Otago is a region with unique ecological environments, in New Zealand and the world. Changing climate zones span changing landscapes from the Alpine Divide to the Pacific Ocean. Central Otago, in its own right, is a region that stands apart, having conditions supporting plants and animals that are found nowhere else on earth.
Central Otago is a semi-desert, with extreme seasonality and diverse landscapes. Outwardly, the region appears barren, however on closer inspection this harsh environment is teeming with as much bio-diversity as a forest - but on a much smaller scale. Many of these species are endemic to Otago. Some are only found in isolated areas of Central Otago, which could be described as a landscape sprinkled with ecological 'islands.' Climate and geography drive this diversity.
Midst this unusual landscape flows one of the most extraordinary rivers on the planet, the Clutha. Ranked among the swiftest rivers in the world, it has perhaps the rarest water type of any river. The Clutha's distinctive, clear turquoise waters are derived from cloudy glacial and snow-melt waters filtered in upland lakes - a particularly rare event world-wide. The Clutha is the highest volume river in New Zealand, and remarkably, it flows through the driest region of the country.
The Clutha River corridor is, effectively, an ecological corridor traversing the entire climate spectrum of Otago. Every section of the Clutha River corridor reflects a specialised set of conditions, and many of the species within each section are adapted specifically to that section, and are often isolated there.
Two of these ecologically unique river environments are the Rongahere Gorge, and the Upper Clutha glacial terrace corridor. Both are threatened by Contact Energy dams.
The below photos of forest species were taken in the Rongahere Gorge along the Clutha River. All of this forest is threatened by the proposed Tuapeka dam.
Protection status was awarded primarily because Birch Island has a nationally significant population of invertebrates, surviving in their isolated refuge, ostensibly because the island has remained predator free. In 1995, scientists investigating the invertebrate fauna on the island discovered several new species, including a Peripatus, a genus of Onychophoran. The Onychophora is an animal somewhat like a permanent caterpillar, part insect and worm. They have been suggested as warranting priority for conservation owing to their status as living fossils, being unchanged in 570 million years. Due to their predatory nature they also have potential as an indicator species in the assessment of biodiversity. Scientists also discovered unusual beetles, moths, snails and springtails. Birch Island has what is considered to be the most intact ecosystem of its kind in New Zealand.
Endangered Native Birds
The Rongahere native river corridor is home to some of New Zealand's rarest and most endangered native birds, including important populations of Karearea / NZ Falcon, South Island Robin, Yellow-Crested Parakeet / Karariki, and Mohua / Yellowhead (Mohoua ochrocephala).
Sightings of Karearea in the Rongahere confirm that the gorge is a favoured habitat for this highly endangered bird. There are no comprehensive figures for the number of Karearea surviving today, though Wingspan estimates no more than 1500 pairs in total. Although they have been fully protected for over 30 years their numbers are still so critically low that they are classified as a 'threatened' species - the second highest conservation priority. Karearea appear on the NZ Twenty Dollar note, but are disappearing from our environment.
The entire Rongahere Gorge would be lost if a dam was built at Tuapeka Mouth, destroying this unique ecological treasure forever.
Upper Clutha Corridor
Contact Energy states a preference for further dams on rivers “already modified” by dams, but this is particularly untrue of the Upper Clutha River, which is one of the most unspoiled, and least modified large wild and scenic rivers in New Zealand. It has characteristics that can rightly be claimed as unique in the world. It ranks among the swiftest of rivers anywhere, and it’s distinctive, clear turquoise waters are produced by a highly rare upland lake filtering process, decidedly atypical of glacial rivers which are normally discoloured to some degree by blue-grey rock flour.
The Upper Clutha River corridor is home to many important plant populations, including pillow native daphne (Pimelea pulvinaris), desert broom (Carmichaelia petriei), cushions (Raoulia), heath plants such as Leucopogon muscosus, and in more sheltered areas yellow-flowered Corokia cotoneaster, and the tree daisy Olearia odorata. Among the many native insects in the Upper Clutha, beetles are prominent. At least two are found only in the valley, including an undescribed chrysomelid in the genus Allocharis.
Numerous gold-rush era heritage sites are found along the upper and lower river. The newly established Reko’s Point Conservation Area beside the river near Luggate is an example of one such site, but many more remain virtually untouched.