Water quality and benthic macroinvertebrate communities in karst landscapes of North Island, New Zealand: influences of water sources, habitat type and anthropogenic disturbances

Abstract

In karst landscapes, aquatic habitats differ in terms of the relative contributions of different water sources (allogenic surface stream vs autogenic karst groundwater) and their geomorphology. Benthic macroinvertebrate community structure in these habitats is likely to vary in response to this heterogeneity, as well as to the physicochemical differences between water flowing through pasture vs native forest dominated catchments. Surveys were conducted to examine the influences of water source, habitat type (main stream-ways and side passages in caves, and epigean springs) and surrounding land use (native forest or pasture) on the water quality and benthic community structure in the Maniapoto Karst, North Island, New Zealand. Generally, springs and cave side passages received more autogenic water, indicated by lower temperatures and higher conductivities, than the main stream-ways of caves. However, in terms of community structure, the epigean springs and cave side passages were most distinct from each other, whilst the main stream-ways of caves were intermediate between the other two habitats. Temperature and nitrate concentrations were higher in sites surrounded by pasture than those in native forest, but surrounding land use exerted less influence on macroinvertebrate community structure than habitat type. A comparison of community structure in caves with high and low tourist traffic failed to identify any significant effects.

Keywords:

• limestone
• cave
• spring
• autogenic
• allogenic
• groundwater

Acknowledgements

We would like to thank all of the landowners who allowed access to sites during this study. Thanks to Dave Smith (Department of Conservation) and Huia Davis for help in locating suitable sites. Thanks also to the many NIWA staff who assisted in the processing of invertebrate samples. Graham Fenwick and two anonymous reviewers provided helpful recommendations to improve the manuscript. Funding for this work was provided by the Foundation for Research, Science and Technology (Contract No. CO1X0503), Environment Waikato and the Department of Conservation. Special thanks to Kevin Collier (Environment Waikato), for without his support and enthusiasm this study would not have been possible.