Ancient creatures re-discovered in southern NZ

Department of Conservation workers and scientists from the National Institute of Water & Atmospheric Research (NIWA) have been searching for phreatoicids (pronced “free-at-o-ik-ids”)

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and found that the survival of these tiny, blind isopods looks promising, provided ground waters and wetlands are protected. The intensive search of over 230 locations yielded phreatoicids at 66 places. The scientists believe they have now found all the known species, including some thought to be extinct, and have even discovered some new ones.

Phreatoicids were surprisingly abundant when present; on Ruapuke Island in Foveaux Strait, for example, densities were estimated at over 200 per square metre. On Stewart Island, phreatoicids were common close to Oban township, as well as the remote Toitoi Flats wetland and other locations. Dense populations were found in several modified habitats, notably in drainage channels downstream of Bayswater Peatland Scenic Reserve near Otautau in Southland, amongst submerged, dead leaves of introduced grasses around road culverts on several roads in Southland, and on Macrocarpa tree roots in one drainage ditch.

Phreatoicids have been described as “ghosts of Gondwana”, unchanged for over 350 million years, phreatoicids date back to the time when the islands that make up New Zealand were part of the great southern land mass known as Gondwana. Phreatocids are also found in South Africa and India which were also part of that landmass. Dr Graham Fenwick, NIWA’s Assistant Regional Manager in Christchurch, stated in a press release that these creatures play a major role in cleansing the region’s groundwater, keeping drinking water naturally pure. Their high abundances prove that they can survive in the face of considerable human changes to the landscape, so long as wetlands, in their various forms, are kept intact.