Skip to main content

Intertidal habitat mapping for ecosystem goods and services: Waikato estuaries

TR201352

Report: TR 2013/52

Author: H Needham, M Townsend, J Hewitt, S Hailes (National Institute of Water & Atmospheric Research Ltd)

Abstract

In January 2013, Waikato Regional Council contracted the National Institute of Water and Atmospheric Research (NIWA), to develop rapid assessment techniques for mapping of intertidal habitats associated with the provision of ecosystem goods and services. Assessment techniques were successfully trialled for mapping the intertidal area of Tairua Estuary.

This report documents the application and adaptation of the habitat mapping methodology for thirteen estuaries and harbours within the Waikato region: Otahu River, Whangamata Harbour, Wharekawa Harbour, Purangi River, Whitianga Harbour, Whangapoua Harbour, Kennedy Bay, Waikawau Bay, Port Charles, Colville Bay, Coromandel Harbour, Te Kouma Harbour and Manaia Harbour.

Field based observations of intertidal areas in each of the 13 study locations were undertaken to rapidly identify habitat characteristics linked to the provisioning of ecosystem goods and services. As much of the intertidal area in each estuary that could feasibly be covered given spring low tides was covered. Handheld global positioning systems (GPS) were used to demark boundaries between habitats, and geo-referenced photographs were collected inside each habitat type. All data were processed and converted into GIS map layers.

Sediment information from each study location was also detailed for each habitat polygon using five broad categories (mud, sand, shell-hash, sandy mud/muddy sand mixture, and gravel mixture). Sediments were classified based on visual observations, textural analysis and sinking depth underfoot. Sediment samples were collected from each estuary for quantitative verification at a later date.

There were three habitats defined by the characteristics/dominance of the flora: seagrass, mangroves and pneumatophores (the aerial roots of mangroves).

There were 12 habitats defined by characteristics/dominance of the fauna: cockles, pipi, cockles and pipi, Wedge shell (Macomona), oysters, crustacean burrows, crabs and cockles, tubeworms and cockles, snails (Amphibola), ‘low density deposit feeders’ (our baseline/LD deposit feeding community composition), ‘mounds and pits’ (similarly dominated by deposit feeders but featuring a distinct surface topography) and ‘low fauna’ (where macrofauna were extremely sparse).

Intertidal habitat mapping for ecosystem goods and services: Waikato estuaries [PDF, 13 MB]

Contents
  Executive summary 4
1 Introduction 5
2 Methods 7
2.1 Derivation of habitat types 7
2.2 Field-gear 7
2.3 Field techniques 8
2.4 Sediment assessment and particle sizes 9
3 Precision obtained in field and repeatabiity 12
3.1 Instruments 12
3.2 Precision 12
3.3 Repeatability 13
4 Habitat categories 14
4.1 Flora 14
4.2 Fauna 15
5 Habitat maps 19
5.1 Otahu River 19
5.2 Whangamata Harbour 21
5.3 Wharekawa Harbour 23
5.4 Purangi River 25
5.5 Whitianga Harbour 27
5.6 Whangapoua Harbour 29
5.7 Kennedy Bay 31
5.8 Waikawau Bay 33
5.9 Port Charles 35
5.10 Colville Bay 37
5.11 Coromandel Harbour 39
5.12 Te Kouma Harbour 41
5.13 Manaia Harbour 42
6 Threats 44
7 Site habitat photos 46
7.1 Otahu River 46
7.2 Whangamata Harbour 47
7.3 Wharekawa Harbour 48
7.4 Purangi River 49
7.5 Whitianga Harbour 50
7.6 Whangapoua Harbour 52
7.7 Kennedy Bay 55
7.8 Waikawau Bay 56
7.9 Port Charles 57
7.10 Colville Bay 58
7.11 Coromandel Harbour 59
7.12 Te Kouma Harbour 60
7.13 Manaia Harbour 61
8 Acknowlegements 62
9 References 63