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Regional estuary monitoring programme (REMP) data report: Benthic macrofauna communities and sediments - July 2002 to April 2004: Southern Firth of Thames and Whaingaroa (Raglan) harbour

Report: TR06/27
Author: Malene Felsing, Nathan Singleton and Bronwen Gibberd

Abstract

In April 2001, Environment Waikato initiated the Regional Estuary Monitoring Programme (REMP) at permanent monitoring sites in the southern Firth of Thames and Whaingaroa (Raglan) Harbour. The REMP is a long-term programme that monitors the temporal changes in intertidal sediment characteristics and benthic macrofauna communities which may occur as a direct or indirect consequence of catchment activity and/or estuary development. This report presents the sediment monitoring results and a suite of 26 'indicator' taxa characteristic of the intertidal benthic communities. It is envisaged that the REMP will provide relevant information useful in setting policy and assisting with the sustainable management of estuaries in the Waikato region.

This report documents the data found from 2 years of the monitoring programme. Detailed discussion and analysis of trends or patterns of change over time in the benthic macrofaunal communities will be reported on every 5 years in a separate trend report series for the Regional Estuary Monitoring Programme.

Regional Estuary Monitoring Programme (REMP) Data Report: Benthic Macrofauna Communities and Sediments - July 2002 to April 2004: Southern Firth of Thames and Whaingaroa (Raglan) Harbour
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Table of Contents

Executive summary vii
1 Introduction 1
2 Methods 1
2.1 Field sites and sampling regime 2
2.2 Sample collection and processing 3
2.2.1 Benthic macrofauna 3
2.2.2 Sediment characteristics 3
2.2.3 Southern Firth of Thames bed level 4
2.3 Statistical analysis 5
3 Results 7
3.1 Benthic macrofauna community structure 7
3.1.1 Southern Firth of Thames 7
3.1.2 Whaingaroa (Raglan) Harbour 7
3.2 Changes in the abundance of individual species and taxonomic groups 10
3.2.1 Southern Firth of Thames 10
3.2.2 Whaingaroa (Raglan) Harbour 14
3.3 Changes in the composition of indicator species/taxa assemblages 18
3.3.1 Southern Firth of Thames 18
3.3.2 Whaingaroa (Raglan) Harbour 30
3.4 Sediment characteristics 41
3.4.1 Surficial sediment grain size 41
3.4.2 Shell hash 44
3.4.3 Sediment organic matter content 44
3.4.4 Sediment photosynthetic pigment concentration 45
3.4.5 Southern Firth of Thames 48
3.4.6 Whaingaroa (Raglan) Harbour 48
3.5 Southern Firth of Thames sediment bed level 48
3.5.1 Kaiaua 48
3.5.2 Miranda 49
3.5.3 Gun Club 49
3.5.4 Kuranui Bay (Tararu) 50
4 Discussion and recommendations 50
References 54
Appendix 1 - Southern Firth of Thames species/taxonomic group abundances 55
Appendix 2 - Whaingaroa Harbour species/taxonomic group abundances 82
Appendix 3 – Sediment grain size distribution 110
Appendix 4 – Dry weight shell hash 114
Appendix 5 – Sediment organic matter content 122
Appendix 6 – Sediment photosynthetic pigment concentration 126
Appendix 7 – QA/QC procedures 130