The Ministry for the Environment, the Ministry of Fisheries and the Department of Conservation commissioned the National Institute of Water and Atmospheric Research (NIWA) to develop environmental classifications covering both New Zealand's Exclusive Economic Zone and the Hauraki Gulf region collectively known as the Marine Environment Classification (MEC). The Ministry for the Environment was the lead agency responsible for coordinating the development of the classification. The purpose of these classifications is to provide spatial frameworks for structured and systematic management by subdividing the geographic domain into units having similar environmental and biological character.
Development of the Marine Environment Classification occurred in six specific phases over a four-year period from 2000 to 2004. The details of each of these phases have been fully documented in a number of reports that are listed in the references section of this report. The purpose of this report is to summarise those development phases in sufficient detail to provide future users of the Marine Environment Classification with a single source of documentation for it. The report overviews the development process, discusses the results of testing of the classification and describes the physical and biological characteristics of classes that are defined by the classifications.
The Marine Environment Classification has been defined using multivariate clustering of several spatially explicit data layers that describe the physical environment. This produces a classification that is hierarchal, enabling the user to delineate environmental variation at different levels of detail and a range of associated spatial scales. A physically based classification was chosen because data were available or could be modelled and because environmental pattern is a reasonable surrogate for biological pattern, particularly at larger spatial scales. Large biological datasets were used to tune the classification so that the physically based classes maximise discrimination of variation in biological composition at various levels of classification detail. The classification has not been optimised for a specific ecosystem component (e.g. fish communities or individual species) but has sought to provide a general classification that has relevance to a broad range of biological groups.
The Marine Environment Classification was developed at two levels of spatial resolution. First a broad scale classification was developed for the entire EEZ, covering the area below the mean high water line (but not including estuaries) from approximately 25 to 58 degrees South and 158 degrees East to 172 degrees West. This classification has a nominal spatial resolution of 1 km, allowing mapping at scales of 1:4,000,000 and above. While the classification can be mapped at finer scales, the 'grain' of the underlying data will become increasingly prominent as the scale is increased. A second classification was developed for the Hauraki Gulf region. This region encompasses waters below the mean high water line (but not including estuaries) and within a line drawn eastward from Bream Head (approximately 36 degrees South) to meet a line drawn from south to north and intersecting Cape Barrier on Great Barrier Island (approximately 176 degrees East). This classification has a nominal spatial resolution of 200 m (i.e. consistent with a maximum map scale of 1:250,000). The purpose of this regional classification was to assess the feasibility of producing higher resolution inshore classifications relevant to the more intensive management issues that frequently occur there.
Statistical tests determined that the Marine Environment Classification classes are biologically distinctive. Thus, the classifications provide managers with useful spatial frameworks for broad scale environmental and conservation management. However the full utility, and indeed limitations of the classifications will only become clear as the classifications are applied to management issues.
At the conclusion of this four-year development project the steering group was satisfied that the Marine Environment Classification provides a useful broad-scale classification of biotic and physical patterns in New Zealand's marine environments and supported its use as a spatial framework for analysis and management of marine conservation and resource management issues. It is important to recognise that a spatial framework is a tool to organise data, analyses and ideas and is only a component of the information that would be employed in any analysis. The steering group considered that the development of the Marine Environment Classification should now move into a phase where it is tested by application to management issues.