KEYSTONE COLEOPTERANS - COLONIZATION BY WOOD-FEEDING ELMIDS OF EXPERIMENTALLY IMMERSED WOODS IN SOUTH-EASTERN AUSTRALIA

Macroinvertebrates on immersed woods in streams in montane south-easte rn Australia respond to differences in wood taxa, according to a 4-mon th colonization study of experimentally positioned sticks. Xylophagous elmids (Coleoptera : Elmidae) strongly preferred local native Eucalyp tus over other types of wood including non-native softer timbers (Pinu s and Alnus). Where gouging elmids were abundant (in native forest str eams with native riparian vegetation), immersed Eucalyptus wood suppor ted high abundances of other macroinvertebrates; in their absence (in open grassland streams), Eucalyptus supported few other macroinvertebr ates. Macroinvertebrate-gouged channels were present disproportionatel y on Eucalyptus sticks relative to other wood species. It is proposed that xylophagous elmid beetles are the principal macroinvertebrate mod ifiers of wood in these south-eastern Australian streams, where their gouging of channels increases surface area, thereby facilitating colon ization by other macroinvertebrates and wood-decaying microorganisms a nd fungi.