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

Figure 5.5 A common blue-tongued lizard in Myrtleford, Victoria.Fish play a vital role in the ecology of rivers, streams,lakes and wetlands (Koehn 2002). They are present ineach trophic level as detritivores, herbivores, omnivoresand carnivores. Across their life cycles they provide foodfor many other species and contribute to water qualityand nutrient cycling. Thirty-three species of fish havebeen recorded within the study area. Eight of these areintroduced and, of the 21 native species, nine arethreatened in Victoria (Appendix 5). Notable threatenedfish include freshwater catfish, Murray hardyhead (seeFigure 5.4), trout cod, Murray cod and silver perch.Invertebrates are an important and diverse group,comprising more than 95 percent of the world’s animalspecies. There are an estimated three and eleven millionspecies of invertebrates worldwide. Invertebrates areinvolved in essential ecological functions such aspollination, herbivory, parasitism, predation, seedharvesting and dispersal, decomposition, scavenging,and soil turnover. All these functions contribute to asustainable ecosystem.The invertebrate fauna of the study area varies withgeography through the dry-sclerophyll forest, riparianzones, arid zones, as well as having a cosmopolitanelement (Mac Nally et al. 2002a). Preliminary studiesindicate that river red gums have a very rich invertebratefauna that changes seasonally in composition andfunction (Yen et al. 2002). The few studies available onterrestrial invertebrates within river red gum ecosystemsindicate that there is high invertebrate species richnessat both individual tree and at ground-level, but theextent and variation across the study area is unknown.River red gum ecosystems in different locations mayappear botanically similar, but differences in invertebratefauna may be great.Little is known about how invertebrate species interactwith each other and with their environment, includingwithin river red gum ecosystems. While there is a richarboreal invertebrate fauna, especially herbivorousinsects, with leaf damage and dieback being significantmanagement issues (see below), there is limitedinformation on the importance of river red gums ashabitat for these arboreal invertebrate species.Current information about arboreal, ground-dwellingand log-dwelling invertebrates is represented in Figure5.6. Robertson et al (1989) collected a total of 100species of ground dwelling invertebrates in river red gumforest sites and 160 species in black box forest with 52of these species being found in both river red gum andblack box forests (See 1 , Figure 5.6). In a study ofremnant river red gum and grey box forests on thenorthern plains near Echuca, a greater number ofground-dwelling invertebrate orders was found in riverred gum compared with pasture (Yen et al. 1996) (See 2 ,Figure 5.6), however there were large seasonaldifferences in composition. In an examination of 4487beetles from 342 species (representing 46 families)collected by Yen et al. (1996), Ward et al. (2002) foundthat summer sampling yielded most species, but winteryielded more specimens.Flooding patterns also affect invertebrate abundance.Ballinger et al. (2005) examined ground-active terrestrialbeetles and spiders before and after a managed flood inBarmah Forest (See 3 , Figure 5.6).60 River Red Gum Forests Investigation 2006