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Mark Cyrus wins best presentation by a PhD student

2 May 2014 - 09:45

The 11th conference of the Aquaculture Association of Southern Africa (AASA) in Stellenbosch saw Mark Cyrus win the ‘best presentation by a PhD student’ award (abstract below).

It is the second time that Mark has won a best student award at an AASA meeting.

 

 Tripneustes gratilla - a new and exciting species for South African Aquaculture

1Cyrus*, M., 1Bolton, J.J. &2Macey, B.m.

1Department of Biological Sciences and Marine Research Institute, University of Cape Town,

Rondebosch 7701; 2Department of Agriculture, Forestry and Fisheries, Aquaculture Research, Private Bag X2, Roggebaai 8012.

Tripneustes gratilla has been proposed as a viable candidate for aquaculture in South Africa due to its fast growth rate, early maturation and high gonadal production. Internationally, the most commercially valuable urchin gonads are large in size, contain few to no gametes, have a firm texture, and are bright yellow or orange in colour. Previous studies have shown that artificial diets generally produce large gonads that are pale in colour, while natural macroalgae diets produce brightly coloured gonads that are small in size. Our research has focused on the development of an artificial diet supplemented with macroalgae and the optimization of a feeding regime to produce high quality gonads. We demonstrated that a formulated feed supplemented with 20% dried Ulva (20U diet) produced high quality gonads in terms of both size and colour. Moreover, dietary Ulva supplementation significantly increased protein digestibility, the chemosensory properties of a formulated feed and feed consumption rates of wild caught urchins. Growth studies on hatchery reared urchins were conducted over a 32 week period to optimize a feeding regime. Somatic growth of urchins fed fresh Ulva (FU) and 20U was similar after 21 weeks, while the gonads of urchins fed FU were significantly smaller. However, after feeding urchins in the FU treatment an artificial diet, with or without dried Ulva supplementation, for an additional 6 weeks, their gonads attained a similar size compared to urchins continually fed 20U. Our results have important implications for the development of a cost-effective and successful echinoculture industry in South Africa.