Threats to invertebrates
The plight of many species of birds and mammals around the world is well known. There is a global awareness about the threats facing animals such as pandas, tigers, rhinoceroses and whales. In Australia there has also been a dramatic reduction in the number of species of medium-sized mammals, and several species have become extinct over the past 150 years. Victoria’s two faunal emblems, the Leadbeater’s Possum and the Helmeted Honeyeater, are both threatened.
Few people give much thought to the plight of our invertebrates, such as insects, spiders, earthworms and crustaceans. These are creatures without backbones and are rarely given the same status as the more charismatic birds and mammals. Yet there are many more species of invertebrates than vertebrates – invertebrates comprise some 98–99% of all animal species –and we have little idea of the number of invertebrate species that are threatened or have become extinct.
Eltham Copper Butterfly
Photographer: Alan Yen / Source: Museum Victoria
If there are so many species of invertebrates compared to vertebrates, why is it necessary to try to save threatened species of invertebrates? The answer is that every species plays a role in ecological systems, and we cannot predict what will happen if even a single species are lost from a system.
The threatened Victorian species
Although all native vertebrates are protected in Victoria, the only invertebrates that are given protection are those listed as threatened under the Flora and Fauna Guarantee Act 1988. These are species that the Flora and Fauna Guarantee Scientific Advisory Committee has considered eligible for listing for protection because they are in a state of demonstrable decline or are subject to threats that could result in their extinction in the foreseeable future.
By 2004, 46 species of non-marine Victorian invertebrates had been listed under the Act:
Acrodipsas brisbanensis
Large Ant-blue Butterfly
Acrodipsas myrmecophila
Small Ant-blue Butterfly
Allocharopa erskinensis
Land snail species
Arachnocampa species
‘Mt Buffalo Glow-worm’
Archaeophylax canarus
Caddisfly
Athanopsis australis
Southern Hooded Shrimp
Australatya striolata
Eastern Freshwater Shrimp
Austrogammarus australis
Freshwater amphipod
The Murray Spiny Cray, Euastacus armatus
Photographers / Source: John Gooderham & Edward Tsyrlin
Austrogammarus haasei
Amphipod
Engaeus mallacoota
Mallacoota Burrowing Crayfish
Engaeus phyllocercus
Narracan Burrowing Crayfish
Engaeus rostrogaleatus
Strzelecki Burrowing Crayfish
Engaeus sternalis
Warragul Burrowing Crayfish
Euastacus armatus
Murray Spiny Cray
Euastacus bispinosus
Glenelg spiny cray
Euastacus crassus
Alpine Spiny Cray
Euastacus diversus
Orbost Crayfish
Euastacus neodiversus
South Gippsland Spiny Cray
Eucalliax tooradin
Ghost shrimp species
Geminoropa scindocataracta
Land snail species
Gramastacus insolitus
Western Swamp Cray
Hemiphlebia mirabilis
Hemiphlebia Damselfly
Heteronympha cordace wilsoni
Western Bright-eyed Brown Butterfly
Hygrobia australasiae
Water beetle species
Hyridella glenelgensis
Glenelg freshwater mussel
Megascolides australis
Giant Gippsland Earthworm
Michelea microphylla
Ghost shrimp species
Myrmecia sp. 17
Bull ant
Notopala sublineata
River snail species
Ogyris idmo halmaturia
Large Brown Azure Butterfly
Ogyris otanes
Small Brown Azure Butterfly
Ogyris subterrestris
Ogyris Butterfly
Ogyris s. subterrestris ssp. nov.
Mildura Ogyris Butterfly
Paralucia pyrodiscus lucida
Eltham Copper Butterfly
Peronomyrmex bartoni
Ant species
Riekoperla darlingtoni
Mt Donna Buang Wingless Stonefly
Riekoperla intermedia
Stonefly
Riekoperla isosceles
Stonefly
Synemon nais
Moth
Synemon plana
Golden Sun Moth
Synemon theresa
Moth
Taskiria otwayensis
Caddisfly species
Thaumatoperla alpine
Stonefly
Thaumatoperla flaveola
Stonefly
Theclinesthes albocincta
Bitterbush Blue Butterfly
Xylocopa aeratus
Metallic Green Carpenter Bee
The Giant Gippsland Earthworm, Megascolides australis
Photographer: Alan Yen / Source: Museum Victoria
The range of invertebrates listed for protection is quite varied taxonomically, and ranges from earthworms and freshwater amphipods to aquatic insects and butterflies. It includes both freshwater and terrestrial invertebrates. This reflects the broad range of threatening processes encountered by our invertebrate fauna, including increased sedimentation in streams, vegetation clearance, and habitat fragmentation.
The threatened status of species such as the Golden Sun Moth is indicative of the loss of vast areas of particular vegetation types since European settlement. In the case of the Golden Sun Moth, almost all Victoria’s native grasslands and grassy open-woodlands have been lost or seriously degraded.
The list of threatened species also highlights the threat faced by species which have their populations restricted to small vulnerable patches of land such as the Eltham Copper Butterfly and Warragul Burrowing Crayfish. Some scientific modelling has predicted that if the Greenhouse Effect does lead to an increase in global temperatures it may lead to reduced snowfalls and the contraction of truly alpine environments in Victoria. If this does occur it may increase the risk of extinction faced by invertebrates which live in alpine environments, or are restricted to a small number of peaks.
What you can do
The important message is that invertebrates are an integral part of our environment and require conservation, just like the better known vertebrate fauna. The 25 listed species represent only a tiny fraction of the Victorian fauna. The Giant Gippsland Earthworm exemplifies the animals that turnover our soils and ensure recycling of essential nutrients and assist drainage. The aquatic insects such as the stoneflies are indicators of clean and healthy water. Some of the butterflies are involved in complex ecological interactions; their larvae feed on a particular species of plant, and many species have a close association with particular species of ants.
Many of the threatened larger animals such as tigers and rhinoceroses are threatened by direct hunting. But most threatened animals, whether vertebrate or invertebrate, are threatened primarily by habitat loss or alteration. The major issue that we must be aware of is that native habitats, no matter how small, are home to a large range of native invertebrate species.