A review of deep-sea benthic biodiversity associated with trench, canyon and abyssal habitats below 1500 m depth in New Zealand waters A.N. Lörz ¹ K. Berkenbusch² S. Nodder¹ S. Ahyong3 D. Bowden¹ P. McMillan¹ D. Gordon¹ S. Mills¹ K. Mackay¹ ¹ NIWA, Private Bag 14901, Kilbirnie, Wellington. ² Department of Marine Science, University of Otago, PO Box 56, Dunedin. 3 Australian Museum, 6 College Street, Sydney, NSW 2010, Australia. New Zealand Aquatic Environment and Biodiversity Report No. 92 2012 Published by Ministry of Agriculture and Forestry Wellington 2012 ISBN 978-0-478-38782-7 (Online) ISSN 1176-9440 (Print) ISSN 1179-6480 (Online) © Crown Copyright, 2012 - Ministry of Agriculture and Forestry Lörz, A.N.; Berkenbusch, K.; Nodder, S.; Ahyong, S.; Bowden, D.; McMillan, P.; Gordon, D.; Mills, S.; Mackay, K. (2012) A review of deep-sea benthic biodiversity associated with trench, canyon and abyssal habitats below 1500 m depth in New Zealand waters. New Zealand Aquatic Environment and Biodiversity Report No 92. 133 p. This series continues the Marine Biodiversity Biosecurity Report series which ceased with No. 7 in February 2005. Requests for further copies should be directed to: Publications Logistics Officer Ministry of Agriculture and Forestry P O Box 2526 WELLINGTON Telephone: 0800 00 83 33 Facsimile: 04-894 0300 This publication is also available on the Ministry of Fisheries website at http://fs.fish.govt.nz go to Document library/Research reports or the MAF website at: http://www.maf.govt.nz/news-resources/publications.aspx. EXECUTIVE SUMMARY Lörz, A.N.; Berkenbusch, K.; Nodder, S.; Ahyong, S.; Bowden, D.; McMillan, P.; Gordon, D.; Mills, S.; Mackay, K. (2012). A review of deep-sea benthic biodiversity associated with trench, canyon and abyssal habitats below 1500 m depth in New Zealand waters. New Zealand Aquatic Environment and Biodiversity Report No 92. 133p. We review the state of knowledge of benthic biodiversity and ecosystem functioning in deep-sea abyssal, canyon and trench habitats in the New Zealand Exclusive Economic Zone and the Ross Dependency, and make recommendations for future deep-sea research in depths exceeding 1500 m. All biological information in scientific papers and reports from New Zealand below 1500 m was reviewed and an exhaustive search of multiple data sources was conducted. The area of the deep seafloor below 1500 m covers more than 65% of New Zealand’s Exclusive Economic Zone. A total of 1489 benthic gear deployments have been conducted by New Zealand- based sampling initiatives since 1955, most of which were focused on obtaining geological samples. Less than 0.002 % of New Zealand’s deep-sea environment (i.e. in terms of seabed area) below 1500 m has been sampled. All taxonomy-based studies of all taxa reported in New Zealand waters below 1500 m have been reviewed. To date, 8 species of Bacteria, 293 species of Protozoa, 785 species of invertebrates, and 56 fish species have been recorded from water depths greater than 1500 m. Most of these species are known only from single or relatively few stations collected mainly during historical, non-New Zealand sampling initiatives, notably the British Challenger, Danish Galathea or Russian Vityaz expeditions. Many of these specimens are held at the associated institutions in London, Copenhagen and Moscow, and are therefore not immediately available for scientific study in New Zealand. Few ecological studies in New Zealand waters have focused on assemblage patterns or processes at depths exceeding 1500 m. Of these, most have been on the Chatham Rise and surrounding areas, with sampling conducted across a wide depth range (from shallow to deep-sea sediments), sometimes as part of interdisciplinary research of particular ecosystem processes. Ecological information on benthic fauna and demersal fish from depths below 1500 m is restricted to the Kermadec Trench. Process- orientated studies are limited to pelagic-benthic coupling (and ocean productivity) research on the Chatham Rise slopes, and trophic interactions research in hadal environments (below 6000 m) of the Kermadec Trench. The scarcity of information from New Zealand is particularly evident when compared with other regions worldwide, for which detailed descriptions of invertebrate and fish assemblages exist, and where the availability of long-term and experimental data has enabled the elucidation of deep-sea ecosystem processes. More than 8000 images are known to have been taken of the seafloor below 1500 m in the New Zealand region, covering an area of approximately 0.016 km2. Over 4000 of the images held at NIWA exist either as paper prints or negatives and ideally should be digitised for future storage and access for analyses. Analysis of these photographic images should yield considerable information about deep-sea biodiversity and ecosystem function in the New Zealand region and could be used to answer a number of research questions (especially around deep-sea benthic biodiversity). Recommendations on how to potentially further analyse existing data from images, databases and actual specimens are provided. The technical challenges, including gear requirements to sample deep- sea New Zealand benthos and potential future investments, are summarised. Ministry of Agriculture and Forestry Review of Deep Sea Benthic Biodiversity • 3 Recent research in the Southern Ocean highlights the ecological and evolutionary importance of the southeastern Pacific Ocean. There are clearly many research questions about benthic ecosystems in New Zealand waters below 1500 m depth that if addressed could increase knowledge to levels similar to those in other regions of the globe. This would require expanding New Zealand’s deep-sea sampling capabilities and developing a long-term, integrated research programme, potentially in collaboration with overseas research institutions. 1. INTRODUCTION The objective of the review is to assess the state of knowledge of biodiversity and ecosystem function in New Zealand deep-sea abyssal, canyon and trench habitats, and make recommendations for future research, under Ministry of Fisheries (MFish) project ZBD2008-27. 1.1 Rationale and aims of the review Seventy-one percent of the Earth's surface is covered by oceans. Of this, 87% of the ocean's surface and 90% of the ocean's volume is covered by water deeper than 1500 m. Habitats such as abyssal plains, deep-sea canyons, seamounts, channels and trenches that occur at depths below 1500 m occupy approximately 65% of New Zealand’s Exclusive Economic Zone (EEZ), distributed in three depth zones — bathyal (down to 3000 m), abyssal (3000–6000 m) and hadal (below 6000 m). Little is known, however, about benthic biodiversity and ecosystem functioning in these zones in New Zealand, or how these are linked to more productive surface waters. The ecological and evolutionary relationships between deep-sea benthic biodiversity in New Zealand and other similar habitats around the world are also unknown. The tectonic setting of New Zealand astride the boundary between the Pacific and Australian crustal plates provides a “natural laboratory” for studying such bathymetrically complex environments. The rationale for the upper depth limit of 1500 m in the present review builds on the preliminary review of New Zealand’s deep-water benthic biodiversity prepared by Key (2002), and relates to the current depth limit of fishing. 1500 m is the maximal depth coverage by biodiversity projects under the regional Ocean Survey 20/20 (OS2020) mapping programme, administered by Land Information New Zealand (LINZ). The present review also includes habitats such as slope, troughs, plateaux and seamounts where they occur below 1500 m water depth. For the purposes of this review, the “New Zealand region” is bounded by latitudes 24° S to 57°30’ S and longitudes 157° E to 167° W. While the primary focus of the present review is abyssal environments within the New Zealand Exclusive Economic Zone (EEZ), we have included the Ross Sea as this is an area where New Zealand has responsibilities to the Comission for the Conservation of Antarctic Marine Living Resources. Data from three primary sources were collated and summarised for the present review: 1) Scientific papers and reports: all published accounts of studies below 1500 m depth in the New Zealand region and the Ross Dependency, including peer-reviewed scientific literature, faunal monographs and technical reports. 2) Databases and collections: emphasis was made on data held by two nationally funded collections that contain most deep-water fauna samples collected historically in New Zealand waters. These samples are housed within NIWA’s Invertebrate Collection (NIC), a core funded (ex FRST- funded) ‘nationally significant’ collection of marine invertebrates, and the National Museum of New Zealand Te Papa Tongarewa, funded by the Ministry of Culture and including deep-water invertebrates and fishes. Other relevant databases (e.g., Specify, Trawl) were also interrogated and relevant metadata collated. 3) Image collections: comprising all photographs of the seabed greater than 1500 m depth in the New Zealand region. These were taken mostly by NIWA or its predecessor organisation (the New 4 • Review of Deep Sea Benthic Biodiversity Ministry of Agriculture and Forestry Zealand Oceanographic Institute of the DSIR), with a small number by foreign vessels. All are available to NIWA but many have not yet been formally databased. 1.2 Specific Objectives Specific Objective 1 To assess the state of knowledge of biodiversity and ecosystem functioning in New Zealand deep-sea abyssal, canyon and trench habitats and make recommendations for future research. 1.3 Physical, geographical, and chemical description of the habitat being reviewed The physiography of environments below 1500 m in the New Zealand region is varied and complex (Figure 1), reflecting tectonic evolution of the largely submerged ‘Zealandia’ subcontinent over the last 80 million years (Kamp 1986; Sutherland 1995, 1999a, b; King 2000a, b; Campbell & Hutching 2007; Wood & Stagpoole 2007). In particular, this tectonic activity has been dominated by the development of an active plate boundary between the Pacific and Australian plates since 25 million years ago.