focus Questions:

What is a sinkhole and howare they formed?How are ground and surfacewaters connected?

Aim:

To gain a better understanding ofgroundwater and surface water interactionsvia the study of sinkholes.

Main Ideas:

Sinkholes are a product ofunconfined aquifers that can beconsidered wetlands when full ofwater.

Sinkholes facilitate flow ofgroundwater to river systems.

The processes of sinkholes need tobe understood when consideringnearby development of land.Appropriate management ofsinkhole landscapes can minimisethe risk of collapses.

Sinkholes form a large part of thelandscape in the Katherine regionpastoral lands that overlielimestone substrates known as theTindal formation (495km2).

Need:Student Sheet 3.2: Sinkholes (below),.Katherine Sinkhole Study poster (may beborrowed from your Regional WaterwatchCoordinator).

Consider:

The poster. An additional useful referenceis Karp, D. Land Degradation Associatedwith the Sinkhole Development in theKatherine Region (Technical Report No11/2002) DIPE, Darwin.

Analysis:

Students work as groups or individually toanswer the questions listed on the studentsheet.

Visit Cutta Cutta Caves or anothersinkhole that is safe to access and visit.Study the rock formations and the fissures.Study the flora and fauna that exist in theselocations. Investigate the culturalsignificance of this type of wetland. Writea report about your visit to the sinkholewetland.

Extension

Design and create your own model of asinkhole to demonstrate to other classes orvisitors to the school.

Reflection:

Why is it important that these sinkholes areconserved as intact wetlands?

Why are water allocation plans importantfor the management of sinkholes andhuman structures that may exist near them?


32

Student Sheet 3.2: Sinkholes

What type of aquifer is prone to sinkholes?

___________________________________________________________

1. Why are sinkholes significant biologically?

___________________________________________________________

___________________________________________________________

___________________________________________________________

2. Draw a labelled diagram of a typical sinkhole structure.

3. What factors can induce a sinkhole to collapse?

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

4. How might induced collapse of sinkholes be avoided?

___________________________________________________________

___________________________________________________________

___________________________________________________________


33

5. Investigate what makes groundwater green in colour and provide yourexplanation.

___________________________________________________________

___________________________________________________________

6. Looking at the rock structure on the surface around sinkhole country, whathas caused the horizontal fractures, and what has caused the verticalfractures?

___________________________________________________________

___________________________________________________________

___________________________________________________________

7. What is the major land use of sinkhole country? Is this land use likely tocause sinkholes to form faster than they would naturally? If so why?

___________________________________________________________

___________________________________________________________

___________________________________________________________

8. Investigate the vulnerability of this type of water resource to pollution.Record your findings.

___________________________________________________________

___________________________________________________________

___________________________________________________________

9. Given the surrounding land uses, what might be some potential pollutants?

___________________________________________________________

___________________________________________________________

___________________________________________________________


34

Crocodile EcologyCrocodile EcologyCrocodile EcologyCrocodile Ecology

Activity 5

Curriculum Links:

SOSE Environments / Environmental Awarenessand Care Env, 3.2, Env 4.2, Env 5.2 / NaturalSystems Env 3.3, Env 4.3, Env 5.3

Focus Questions:


Aims:1. To develop research/ report writing

skills.

2. To learn about the ecology anddistribution of crocodiles, includingtheir adaptive features andinterrelationships with theirenvironment.

Main Idea:

Saltwater crocodiles can be foundin many coastal areas and riversystems of the NT.

Breeding territories are establishedin freshwater areas. 40 to 60 eggsare usually laid in nests made fromplant matter and mud. Nests areconstructed between November andMarch. Juveniles hatch after around90 days.

Crocodiles are often are viewed asman-eaters. Although many peoplehave been injured and killed eachyear, many tragedies could have beavoided with increased awareness.

Unregulated hunting, mainlybetween 1945 and 1970,dramatically reduced Australiancrocodile populations.

Conservation measures, includinghunting bans, have been successfulin protecting crocodiles.

(http://www.flmnh.ufl.edu/cnhc/csp_cpor.htm).

Need:

‘Crocodile Features’ and ‘CrocodileRelationships’ and ‘CrocodileAppreciation’ from the web site:http://www.mesa.edu.au/friends/croc_kit/index.html

Consider:Look at the information and follow theprompts on the web site.

Investigation:Investigate the distribution of saltwater andfreshwater crocodiles in the NT.

Analysis:

How have humans exploited crocodilepopulations in the past? Research thehistory that has resulted in laws that protectcrocodiles.

ExtensionProvide an extension into the arts, drama,games and music to develop anappreciation of crocodiles.


35

Aquatic Adaptations to AridAquatic Adaptations to AridAquatic Adaptations to AridAquatic Adaptations to AridEcosystems?Ecosystems?Ecosystems?Ecosystems?

Activity 6

Curriculum Links:SOSE Environments / Natural Systems Env 3.3,Env 4.3, Env 5.3

Science Concepts and Context / Life and Living CC3.2, CC 4.2, CC 5.2

Indigenous Languages and Cultures NaturalEnvironment

Focus Question:

What adaptations enableplants and animals to live inarid aquatic environments?

Aim:To gain an understanding of the widevariety of adaptations which enable aquaticanimals to live in regions where very littlesurface water exists.

Main Idea:

Many animals have developedstrategies which enable them tocope with the highly seasonalconditions in which they live.These include (Davey 1983):

• sheltering from sun/wind;• reducing water requirements;• reduced excretion of water;• tolerance to dehydration;• ability to absorb large amounts of

water in short time periods;• increased storage of water;• utilising water from plant and

animal tissues when digested;• utilising water from night dews;• life cycles suited for infrequent and

short duration water supply.

Need:Research material

Consider:

Discuss and research the many differentadaptations animals in the NT have toseasonal water shortages.

Analysis:Students choose a species to study,investigate its life cycle.

What body parts are involved in theadaptation, eg: skin, legs, feet, moth,behaviour, internal processes?

Students write a report, which includes adiagram, about the species that is chosenand then present this to the class.

Reflection:What variations might there be inadaptations of Top End and Arid Zonespecies?

Extension:

Investigate indigenous stories whichexplain how or why the different animalshave the body features that they do?


36

PPPPlantlantlantlant Recognition Recognition Recognition Recognition Trail Trail Trail Trail(Adapted from the “Catchment Education Resource Book” NRE 1998 Vic.)

Activity 7

Curriculum Links:SOSE Environments / Natural Systems Env 3.3,Env 4.3, Env 5.3


Indigenous Languages and Cultures NaturalEnvironment

Focus Question:

How does water interact withplants?

Aims:1. To increase student appreciation of

plants.

2. improve student identification skills.

Main Ideas:

Plants form an essential part of thewater cycle. Additionally manyplants have importantenvironmental, cultural andhistorical significance.

*If you need assistance in identifying yourlocal trees, contact DIPE or GreeningAustralia.

Need:Paper, pencils, cardboard and laminate.

Consider:Select an area with a diversity of trees thatstudents regularly visit.

Choose 10 distinctive and prominent treesfrom this area for use in the trail. Try toselect a range of native species.

Photograph each tree so that yourphotograph shows the basic form of thewhole tree.

Collect a sample of the leaves and barkfrom the tree (bark rubbings may also betaken using pencils and paper). If flowers,buds, or cones are available then they canalso be collected and photographed orpressed in a plant press.

Make a permanent recognition card foreach tree by placing the photographs backto back and laminating them.

The trail cards can be used in a variety oforienteering and recognition activities.

Analysis:Research the natural habitats of each ofyour identified plants. What is therelationship between habitat, watersaturation and plant type?

Extension:Of the trees identified are any of thesenaturally found in riverine and aquaticenvironments? Examples includeMelaleuca (paperbarks), Pandanus (screwpalms) and Eucalyptuscamaldulensis(River red gums)

Can you determine any physical features ofplants which indicate the type ofenvironment which they are best suited to?

Research some of the many indigenoususes of riverine and aquatic plants


37

Riparian Vegetation StudyRiparian Vegetation StudyRiparian Vegetation StudyRiparian Vegetation Study

Activity 8

Curriculum Links:SOSE Environment / Place, Landforms andFeatures Env 1.1, Env2.1, Env 3.1 / NaturalSystems Env 1.3, Env 2.3 Env 3.3

Focus Question:

Why is riparian vegetationimportant?

Aim:To understand the value of riparianvegetation.

Main Idea:

Vegetation that grows on theriverbanks is known as the riparianzone.

Riparian vegetation providesessential habitats for the animalsliving in the river.

Riparian vegetation influencesstream health by slowing overlandrun-off and trapping soil particlesthereby reducing soil erosion.

Riparian vegetation is oftencomposed of plants which prefermoist conditions and are adapted tooccasional flooding.

Need:Transport, video (as below) excursionpapers and pens.

Consider:Watch the video’s River Floodplains andRivers, Streams and Billabongs. List someof the plants and animals associated withwaterways.

Choose a river site to visit, guidance maybe required from your RegionalWaterwatch Coordinator.

Analysis:Discuss what riparian vegetation is? Createa diagram with the class to explain it.

Discuss via a retrieval chart the value ofriparian vegetation.

Talk about vegetation and animalinteractions; vegetation and soilinteractions, vegetation and waterinteractions – then relate this to the ripariansituation.

Make observations on site: describe/drawthe vegetation structure, i.e. types ofplants; collect different leaf or flower orfruit types to represent the diversity of thevegetation.

While on site consider the question: is theriparian zone a dynamic system over time?

Back in the classroom, students create abrochure about the importance of riparianvegetation.

Reflection:What would water quality be likewithout riparian vegetation? Whatfactors might impact on riparianvegetation?


38

Aquatic PlantsAquatic PlantsAquatic PlantsAquatic Plants

Activity 9

Curriculum Links:SOSE Environment / Natural Systems Env 1.3, Env2.3 Env 3.3


Focus Question:

What are the different plantstypes associated withwaterways and why are theyimportant?

Aim:

To study the role of plants in an aquaticenvironment.

Main Idea:

Riparian vegetation (vegetation thatgrows on the riverbanks) providesessential habitats for the animalsliving in the river. Riparianvegetation influences stream healthby slowing overland run-off andtrapping soil particles therebyreducing soil erosion.

Bank vegetation provides protectionfrom erosion. Trees overhanging thestream keep the water cool. Leavesand branches can fall into the stream,as well as insects and other animals,and these provide food andprotection for river animals.

Aquatic vegetation native to the NThas many diverse forms, all of areimportant in maintaining healthyaquatic habitats. Many of the planttypes found in the water providevaluable food and habitat for aquaticfauna. Plants also assist inoxygenating the water through theprocess of photosynthesis.

Consider

Discuss how a combination of plant typescan benefit aquatic and land animals.

Analysis:

What roles do plants play in the aquaticecosystem?

Create a series of labelled pictures ofplants which the students know to exist innearby waterways.

Describe what happens in the processcalled ‘photosynthesis’?

Draw an aquatic food chain.

How are nutrients recycled? Why do youthink this is an important process ofwetlands?

Reflection:Think about the role of the sun drivingthe energy cycle of the wetland.

How is heat energy transformed intoorganic matter?


39

Field Excursion toField Excursion toField Excursion toField Excursion toIdentify Local HabitatsIdentify Local HabitatsIdentify Local HabitatsIdentify Local Habitats

Activity 10



Focus Questions:

What are some of the aquatichabitats present in the NT?Why is riparian vegetationimportant?

Aims:1. To become familiar with the use and

meaning of the term habitat.

2. To explore some local examples ofaquatic habitats.

Main Ideas:

A habitat is a place that providesfood, water and shelter for plantsand/or animals that are occupyingand using the space and resources.

Need:

Transport, sketch pad, pens and writingpaper. ‘Stream Habitat Terms’ StudentSheet (overleaf) Assistance fromWaterwatch.

Consider:Visit a range of aquatic environmentswithin your local area.

Investigation:

Ask students to take note of the physicalfeatures of the site(s), eg: the water bodycross section, the type of geology, soils,vegetation and animals present.

Can the sites(s) be divided into smallerhabitats such as riffles, pools, banks,verges and river bends?

Record the different plants and animalspresent in each of these habitats. With theassistance of your local expert, you willalso be able to sample the aquaticmacroinvertebrates.

Analysis:

What were the different species found ineach of these areas of the site(s)? Did somespecies overlap in their distribution? Weresome specific to particular zones?

How many habitats were present at thesite(s)? Draw and label a diagram showingthe cross section of the site(s) and thevarious habitats present.

If possible, create a short video from thesite visits explaining the differencebetween the different stream habitats.

Back in the classroom, as a class create amural of the site(s).

Reflection:Is it possible that the types of habitatpresent at a site can change over time?


40

Student Sheet 3.3Stream Habitat Terms

(Source: Waterwatch Education Kit, Waterwatch Vic and Barwon Water 1997)

A river is more than just water. It is a habitat for many different animals.The plants in and beside the water are very important parts of this habitat.

1. Label the ‘verge’, ‘bank’, and ‘in stream vegetation’ zones of a river on thedrawing ‘River Habitats’. Draw in the plants roots.

2. Water levels in rivers keep changing. Draw in 4 different water levels, andlabel them, to show likely water levels in different seasons.

3. Circle the correct answer and fill in the blanks below

Riffles are (deep / shallow), rocky sections of a creek or river. The water moves (faster/ slower) as it bubbles over the rocks and stones.

Pools are (shallower / deeper) areas of the waterway. Here the water flows (slowly /quickly) and the streambed is usually of s ___ ___ ___ or m ___ ___ .

4. Fill in the blanks about riverside vegetation.

Overhanging trees provide s ___ ___ ___ ___.

Leaves fall into the water and provide f ___ ___ ___.and s ___ ___ ___ ___.___ ___

Insects living in riparian vegetation provide f ___ ___ ___ for aquatic animals.

5. Vegetation includes leaves, twigs, branches, roots and stems. How might thein-stream vegetation influence animal life in the river?

________________________________________________________________

________________________________________________________________

6. How might the river bank vegetation influence life in and around the river?

________________________________________________________________

________________________________________________________________

7. How might the river verge vegetation influence animal life in the river?

______________________________________________________________

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The Fresh WaterThe Fresh WaterThe Fresh WaterThe Fresh WaterAquariumAquariumAquariumAquarium

Activity 11



Focus Question:

What is an Aquatic Habitat?

Aim:To learn about the basic needs of animalsliving in water through the use of anaquarium as a model of an aquatic habitat.

Main Idea:

A habitat is a place that providesfood, water and shelter for plantsand/or animals that are occupyingand using the space and resources.

An aquatic habitat is one that ananimal or plant uses to live orreproduce in, where water is themedium in/on which the organismlives.

Need:Use an aquarium or fish bowl that has beenset up in your classroom or somewhere inthe school.

Consider:What life is like in a freshwater aquarium?

Discuss:

The needs of the fish; these being oxygen,water, food, shelter and waste disposal.

How these needs are satisfied in anaquarium?

Other kinds of living things you can havein an aquarium.

Why plants are put in the aquarium?

Needs How these are satisfiedoxygen air pump, plantswater Owner providedfood Owner provided, algae on glasswastes filtered/ tank cleanedshelter plants, rocks, ornaments

Analysis:

What do all animals and plants need theirhabitats to provide?

Students write a story about what it islike to be a fish living in an aquarium.They might like to talk about theinteraction required with humans in orderto keep them alive.

Read Longneck's Billabong. Talk aboutLongneck's needs and how they aresatisfied? Compare his needs with theneeds of a fish in the aquarium and howits needs were satisfied.

Reflection:

Reflect on how aquatic animals in thereal world do not require humans tomaintain their habitats for them.


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Surviving in EphemeralSurviving in EphemeralSurviving in EphemeralSurviving in EphemeralAquatic HabitatsAquatic HabitatsAquatic HabitatsAquatic Habitats

Activity 12

Curriculum Links

SOSE Environment / Natural Systems Env 3.3, Env4.3 Env 5.3


Indigenous Languages and Culture NaturalEnvironment

Focus Question:

What adaptations enableplants and animals to live inephemeral aquaticenvironments?

Aims:1. To introduce students to the concept of

ephemeral habitats.

2. To review how organisms surviveephemeral habitats.

Main Idea:

Ephemeral water bodies are thosethat only hold water for part of theyear.

These are usually small creeks,lagoons, rock pools or low lyingareas in the arid zone.

NeedResearch materials, art and craft materials.

Consider:

Read ‘Wetlands’ by Tricia Oktober andwatch the very last few scenes from thevideo: ‘The Call of Kakadu’ or ‘OurLiving Deserts’.

How do plants and animals survive wherethe habitat is only seasonally under water?Talk about what happens to the plants andanimals as the water disappears. Examplesinclude:

• Migration of larger animals to morepermanent waterways, such as rivers;

• Aestivation: Some animals, such asturtles and burrowing frogs dig into themud to aestivate (sleep) through thedry times;

• Entering periods of dormancy: Someplants stop growing, but their rootsremain protected in the soil until thenext wet period.

Analysis:

As a class, research some examples ofanimals that use the mechanisms orstrategies for survival over the dry periodas discussed above.

Each student may like to create a posterabout a particular type of aquatic animaland how it lives in the water. If thestudents work in groups, they may makeup a play about the animal.

Extension:As a class, create a mural of a billabong,including local animals and plants whichyou would expect to find in this type ofwaterway. Yolgnu Matha names have beenincluded. You may like to research localindigenous languages for the labelling ofyour own mural. Discuss and illustratewhere each animal would go if thebillabong was to dry up


44

English to Yolngu Matha Translations

Water BirdsEnglish Yolngu Matha

egret gany'tjurr or gomu`ubrolga gu[urrkumagpie geese gurrumattjijabiru nama'kingfisher djirrintiti (didi for short)kookaburra garrukal'duck muthalicrested terns ŋurula

Water PlantsEnglish Yolngu Matha

water chestnuts Rakäylotus lily Dhatamlotus lily bulbs Nindan or Burpuwater lily wäkwak or dhoŋgureeds garriyakBullrush Gulwani'pandanus nuts gungamangrove ferns mayawarkumangrove holly banuminyLeichart pine RulkarriCannonball mangrove Gukawuvines gathurrmyred flowered mangrove milinyarrswamp fern garkuFlagellaria Darwirrgrass ritharrmangroves gathul'yellow flowered hibiscus (Yirrkala creek) mapadhurrwater lily bulbs nin dan burpaspecial grass bulmirri


45

Water AnimalsEnglish Yolngu Matha

macroinvertebrates gapuwuy nhäŋiniŋsnails men duŋshrimp markileech djalŋinymussel djarrwitworm mewirri (raypinpuy gapuwuy mewirri)water mite gapuwuy djukubaby mozzie borrutj yothusandfly larvae (midgee) mindjirri yothuwater scorpion dimidimitadpoles wolkwulkbeetles momu-ŋaniybeetle larvae miyirutrue bugs yir'yirŋanicaddisfly larvae momu-ŋanidragonfly nymphs dikarr-ŋani buku-warthunayafile snake (live near Lotus Lilies) djaykuŋ'mangrove jack Djembirricrocodile bärucrocodile eggs bäru mapu' or lanyarrcrocodile nest ŋulurr or ngulwurrsmall bandicoot wan'kurrabig fish balinsmall fish ratjukarcher fish watpirriyi or nyingagyinablack brim matpunacat fish wilitjwiltjgarfish nyuŋulacrab (mangrove, red and yellow nippers) ginybirkpignose turtle madalatjlong necked turtle minhalabig freshwater turtle ŋokawufreshwater stingrays guyapindibats mattjurr'owl worr'wurrfrogs garkmanbuffalo detuŋ or mewuŋpigs norrŋ'norrŋferal wakinŋuwater rats nyiknyik


46

butterflies bonbaolive python wititjwater python mokumilŋiny'mi (gatj)eel rangu'cockroach boduk (with white stripes)green ants ŋarmukhoney bees (go looking for water) dawurrfreshwater mussels djarrwitgrey teal muthali


47

Life in Our WaterwaysLife in Our WaterwaysLife in Our WaterwaysLife in Our Waterways(Adapted from Waterwatch Education Kit. 1997 Waterwatch Vic, Barwon Water)

Activity 13



Focus Questions:

What are some of theorganisms that live in theaquatic habitats of the NT?

Aims:1. To become familiar with some

freshwater plants and animals.

2. To develop an understanding of whataquatic animals eat, where they live andwhat adaptations they possess for life inan aquatic environment.

Need:“What Am I” card template one copy perstudent. Safety pins.

Additional references:Wetlands Wildlife: Gould League ofVictoria.Ponding: Gould League of Victoria.Water Plants in Australia: Sainty & Jacobs.

Consider:Explain the terms invertebrate, macro-invertebrate, crustacean, nymphs, larvae,detritus and carrion (see glossary).

Decide which local wetland plants and/oranimals to include in this activity.

Analysis:Students research and prepare the cards forthe 'What Am I?' game.

Use the ‘What Am I’ to increase thestudents knowledge of aquatic plants andanimals by holding a quiz session.

Students research and prepare posters toillustrate the aspects of the chosen speciesas listed for the ‘What Am I’ card.

Use the poster as part of a presentation tothe class to explain how the support,transport or reproductive systems of theiraquatic plant or animal helps it to survivein a wetland environment.

Use the cards or posters to demonstratefood chains.

Habitats:

Create a class mural of a cross section ofa river scene, showing different kinds ofmicro-habitats. You could include fallenbranches, pools, riffles, stones, andvegetation. Use the mural to review waysthe river bank vegetation is important toaquatic habitats(shade, shelter and foodsupply). Students draw the plant oranimal identified in their ‘What Am I’card in the correct location.

Students research and write a story abouta day in the life of an aquatic animal,describing how it lives and what type ofhabitat it needs. Explain how a change inwater availability or quality could affectits survival?

Reflection:

How does Waterwatch monitoringinvolve the study of life in ourwaterways? Why do you think thismonitoring is important?


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Student Sheet 3.4What Am I?

Plant/Animal name

What it eats

What eats it

Preferred aquatichabitat

Special features

An illustration


49

Adaptations for SeasonalAdaptations for SeasonalAdaptations for SeasonalAdaptations for SeasonalChangesChangesChangesChanges

Activity 14

Curriculum Links:SOSE Environment / Natural Systems Env 3.3

Science Concepts and Context / Life and Living CC3.2

Focus Question:

What is metamorphosis andhow does it enable survival inseasonal climates?

Aim:To understand the concept that lifecyclestrategies are a form of adaptation to aparticular environment.

Main Idea:

An aquatic macro-invertebrate is ananimal without a backbone, thatspends all or part of its life inwater.

Many aquatic invertebrates undergometamorphosis. The wordmetamorphosis comes from meta(change) and morph (shape) – achange in shape, not just size.

Need:

Research materials, macroinvertebratesurvey equipment and the NT Guide toMacroinvertebrates (included in thiseducation kit)

Consider:There are two types of metamorphosis

Metamorphosis involving nymphs.

(Example:dragonfly)

The egg hatches into a small nymph whichgrows through a number of size stages(called instars). This is usually the longpart of the animal’s life. Finally, for anaquatic invertebrate like a dragonfly, itemerges from the water as an adult.

The adult dragonflies then mate on land.The female then lays her eggs on plantsthat grow near water. Often the eggs willnot hatch for several months until the rainsof the next wet season wash them into awaterway.

Metamorphosis involving larval andpupae stages.

A well-known example is the life cycle ofthe mosquito. Eggs hatch into larvae,which after a period of time will attach to aplant or rock and becomes a pupa. Thepupa then splits to reveal the adult.

The NT Guide to Macroinvertebratesprovides examples and pictures of nymphsand larvae which live in our waterways

Analysis:Students prepare a poster depicting thevarious stages of aquatic macroinvertebrateof their choice which undergoesmetamorphosis

ExtensionContact your regional Waterwatchcoordinator to undertake macroinvertebratesampling. Macroinvertebrates areconsidered to be biological indicators, thismeans sampling can reveal informationabout the health of a particular waterway.


50

Adaptations ofAdaptations ofAdaptations ofAdaptations ofMacroinvertebratesMacroinvertebratesMacroinvertebratesMacroinvertebrates

Activity 15

Curriculum Links:

SOSE Environment / Natural Systems Env 3.3Science Concepts and Context / Life and Living CC3.2

Focus Questions:


Aim:To recognise the different features ofmacroinvertebrates which have enabledthem to adapt to a variety of environments.

Main Idea:

Aquatic macroinvertebrates are animportant part of aquaticenvironments and food chains.

Many macroinvertebrates aresensitive to the condition of thewater. Measuring their presence orabsence is one good way to measurethe quality of the water.

Macroinvertebrates are found ingreatest numbers in riffle areas.Stones provide places for attachmentand predator evasion. These areas areoxygen rich environments and algaegrowing on the rocks can alsoprovide oxygen, food and shelter.

Need:Art and craft materials.

Consider:

Life in the fast lane:Small animals living in moving waterneed to be able to hang on so they are notswept away. They often have specialhooks or suction attachments to hold ontorocks or vegetation. They often havestreamlined or flattened surfaces. Somebuild structures to keep themselves inplace. Food is grabbed as it passes by inthe water rather than being chased.

A quiet(er) life:The animals in quiet waters do not haveto hold on all the time. They have tochase their food so need to move morethan riffle species. Some have specialadaptations to live on the surface, someon the bottom. Some live in the leaf litteraround the edges and others burrow intothe soft sediment.

Worms that live in mud need to haveways to cope with the low oxygen levelsin the mud. Some aquatic worms haveblood pigments that are very efficient atpicking up the oxygen that is present.Another way some animals cope withlow oxygen levels is to increase the ratethat oxygen passes over their gills.

Analysis:Draw or create and three dimensionalstream, which shows the different typesof habitats that macroinvertebrates caninhabit.

Reflection:What might happen to the total number ofmacroinvertebrates at a site if there wasonly one habitat type present – comparedto a site that had several habitat typespresent?


51

Take Home MessagesTake Home MessagesTake Home MessagesTake Home Messages

Activity 16

Curriculum Links:SOSE Environments / Environmental Awareness andCare Env, 1.2, Env 2.2, Env 3.2

Aim:To share knowledge with family and friends,which emphasises the importance of lookingafter our planet’s water resources.

Main Idea:

Interesting facts about aquaticecosystems and habitats can beshared by all.

Need:

Pens, scissors and card, magnets or doublesided sticky tape/blue tack.

Consider:Students may use the samples below or theymay want to make up their own ‘learnings’.

Analysis:Cut the following cards out and use them athome. Students may pass onto a friend orfamily member.


52

Did You Know?The coastal floodplains of the NT contain Australia’s largest areas of relatively

unmodified wetlands, covering an area of approximately10 000 km 2

Did You Know?An estuary is an area where saltwater from the sea mixes with freshwater from

the land, examples include the mouths of a rivers, salt marshes and coastallagoons.

Did You Know?Inland rivers do not have opportunity to drain to the ocean. Instead river

channels move towards landforms called flood-outs.

Did You Know?A habitat is a place that provides food, water and shelter for plants and/or

animals that are occupying and using the space and resources.

Did You Know?There are twenty-nine varieties of fish, which occur in the harsh, ephemeralwaters of central Australia. These species are well adapted to live in waters,

which vary over a great range of salinities, temperature fluctuations, and oxygenlevels.

Did You Know?Adult barramundi males turn into females to breed.


53

INDEXabiotic, 3Aboriginal, 2adaptations, 42aestivation, 17, 51algae, 22animals, 28aquatic plants

emergent, 22floating attached, 22free floating, 22submerged, 22

aquatic vegetation, 45aquifers, 18archerfish, 8arid adaptations, 17Arnhem Land, 2, 16bank stabilisation, 26bank vegetation, 45barramundi, 14, 35, 36Barringtonia, 20Berry Creek, 10billabong, 4billabongs, 15biological indicators, 28biota, 3brackish, 14buffers, 26claypans, 18clearing, 26coastal lagoon, 14conservation, 15creek, 8crocodile hunting, 15crocodiles, 4, 15, 41cultural significance

sinkholes, 11cultural usage

lotus, 6magpie geese, 6mangroves, 14pandanus, 8, 13paperbark, 13

culture, 2Cutta Cutta, 38damselfly, 10dehydration, 17dolomite, 11dormancy, 51Dreamtime’, 2ecosystem, 1, 3

ecotone, 3Eleocharis, 6erosion, 20, 23, 24, 25, 26erosive potential, 20estuary, 10, 14Eucalyptus, 20evaporation, 18, 19evapotranspiration, 26feral animals, 4fish kills, 6, 37fishing controls, 36Flood outs

Andado Station, 18flood-outs, 18floodplains, 4, 5, 15, 22food chain, 15, 29food web, 3frog

green tree, 11water holding, 17

gills, 10grazing, 4groundwater, 10, 18habitat, 3, 24, 25, 26, 31, 46

aquatic, 50habitat types, 23habitats

aquatic, 55halophytic plants, 18herbicides, 26improved pastures, 4infiltration, 18invertebrates, 22Katherine, 38language, 2larvae, 28lifecycle, 35limestone, 11lotus, 6macroinvertebrate, 58, 60macroinvertebrates, 10, 28

adaptations, 32carnivores, 29collectors, 29detrivores, 29grazers, 29herbivores, 29predators, 29shredders, 29

magpie geese, 6


54

mangroves, 14, 20Mary River, 4, 5, 15, 36Melaleuca, 20metabolic processes, 17metamorphosis, 10, 11, 30, 58migration, 51Nelumbo, 4, 6Nhulunbuy, 2nutrients, 26nymph, 10, 31Nymphaea, 22Oryza, 6Pandanus, 8, 9, 13, 20pans, 18paperbark, 20paperbark swamps, 13pesticides, 26photosynthesis, 19, 45plant recognition, 43plants, 19playas, 18pool, 3, 23, 31rainfall, 26Ramsar, 3Rhizophora, 14riffle, 3, 23, 31riparian, 3, 20, 24, 26, 27, 28riparian vegetation, 24, 44river bank, 3, 25, 26, 23

artificial changes, 23, 24gradual sloping, 23steeply sloping, 23undercut, 23verticle, 23

river habitats, 49River red gums, 20rivers, 15, 16, 18

arid, 17Flora River, 16Goyder River, 16King River, 16

Todd River, 17run, 3, 6, 20, 23, 31salt, 18salt marshes, 14saltpans, 18saltwater intrusion, 4sand bed, 3saturation, 26sediment, 26shading, 25sinkhole, 11sinkholes, 38spawn, 35, 36Springs, 10

Berry, 10Mataranka, 10

stream, 3, 8, 25, 26swamps, 15, 22sweat, 17toxins, 37translations, 52transpiration, 19tributaries, 8, 16vegetation

aquatic, 20bank, 20fringing, 20riparian, 20

water animals, 53water birds, 52water cycle, 19, 43water lily, 22water plants, 52water quality, 10, 26water vapour, 19weeds, 4, 26Wetland, 3woody debris, 25Yirrkala, 2Yolngu Matha, 52

n.t. waterwatch

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