This report presents and tests a macroinvertebrate metric for New Zealand streams and rivers that is sensitive to changes in flow. It will help freshwater scientists and managers test whether changes in flows are affecting conditions for aquatic life in streams and rivers.
Invertebrates living in streams and rivers, such as snails and insect larvae (referred to as macroinvertebrates), have different levels of tolerance to pollution and damage to habitat. This allows freshwater scientists and managers to use measures of stream macroinvertebrates as indicators of ecosystem health in our waterways.
In New Zealand, the widely used Macroinvertebrate Community Index (MCI) was developed to indicate the effects of organic pollution, but does not diagnose what could be causing stress. For example, flow, sediment, and periphyton (slime), as well as many other factors, can all influence MCI scores.