Identifying freshwater ecosystems with nationally important natural heritage values

This report describes a biogeographic classification for use in identifying water bodies of national importance in New Zealand. The classification aims to identify geographic units likely to have experienced similar physical disturbance regimes, while taking cognisance of potential recolonisation pathways and/or geographic barriers to the dispersal of freshwater biota. The classification is based on: biotic distributions, particularly those of non-diadromous fish (the New Zealand Freshwater Fish Database); genetic similarity between different populations, as determined from molecular analyses; and physical disturbances, particularly the Last Glacial Maximum, volcanic eruptions in the central North Island and seismic activity, especially in mountainous parts of the South Island. Seven biogeographic provinces and 19 units have been defined.