7 results for Tempero, Grant Wayne, Unclassified

  • Destratification – fact sheet

    Tempero, Grant Wayne; Paul, Wendy J. (2015)

    Unclassified
    University of Waikato

    During summer, the surface waters of lakes warm and become less dense than the colder bottom waters. This process is known as stratification and prevents surface and bottom water mixing. Stratification can occur intermittently in shallower lakes or for up to 9 months in deeper lakes (Figure 1). Under natural conditions stratification normally breaks down during the winter months when surface temperatures equilibrate with the bottom of the lake.

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  • Exclusion and removal of pest fish from Lake Ohinewai – fact sheet

    Tempero, Grant Wayne; Ling, Nicholas; Daniel, Adam Joshua (2015)

    Unclassified
    University of Waikato

    Many of the shallow lakes in the lower Waikato River floodplain have significantly degraded water quality as a result of nutrient and sediment enrichment from non-point sources. Pest fish species such as koi carp, goldfish, and catfish have exacerbated lake decline by resuspending lake sediments and uprooting submerged macrophytes. This this resulted in a collapse of submerged macrophytes and progression from clear-water oligotrophic state to a eutrophic (algal-dominated) state.

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  • Pest Fish Control - Fact Sheet

    Tempero, Grant Wayne; Collier, Kevin J.; Hicks, Brendan J. (2015)

    Unclassified
    University of Waikato

    Due to their negative impacts on water quality and native biodiversity in New Zealand, regional councils have included a number of introduced freshwater fish species such as koi carp, rudd, brown bullhead catfish, goldfish, tench, gambusia (mosquitofish) and European perch (Figure 1) in their pest management plans. The Department of Conservation and regional councils undertake control and eradication programmes around New Zealand every year in order to contain their spread and reduce their impacts. Nearly all regions of mainland New Zealand have at least one of these species but they are most prevalent in the Auckland and Waikato regions. LERNZ has been researching the population ecology and capture methods of pest fish populations in order to develop efficient methods for their control.

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  • New Zealand pest fish species: Koi carp and Gambusia – fact sheet

    Tempero, Grant Wayne (2015)

    Unclassified
    University of Waikato

    New Zealand has a total of about 36 native freshwater fish species, and a further 22 (39% of all freshwater fish) have been introduced from overseas. Like all introduced species, they have some impact on New Zealand's native ecosystems, but some cause more problems than others.

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  • Flocculation and sediment capping – fact sheet

    Tempero, Grant Wayne; Paul, Wendy J. (2015)

    Unclassified
    University of Waikato

    Sediment capping and flocculation are in-lake techniques designed to reduce internal nutrient loads from the bottom sediments of lakes. These loads are roughly equivalent in magnitude to external loads. Case studies of the Rotorua lakes (Figure 1) show that with careful design and management, sediment capping and flocculation can reduce nutrient concentrations and the likelihood of algal blooms. Relevant actions can include: (i) reducing bioavailable phosphorus in stream inflows through continuous addition of the active material to the stream, (ii) removing bioavailable phosphorus, and flocculation and sedimentation of nutrients, and (iii) altering sediment composition so that nutrients are more efficiently retained within the bottom sediments

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  • LERNZ: Lake Ecosystem Restoration New Zealand – Fact Sheet

    Tempero, Grant Wayne; Hamilton, David P. (2015)

    Unclassified
    University of Waikato

    Based at the University of Waikato (Figure 1), the aim of the LERNZ research programme is to provide end-users such as community groups, regional councils and governmental agencies with practical tools and expertise for restoring indigenous biodiversity and water quality in lakes. The research programme is centred around two main themes: • New models and technologies to effectively manage harmful algal blooms • New pest fish management and control technologies LERNZ is based at the University of Waikato, Hamilton New Zealand, and has established a number of collaborations with domestic and international research organisations since its inception in 2005.

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  • Nutrient and sediment loads from farm drains – fact sheet

    Tempero, Grant Wayne; Hamilton, David P. (2015)

    Unclassified
    University of Waikato

    Runoff from intensive agriculture has been identified as a major contributor to the decline of New Zealand's freshwater ecosystems. Excessive nutrient and sediment losses to lakes and rivers lead to reduced water clarity and quality, which in turn leads to reductions in biodiversity and amenity and aesthetic values.

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