Qualitative and quantitative variation in the macrobenthic fauna of the Original Lake and new lake areas of Great Lake and Arthurs Lake, Tasmania

Abstract

Faunal variation between sample sites in Great Lake and Arthurs Lake, using both qualitative and quantitative data, was analysed. Cluster analysis and principal coordinates analysis showed that the fauna of the original lake areas of both lakes is distinct from the fauna of the newly flooded areas. Closer relationships exist between the faunas of the old level of the two lakes than between the faunas of the old and new levels within either lake. The distinction is not attributable to depth but may be influenced by substrate differences. The effects of abnormal fluctuations in water level on benthic fauna are discussed. Biomass variation between the sample sites was examined in relation to component species groups. The sites at the old level were dominated by oligochaetes whereas chironomids contributed most to the sites at the new level. Consistent seasonal peaks were evident in the biomass at sites at the new level but not at sites at the old. The mean annual biomass levels (wet wt) for Great Lake (13.9 g m^-2) and Arthurs Lake (35.9 g m^-2) are compared with recorded values for other Australian and overseas lakes. Biomass levels of Australian lakes in general are also discussed.