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Development of a reference site network for invertebrate monitoring of wadeable streams in the Waikato

Report: TR05/29
Author: Kevin Collier, Johlene Kelly (Environment Waikato), Andy Haigh (GIServices)

Abstract

Every year Environment Waikato carries out state of the environment monitoring at over 100 stream and river sites throughout the Region, referred to as the Regional Ecological Monitoring of Streams (REMS) programme, using stream invertebrates as indicators of ecological condition. A review of the REMS programme in 2001 highlighted significant inadequacies in the number, geographic spread and selection of reference sites, short-comings that impeded comparisons of similar types of streams within and between ecoregions.

The following report describes the steps taken to identify accessible sections of wadeable streams (order 1-4) suitable for the REMS reference site network, stratified by four regionally dominant stream types and seven zones within the region. Use of GIS linked to stream typology, available spatial databases and aerial photography greatly enhanced the objectivity and efficiency of reference site selection.

Significant differences in invertebrate community composition were evident among some of the zones and stream types identified a priori, providing qualified support for the typology and spatial framework used in reference site selection. Variability among stream types was reduced using a multivariate analysis of a range standardised condition and diversity metrics derived from the invertebrate data. The metrics total sample richness, Margalef diversity, EPT richness and % EPT (both excluding Hydroptilidae), % dominant taxon, and MCI and QMCI were all found to have low variability among reference sites and were recommended for use in future analyses. A core set of 26 reference sites was identified as suitable for wadeable stream monitoring in the future.

Development of a Reference Site Network for Invertebrate Monitoring of Wadeable Streams in the Waikato
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Table of contents

Acknowledgements iii
1 Introduction 1
2 Methods 1
2.1 Background 1
2.2 Representing geographic spread and stream type 2
2.3 Site identification 5
2.4 Site selection and verification 9
2.5 Field sampling 11
2.6 Data analysis 12
3 Results 13
3.1 Representativeness of sites 13
3.2 Physico-chemical characteristics 17
3.3 Invertebrate communities 18
Conclusions 26
References 27
Appendix 1 29
Appendix 2 31
Appendix 3 33