Research Commons
      • Browse 
        • Communities & Collections
        • Titles
        • Authors
        • By Issue Date
        • Subjects
        • Types
        • Series
      • Help 
        • About
        • Collection Policy
        • OA Mandate Guidelines
        • Guidelines FAQ
        • Contact Us
      • My Account 
        • Sign In
        • Register
      View Item 
      •   Research Commons
      • University of Waikato Theses
      • Higher Degree Theses
      • View Item
      •   Research Commons
      • University of Waikato Theses
      • Higher Degree Theses
      • View Item
      JavaScript is disabled for your browser. Some features of this site may not work without it.

      Environmentally Sustainable Aquaculture: An Eco-Physical Perspective

      Longdill, Peter C.
      Thumbnail
      Files
      01front.pdf
      227.6Kb
      02Chapter1.pdf
      1021.Kb
      03Chapter2.pdf
      447.8Kb
      04Chapter3.pdf
      2.753Mb
      05Chapter4.pdf
      2.905Mb
      06Chapter5.pdf
      2.213Mb
      07Chapter6.pdf
      861.9Kb
      08Chapter7.pdf
      4.386Mb
      09Chapter8.pdf
      115.5Kb
      10Chapter9.pdf
      225.7Kb
      Data & Appendices.zip
      Supplementary material, 945.8Mb
      Citation
      Export citation
      Longdill, P. C. (2008). Environmentally Sustainable Aquaculture: An Eco-Physical Perspective (Thesis, Doctor of Philosophy (PhD)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/2604
      Permanent Research Commons link: https://hdl.handle.net/10289/2604
      Abstract
      The New Zealand aquaculture industry during the late 1990s and early 2000s experienced a significant and sustained period of growth. Greenshell mussels (Perna canaliculus) are proving to be a popular and valuable cultured species, with large domestic and international markets. Traditionally, these bivalves have been farmed within enclosed embayments and on relatively small scales (~3 Ha). The recent expansion of the industry coupled with the near saturation of existing 'traditional' sites and new culture technologies has led the industry toward alternate environments, notably exposed offshore sites. Initial proposals within the Bay of Plenty have included multiple farms of ~4500 Ha each. This novel approach to shellfish culture created uncertainty with respect to potential environmental impacts, cumulative effects, and sustainable carrying capacities within these exposed open-coast locations. In zoning for Aquaculture Management Areas (AMAs), environmental managers must be informed of each of these aspects to ensure the rational and sustainable use of the coastal-marine space.

      The overall goal of this study is to determine the potential for environmentally sustainable large-scale offshore mussel culture within the Bay of Plenty marine environment. The long term sustainability of aquaculture development on an open coast is a function of many influences which can vary in both time and space. The benthic environments of the Bay of Plenty exhibit great variability in their ability to assimilate waste inputs from suspended mussel culture; a direct function of the variability in sedimentary environments and benthic habitats within the region. Specifically, silty sediments with low natural organic contents, generally found between 40 and 100 m depths are the most suitable locations for sustainable mussel aquaculture from an environmental impact perspective. Both observations and model predictions indicate productivity potential within the region to be greatest within neritic zones of the western Bay of Plenty. Local wind forcing is the predominant mechanism forcing local shelf currents. Current meter data and numerical modelling tests from this study indicate that local winds explain the majority of water current variability on the shelf, generate the delivery of new nutrients to the shelf through upwelling, and hence create the variability in productivity potential. Complicating the AMA zoning process for environmental managers, however, are existing uses of, and societal values toward, the coastal-marine environment. GIS planning tools have been shown to be effective at minimising conflicts and maximising sustainability potential through informed site selection. Within the Bay of Plenty, these preferential sites are located on the mid-shelf (60-80 m depths) offshore from Pukehina, Matata, and Whakatane.

      This study shows that the simulated cumulative lower trophic-level depletion impacts of two large (~5000 Ha) proposed offshore mussel farms vary seasonally as a result of subtle changes in ecosystem dynamics and mussel feeding patterns. At proposed stocking densities, largest relative impacts are expected during autumn and winter, when relative phytoplankton biomass is low and growth rates slow. During spring, while absolute impacts are greater than those during autumn/winter, greater phytoplankton-zooplankton biomass and faster growth rates result in quicker recovery times and reduced 'depletion halo' extents. Year-long predicted impacts are below those applied as 'acceptable limits of change', both within New Zealand and internationally, indicative of the ecological carrying capacity.
      Date
      2008
      Type
      Thesis
      Degree Name
      Doctor of Philosophy (PhD)
      Publisher
      The University of Waikato
      Rights
      All items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
      Collections
      • Higher Degree Theses [1714]
      Show full item record  

      Usage

      Downloads, last 12 months
      488
       
       

      Usage Statistics

      For this itemFor all of Research Commons

      The University of Waikato - Te Whare Wānanga o WaikatoFeedback and RequestsCopyright and Legal Statement