The invertebrate cave fauna of Tasmania : ecology and conservation biology

The invertebrate cave fauna of Tasmania is reviewed, based on collections from more than 130 caves in 31 karst areas. These totals represent approximately 14% of the known caves and about one half of the cavernous karst areas in the State. The distributions, ecological and conservation status of all taxa are discussed. More than 150 species, representing some 130 families in five phyla were identified. Species in at least 34 genera can be classified as troglobites or stygobionts. The fauna includes rare species, and species which are phylogenetic relicts, or have Gondwanaland affinities. Many taxa are undescribed. More so than for mainland Australia, the Tasmanian cave fauna shows a pattern of similarity with the cave faunas of other glacial and periglacial regions such as New Zealand, Japan, United States and Europe. The disjunct distribution patterns shown by some genera of harvestmen and beetles support the Pleistocene-effect theory to explain the evolution of terrestrial troglobites. The cave stygobiont fauna includes species of syncarids, amphipods, heteriids, phreatoicids, flatworms and hydrobiid molluscs. At least the amphipod component of this fauna did not develop from hypogean ancestors, but probably colonised caves from adjacent surface waters. Tasmania has the richest cave faunal assemblages in temperate Australia, with more than 70 taxa, consisting of more than 15 cave obligate species, recorded from some karst systems. Non karstic caves, such as dolerite boulder caves, also contain troglobitic species. Geological structure directly affects cave species diversity and ecological complexity. There is a general relationship between cave size and density, and species richness. Size of the karst area, vertical relief of the limestone outcrop and the type of surface vegetation also influence biodiversity in caves. Some populations of cave invertebrates in Tasmania are 'vulnerable' or 'endangered', whilst others have recently become extinct. They are threatened by limestone quarrying, forestry operations, agricultural practises and recreation. The effect of quarry operations on Bradley Chestermans Cave include sedimentation, gross pollution and local extinction of aquatic fauna. Quarry run off has caused depletion of populations of aquatic snails in the Exit Cave system. Management requirements for Kubla Khan Cave include the protection of sensitive habitats from the impacts of cave visitors. Twenty eight sites of special conservation value are listed. Conservation and management initiatives for Tasmania are discussed, including collecting ethics, vulnerable habitats and species, and minimum impact caving techniques.