Induction of triploidy in the South African abalone, Haliotis midae, by the use of hydrostatic pressure

[摘要] ENGLISH ABSTRACT: The indigenous abalone, Haliotis midae has been a successfully cultured aquaculturespecies in South Africa since 1990. It has a slow growth rate and takes from two to fiveyears to reach market size. Like for most other commercially important abalone species,the slow growth rate of H. midae is a cause of concern with regard to the profitability offarming and global competitiveness of the species.Ploidy manipulation of the maternal genome, a universally growing practice in shellfishculture, is considered a promising method to improve the growth rate of abalone - adesirable trait in aquaculture organisms from a commercial perspective. Thismanipulation technique is employed to achieve sterility, which results in limited gonaddevelopment. The consequent re-allocation of resources to somatic growth results inimproved growth.The purpose of this study was to establish a viable method for the induction andvalidation of triploidy, on a commercial scale, in the South African abalone, H. midae. Thefocus was on hydrostatic pressure as a method of induction and flow cytometry as themethod of validation.The results obtained confirm hydrostatic pressure as an effective method for theinduction of triploidy in H. midae, delivering high percentages of triploidy (>80%) over awide range of pressures and times, in 48 hour-old larvae. Hydrostatic pressure had anegative effect on survival in 20 hour-old larvae. Flow cytometry was validated as areliable, fast and accurate, though expensive, method for identification of triploidy inH. midae.As an outcome of this study a manual of 'Procedures for the Induction and Validationof Triploidy in the abalone is presented (Appendix 1) together with recommendations forfurther studies on triploidy in the South African abalone, H. midae.

[发布机构] Stellenbosch University