Ecologists in New Zealand say the island nation's freshwater species are in serious trouble. In a recent report, scientists reveal 74 percent of the islands' freshwater fish, mussel and crayfish species are threatened by extinction.

Freshwater biodiversity is threatened by a variety of factors, say Mike Joy and Professor Russell Death, two of New Zealand's leading freshwater ecologists. The most significant threat, however, is water quality.

A combination of pollution and algae, fueled by fertilizer runoff, are choking out native species.

Combine diminishing water quality and shrinking habitat with the pressures of commercial exploitation and exportation, and it's no surprise that New Zealand's freshwater species are disappearing.

Despite public concerns about water quality, researchers say the government continues to do little to effectively combat the problem.

"The government's plans to drastically increase agricultural production will exacerbate all the problems," Mike Joy, a researcher at Massey's Institute of Agriculture and Environment, said in a press release. "There are even plans to increase development of our rivers and wetlands, exacerbating these problems. It [fresh water quality] is a taonga of paramount importance and valued for its contribution to biodiversity, recreation, the economy and the overall wellbeing of New Zealanders."

The new report was published by the Society for Conservation Biology. The study's senior author, Emily Elston, says stronger water quality standards alone won't save New Zealand's freshwater biodiversity. A more comprehensive approach is necessary.

Among other things, the reports authored by Elston and her colleagues, calls for a more holistic approach to conservation -- with stronger efforts to restore and maintain the health of wetlands, estuaries, groundwater ecosystems and wide riparian zones, which connect freshwater habitat.

Researchers also call for stricter regulations on commercial and recreational harvesting of the nation's endemic fish species and invertebrates.

"We can implement some real changes which will not only improve the freshwater environments for the species living in them, but also for us by providing clean water and wonderful places for fishing," Elston said. "We have to do something about the increasingly poor state of our rivers, lakes and groundwater resources. Business as usual is no longer an option."