Notopala sublineata: an endangered snail within the Murray-Darling Basin, NSW

The introduction of flow regulation to the river systems of the Murray-Darling Basin (MDB) in southeastern Australia has caused significant alterations to the native aquatic invertebrate communities. There has been an almost complete disappearance of the freshwater molluscan diversity, particularly the viviparid snail Notopala sublineata. The subspecies Notopala sublineata sublineata is assumed to be extinct in the wild and Notopala sublineata hanleyi is surviving solely in an irrigation pipeline off the lower Murray River in South Australia. This thesis examines the macroinvertebrate communities of the littoral zone from river sections along the Murray, the Murrumbidgee, the Namoi, the Upper Barwon-Darling and the Lower Darling rivers. The goal of these surveys was to detail the macroinvertebrate assemblages, specifically the molluscan diversity, surviving within the rivers and irrigation structures and ultimately to determine the current distribution and conservation status of Notopala sublineata sublineata and Notopala sublineata hanleyi. The macroinvertebrates collected during these surveys indicate a shift in the aquatic invertebrate community from taxon found in lotic systems to invertebrates that show a preference to lentic systems. The results also support reports that there has been a severe decline in the molluscan diversity, with a total of only eight species collected, of which only three species occurred within the river channels. The results also indicate a complete loss of both Notopala sublineata subspecies from the rivers of the MDB, increasing the possibility that Notopala sublineata sublineata is extinct. A living population of Notopala sublineata hanleyi was discovered, however, in the Western Murray Irrigation pipeline off the Murray River in NSW. This surviving population now provides an opportunity for breeding and rehabilitation projects in NSW. Although individual attention needs to be paid towards Notopala sublineata the listing of Endangered Ecological Communities and the establishment of subsequent recovery programs for those communities is the best option for the conservation of the aquatic macroinvertebrates of the MDB.