Discussion Paper - Part A - Victorian Environmental Assessment ...

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Egrets generally only breed in living trees with at leasthalf a metre of water beneath them. If the waterrecedes, the egrets will abandon the nest, even if theyoung are close to fledging. Following spring floods, theextensive river red gum forests of the Barmah andGunbower areas provide the only Victorian breedingsites for colonies of great and intermediate egrets, andmajor breeding colonies of other herons, cormorants,ibis and darter.The lack of adequate spring floods in recent decades hasresulted in an almost complete lack of breeding by manycolonial waterbirds, particularly intermediate and littleegrets, which are classified as critically endangered inVictoria, and also the great egret, which is endangered.Little egrets bred in Gippsland in 1993, near Geelong in1998-2004 and in Gunbower Forest in the early 1970s.Intermediate egrets are known to have bred at only twosites in Victoria: Ryans Lagoon (near Wodonga) in 1981and Gunbower Forest in the early 1970s and one nest in1993. Great egrets bred at many sites in the 1970s and1980s but had not been recorded breeding in Victoriasince 1993. There are probably fewer than 200 breedingpairs remaining. Increased environmental flows in 2005under the Living Murray initiative (see chapter 15)resulted in great egrets breeding in Gunbower Forestand both great and intermediate egrets breeding inBarmah Forest.The carpet python is another threatened species foundwithin riverine forests. This species inhabits two distincthabitat types within Victoria: river red gum forests andassociated black box woodlands along rivers andstreams, and also rocky hills with Blakely’s red gum.Increased predation and habitat clearing as well asdecreased prey availability are thought to reduce carpetpython populations (Allen et al. 2003). Carpet pythonsare ambush predators which use fallen timber, groundcover and rocks to hide from potential prey and toshelter from predators. Removing this cover for firewoodand landscaping, threatens the survival of carpetpythons. Carpet pythons are also sometimes killed byhumans.River red gums are a keystone eucalypt tree species forterrestrial invertebrates because of they provide bothfood and shelter, as well as leaf litter and coarse woodydebris on the forest floor. Recent research indicates thatflooding has significant food-chain implications forterrestrial invertebrates. Larger invertebrate predators,such as carabid beetles and lycosid spiders, increase inresponse to flooding thereby sustaining largerpopulations of insectivorous vertebrates that prey uponthem.Aquatic species are likely to be particularly sensitive tochanges in the river system. The critically endangeredsilver perch, for example, spawns partly in response torises in water level and temperature. Given the greatchanges in the region’s hydrology since Europeansettlement (see chapters 3 and 15), it is perhapsunsurprising that seven of the 21 native fish speciesrecorded in the study area are threatened. Many of thestudy area’s streams and rivers now provide the mostimportant Victorian habitat for species such as thecritically endangered trout cod and Murray hardyhead,and the endangered Murray cod (see box 5.2),freshwater catfish and Macquarie perch.In addition, the Lowland Riverine Fish Community of thesouthern Murray-Darling Basin is listed under the Floraand Fauna Guarantee Act 1988. This community has 15fin fish species: ten that are listed individually under thatAct, and five that are not—golden perch, flat-headedgalaxias, bony bream, flat-headed gudgeon and westerncarp gudgeon.Eucalypt (Box) WoodlandWoodlands dominated by eucalypts other than river redgums and black box, particularly grey box and yellowbox, also provide significant habitat for woodland birds,small mammals and reptiles. These woodlands providesimilar kinds of ecological services as the river red gumforests, but have fewer wetlands and do not usuallyflood naturally. The dominant eucalypts are not adaptedto periodic inundation and consequently have notdeclined with reduced flooding. However, Margules andPartners et al. (1990) estimate that approximately 33percent of the floodplain vegetation along the RiverMurray has been cleared and much of this would havebeen box woodland (not necessarily all in the River RedGum Forests study area).Grey box has a wider distribution in the study area thanblack box, occurring from Wodonga in the east toKerang in the northwest with an outlying populationnear Robinvale (see Figure 5.1). Grey Box is thedominant eucalypt on many roadsides in the VictorianRiverina Bioregion. Like black box and river red gum,grey box wood is strong and durable and widely usedfor products such as fence posts. It was widely clearedfrom its pre-European distribution and remains mostly onroadsides and as single paddock trees.Yellow box is widely distributed across Victoria but islargely absent from the north and south west and alpineareas (see Figure 5.1). Yellow box wood has similarcharacteristics to grey box wood and the trees are alsogood honey producers, flowering from September toJanuary.Buloke is a leaf-less tree that grows to 5-15 m. It isdistributed in north and west Victoria and is commonlyfound with grey box and slender cypress-pine.Approximately 97 percent of the original bulokewoodland in Victoria has been removed (DNRE 1997b).Most remnant buloke trees occur as scattered trees,many in paddocks and along roadsides. This history hasnegatively affected many species that inhabit bulokewoodlands, such as the grey-crowned babbler.Buloke Woodlands of the Riverina and Murray-DarlingDepression Bioregions have been listed as anendangered community under the CommonwealthEnvironment Protection and Biodiversity ConservationAct 1999. Remaining examples are threatened bycontinued clearing, weed invasion, fertiliser andherbicide drift and grazing by rabbits and stock. Thiscommunity is poorly represented in conservation reservesthroughout its range.Large old tree sitesLarge old trees are particularly important in both riverineforests and eucalypt woodlands. Large trees provide amore open forest structure, with a greater area andvariety of foraging substrate for insectivorous fauna.They also provide abundant bark and fallen timber,Discussion Paper71
Box 5.2 Murray CodThe Murray cod is Australia’s largest freshwater fish (up to113 kg)—a premier angling species—and generatesconsiderable public interest because of its size, ‘mystique’and excellent eating qualities (see Figure 5.14 and Figure5.15). This interest elevates the Murray cod’s importancefrom being merely a fish to being a significant part ofAustralian folklore and cultural heritage. Murray cod werenaturally abundant and traditionally a major part of thediet for Aboriginal people in the area, as well as animportant cultural icon. Early European settlers ate Murraycod and a substantial commercial fishery existed until theearly 1900s. Since then, the species has declineddramatically and is now endangered in Victoria and listedas vulnerable under the Commonwealth EnvironmentProtection and Biodiversity Conservation Act 1999. Murraycod are an important component of the native fishcommunities of the Murray-Darling Basin and share manythreats with other fish species.Murray cod lay sticky eggs on hard surfaces likesubmerged wood, when temperatures rise over 15°C(Koehn & Harrington 2006). The adult male guards theeggs and the hatched larvae drift away from nest sites inthe water column, making them susceptible to changes inflow regimes and loss into irrigation off-take channels andpumps. Spawning appears to occur in most years undervarious flow conditions and the survival of post-larval fishis thought to determine overall population recruitment.Survival of post-larval fish may be enhanced by increasedfood availability following flooding. Natural flow regimesalso provide spawning cues for many other native species.Cold water releases from storages such as LakesDartmouth and Hume can reduce spawning andrecruitment success, reducing fish populations.Murray cod migrate upstream (up to 100 km) beforespawning and then return downstream, usually to theiroriginal location (Koehn 1997), making both upstreamand downstream fish passage important factors in theirlife cycle. Both adult and juvenile Murray cod selecthabitats with structural wood in the main river channels,close to the banks and with overhanging vegetation.Figure 5.14 Murray cod.Figure 5.15 Victorian distribution of Murray cod.Source: Atlas of Victorian Wildlife 2006Although they will use floodplain channels when theycontain flowing water, the cod do not appear to use thefloodplain itself. They also prefer slower, shallower waters.Removal of instream woody habitats has been widespreadin major rivers in the past and the re-instatement of thesehabitats is now recognised as an important rehabilitationmeasure.Past commercial catches of Murray cod have removedapproximately 160 tonnes of fish per year (or 32,000individuals weighing an average of 5 kg) from the lakesand rivers around Barmah in the 1860s (King 2005). Thehighest numbers were taken when the fish werespawning. Although these fisheries are now closed,Murray cod are still fished recreationally (Koehn 2005b).There is evidence to suggest that overfishing could be aproblem for some populations. Illegal fishing also occursand, although not quantified, is believed to be substantialin some areas. Artificial stocking of Murray cod tosupplement the population is now widespread, but thismay have implications for the genetic diversity of thepopulation.There have been substantial deaths of Murray cod in theBroken Creek, and Ovens and Goulburn Rivers in the pastfew years (King 2005; Koehn 2005a). These have causedconsiderable public concern and have resulted in the lossof valuable breeding stocks. While some recovery inMurray cod populations has been reported in NSW andQueensland, any recovery in Victoria is yet to bedemonstrated scientifically.As part of the requirements of being listed as athreatened species under the CommonwealthEnvironment Protection and Biodiversity Conservation Act1999, Murray cod will be the focus of actions outlinedunder a forthcoming National Recovery Plan. Thisincreased management, addressing the key threats andrecovery actions for Murray cod is intended to assist in therehabilitation of the species.72 River Red Gum Forests Investigation 2006
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2 GeologyGeology underpins the dive
Page 5 and 6:
Figure 2.2 Schematic diagram of fol
Page 10 and 11:
et al. 2000). This Selwyn Block is
Page 12 and 13:
Figure 2.4 Murray Basin during the
Page 14 and 15:
quartz sand and gravel beds, carbon
Page 17 and 18: Box 3.1 River MeandersRivers rarely
Page 19 and 20: lakes by flooding from Chalka Creek
Page 21 and 22: major valleys. The large, older fan
Page 23: ecommending representative areas fo
Page 26 and 27: Box 3.2 Barmah Area GeomorphologyTh
Page 28: 4 Climate andHydrological SystemsAu
Page 31 and 32: Figure 4.1 Annual anomalies (based
Page 33: such as messmate have a thick prote
Page 36: Natural Hydrology of the River Murr
Page 39: Table 4.3 Stream flow in major Vict
Page 42 and 43: GroundwaterHydrology also relates t
Page 44 and 45: FloodplainsThe floodplains of the R
Page 46 and 47: 5 BiodiversityBiodiversity is impor
Page 48 and 49: Ecosystem Assessment 2005). Species
Page 51: Figure 5.2 Hairy darling-pea on a r
Page 57 and 58: Figure 5.5 A common blue-tongued li
Page 59: Threatened VertebratesBased on cons
Page 64 and 65: Figure 5.8 Mature river red gum on
Page 66 and 67: Figure 5.12 Tangled lignum at Mulcr
Page 70 and 71: which is essential habitat for some
Page 72 and 73: dependent species including darling
Page 74: Table 5.7 Summary of risk levels to
Page 77 and 78: Figure 5.22 Koala in a river red gu
Page 79 and 80: Examples include the larvae of leaf
Page 81 and 82: Figure 5.27 Cattle on the bank of t
Page 83 and 84: Table 5.8 Comments on fire from exp
Page 85 and 86: 6 Indigenous LandAssociationsThis c
Page 89 and 90: Table 6.1 Summary of area in Victor
Page 91 and 92: waters. The Joint Body is funded to
Page 93 and 94: Consultative ManagementConsultative
Page 95 and 96: 7 Non-IndigenousHistoryThe resource
Page 97 and 98: Figure 7.2 Murray Downs homestead (
Page 99 and 100: Reception Centre established in 194
Page 101 and 102: and rural water supply became the r
Page 103: FisheriesThe collapse of the Murray
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