Browsing by Author "Troell, Max"

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    Biological and economical feasibility studies of using seaweeds Ulva lactuca (Chlorophyta) in recirculation systems in abalone farming
    (2006) Robertson-Andersson, Deborah; Bolton, John J; Troell, Max; Probyn, T; Smit, A J
    The aim of this study was to investigate whether a land-based recirculating seaweed-abalone integrated aquaculture system using Ulva lactuca was feasible as well as to test the differences between a commercial gravel bed recirculation system to an existing flow through system. These studies were carried out at two abalone farms: Danger Point (I & J) (140 km east of Cape Town) and at Jacobs Bay (JSP) (120 km north of Cape Town. South Africa). In both studies no significant difference in terms of water quality, abalone growth rates and abalone health were found. It was found that a seaweed /abalone recirculating system at the designed water exchange rates (25 %) was nitrogen limited and that the system as designed could be run at 75 % recirculation rate and remove a significant proportion of the dissolved nutrients (ammonium, phosphorus, nitrate and nitrite).
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    A comparison of suspended particle size and sediment loading produced by artificial and seaweed diets in integrated flow-through and re-circulating aquaculture systems on a commercial South African abalone farm
    (2005) Potgieter, Michelle; Bolton, John J; Troell, Max; Robertson-Andersson, Deborah
    The future of abalone farming in Soulh Africa may provide benefits by the integration of abalone-seaweed re-circulation systems. This is a new system design of abalone fed on a kelp diet integrating seaweed culture facilitated by a re-circulation system. This kind of culture has the potential to increase abalone growth through increased water temperature, minimizing pumping costs while also incorporating production of on-farm seaweed resources. This has, however, the potential disadvantage to increase the suspended particulale concentration in the tank environment, with subsequent negative effects on abalone health. This study ties in with an existing Swedish-South African joint project. The results of this study will be used as inputs when trying to model a complete commercial recirculated abalone farm. Divided into two experiments this study records suspended particulate matter, particle size range and water nutrient concentrations (phosphate, ammonium and nitrite).