Browsing by Author "Huggett, Jenny A"

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    Accommodating dynamic oceanographic processes and pelagic biodiversity in marine conservation planning
    (Public Library of Science, 2011) Grantham, Hedley S; Game, Edward T; Lombard, Amanda T; Hobday, Alistair J; Richardson, Anthony J; Beckley, Lynnath E; Pressey, Robert L; Huggett, Jenny A; Coetzee, Janet C; Van der Lingen, Carl D
    Pelagic ecosystems support a significant and vital component of the ocean's productivity and biodiversity. They are also heavily exploited and, as a result, are the focus of numerous spatial planning initiatives. Over the past decade, there has been increasing enthusiasm for protected areas as a tool for pelagic conservation, however, few have been implemented. Here we demonstrate an approach to plan protected areas that address the physical and biological dynamics typical of the pelagic realm. Specifically, we provide an example of an approach to planning protected areas that integrates pelagic and benthic conservation in the southern Benguela and Agulhas Bank ecosystems off South Africa. Our aim was to represent species of importance to fisheries and species of conservation concern within protected areas. In addition to representation, we ensured that protected areas were designed to consider pelagic dynamics, characterized from time-series data on key oceanographic processes, together with data on the abundance of small pelagic fishes. We found that, to have the highest likelihood of reaching conservation targets, protected area selection should be based on time-specific data rather than data averaged across time. More generally, we argue that innovative methods are needed to conserve ephemeral and dynamic pelagic biodiversity.
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    The effect of chlorine, heat and physical stress on entrained plankton at Koeberg Nuclear Power Station
    (1988) Huggett, Jenny A; Cook, Peter
    The large volume of seawater used for cooling at Koeberg Nuclear Power Station contains many planktonic organisms which are exposed to heat, chlorine and physical stress during their passage through the system. Phytoplankton biomass, measured as chlorophyll a, was reduced by an average of 55.32% due to entrainment, and productivity was decreased by 38.30% on average, mainly due to chlorination. Zooplankton mortality averaged 22.34% for all species and 30.52% for copepods, the dominant group. The copepod Paracartia africana was used in laboratory experiments designed to simulate entrainment. Latent mortality was monitored up to 60 hours after a 30-minute application of stress factors (physical stress was not simulated), and approximately 75% of the total mortality occurred within the 30-minute period. Male Paracartia experienced higher mortalities than females. Extrapolation of these results predicts an overall entrainment mortality (including latent mortality) of 40% for copepods and 29.04% for total zooplankton, although the latter cannot be substantiated. Plankton entrainment at Koeberg was not considered to be overly detrimental to the marine environment because of the very localised area affected, rapid dispersion of heat and chlorine, rapid regeneration times of phytoplankton and some zooplankton, low abundance of commercially important species and potential recruitment from the surrounding productive Benguela upwelling region.