Worsening droughts threatening New Zealand's indigenous wildlife

The increase in extreme droughts is a major threat to New Zealand's unique biodiversity, according to a University of Canterbury study.

New Zealand farmers were hard hit by one of the worst droughts on record in March, but as droughts became more frequent and intense, native creatures were also suffering, said researcher Richard White.

The study measured the impact of the drought on the endangered brown mudfish living in shallow pools in the ancient forests of the west of the South Island, where the rainfall was normally about 10 mm a day.

"Brown mudfish are extremely hardy and can cope with long periods without water, which they frequently experience in their forest pools, some of which are only 5 cm deep," White said in a statement Monday.

"However, this year's drought may have been more intense than the fish may have previously experienced and their population response to the drought may be indicative of how less hardy fish species will cope with future climate change."

More than 850 mudfish from 41 areas were monitored during the drought, which brought a maximum daily water deficit of 91 mm.

"The drought had a massive effect on brown mudfish mortality, with 25 percent of fish dying in most areas and up to 45 percent dying in the most shallow, drought-prone pools," said White.

"In contrast, almost no fish died during the non-drought period leading up to March. These results alarmingly show that drought can be devastating to even the most drought-hardy fish in New Zealand."

White said less drought-hardy fish, such as whitebait and trout, might have fared far worse.