Browsing by Author "Sankar, Kishan"

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    Life on a gradient : activity levels of the seastar Patiriella exigua in different abiotic conditions
    (2005) Sankar, Kishan; Dunbar, Katherine; Griffiths, Charles L
    Two morphs of Patiriella exigua occur in South Africa. These morphs occur on opposite sides of a temperature divide present at Cape Point. The green morph occurring on the West Coast (cold temperate) and the mottled morph occurring on the South Coast (warm temperate). In a previous study by Katherine Dunbar these two morphs were shown to be the same species. This project tests if there is a physiological difference between the two morphs of P. exigua. This was achieved by observing the activity coefficient of righting response of the two morphs of P. exigua under different temperatures and dissolved oxygen concentrations. The green morph was collected from Green Point (West Coast) and the mottled morph from Kalk Bay (South Coast). The results of a general linear model indicated that temperature and dissolved oxygen were significant factors determining righting time of P. exigua with P-values of less than 0.05. AT-test indicated that there was a significant difference between the righting times of the two morphs of P. exigua with the green morph turning at a faster rate than the mottled morph when placed under similar conditions.
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    Setting optimal diet ratios of kelp (Ecklonia maxima (Osbeck) Papenfuss) and formulated feed, and tests of a recirculating system using Ulva (Chlorophyta) as a biofilter, in South African abalone (Haliotis midae) cultivation
    (2010) Sankar, Kishan; Bolton, John J; Robertson-Andersson, Deborah
    Land-based abalone aquaculture in South Africa, based on the local species Haliotis midae, started in the early 1990's and has grown rapidly in the last decade. This has led to numerous studies into various aspects of farming H midae. There are two aims of this study, (i) to test the relative benefits of different ratios of kelp and the formulated feed Abfeed(R) K26 (feed component), (ii) to test the suitability of farming H midae with 50 % and 75 % recirculation rates (recirculation component) in an integrated system using the green seaweed Ulva as a biofilter. Aims for both components were to investigate the performance of the systems in terms of health of abalone, growth rates of abalone, sediment loadings and water quality. Both components were conducted on Irvin & Johnson Ltd Cape Abalone farm in Gansbaai, 140 km east of Cape Town.
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