by Eugenie Sage
Yesterday was the UN International Day for Biological Diversity. The theme for this year was Water and Biodiversity. In New Zealand our native freshwater species are extremely vulnerable. Our longfin eels are on a pathway to extinction yet are still being caught commercially. Other freshwater species have no or little protection compared to our terrestrial species. Threats to our freshwater species include habitat destruction and degradation, whether through water pollution, changes to the river (eg channelisation for flood control) or vegetation clearance on river banks ( which results in lack of shade and shelter, so water temperatures increase and there are fewer shady areas for fish to hide).
Additionally many of our freshwater fish migrate to the ocean meaning dams and other obstructions to river flow can isolate populations and prevent access to parts of catchments. The draining of around 95% of our wetlands means that many species which call wetlands home are left with nowhere to live with nowhere to live.
We can make a difference to the survival of our freshwater fish, and by doing so make our rivers safe for swimming. We need strong national environmental standards for water quality so that councils will include effective rules in their plans. Rules which limit the amount of pollutants in our rivers, streams, and lakes and which focus on maintaining and enhancing water quality. We don’t want limits on nitrate and phosphorus which allow water quality to decline further as intensive agriculture expands.
Effective national standards for water quality would ensure that we work to have nitrogen levels in rivers and streams below the levels which encourage phytoplankton growth and algal blooms. These blooms make rivers unsightly, can reduce oxygen levels so that fish die and can be toxic to larger animals such as dogs and humans. The Government is working on national objectives for water quality. Given National’s agenda of promoting and subsidising irrigation development these objectives are unlikely to ensure that children can swim safely in our rivers. We need limits on pollution that protect our environment, the cornerstone of our economy. We need them now.