1.0 Introduction
1.1 The biological diversity of New Zealand's marine ecoregion
Marine biodiversity is among the great taonga (treasures) of Aotearoa New Zealand. The geological isolation, range and complexity of habitats, and number of major ocean currents that influence New Zealand have created diverse marine communities. New Zealand's marine environment spans over 30 degrees of latitude, from subtropical waters to the subantarctic, and extends from the shallows to the deep sea. Comprising more than 4.2 million km2, the Territorial Sea and Exclusive Economic Zone (EEZ) are around 15 times the land area of New Zealand, making the country's jurisdiction predominately marine.
An estimated 22,000-23,0001species inhabit the marine environment of New Zealand, but to date fewer than 12,000 have been identified (Ministry for the Environment 2004). Among the known species are 126 seabirds, 50 marine mammals, more than 1,000 fish, 2,000 molluscs (e.g. snails, shellfish, and squid), 696 sponges, 615 echinoderms (e.g. kina, sea stars, sea cucumbers), 758 species of seaweed, and 700 species of micro-algae (Department of Conservation and Ministry for the Environment 2000; A. Stuart, personal communication, 2004). New species are being identified with almost every research sampling effort, some of which are known to occur only in New Zealand. Marine scientists estimate that as much as 80% of New Zealand's indigenous biodiversity is found in the sea (Department and Conservation and Ministry for the Environment 2000).
The wealth of New Zealand's marine life can be found living in such diverse habitats as mudflats, mangroves, seagrass and kelp beds, rocky reefs, seamounts, canyons, fiords, open water pelagos, and deep sea trenches. Some of these environments host unusual species assemblages that reflect the convergence of warm and cold waters or the influence of other physical forces. Conserving the fullest possible range of biodiversity - genes, species, communities, and ecological phenomena - at a scale that encompasses all of these environments is the ultimate goal of ecoregion conservation.
This document reports on the outcomes of an initial stage in New Zealand's Marine Ecoregion Initiative: a workshop in which marine scientists delineated and described key biodiversity sites and features in the ecoregion. The workshop served to summarise and synthesise biogeographic information on New Zealand's marine biodiversity, which is otherwise widely dispersed among various published and unpublished sources. The result is a collection of maps and descriptions of key biodiversity areas in the ecoregion that can serve as an information resource for those seeking a greater understanding of New Zealand's marine biodiversity.
1.2 Scope of this report and relation to other information initiatives in New Zealand
This report outlines the scope of the ecoregion project and relation to other information initiatives in New Zealand, explains the methodology and criteria employed by workshop participants to identify key marine biodiversity sites and features, presents the participants' selected areas and their attributes, identifies gaps in marine biodiversity knowledge, and explores future steps for conserving New Zealand's marine biodiversity.
The contents of this report reflect information generated by a group of marine scientists during a two-day workshop. The outcomes of the workshop are meant to serve as a summary of marine biodiversity in New Zealand and an indication of those areas and features, such as habitats, species concentrations and assemblages, and unique ecological phenomena, that marine experts recognise as having special physical and biological attributes. Due to the large spatial scale at which the assessment was conducted, this report is not intended to be a directory to the specific locations of marine species or assemblages in New Zealand waters. References to more detailed information are provided where available for the key areas identified by workshop participants.
Expert workshops led by WWF in other ecoregions of the world have included an assessment of threats posed to biodiversity through human activities. In the New Zealand exercise threats to marine biodiversity were not formally assessed, nor were threats used as a major criterion for determining the key areas for marine biodiversity. A subsequent process will identify threats to New Zealand's marine biodiversity. Threat identification is likely to draw upon the outputs of the marine scientists' workshop, but is a process that will involve a wider group of stakeholders with interests in the marine environment.
The marine ecoregion project initiated by WWF-New Zealand complements other spatially based information initiatives underway to aid understanding of New Zealand's marine environment. Other projects operating in New Zealand include the National Aquatic Biodiversity Information System (NABIS), The Marine Environment Classification System (MEC), the Interim Nearshore Marine Classification (INMARC), and the Estuary Environment Classification (EEC). Lack of knowledge about the marine environment is a major impediment to effective management. Importantly, this collection of initiatives has potential to bridge those information gaps with the help of geographic information systems (GIS). A description of the projects is included in Appendix 2.
1.3 WWF and the ecoregion approach to conservation
WWF's mission is to stop degradation of the planet's natural environment and to build a future in which humans live in harmony with nature, by conserving biological diversity, ensuring the sustainable use of resources, and reducing pollution and wasteful consumption. Scientists and conservationists worldwide have acknowledged that attainment of conservation goals requires thinking, planning, and acting at the appropriate spatial and temporal scales (IUCN, WRI, and WWF 1999).
Adoption of the ecoregion as the spatial unit that best describes the patterns of biodiversity reflects increasing recognition of the need to expand the scale at which we address biodiversity conservation.
An ecoregion is "a large unit of land or water that contains a characteristic set of natural communities that share a large majority of their species, dynamics, and environmental conditions" (Olson et al. 2000: 2). Through identification of 238 terrestrial, freshwater, and marine ecoregions as priorities for conservation action, collectively known as the Global 200, WWF has taken a more comprehensive and representative conservation approach than has ever been attempted on a global scale. The ecoregions of the Global 200 are a focus for conservation efforts because "they harbour the most outstanding and representative examples of the world's diverse ecosystems" (Olson et al. 2000:1). Ecoregion conservation emphasises not only expansion of the geographic areas in need of consideration, but also the temporal horizon for planning, and engagement with a wide range of stakeholders. The methodology applied in selecting the Global 200 is outlined in Appendix 1.
Ecoregional planning embraces an ecosystem-based approach to management, which requires the ability and authority to plan in accordance with ecological processes and systems. Both ecoregionbased conservation and the ecosystem-based approach anticipate, plan, and act beyond political boundaries. Even in ecoregions that have a well-developed government infrastructure for conservation and sustainable use of the marine environment, responsibility for various marine management issues is often spread across departments with different, and sometimes conflicting, mandates. As a result, co-ordination challenges continuously arise for managing competing uses of the marine environment.
Planning at the ecoregion scale presents new conservation opportunities that might be neglected by approaches constrained by political units. At the ecoregional scale:
- Patterns of biodiversity can be contemplated along spatial and temporal parameters that reflect ecosystem processes rather than legal or jurisdictional boundaries and timelines;
- Participants in the process have the opportunity to exchange ideas independent of political and funding considerations;
- Resources for conservation can be drawn from a wide range of stakeholders at various levels; and
- Socio-economic issues that cross borders, such as international demand for a particular commodity, can be addressed.
WWF-New Zealand has initiated ecoregion conservation in the hope of realising new conservation opportunities in New Zealand's marine environment.
1.4 The New Zealand Marine Ecoregion
The marine environment of New Zealand was one of three Global 200 ecoregions selected among the temperate shelf and seas of the Southern Ocean2. The physical environment of New Zealand is best described as a large bathymetric platform where the Pacific and Indo-Australian plates collide. New Zealand intersects the general west to east flow of the subtropical and subantarctic surface waters, deflecting currents either northward or southward off the west coast, and creating permanent eddies off the east coast of the North Island. The Subtropical Front is the circumpolar boundary between the warm, nutrient-poor, and salty waters of the subtropics and the cold, nutrient rich, and less saline water of the subantarctic. To the west of New Zealand, the Subtropical Front generally lies at Fiordland's latitude, while to the east it follows the Chatham Rise.The Deep Western Boundary Current is another major current that influences the region. It sweeps along New Zealand's south-east continental margin, flowing below 2000m depth, in consort with the overlying Antarctic Circumpolar Current (ACC) (L. Carter 2004, personal communication). The deep current then flows around the Chatham Rise, and along the Kermadec Ridge, infusing the Pacific with waters rich in oxygen and nutrients. The coincidence of these water masses contributes to the diversity of marine habitats found in the New Zealand ecoregion. New Zealand's currents are illustrated on 3.0 Results.
The great diversity and productive nature of New Zealand's marine environment among pacific south temperate and subpolar ecosystems led to its inclusion in the Global 200 (Olson et al. 2000). Biological attributes that distinguish New Zealand include a rich diversity of aquatic plants, fish, bivalves, bryozoans, seabirds, and a diverse community of marine mammals (Olson et al. 2000). The high levels of diversity, and possibilities for concerted conservation action in the New Zealand marine ecoregion make it a priority for WWF globally as part of a subset of Global 200 ecoregions for immediate action.
Compared with terrestrial ecoregions, marine ecoregions are considered to be more spatially and temporally dynamic ecological and biogeographic units. Thus, precise boundaries were not defined for marine ecoregions during selection of the Global 200. In New Zealand the 200 nautical mile boundary of the Exclusive Economic Zone has served as a proxy for the ecoregion, although delineation of key biodiversity areas during the workshop was not constrained by this jurisdictional border.
Extensive data has been collected and literature published for New Zealand's marine environment as a whole, however, there are still substantial gaps in the formal inventory of New Zealand's marine biodiversity. In their review of marine biodiversity research in New Zealand, Nelson and Gordon (1997) comment, "qualitative knowledge of the New Zealand marine biota is still very much in the discovery phase, even for macrobenthic organisms, and quantitative knowledge of distributions is restricted to very small areas of sea floor" (62). The dearth of scientific knowledge about the marine environment is attributed to inadequate sampling. There are more than 9,000 scientific sampling stations spread around New Zealand's sea floor (Nelson and Gordon 1997), but they are not representative of the full range of marine habitats. For accessibility reasons, 80% of all scientific sampling has been carried out in the 0-1000m depth range, which represents 28% of the sea-surface area of the Exclusive Economic Zone (Nelson and Gordon 1997). Furthermore, these stations do not include sampling of the water column above the sea floor, making the sampling effort seem even more insignificant (Nelson and Gordon 1997).
Compounding the difficulty of understanding New Zealand's marine environment is the relative inaccessibility of information that has been collected on biodiversity. In general, information about marine habitats and biodiversity is widely dispersed in the published and unpublished literature. Despite an active research community, biogeographical information for some marine areas has not been updated in decades (e.g. trenches).
In light of the current information deficiencies, WWF-New Zealand convened a group of marine scientists to convey their knowledge of the distribution of New Zealand's marine biodiversity. The aims of the workshop were to:
- Delineate key biodiversity areas in New Zealand's marine ecoregion through the consensus of scientific experts;
- Establish links with key experts on New Zealand's marine environment;
- Start a process of outreach to potential users of the information;
- Identify information gaps and other obstacles to assessing marine biodiversity;
- Agree on future steps for the assessment and conservation of New Zealand's marine biodiversity; and
- Formulate a common statement for the conservation of marine biodiversity in the New Zealand region.