Browsing by Author "Richardson, Anthony J"

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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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    A novel quantitative, sub-provincial approach to characterizing the shape of chlorophyll profiles
    (2001) Silulwane, Nonkqubela F; Richardson, Anthony J; Mitchell-Innes, Betty A; Shillington, Frank
    In this study, novel approaches such as artificial neural networks and generalized modelling have highlighted the variability in profile shape and enabled its improved prediction. This will lead to superior regional estimates of primary production.
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    Variability of copepod abundance and growth in the southern Benguela upwelling system and implications for the spawning of the Cape anchovy
    (1998) Richardson, Anthony J; Field, John G; Verheye, Hans M; Moloney, Coleen L
    In the southern Benguela upwelling system, anchovy spawn serially between September and February each year. It has been suggested that this energy-intensive reproductive strategy requires continual ingestion of copepods, which dominate the diet of anchovy at this time. This thesis investigates the spatial and temporal variability of copepod abundance and growth, and their impact upon the spawning of anchovy. Sampling was conducted monthly between August-March 1993/94 and 1994/95 .. It is noteworthy that the primary spawning ground of anchovy, the western Agulhas Bank, had a significantly smaller biomass of copepods than the adjacent West Coast region. In terms of the growth rates of copepods, the effect of food-limitation on fecundity and somatic growth outweighed that of temperature.