REVIEW OF THE STATUS, DISTRIBUTION, AND CONSERVATION OF FRESH-WATER INVERTEBRATES IN NEW-ZEALAND

The international significance of the New Zealand freshwater macroinvertebrate fauna is established, existing and potential threats to it are reviewed, and regional patterns of invertebrate distribution based on current information are examined. Distinctive features of international significance are the poor representation or absence of some invertebrate groups, a high degree of speciation amongst other groups, an apparently large number of primitive species, a high degree of endemicity, and the southern-most representatives of some cosmopolitan groups. The greatest threat to freshwater invertebrates has been loss and reduced quality of habitat caused by human-induced modifications to the catchment, riparian and channel environments, and changes to water quality and river flows. Predation by alien species of invertebrates, fish, and birds may also have had significant impacts on the native aquatic invertebrate fauna. Analysis of invertebrate distributions has identified 154 species known from surface waters on mainland New Zealand that have ''restricted'' distributions (known from three or fewer Ecological Regions). Twenty species colonising underground waters are also known from three or fewer Ecological Regions, and 36 species of freshwater invertebrates are known only from offshore islands. Species- and habitat-based approaches to invertebrate conservation are evaluated.