Biogenic habitats on New Zealand’s continental shelf. Part II: National field survey and analysis New Zealand Aquatic Environment and Biodiversity Report No. 202 E.G. Jones M.A. Morrison N. Davey S. Mills A. Pallentin S. George M. Kelly I. Tuck ISSN 1179-6480 (online) ISBN 978-1-77665-966-1 (online) September 2018 Requests for further copies should be directed to: Publications Logistics Officer Ministry for Primary Industries PO Box 2526 WELLINGTON 6140 Email: [email protected] Telephone: 0800 00 83 33 Facsimile: 04-894 0300 This publication is also available on the Ministry for Primary Industries websites at: http://www.mpi.govt.nz/news-and-resources/publications http://fs.fish.govt.nz go to Document library/Research reports © Crown Copyright – Fisheries New Zealand TABLE OF CONTENTS EXECUTIVE SUMMARY 1 1. INTRODUCTION 3 1.1 Overview 3 1.2 Objectives 4 2. METHODS 5 2.1 Selection of locations for sampling. 5 2.2 Field survey design and data collection approach 6 2.3 Onboard data collection 7 2.4 Selection of core areas for post-voyage processing. 8 Multibeam data processing 8 DTIS imagery analysis 10 Reference libraries 10 Still image analysis 10 Video analysis 11 Identification of biological samples 11 Sediment analysis 11 Grain-size analysis 11 Total organic matter 12 Calcium carbonate content 12 2.5 Data Analysis of Core Areas 12 Benthic community characterization of core areas 12 Relating benthic community data to environmental variables 13 Fish community analysis from DTIS video counts 14 2.6 Synopsis Section 15 3. RESULTS 17 3.1 Sediment analysis 19 3.2 Regional Descriptions 24 Middlesex Bank to North Cape 24 Middlesex Bank (Site 7) 24 The Three Kings Islands (Sites 5, 6) 26 Cape Reinga west (Sites 8, 9) 29 North Cape (Sites 1–4) 31 West Coast North Island – Kaipara and North Taranaki Bight canyon heads 35 “Three Holes Canyon” (Site 10) 36 North Taranaki Bight “North block” (Site 11) 38 The “Coral Canyon” – North Taranaki Bight (Site 13) 39 “The Drop Off”, North Taranaki Bight (Site 12) 41 “The Well”, North Taranaki Bight (Site 14) 43 Golden and Tasman Bays / D’Urville Island 46 Separation Point (Site 15) 46 West of D’Urville Island, Tasman Bay (Site 16) 49 North-east of D’Urville Island, outer Marlborough Sounds (Site 17) 51 East of D’Urville Island (Site 18) 52 Kaikoura to Banks Peninsula region 55 Conway Ridge (Site 19) 56 North Canterbury, Pegasus Canyon and Pegasus Bay “Wire-weed” areas (Sites 20, 21 and 22) 58 The Otago region 62 The “Hay Paddock” (Site 23) 63 Inshore of the Hay Paddock (Site 24) 65 Cornish Head (Karitane) Canyon (Sites 29 and 30) 67 Otago Shelf bryozoan thickets (Site 25) 71 Otago Shelf queen scallop grounds (Sites 26 and 27) 73 Southland region 76 East Stewart Island reef (Site 31) 76 The Mutton-Bird Islands and southern Foveaux Strait (Sites 32 and 33) 78 Mason Canyon, west of Codfish Island, Southland (Site 34) 81 East Cape region 84 Table Cape (Sites 35 and 36) 85 Eastern Ariel Bank (Site 37) 88 East coast “White straw” (tube-worm) areas (Site 38, 39 and 40) 90 Ranfurly Bank (Sites 41 – 45) 92 4. ANALYSIS OF CORE AREAS 96 4.1 North Taranaki shelf edge canyons (Sites 13 and 14) 96 Multibeam mapping and topographic features of North Taranaki canyons 96 Invertebrate diversity from biological sampling of north Taranaki canyons 99 Invertebrate assemblages observed in DTIS imagery from the north Taranaki canyons. 101 Non-hierarchical cluster analysis of benthic fauna observed in DTIS images from the North Taranaki canyons 104 All fauna 104 Sessile fauna only 106 Relationships between benthic community data, remote sensing and other potential explanatory variables for the north Taranaki canyons. 113 Fish diversity and abundance in the north Taranaki canyons 116 Biological samples (beam trawl and rock dredge) 116 DTIS (video) 117 4.2 East Coast South Island: North Canterbury Bight, and Hay Paddock 122 Multibeam mapping and topographic features of east coast South Island “wire-weed” beds 122 Invertebrate diversity from biological sampling in the east coast South Island “wire-weed” beds 126 Invertebrate assemblages observed in DTIS imagery from the east coast South Island “wire-weed” sites 129 Non-hierarchical cluster analysis of benthic fauna observed from the east coast South Island “wire-weed” sites. 135 Full community data 135 Sessile (habitat-formers) data 136 Mobile fauna 145 Relationships between benthic community, remote sensing and other potential explanatory variables for east coast South Island “wire-weed” sites. 147 Full community 147 Sessile fauna only 149 Fish diversity and abundance observed at east coast South Island “wire-weed” sites. 150 Biological samples (beam trawl) 150 DTIS (video) 152 4.3 Ranfurly Bank 159 Multibeam mapping and topographic features of Ranfurly Bank 159 Invertebrate and algal diversity from biological sampling on Ranfurly Bank 164 Macro-algae 164 Invertebrates 165 Central (<50 m water depth) – Site 42 165 Mid slopes (50 to 110 m) – Sites 41 and 43. 165 Deep slopes and outcrops (>110 m) – Sites 44 and 45 167 Invertebrate assemblages from DTIS imagery from Ranfurly Bank 169 Non-hierarchical cluster analysis of benthic fauna observed at Ranfurly Bank 171 Full community 171 Sessile fauna only 173 Relationships between benthic community data and remote sensing and other potential explanatory variables for Ranfurly Bank 183 Full community 183 Sessile fauna only 184 Fish diversity and abundance observed on Ranfurly Bank 186 5. BROADER SCALE SYNOPSIS 192 5.1 Nature and extent of the biogenic habitats observed. 192 5.2 Ecological roles 201 Primary production 201 Bentho-pelagic coupling and secondary production 202 Enhanced Biodiversity 203 Fish nursery areas 204 Sea perch (Helicolenus spp.) 204 Ling (Genypterus blacodes) 205 Blue cod (Parapercis colias) 206 Tarakihi (Nemadactylus macropterus) 207 5.3 Taxonomic advances 207 5.1 Correspondence between LEK and Tangaroa voyage observations and results. 213 5.2 Large scale threats to biogenic habitats 224 Commercial fishing 224 Sedimentation 229 5.3 The power of multibeam sonar to detect and map biogenic habitats 234 6. FINAL CONCLUDING REMARKS 238 7. ACKNOWLEDGEMENTS 238 8. REFERENCES 239 9. APPENDICES 251 Appendix 1: Shipboard data collection methods in full 251 Appendix 2: Sediment size: size scale adopted in GRADISTAT 254 Appendix 3: OTUs used in Taranaki Canyons still image analysis. 255 Appendix 4: OTUs used in East Coast South Island still image analysis. 257 Appendix 5: OTUs used in Ranfurly Bank still image analysis. 259 EXECUTIVE SUMMARY Jones, E.G.; Morrison, M.A.; Davey, N.; Mills, S.; Pallentin, A.; George, S.; Kelly, M.; Tuck, I. (2018). Biogenic habitats on New Zealand’s continental shelf. Part II: National field survey and analysis. New Zealand Aquatic Environment and Biodiversity Report No. 202. 261 p. Biogenic habitats are a key component of coastal and continental shelf ecosystems throughout the world, and the associated economic and social values that human society receives from those systems can be significant. A project to map and determine the biodiversity and significance of biogenic habitats in New Zealand was conducted in two steps. First to tap into the knowledge held by commercial fishers through Local Ecological Knowledge (LEK) interviews and a review of existing scientific literature; second, to conduct field surveys to sample and map the key biogenic areas identified through LEK, and other sources. This report describes the findings from the field surveys. Two surveys to characterise biogenic habitats were undertaken from March to June 2011 using RV Tangaroa. The biogenic habitat locations ranged from Three King Islands down to Stewart Island, including off the northern Kaipara Harbour, the North Taranaki Bight, D’Urville Island, the North Canterbury Bight, the North Otago shelf, southern Foveaux Strait, areas off Gisborne, and Ranfurly Bank off East Cape. Overall, 35 sites within six geographic regions were visited. Multibeam sonar was deployed at most sites, and underpinned the associated biological and seafloor sampling, which summed to 194 Deep Towed Imaging System (DTIS), 28 beam trawl, 35 rock dredge, and 124 sediment samples/deployments. A diverse range of seafloor types and ecological assemblages were encountered, including sponge gardens on both soft and hard seafloors, extensive chaetopterid tube-worm meadows, deep-water rhodolith beds and Ecklonia radiata (brown kelp) beds (a ‘new’ deep-water form), bryozoan thickets, hard and soft corals, sea urchin and sea pen fields on soft sediments, gorgonian fields, and crinoid fields. The surveys produced a close correspondence between areas identified as biogenic habitats by the LEK process, and the empirical field observations. Biological collections returned over 1000 species (a conservative estimate), including 919 invertebrate species (95 new to science (10.3%), 13 new to New Zealand); 46 macro-algae (11 new to science (24%)), and 76 small fish species (10 described only to genus, 3 new species described; putatively 17% new species). Sponges were a particularly under-described group despite being important habitat formers, with 54 new species out of the 120 identified from the samples processed to date (43%). Three regions were analysed in greater detail; two canyons along the North Taranaki Bight, the east coast South Island “Hay Paddock” and “Wire-weed” areas, and Ranfurly Bank, East Cape. The multibeam, DTIS, and biological samples from these three areas were processed, and in- depth descriptive and statistical analyses completed to describe the species assemblages, and their distribution relative to both remotely and directly measured physical variables. Non- heirarchichal k means clustering was used to identify faunal communities based on the sessile macrofauna observed in still images. Of the fourteen “habitat clusters” identified, some could be classed as biogenic habitats, with important sessile taxa including sponges, chaetopterid tube worms, red/brown/green macro-algae, bryozoans, gorgonians, corals, ascidians, and hydroids.