Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The species Haliotis midae is the only commercially exploitable abalone species of the six found in the South African coastal waters. This species is under substantial pressure from both legal and illegal harvesters, to such an extent that it could be commercially extinct within four years. Efforts to alleviate the pressures on the natural populations of both illegal and legal harvesting are being made. The genetic management systems for abalone farming and ranching activities should be carefully evaluated. The loss of genetic diversity and the risks of contaminating the gene pools of natural populations in the vicinity of a farm should be minimized. Genetic evaluation studies will be at great importance to acquire the necessary data needed for genetic diversity and differentiation analysis. The aim at this study was to develop species-specific microsatellite DNA markers to assess the genetic diversity and differentiation within and between the brood stock and commercial stock of the Sea Plant Products abalone farm (Hermanus, Republic of South Africa) and natural populations related to the brood stock. The species-specific DNA markers were also used for parentage assignments within the tarm population (first for abalone) and preliminary OTL (quantitative trait loci)-discovery analysis studying growth rate segregation. Samples were taken of the farm's brood stock and commercial stock (Rows 2, 3, 4) as well as from two natural populations (Saldanha Bay and Black Rock) related to the brood stock. Various statistical parameters and software packages were used to assess genetic diversity and differentiation, to infer parentage and to look for OTL's. Eight species-specific microsatellite DNA markers were designed and used for data analysis. Data analysis showed a loss at genetic diversity from the brood stock to the commercial stock caused by the subdivision of the original brood stock into rows and the differential contributions of parents to the offspring. No genetic differentiation (Fst) was detected between the farm and natural populations, except for the offspring of Row2. levels of inbreeding (ns) were high for all loci within the populations. Thirty-eight percent of all studied offspring were confidently assigned to a couple. The preliminary QTldiscovery suggested the segregation of a number of alleles and genotypes with growth rate. The study concluded that the commercial abalone population of the Sea Plant Products abalone farm holds no threat to the disruption of the genetic diversity of the natural populations. It is proposed that the farm implement a rotational breeding program to increase the genetic diversity of the commercial population. Any newly acquired brood stock must be profiled before their introduction into the breeding program to assess the influence of the animals on the current levels of genetic diversity within the farm. The accuracy and reliability of parentage assignments and QTl-discovery need to be optimised by adding more loci and sampling more animals or even by trying and developing new methods. / AFRIKAANSE OPSOMMING: Van die ses perlemoen spesies wat langs die Suid-Afrikaanse kus gevind word, is die spesie Haliotis midae die enigste een wat van kommersiële belang is. Wettige, sowel as onwettige versameling, plaas hierdie spesie onder sulke geweldige druk dat dit dalk binne vier jaar verlore kan wees vir die kommersiële bedryf. Verskeie strategieë word tans geïmplimenteer om hierdie druk te verlig. Die genetiese bestuurstrategieë binne perlemoen plase moet deeglik ondersoek word. Die verlies aan genetiese diversiteit en die moontlikheid vir die kontaminering van die natuurlike populasies in die omgewing van die plaas se geenpoel, moet uitgeskakel word. Genetiese evaluasies sal van groot belang wees om die nodige data vir genetiese diversiteit- en differensiasie-analises te verkry. Die doel van die studie was om spesies-spesifieke mikrosatelliet DNA merkers te ontwikkel wat gebruik sou word om die genetiese diversiteit en differensiasie binne en tussen die broei diere en die kommersiële diere van Sea Plant Products se perlemoen plaas (Hermanus, Republiek van Suid- Afrika) en die natuurlike populasies wat verwant is aan die broei diere, te bepaal. Die spesies-spesifieke DNA merkers is ook vir ouerskap-bepalings binne die plaas se populasie gebruik, asook vir voorlopige OTL (quantitative trait locI) - ontdekking met betrekking tot groeitempo segregasie. Monsters van die plaas se broei diere en kommersiële diere (Ry 2, 3, 4) asook van twee natuurlike populasies (Saldanha Baai en Black Rock) wat verwant is aan die broei diere, is geneem. 'n Verskeidenheid van statistiese parameters en sagteware pakette is vir die genetiese diversiteit- en differensiasie-analises, vir ouerskap-bepalings en vir die opspoor van OTL's gebruik. Agt spesies-spesifieke mikrosatelliet DNA merkers is ontwerp en toe gebruik vir die data analises. 'n Verlies aan genetiese diversiteit vanaf die broei diere na die kommersiële diere is deur die data analises uitgewys. Dit is veroorsaak deur die verdeling van die oorspronklike broei diere in rye en die differensiële bydraes deur die ouers na die nageslag. Geen genetiese differensiasie (Fst) is tussen die plaas se populasie en die natuurlike populasies gevind nie, maar die nageslag van Ry 2 het wel differensiasie getoon. Die vlakke van inteling (Fis) was hoog oor alle lokusse binne alle populasies. Agt-en-dertig persent van die nageslag wat bestudeer is, was suksesvol met 'n ouerpaartjie geassosieer. Die voorlopige OTL-ontdekking studie toon die potesiële segregasie van 'n aantal allele en genotipes saam met groeitempo. Die bevindinge van die studie is dat die kommersiële populasie op die Sea Plant Products perlemoen plaas, geen bedreiging vir die versteuring van die natuurlike populasies se genetiese diversiteit inhou nie. Daar is voorgestel dat die plaas 'n rotasie-basis broeiprogram moet implimenteer om sodoende die genetiese diversiteit van die kommersiële populasie te verhoog. Enige nuwe broei diere se genetiese profiel moet ook voor die tyd ondersoek word om te sien wat se effek hierdie diere op die huidige genetiese diversiteit van die kommersiële populasie sal hê. Die akkuraatheid en betroubaarheid van die ouerskap-bepalings en OTL-ontdekking moet optimiseer word deur of meer lokusse te bestudeer, of meer diere in analises te gebruik of selfs om nuwe tegnieke te probeer of te ontwikkel.

Thesis (MSc(Agric))--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The pnmary alm of this study was to investigate the national competitive advantage of the South African abalone industry. A further aim was therefore to investigate the environment, in which the South-African abalone industry operates. Secondary aims included presenting a detailed description of the roleplayers in the South African abalone industry, and considering whether the South African abalone industry can be made more competitive and, if so, how this can be achieved. The achievement of these aims required a framework to establish which data is necessary for the task. The framework selected involved a combination of Porter's Five Forces analysis and Diamond Model. The study suggests that South African abalone firms should promote South African abalone more actively, invest more funds in human resources, and that the industry's faith in government needs to be restored, which can be achieved by improving the services offered by public institutions like the South African Bureau of Standards (SABS), the Department of Trade and Industry (DTI) and Marine and Coastal Management (M&CM). / AFRIKAANSE OPSOMMING: Die doel met die studie was om die nasionale kompeterende voordeel van die Suid Afrikaanse perlemoen industrie te ondersoek. Om dit te bereik, moes die omgewing waarin die industrie fuksioneer ontleed en die rolspelers in die industrie deeglik beskryf word. 'n Verdere doel was om te bepaal of dit moontlik is om die kompeterendheid van die industrie te verhoog, en indien wel, hoe dit bereik kan word. Die raamwerk wat gekies is om die doelstellings te bereik bestaan uit 'n kombinasie van Porter se "Five Farces" analise en "Diamond Model". Die resultate dui aan dat die industrie Suid-Afrikaanse perlemoen meer aktief moet bekendstel, individuele ondernemings meer in hul menslike hulpbronne moet investeer, en dat die industrie se vertroue in die nasionale regering herstel moet word, deur die dienste te verbeter wat deur publieke instellings soos die Suid-Afrikaanse Buro van Stanaarde (SABS), Departement Handel en Nywerheid en Mariene- en Kusbestuur verskaf word.

Thesis (MScAgric)--Stellenbosch University / ENGLISH ABSTRACT: Triploidy is the genetic state of containing three sets of chromosomes per cell in stead of two as in diploid organisms. The South African abalone (Haliotis midae) is naturally a diploid organism that sexually matures between four to eight years of age. Early sexual maturity is a disadvantage in cultured abalone stock, as the process of gonad development and spawning is energy demanding, causing energy to be diverted away from somatic growth. This same problem has been extensively experienced in diploid bivalve molluscs, where triploidy has since been applied as a means to prevent sexual maturation from occurring, thereby speeding up the growth process and shortening the time to marketing. Because triploidy was effective in bivalves, it was thought that it could contribute to faster growth in abalone as well. A procedure for the induction of triploidy in the abalone, Haliotis midae, was developed by De Beer (2004) and yielded up to 100 percent triploidy in treated abalone larvae. The next step was to compare the growth of the diploids and triploids to establish whether there was indeed a growth advantage on the part of the triploids, in view of commercial application. By using the same techniques as described by De Beer (2004), three groups consisting of triploid and diploid siblings were produced and subscribed to a comparative growth trial. The groups were spawned in three different seasons. The main objective was to establish whether there was in fact a difference in growth between diploid and triploid siblings, and whether seasonal effects were associated with growth advantages for either triploids or diploids. The two growth parameters measured were shell length and body weight. Measurements commenced at eight months of age, when the abalone could be individually tagged and continued up to the age of 24 months. The over-all results provided no convincing evidence of statistically significant faster growth of triploid juveniles compared to that of diploids up to two years of age. Growth differences were detected between seasons, but could not confidently be ascribed to seasonal environmental effects. The regression of shell length to body weight was similar for diploids and triploids. / AFRIKAANSE OPSOMMING: Triploiede organismes bevat drie stelle chromosome per sel in plaas van twee soos dit normaalweg in diploiede diere voorkom. Die Suid Afrikaanse perlemoen (Haliotis midae) is van nature ‘n diploiede organisme wat tussen die ouderdom van vier tot agt jaar seksueel aktief word. Vroeë seksuele aktiwiteit is ongewens in kommersiële akwakultuur aangesien energie spandeer word aan gonade ontwikkeling in plaas van somatiese groei. Dieselfde probleem is vroeër in die oester bedryf ondervind waar dit deur middel van triploiede induksie aangespreek is. Triploiedie veroorsaak steriliteit en kan gebruik word as ’n metode om steriliteit op groot skaal te induseer. Steriliteit sou dan meebring dat meer energie beskikbaar is vir somatiese ontwikkeling, wat verhoogde groeitempo en n verkorte tyd tot bemarking beteken. Op soortgelyke wyse is dus gepostuleer dat triploiedie in perlemoen ook tot steriliteit kon lei. ‘n Triploiede induksie metode was ontwikkel deur Mathilde de Beer (2004) wat ‘n hoë persentasie triploidie in geinduseerde perlemoen opgelewer het. Die volgende logiese stap was om die groei van diploiede diere met die van triploiede diere te vergelyk om te bepaal of triploiedie wel ’n groei voordeel tot gevolg het met die oog op kommersiële toepassing. Deur van dieselfde tegnieke as De Beer (2004) gebruik te maak, is drie groepe, elk bestaande uit verwante diploiede en triploiede diere, geproduseer en ingeskryf aan n vergelykende groei proef. Die groepe was in drie verskillende seisoene geproduseer. Die hoof doelstelling van die proef was om groeitempo van diploiede en triploiede diere te vergelyk, asook om die invloed van seisoen op groei van diploide en triploide te bepaal. Twee groei eienskappe naamlik skulp lengte en liggaamsmassa is gemeet vanaf ‘n ouderdom van agt maande (wanneer die diere individueel gemerk kon word) tot ‘n ouderdom van 24 maande. Die algehele resultate het gedui op geen betekenisvolle verskil tussen die groei van triploiede en diploiede perlemoen tot op die ouderdom van twee jaar. Verskille het voorgekom in die groei tussen seisoene, maar daar kon nie bewys word dat die verskille die gevolg van seisoenale omgewingseffekte was nie. Diploiede en triploiede het dieselfde skulp lengte tot liggaamsmassa verhouding getoon tot op twee jaar ouderdom.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The species Haliotis midae is the only abalone species of commercial importance to the South African fisheries industry. The species is currently under substantial pressure due to commercial harvest and illegal poaching, to the extent that genetic and biodiversity may be under threat. The species is also being cultured in commercial systems for supply to international markets. The South African production for 2002 amounted to 350 tons. The commercial production of abalone may also have implications with regard to genetic diversity of natural and commercial populations. The aim of this project was to assess the genetic diversity of the natural and commercial populations of abalone at the I&J Abalone Farm, Danger Point, Gansbaai, in South Africa, in order to make recommendation with regard to possible impact on natural diversity as well as internal management systems. Distortion of natural genetic diversity or a loss of internal diversity will have detrimental consequences. Representative samples have been obtained from the surrounding natural population, as well as the commercial populations, including the broodstock and various progeny groups. Both mtDNA and AFLP molecular techniques were used to assess genetic diversity. Data analysis showed that the genetic profile of the commercial population display sufficient genetic variation. The genetic structure of the commercial population also displays no significant deviation from that of the surrounding natural population, i.e. the population of origin. The results through give indication of a small, though unsignificant loss of genetic variation from the broodstock to the subsequent progeny groups. The investigation conclude that the commercial populations of abalone at the I&J Abalone Farm, Danger Point, Gansbaai, in its current format holds no threat to the disruption of the genetic diversity of the surrounding natural population. Further, the commercial population possesses sufficient genetic variation in view of future genetic development. There is signs of a slight loss of genetic variation in the change over from the broodstock to the progeny groups. This would necessitate careful and controlled replacement of the original broodstock with new animals from the commercial progeny groups as part of an ongoing process of domestication. / AFRIKAANSE OPSOMMING: Die spesie Haliotis midae is die enigste perlemoen spesie van kommersiële belang vir Suid Afrikaanse visserye. Die spesie verkeer tans onder toenemende druk as gevolg van kommersiële en onwettige vangste, tot so 'n mate dat genetiese en biodiversiteit daardeur geaffekteer kan word. Die spesie word in toenemende mate kunsmatig gekweek vir voorsiening aan internasionale markte. Suid Afrikaanse produksie vir 2002 beloop reeds sowat 350 ton per jaar. Die kunsmatige produksie van perlemoen het ook moontlike implikasies op die genetiese diversiteit van natuurlike en kommersiële populasies van die perlemoen, Haliotis midae. Die doel van die projek was om die aard van genetiese diversiteit van die natuurlike en kommersiële populasies van perlemoen by die I&J Perlemoen Plaas, Danger Point, Gansbaai in Suid Afrika te ondersoek, ten einde aanbevelings te maak ten opsigte van moontlike impak op natuurlike diversiteit asook ten opsigte van interne genetiese bestuurstelsels. Versteuring van natuurlike diversiteit of verlies van interne diversiteit hou nadelige gevolge in. Verteenwoordigende monsters is versamel vanuit die omliggende natuurlike populasies, sowel as van die kommersiële populasie op die plaas, insluitend die teelmateriaal en verskillende nageslaggroepe. Beide mtDNA en AFLP-molekulêre tegnieke is gebruik tydens die ontleding van genetiese diversiteit. Dataontleding het aangetoon dat die genetiese profiel van die kommersiële populasie voldoende genetiese variasie demonstreer. Die genetiese struktuur van die kommersiële populasie toon verder geen betekenisvolle verskil met die omliggende natuurlike populasie nie, dit wil sê met die populasie van oorsprong nie. Die resultate toon verder 'n geringe, dog nie betekenisvolle verlies van genetiese variasie wat waargeneem word met oorgang van die teelmateriaal na die onderskeie nageslaggroepe. Die bevindinge van die ondersoek is dus dat die kommersiële populasie op die I&J Perlemoen Plaas, Danger Point, Gansbaai, in die huidige formaat, geen bedreiging inhou vir die versteuring van die omliggende natuurlike genetiese diversiteit nie. Verdere bevindinge is dat die kommersiële populasie oor voldoende genetiese diversiteit beskik met die oog op toekomstige genetiese ontwikkeling. Daar is tekens van 'n geringe afname in genetiese diversiteit met die oorgang vanaf die teelmateriaal na die nageslaggroepe. Dit beklemtoon die belang van 'n gekontroleerde vervanging van die oorspronklike teelmateriaal met nuwe teeldiere vanuit die kommersiële populasie as deel van die domestikasieproses.

Haliotis midae is the cornerstone of the South African abalone fishery. For more than a decade, the wild abalone stock of South Africa has suffered decline due to over-exploitation and illegal activities such as poaching. Prior to 1970, no regulations were in place concerning the annual landings. As a result the fishery was exploited as if it were an infinite resource. It is this initial uncontrolled harvesting (regardless of age) and poaching that has driven the abalone resource decline. Due to the slow growth rate exhibited by abalone as a species, natural replenishment of wild stock following exploitation and poaching was far below the rate of exploitation of this resource. Studies on the growth of abalone have mainly been conducted under laboratory conditions. The purpose of this study was to measure the growth of abalone, fed different diets, under commercial culture conditions. Three food types were used namely; commercial pellets, seaweed (Ulva spp.) and dried kelp bars (Ecklonia maxima). Four diets were obtained from the three food types namely; combination of commercial pellets and seaweed (Diet A), commercial pellets only (Diet B), seaweed only (Diet C) and dried kelp bars only (Diet D). The food types used in this study represent both artificial (Commercial pellets) and natural feeds (seaweed and kelp) used in commercial abalone culture. The growth of two cohorts (40-50 mm and 50-60 mm) was followed over a 426 day period, with data for the first 183 days being used for statistical analysis to determine performance of a given diet. The best growth rates were found in abalone fed Diet A (40-50 mm: 2.64 mm.month-1; 50-60 mm 2.78: mm.month-1) and B (40-50 mm: 2.20 mm.month-1; 50-60 mm: 2.35: mm.month-1). These (Diets A and B) gave higher growth rates when compared to Diets C and D (natural diets), whose growth rates ranged between 0.50 mm.month-1 and 1.71 mm.month-1 for both cohorts. Also observed in this study was that, the mixture of formulated diet and seaweed gave better growth than formulated diet given exclusively.

Abalone Haliotis midae farming in South Africa is highly intensive, employing pump-ashore, flow-through systems. Despite the known sensitivity of abalone to water quality, there is only a rudimentary understanding of water quality dynamics on South African abalone farms and its effects on abalone production. Furthermore, the potential for reusing the relatively dilute abalone farm effluent to culture other animal species has not been investigated. This study investigated the dynamics of water quality and growth on a South African abalone farm and assessed the suitability of the effluent for the culture of silver kob Argyrosomus inodorus and bloodworm Arenicola loveni loveni. Monitoring of water quality and abalone growth in abalone tanks revealed that oxygen concentrations decreased, while H⁺ ion and free-ammonia (NH₃) concentration increased in a gradient between the inflow and outflow. Abalone growth was positively correlated with oxygen concentration and negatively correlated with free-ammonia and H⁺ ion concentration. The oxygen (O) concentration of the farm influent was dependent upon the influents’ temperature (T) and was described by the relationship O (mg L⁻¹) = 11.244 – 0.208T (r²=0.74). Linear regression analysis of data collected from abalone farm tanks revealed that the concentration of total ammonia at the outflow of abalone tanks (μg TAN L⁻¹) was dependant upon temperature (°C), flow-rate (L s⁻¹ kg⁻¹ H. midae), abalone size (g) and length of time since the tank was last cleaned (d) (n = 125, r² = 0.80). The production of total ammonia (μg TAN s⁻¹ kg⁻¹) was related to temperature, abalone size and days that the tanks remained un-cleaned (n = 125; r² = 0.81). A diurnal cycle of respiration was evident in abalone tanks with higher oxygen consumption and H+ ion production at night. The oxygen concentration of farm effluent was related to temperature, farm biomass and flow rate by means of a linear regression equation (n = 40; r² = 0.69). The results demonstrated the importance of optimising the flow-rate per unit of biomass for various temperatures and sizes of abalone. As abalone size and temperature cannot be controlled under farm conditions, the flow-rate per unit of biomass which the abalone culture system receives will determine the quality of the culture water. The specific growth rate (0.48 ± 0.01 % BW d⁻¹), mortality (1.8 ± 0.5 %), feed conversion ratio (3.0 ± 0.2) and protein efficiency ratio (1.0 ± 0.1) of silver kob kept in either abalone farm effluent or control seawater for 120 days did not differ significantly (t-test, P>0.05). A 90 day growth trial indicated that abalone farm effluent is a suitable culture medium for bloodworm. Bloodworm supplied with control seawater lost weight at 0.19 ± 0.04 % BW d-1, while those given abalone effluent grew at 0.39 ± 0.07 % BW d⁻¹. Mortality was 6 ± 3 % in effluent and 11 ± 8 % in seawater. The bloodworm were efficient at processing solid waste. Abalone farm effluent initially contained 7.7 ± 13 mg L⁻¹ more suspended solids than control seawater, which contained 3.5 ± 0.5 mg L⁻¹, but after passing through bloodworm systems the concentration in abalone effluent was reduced to only 1.4 ± 3.5 mg L⁻¹ above that in control seawater. Therefore, abalone farm effluent could be reused as a culture medium for both silver kob and bloodworm. Future work is needed to investigate aspects of the feasibility of such systems such as growth rates at different sizes and stocking densities.

Terebrasabella heterouncinata is a small K-selected sabellid polychaete. It is a simultaneous hermaphrodite with a semi-continuous mode of reproduction, producing relatively few large eggs that are brooded within the parental burrow until the larvae emerge, to settle on the growing edge of the abalone shell. Despite its low fecundity, this worm has become problematic on abalone farms in South Africa. The present study was conducted to gain an understanding of the life history patterns of T. helerouncinata to determine how they contributed to the success of these worms under altered conditions. This study demonstrated that conditions prevalent on abalone farms were conducive to enhancing the reproductive success of this worm, and suggests that larger, more fecund worms may have been selected for in the decade that these worms have been present on the farms. Increased nutrient availability, and possibly the increased stability of the farm environment relative to its natural environment, has led to a 1.5-fold increase in the average size of the worms. Body size was found to be positively correlated with brood size, and this resulted in worms on farms brooding 3 to 4.5 times more offspring at a time than worms from wild abalone. The ability to increase the number of eggs produced at a time may have been limited by the fact that these worms have only two ovaries. Thus, the increase in fecundity may have been related primarily to the increase in the rate at which the eggs were laid by the worms on the farms, and the increase in the coelomic space available for the storage of these rapidly developing eggs. The ability to increase the rate at which oocytes develop may be related to the vitellogenic mechanisms employed by these worms. Vitellogenic oocytes are able to incorporate high molecular weight yolk precursors from the surrounding coelomic fluid through endocytotic activity. This may allow the oocytes to increase the rate at which they incorporate yolk material under conditions of nutrient enrichment. The increase in fecundity did not occur at the expense of offspring size and, presumably, quality. The increased reproductive output on the farms was compounded by a proportionate increase in the number of reproducing worms within the population. In addition, these worms are long-lived (worms from farmed abalone reached a maximum age of approximately 40 months) and exhibit negligible senescence. Thus, their reproductive output did not change significantly with an increase in age. Furthermore, the proportion of the reproductive worms did not decrease with an increase in age. Thus, within the age range tested, worms of all ages have the potential to make equal contributions to population growth. While diet and abalone stocking density could not be identified as having a significant effect on reproductive output and infestation rate under intensive culture conditions, it was demonstrated that in a naïve abalone population, the total intensity of infestation increased exponentially with time. This increase may be a consequence of an increase in fertilisation success. These worms continuously produce entaquasperm that are released into the water column. The sperm are collected by other individuals that then store the sperm in a single spermatheca. The ability to store sperm relieves individuals of a dependence on the synchronisation of spawning of eggs and sperm. As the population size and density increases, there could be more individuals releasing sperm into the water column, resulting in a continuous supply of sperm. The increased production of eggs would therefore not be constrained by a lack of sperm. The stored sperm are released into the brood chamber to fertilise eggs as they are laid, and this would probably increase the fertilisation success in the species. This study also provides evidence to suggest that reproduction in this worm has a seasonal component. Future studies should concentrate on measuring fertilisation success in greater detail, measuring the effect of season on reproduction, determining whether there are genetic differences between worms on farmed and wild abalone and determining whether wild worms have similar life-spans and age-related fecundity as worms on farms.

The abalone (Haliotis midae) culture industry in South Africa is becoming increasingly dependent on the use of formulated feeds, due to limitations in the supply of kelp. The bulk of the feeds that are currently available were developed based on the requirements of juvenile abalone cultured within the optimal temperature range for growth (18 - 20 °C). However, most abalone farming facilities are land-based pump ashore operations and are thus mostly exposed to temperatures outside of this range. In addition, these feeds have been found to be unsuitable for abalone cultured at elevated water temperatures (> 20°C). The aim of the study was to develop size and temperature specific diets for H midoe through optimisation of dietary protein, energy and lipid levels. Abalone were cultured under farm-like conditions in three partially recirculating temperature controlled systems at either 18, 22 or 24°C and fed formulated diets containing graded levels of protein (18,22 and 26 %) and energy (11.6, 13.5 and 16.2 MJ.kg·I ). Abalone were stocked into baskets at 5 % of available of surface area (n=36) and each diet (n=9) was fed to four baskets of abalone at each of the three temperature regimes for ten weeks. Abalone growth was temperature dependent, with growth declining from 4.33 g.month-I for abalone cultured at 18°C to 0.77 g.month-I at 24°C. Dietary protein could be reduced from 26 to 18 % provided dietary energy levels were maintained at 13.5 MJ.kg- l • A dietary energy level of 11.6 MJ.kg-1 was insufficient to meet the energetic requirements of H midae regardless of the protein content of the diet. The effects of water temperature and body size on the protein requirements of H midae were investigated by culturing abalone at temperatures within the optimal range for abalone farming (i.e. 14, 16 and 18°C). Three size classes of abalone (15, 50 and 80 mm) were fed formulated feed containing graded levels of dietary protein (20, 26, 32, 38 and 44 %) under controlled laboratory conditions for 12 weeks, and, in a separate experiment, under commercial farm conditions for 24 weeks. It was not possible to convincingly define the optimal protein levels for abalone of different sizes in this experiment because growth rates fell below average commercial growth rates obtained on farms. Growth was temperature dependent in the laboratory trial, with the rate of weight gain of the 15 mm (ANOV A: p=0.002) and 50 mm abalone (ANOV A: p=0.02) increasing significantly with an increase in temperature from 14 to 18°C. In the farm trial, dietary protein content did not affect the growth rate of the 10-15 or 80 mm abalone (ANOVA: p>0.05), however, the 50 mm abalone displayed significantly higher weight gain on the 32 % (4.72±0.20 g.month-I ) and 38 % (5.01±0.34 g.month-I ) protein diets compared to those fed the 20 % protein diet (3.75±0.13 g.month-I ) (ANOVA: p=O.OI). Although definition of optimal dietary protein levels were not possible, the effects of dietary protein content and water temperature on the growth of H midae were independent signifying that the protein requirements of abalone are temperature independent. In addition, there was no evidence to indicate that abalone of the different sizes tested here had different dietary protein requirements. The size specific dietary lipid and protein requirements of H midae were investigated by feeding two size classes of abalone (30 and 60 mm initial shell length) diets containing graded levels of dietary lipid (4, 7, 10, 13 and 16 %) and protein (34 - 39 %) for 12 weeks. The 30 and 60 mm abalone were stocked at 7 (n=200) and 9 % (n=36) of the available basket surface area respectively and each diet was fed to four baskets of abalone of each size class. The protein requirements of H. midae are influenced by the amount of available dietary energy and thus it is possible that the ability of abalone to utilise lipids as a source of energy differs in the presence of varying levels of dietary protein. High levels of dietary lipid negatively affected the growth, condition factor and soft tissue glycogen content of both size classes of abalone. This negative effect was greater in the 30 mm size class compared to the 60 mm abalone. The corresponding increase in feed consumption and feed conversion ratio in response to increasing levels of dietary protein also provides evidence that abalone are unable to utilise dietary lipids as an energy source and high levels of dietary lipid probably inhibit the uptake of carbohydrates and protein. High dietary lipid levels did however appear to promote gonad maturation. It was possible to reduce dietary protein from 34 to 20 % without negatively affecting growth through the maintenance of dietary energy levels and thus it is recommended that future experiments on the energy content of formulated feeds should focus on the improved use of carbohydrates. Reductions in the protein portion of formulated feeds for H. midae are possible provided the diet contains sufficient levels of energy supplied from carbohydrates. As the ability of abalone to utilise dietary lipid is limited, lipids are unlikely to play a significant role as an energy source in abalone feeds. Further investigations should focus on the utilisation of various carbohydrate sources in abalone feeds.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The indigenous abalone, Haliotis midae has been a successfully cultured aquaculture species in South Africa since 1990. It has a slow growth rate and takes from two to five years 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 of farming and global competitiveness of the species. Ploidy manipulation of the maternal genome, a universally growing practice in shellfish culture, is considered a promising method to improve the growth rate of abalone - a desirable trait in aquaculture organisms from a commercial perspective. This manipulation technique is employed to achieve sterility, which results in limited gonad development. The consequent re-allocation of resources to somatic growth results in improved growth. The purpose of this study was to establish a viable method for the induction and validation of triploidy, on a commercial scale, in the South African abalone, H. midae. The focus was on hydrostatic pressure as a method of induction and flow cytometry as the method of validation. The results obtained confirm hydrostatic pressure as an effective method for the induction of triploidy in H. midae, delivering high percentages of triploidy (>80%) over a wide range of pressures and times, in 48 hour-old larvae. Hydrostatic pressure had a negative effect on survival in 20 hour-old larvae. Flow cytometry was validated as a reliable, fast and accurate, though expensive, method for identification of triploidy in H. midae. As an outcome of this study a manual of “Procedures for the Induction and Validation of Triploidy in the abalone” is presented (Appendix 1) together with recommendations for further studies on triploidy in the South African abalone, H. midae. / AFRIKAANSE OPSOMMING: Die inheemse perlemoen, Haliotis midae, is sedert 1990 ‘n suksesvol gekweekte akwakultuur spesie in Suid-Afrika. ‘n Kenmerk van die spesie is die stadige groeitempo van tussen twee en vyf jaar ten einde bemarkbare grootte te bereik. Soos vir die meerderheid perlemoen van kommersiële belang, is hierdie stadige groeitempo rede tot kommer met betrekking tot die winsgewende kweek en wêreldwye mededingendheid van die spesie. Die manipulasie van ploïdie van die moederlike genoom is ‘n toenemende praktyk in skulpvisboerdery en word gereken as ‘n belowende metode om die groeitempo van perlemoen te verbeter. Hierdie manipulasietegniek word gebruik om steriliteit te verkry wat manifesteer as onderdrukte ontwikkeling van die geslagsklier. Die gevolg is die herkanalisering van bronne na somatiese groei. Die doel van hierdie studie was om ‘n lewensvatbare metode vir die induksie van triploïdie op ‘n kommersiële skaal in die Suid-Afrikaanse perlemoen, H. midae, te vestig. Daar is op hidrostatiese druk as metode vir die induksie en vloei-sitometrie as metode vir die geldigverklaring van triploïdie gefokus. Die resultate van hierdie studie bevestig dat hidrostatiese druk ‘n effektiewe metode vir die induksie van triploïdie in H. midae is. Hoë persentasies van triploïdie (>80%) is oor ‘n wye reeks van drukke en tye in 48 uur oue larwes verkry. Daar is gevind dat hidrostatiese drukbehandeling ‘n negatiewe effek op die oorlewing van 20 uur oue larwes het. Vloei-sitometrie is bevestig as ‘n betroubare, vinnig en akkurate, maar duur metode vir die identifikasie van triploïdie in H. midae. As ‘n uitvloeisel van die studie word ‘n handleiding “Procedures for the Induction and Validation of Triploidy in the abalone” (Appendix 1) aangebied tesame met aanbevelings vir verdere studies rakende triploïdie in die Suid-Afrikaanse perlemoen, H. midae.

A gradient of sea temperatures is created along the South African coastline by the confluence of the cold Benguela Current on the West coast with the warm Agulhas Current on the East coast. This temperature gradient allows for an assortment of species to occupy the variety of microenvironments occurring in this area. Amongst these species is commercially important South African abalone, Haliotis midae, which although being capable of existing across this wide range of temperatures grows larger on the cooler West coast. Abalone reared on the warmer East coast however, experience greater mortalities especially during the more thermally variable summer months. The aim of the study was thus to assess the zone of tolerance for H. midae by exposing abalone to fluctuating temperatures in an attempt to model environmental temperature instability, a scenario which may likely be worsened by global climate change. Animals from the West and East coasts were exposed to two thermal treatments of fluctuating temperatures with the first group being kept at 16°C±2 and the second group kept at 16°C±4. The control group was maintained at a constant 16°C indicating that the mean temperature experienced by all three groups was 16°C. Oxygen consumption, nitrogen excretion and O:N ratio were assessed at the organismal level to give an indication of metabolic rate, amount of protein excreted and type of metabolic substrate utilized respectively. At the biochemical level, D-lactate accumulation was quantified to indicate whether metabolism was proceeding aerobically or anaerobically. Heat shock protein 70 (Hsp70) expression and degree of carbonylation were analyzed at the proteomic level with Hsp70 also being assessed at the transcriptomic level. All biological responses were measured at days 1, 3, 7 and 14 of the two week exposure. Oxygen consumption rates were significantly elevated on day 14 when comparing treatment group animals to control group animals of the same biogeographic region. P < 0.05 for both treatment groups from the West coast, while P < 0.001 for the East coast treatment groups. The ammonia excretion rates of the West coast animals were significantly lower than those of the controls at day 14 with P < 0.001 for both treatment groups, while ammonia excretion rates were elevated in East coast animals at day 14, although not significantly. Trends similar to those seen for ammonia excretion rates were exhibited by O:N ratios. West coast animals showed lower than control O:N ratios at day 14 (P < 0.01 for both treatment groups) while East coast animals displayed higher than control values (P < 0.05 only for the 16°C±2 group) at day 14. D-lactate, having been detected only for the West coast animals, showed no significant differences but large degrees of variation were noted on days 1 and 7. Carbonylation was evident for animals from both biogeographic regions with baseline carbonyl accumulation for East coast animals being greater (non-significantly) than that of the West coast animals. The hsp70 gene expression remained low for both biogeographic groups with West coast animals appearing to show slight elevations in expression at days 1 and 7, days which also displayed high degrees of variability. The West coast animals appeared to be better suited to coping with the thermal fluctuations, as they not only transiently reduced oxygen consumption rate to reduce ROS production, but also utilized the assistance of the D-lactate pathway possibly to maintain metabolism, both of which were not observed in the East coast animals. Although West coast abalone seemed to have slightly elevated hsp70 expression (suggestive of a repair response) when compared to their East counterparts, both groups of abalone were shown to have incurred notable amounts of protein damage (i.e. carbonylation). This suggests impairments in both protective and repair responses for animals from both biogeographic regions. The lack or attenuation of physiological responses noted in East coast abalone may be due to limitations in thermal adaptation but subsequent studies are required to confirm this notion. The information obtained from this study may assist in providing an insight into the mechanisms responsible for thermal limitation in H. midae and how this species is likely to respond to future periods of thermal instability which may be worsened by global climate change. An understanding of the processes leading up to limitations may potentially assist the abalone aquaculture industry in altering culturing practices early on to support optimal performance in abalone. / M.Sc. University of KwaZulu-Natal, Durban 2014.