Abstract:
The Hauraki Gulf Marine Park, established in 2000, is recognised for its outstanding biological diversity, and encompasses a variety of marine ecosystems from shallow bays and estuaries to deep offshore oceanic environments (Hauraki Gulf Forum, 2011). Information about hotspots of biological and habitat diversity can be used to determine high priority locations for protection or restoration of biodiversity, and inform placement of a network of representative Marine Protected Areas (MPAs). The importance and benefits of a representative network of MPAs to the New Zealand people and in the context of conservation, education, and the economy is so important that ensuring a systematic approach to the creation of this network is within the public interest (Ballantine, 2014). The Hauraki Gulf Marine Park is currently the focus of a pilot Marine Spatial Plan, launched in September 2013, and the content of this thesis is designed with the intent of informing that process. This thesis is separated into two chapters, each with their own literature review, methods, results and discussion. These are preceded by an introduction to regulatory guidelines in New Zealand that underpin biodiversity conservation and a review of Marine Spatial Planning internationally (Chapter One) to illustrate data that is used to inform this process globally. Chapter Two considers the role of biodiversity in the Hauraki Gulf Marine Park and the extent to which identification and protection of all habitat types can be enacted. A custom classification was developed, based on the New Zealand Coastal Classification (DoC and MFish, 2011), and identified 46 habitat types in the Hauraki Gulf Marine Park. In its existing state, Marine Reserves and Cable Protection Zones (CPZs) cover more than 5% of the Hauraki Gulf Marine Park; however all environmental categories (based on depth, substrate and exposure) are under-represented within MPAs. Of the 46 identified habitat types, only two meet and exceed the 10% guideline for biodiversity protection. Half of the habitats identified were not protected within any MPA. The Gulf is characterised as moderately exposed, with predominantly mud and sandy mud substrates, located primarily at depths of between 30-200 m. Mangroves are the predominant type of estuarine vegetation, comprising 76% of estuarine vegetation found in the HGMP, although less than 5% of the mangrove distribution is located within existing MPAs. There are currently a small proportion of Marine Reserves located in depths greater than 30 m, which is problematic when attempting to protect representative areas for biodiversity purposes, due to the Gulf being primarily being comprised of depths of 30–200 m. CPZs protect larger extents of deeper waters in the Gulf, and are considered to afford conservation of marine biodiversity although it is not their primary objective. Chapter Three carries forward datasets used and created in Chapter Two and utilises the conservation software Zonation (a Decision Support Tool) to identify priority sites in the Hauraki Gulf Marine Park for protection of biodiversity. The results identified a number of sites in the Gulf for biodiversity prioritisation, some of which varied depending on the input dataset and the Zonation cell removal rule utilised. A landscape solution, which incorporated aggregation tools, reduction in edge effect, and a mask file of existing MPAs in the Gulf to ensure that these were selected in the top 10% of the landscape, was considered to be the most appropriate solution from a biodiversity perspective. The inner Firth of Thames, the waters surrounding Cape Colville, the Waitemata, Coromandel and Mahurangi Harbours and several offshore islands were some of the areas identified as important for biodiversity prioritisation. These results were also compared to a landscape solution using a biotic dataset (demersal fish distribution) and against a recreational fishing effort layer, which considerably altered the initial landscape solution.