Inadequate information of the nutritive physiology and the dietary requirements of abalone are the principle factors that currently limit the development of a formulated feed for the commercial culture of Haliotis midae. The need to develop a method to determine apparent digestibility co-efficient's for abalone in order to facilitate further applied nutritional research was identified. Animals between 50 and 80 mm were collected from natural stocks along the east Cape coast of South Africa at Port Alfred and Great Fish point, and acclimated to laboratory conditions. Initial trials demonstrated that H. midae accepted and preferred a semi-purified diet to the seaweed Plocamium corallorhiza, one of the main components of it's natural diet. A technique of determining apparent digestibility co-efficient's (ADC) using the indirect method with chromic oxide as an inert marker was developed. Digestibility trials yielded higher dry matter (DMADC) and crude protein apparent digestibility co-efficient's (CPADC) for the semi-purified diet than for two species of algae, Gelidium amanzii and P. corallorhiza (83.7% and 95.6%, 70.7% and 80.0%, and 29.9% and 57.3% respectively). The ability of the animals to utilize terrestrial animal and plant ingredients efficiently makes it feasible to use conventional feed ingredients in formulated feeds for H. midae. Trials to determine the effect of different temperatures (15°C, 18°C and 22°C) on DMADC and CPADC of the semipurified diet showed that peak digestibility occurred at 18°C. There was also a positive relationship between temperature and consumption rate. Although no enzyme studies with H. midae have been conducted, the peak ADC's at 18°C is attributed to an increase in enzyme activity at this temperature. Transit time, an inverse function of temperature and consumption, is considered to be responsible for the decrease in the ADC' s at 22°C in conjunction with a possible decrease in enzyme activity at this temperature. A photoperiod trial to investigate the effect of darkness on DMADC and CPADC of the semi-purified diet revealed that digestive efficiency decreased with increasing hours of darkness. There was also a positive relationship between duration of darkness and the rate of consumption. The decrease in ADC's is attributed to decreased transit times as the duration of darkness increased . The contribution of this project to the understanding of abalone nutrition, the development of a formulated abalone feed and systems design for abalone farms is discussed.

In the late 1980's abalone culturalists noticed reduced growth rate and shell deformities in some abalone stocks. These problems were the result of infestations by a shell boring polychaete, Terebrasabella heterouncinata. Under intensive abalone culture conditions the level of infestation can reach epidemic proportions and there are often severe consequences for the host abalone. Heavy sabellid infestation levels have placed the economic viability of several South African farms under threat. This study formed part of an ongoing project that is aimed at investigating the basic biology of Terebrasabella heterouncinata. The majority of abalone farmers in South Africa feed their abalone either naturally occurring kelp (Ecklonia maxima) or the formulated abalone feed, Abfeed. Farmers have suggested that the use of Abfeed is associated with higher sabellid infestation levels and changing the abalone diet from Abfeed to kelp helps reduce sabellid infestation. Speculation has arisen indicating that older, slower growing abalone are more susceptible to sabellid infestation. The effect of host abalone diet history and their growth on sabellid settlement success, morphometries and reproduction was quantified. To better understand the plasticity of the expression of life history traits the variability of morphometric and reproductive characteristics was compared between different farm environments. And more...

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Nearly all South African abalone farms function on an intensive pump-ashore, flow-through system. Large volumes of sea water that are pumped ashore flow through abalone or kelp harvesting tanks and finally gravitate back to the ocean. If the effluent from an abalone farm can be desalinated without permanent membrane fouling, then sea water reverse osmosis (SWRO) technology can be integrated effectively with established abalone farms without having to increase the farms’ intake system capacities. Without the need to construct and maintain an intake system, the overall cost of desalination can be reduced. Therefore, the aim of this study was to determine the feasibility and viability of integrating a SWRO desalination plant with a typical South African abalone farm. The project focused on four areas of concern, namely: - characterisation of typical South African abalone farm water - SWRO desalination plant pilot study and membrane fouling behaviour - general operation of a typical abalone farm and its implications for desalination - cost estimates and implications for the integration of an SWRO desalination plant with an abalone farm During a nine-month on-site investigation, sea water turbidity was reduced by up to 43% from a mean value of 0.82 NTU in the influent stream to 0.47 NTU in the combined effluent stream from the abalone tanks. Even with spikes in the influent turbidity, the turbidity of the combined effluent from all abalone tanks (excluding tank flush water) remained below 1 NTU. Dissolved organic carbon (DOC) in both the influent and combined effluent remained below 1 mg/litre. Ultrafiltration (UF) was selected as pre-treatment to the reverse osmosis (RO) in order to minimise potential fouling of the RO membranes. Membrane compaction of both the UF and RO membranes contributed significantly to initial flux losses – as much as 18% for the polyethersulfone (PESM) UF membranes and 20% for the thin film composite (TFC) polyamide RO membrane. However, this is comfortably in line with typical compaction values quoted in the literature. Without pre-flocculation, the UF was able to operate at a specific flux between 45 and 55 litre/m2/h (LMH) and recoveries ranging between 60 and 75%. Corresponding trans-membrane pressure (TMP) ranged between 0.59 and 0.76 bar. With ferric chloride pre-flocculation at a concentration of 3 mg/litre (as Fe3+) the UF could be operated at notably lower TMP values between 0.11 and 0.36 bar. These results indicate that provision should definitely be made for pre-flocculation when using UF as pre-treatment, despite the fact that the DOC concentrations and turbidity of the abalone farm effluent are quite low (DOC <1 mg/litre, NTU <1). It furthermore highlights the inability of DOC and turbidity alone to predict the membrane fouling potential of water. A better indicator of membrane fouling potential, albeit not perfect, is the modified fouling index (MFI0.45). This index follows a linear trend with foulant concentration and serves as a good indicator of the filterability of water. On-site measurements showed an increase in mean MFI0.45 values from 29 s/litre2 for the influent to 48 s/litre2 for the effluent from the abalone tanks, thereby confirming the need for pre-flocculation as part of UF pre-treatment. Chemically enhanced backwashing (CEB) of the UF membrane at least every 24 hours was found to be essential for its stable operation. Therefore, UF with pre-flocculation (3 mg/litre Fe3+) and regular CEB can be used effectively as pre-treatment method for the desalination of abalone farm effluent water. An RO ‘feed-and-bleed’ system was used to simulate the typical performance of the last membrane in a full-scale RO membrane bank. This RO membrane performed well with no signs of extreme fouling. The membrane produced a good quality permeate – for the last membrane in a membrane bank – reducing the TDS of the RO feed from 33 493 mg/litre to 969 mg/litre. These results compared well with simulated values by Reverse Osmosis System Analysis (ROSA; an RO simulator by DOW), indicating a TDS reduction from 33 271 mg/litre to 1 409 mg/litre at a feed pressure of 56 bar, and overall recovery of 44%. A steady performance of the RO membrane during the pilot study indicated that it is possible to desalinate abalone effluent water without notable permanent membrane fouling. A stable normalised flux rate of 8 LMH was achieved and RO membrane integrity remained intact with a salt rejection that ranged from 98.0 to 98.5%. No sudden reduction in permeate flux was observed as a result of fouling by unknown constituents present in the UF permeate. DBNPA (a non-oxidising disinfectant) was dosed once per week at a concentration of 10 – 30 mg/litre for 30 minutes. Scaling was controlled effectively by means of an antiscalant dosed at a concentration of 11 – 12 mg/litre in the feed stream. The CIP frequency was not optimised but a CIP frequency of once every 6 – 8 weeks appeared to be more than adequate to prevent permanent membrane fouling Advantages of integrating an SWRO desalination plant with a South African abalone farm include: - no lengthy and costly environmental impact assessment (EIA) is required to build a new intake system - shared capital and operational cost of intake system - dual incentive to keep constant good quality water flowing through the farm - early warnings regarding occurrences such as algal bloom and red bait - shared operational and management cost to keep pipelines clean - electricity saved (pumps for intake system) Disadvantages of integrating an SWRO desalination plant with a South African abalone farm include: - will require diverting of the abalone tank wash water from regular effluent - possible water ‘down-times’ due to maintenance operations on abalone farm Based on information from the literature the fixed capital cost depreciation rate (FCCDR) typically contributes approximately 40% and the operation and maintenance (O&M) cost typically contributes 60% to the unit production cost (UPC) of desalinated water. Furthermore, a SWRO desalination plant’s intake system can contribute between 5% and 33% to the FCCDR, depending on the nature and design of the plant. Consequently, the intake system can contribute between 2% and 13% of the UPC of desalinated sea water. This implies possible cost savings of between R0.15/m3 and R2.37/m3 for the production of fresh water (depending on site-specific design factors) when desalinating sea water effluent from on-shore abalone tanks. Integration of an SWRO desalination plant with a South African abalone farm is feasible and viable, provided that the necessary steps and precautions are taken to ensure a smooth and stable operation of the SWRO desalination plant. Cost savings on the part of all the stakeholders are possible if the correct contract can be negotiated. / AFRIKAANSE OPSOMMING: Byna alle Suid Afrikaanse perlemoenplase funksioneer op ‘n seewater deurvloeistelsel. Groot volumes seewater word aan wal gepomp en vloei deur die perlemoen of kelp-oes tenks. Hierdie water vloei dan uiteindelik terug na die oseaan as gevolg van swaartekrag. Indien die afvalwater van die perlemoenplase ontsout kan word sonder permanente membraanbevuiling kan seewater tru-osmose (SWTO)-tegnologie effektief met gevestigde perlemoenplase geïntegreer word sonder om die plase se water inname-stelsels se kapasiteite te vergroot. Sonder die behoefte aan uitbreiding en instandhouding van ‘n water inname-stelsel by so ‘n plaas behoort die totale koste van ontsouting aansienlik minder te wees. Die doel van hierdie studie was dus om die uitvoerbaarheid en lewensvatbaarheid van ‘n integrasie van ‘n SWTO ontsoutingsaanleg met ‘n tipiese Suid Afrikaanse perlemoenplaas te ondersoek. Ten einde dit te doen, het die projek op vier areas van belang gefokus, naamlik: - karakterisering van tipiese Suid-Afrikaanse perlemoenplaas water - SWTO ontsoutingsaanleg loodsstudie en membraan bevuilingsgedrag - algemene bedryf van ‘n tipiese perlemoenplaas en die implikasies vir ontsouting - kosteberamings en koste-implikasies met betrekking tot die integrasie van ‘n SWTO ontsoutingsaanleg met ‘n perlemoenplaas Gedurende ‘n nege maande op-perseel ondersoek is seewater troebelheid verminder met tot 43% van 'n gemiddelde waarde van 0.82 NTU in die invloeistroom tot 0.47 NTU in die gekombineerde afvalwaterstroom wat die tenks verlaat. Selfs met skerp wisseling in die invloeistroom troebelheid, bly afvalwaterstroom troebelheid deurgaans onder 1 NTU met die uitsondering van tenk spoelwater. Opgeloste organiese koolstof (OOK) in beide die invloeistroom en die gekombineerde afvalwaterstroom het deurgaans onder 1 mg/liter gebly. Ultrafiltrasie (UF) is gebruik as voorbehandeling vir die tru-osmose (TO) om sodoende potensiële bevuiling van TO membrane te minimaliseer. Membraan kompaksie van beide die UF en TO het merkbaar bygedra tot aanvanlike deurvloeiverliese – so veel as 18% vir die poli-etersulfoon (PESM) UF membrane en 20% vir die dun film saamgestelde (DFS) poli-amied TO membraan. Hierdie is egter gerieflik binne die tipiese kompaksiewaardes soos aangehaal in die literatuur. Sonder flokkulasie was die UF in staat tot temperatuur aangepaste deurvloeitempo van tussen 45 en 55 liter/m2/h (LMH) teen herwinningstempo’s tussen 60 en 75%. Ooreenstemmende trans-membraandrukkings (TMD) het gewissel tussen 0.59 en 0.76 bar. Met ysterchloried voor-flokkulasie teen 'n konsentrasie van 3 mg/liter (as Fe3+) kon die UF teen merkbaar laer TMD waardes bedryf word – tussen 0.11 en 0.36 bar. Hierdie resultate dui daarop dat daar beslis voorsiening vir pre-flokkulasie gemaak moet word wanneer UF as voorbehandeling gebruik word, ten spyte van die feit dat die OOK konsentrasie en troebelheid van die afvalwater van die perlemoenplaas redelik laag is (OOK <1 mg / liter, troebelheid <1 NTU). Verder lig dit die onvermoë uit om OOK en troebelheid alleen te gebruik om membraanbevuilingspotensiaal van water te voorspel. ‘n Beter aanwyser van membraanbevuilingspotensiaal, alhoewel nie perfek nie, is die aangepaste bevuilingsindeks (MFI0.45). Hierdie bevuilingsindeks volg ‘n lineêre neiging met die konsentrasie van onsuiwerhede en dien as ‘n goeie aanwyser van die filtreerbaarheid van water. Op-perseel metings het getoon dat ‘n toename in gemiddelde MFI0.45 waardes van 29 s/litre2 vir die invloeistroom tot 48 s/litre2 vir die afvalstroom van die perlemoentenks die behoefte vir voor-flokkulasie as deel van UF voorbehandeling bevestig. Chemies versterkte terugspoeling (CVT) van die UF membrane ten minste elke 24 uur is noodsaaklik gevind ten einde bestendige werking te verseker. Dus kan UF met voor-flokkulasie (3 mg/liter Fe3 +) en gereelde CVT effektief as voorbehandeling metode vir die ontsouting van perlemoenplaas afvalwater gebruik word. ‘n TO ‘voer-en-bloeistelsel’ is gebruik om die tipiese prestasie van die laaste membraan in ‘n volskaalse TO membraanbank te simuleer. Hierdie TO membraan het goed presteer sonder tekens van buitensporige membraanbevuiling. Vir die laaste membraan in ‘n membraanbank het die membraan goeie gehalte finale water gelewer – ‘n vermindering van die totaal opgeloste stowwe (TOS) van die TO voerwater van 33 493 mg/liter tot 969 mg/liter is behaal. Hierdie resultate het goed vergelyk met gesimuleerde waardes deur Reverse Osmosis Analysis System (ROSA, ‘n TO simulator deur DOW) wat ‘n TOS vermindering van 33 271 mg/liter tot 1 409 mg/liter by ‘n voerdruk van 56 bar en ‘n algehele herwinningstempo van 44% aandui. ‘n Bestendige werking van die TO membraan tydens die loodsstudie het getoon dat dit moontlik is om perlemoenplaas afvalwater te ontsout sonder merkwaardige permanente membraanbevuiling. 'n Stabiele genormaliseerde deurvloeitempo van 8 LMH is bereik en TO membraan integriteit het ongeskonde gebly met 'n sout verwerping wat gewissel het van 98.0 tot 98.5%. Geen skielike afname in finale water deurvloeitempo is waargeneem as gevolg van bevuiling deur onbekende onsuiwerhede in die UF finale water nie. DBNPA (‘n nie-oksiderende ontsmettingsmiddel) is een keer per week teen ‘n ‘n konsentrasie van 10 – 30 mg / liter vir 30 minute gedoseer. Mineraal skaalvorming is effektief beheer deur die dosering van ‘n anti-skaalmiddel teen 11 – 12 mg/liter in die TO voerstroom. Die skoonmaak-in-plek (SIP) frekwensie is nie ge-optimeer nie, maar ‘n SIP een keer elke 6 – 8 weke is meer as voldoende gevind om mikrobiese bevuiling te voorkom. Voordele van die integrasie van 'n SWTO ontsoutingsaanleg met 'n Suid-Afrikaanse perlemoenplaas sluit die volgende in: - geen lang en duur omgewings impak ontleding (OIO) is nodig vir die bou van ‘n nuwe inname-stelsel nie - gedeelde kapitaal en operasionele koste van inname-stelsel - tweeledige aansporing om konstant goeie gehalte watervloei deur die plaas te verseker - vroegtydige waarskuwings ten opsigte van gebeurtenisse soos rooigety - gedeelde bedryfs- en bestuurskoste om voerpype skoon te hou Nadele van die integrasie van 'n SWTO ontsoutingsaanleg met 'n Suid-Afrikaanse perlemoenplaas sluit die volgende in: - vereis herleiding van perlemoentenk spoelwater weg van gereelde afvalwater - moontlike watervloei-aftye weens instandhoudingsbedrywighede op die perlemoenplaas Gebaseer op inligting uit die literatuur dra die vaste kapitaal koste waardeverminderings-koers (VKKWK) gewoonlik ongeveer 40% en die bedryfs- en instandhoudingskoste (B&I) ongeveer 60% by tot die produksiekoste per eenheid (PKE) van ontsoute water.Verder kan ’n SWTO ontsoutingsaanleg se inname-stelsel tussen 5% en 33% tot die VKKWK bydra afhangende van die aard en ontwerp van die aanleg. Gevolglik kan die inname-stelsel tussen 2% en 13% tot die PKE van ontsoute seewater bydra. Dit impliseer ‘n moontlike kostebesparing van tussen R0.15/m3 en R2.37/m3 vir die produksie van vars water wanneer die afvalwater van perlemoentenks ontsout word. Integrasie van 'n SWTO ontsoutingsaanleg met 'n Suid-Afrikaanse perlemoenplaas is uitvoerbaar en lewensvatbaar indien die nodige stappe en voorsorgmaatreëls geneem is om ‘n vlot en bestendige werking van die SWTO ontsoutingsaanleg te verseker. Kostebesparings vir alle belanghebbendes (beleggers) is moontlik indien daar oor die korrekte kontrak onderhandel kan word.

ENGLISH ABSTRACT: The first successful captive spawning of the South African abalone Haliotis midae occurred in the 1980’s and subsequently the commercial abalone industry in South Africa has developed, with an estimated investment of US$ 12 million and annual output of 500 to 800 tons by 2001, making South Africa the biggest abalone producer outside of Asia. Natural kelp is currently the major feed and the development of a suitable substitute, and improved disease management in abalone culture are seen as the primary factors limiting expansion of the industry in South Africa. Further, abalone growth rates are very slow and improvements in growth rate will lead to shortened production times with benefits to producers. Diseases in aquaculture have traditionally been combated using antibiotics as treatment (therapeutic usage) and preventative measure (prophylactic usage). In terrestrial livestock management, antibiotics are also used as growth promoters. The use of antibiotics in aquaculture has recently sparked concerns about the development of antibiotic resistance in pathogens of humans and aquaculture organisms, and alternative strategies to using antibiotics mainly focus on manipulating the microbial composition in the host organism, in order to establish a beneficial microbial population to prevent disease. The role that organic acids and their salts can play as growth promoters in the South African abalone Haliotis midae, and as manipulators of the gut microflora of this species of abalone was investigated and compared to the effects of antibiotics. Three different treatments were tested against a negative control and a positive control containing 30ppm avilamycin, a commercial antibiotic growth promoter (AGP) used in the pig and poultry industry. The 3 treatments consisted of 1% acetic and 1% formic acid (treatment AF), 1% sodium benzoate and 1% potassium sorbate (treatment SBPS), and 1% benzoic and 1% sorbic acid (treatment BS). Three different experiments were conducted to test the effects of the different acids and salts. The first experiment was under controlled optimum water temperature conditions (16.5ºC), another at elevated water temperature (20.5ºC) in order to test response during temperature stress conditions, and the final trial was conducted under uncontrolled practical production conditions. In an attempt to establish the mechanism by which the treatments have their effects (if any), the composition of the gut microflora of the abalone was monitored. It was found that the organic acids and salts investigated can enhance the growth rate of Haliotis midae in the size class 23 mm to 33 mm mean length significantly when compared to both control treatments. It was further found that the tested AGP had no effect on growth rate. None of the treatments had a significant effect on feed conversion ratio (FCR), Incidence cost (IC) or feed intake. It could also not be shown that the treatments affected the intestinal microflora of the abalone, although this might be due to inadequate microbiological methods. The mechanism by which the acids and salts have their effects could not be established. It was found that the animals in the controlled system underwent an initial adaptation period, which led to improvement in specific growth rate (SGR), FCR and IC as the experiment progressed during the controlled optimal conditions experiment. Large differences in FCR and IC was seen for controlled optimal conditions and production conditions which means that there is still a large scope for developing methods to improve practical on-farm feed utilisation by abalone. SGR, FCR and IC were negatively influenced by raising water temperature from 16.5ºC to 20.5ºC. The composition of the gut microflora of the abalone also changed significantly after the water temperature was raised. It appears that animal weight gain and shell growth respond differently to changing water temperatures, which is reflected in a change in Fulton condition factor. A relationship between the length and weight of abalone between 15 mm and 47 mm was established and it was found that Haliotis midae does not follow an isometric growth relationship. This relation can be used as a tool to improve farm management and therefore also profitability. Various micro-organisms were isolated from Haliotis midae during the trial, but their relationship and interaction with abalone is not clear. Clear dominance by specific species of bacteria was observed during certain periods. The current research has clearly showed the potential of organic acids and their salts to act as growth promoters in the South African abalone Haliotis midae, with application in both the local aquaculture and feed manufacturing industries. The possibility further exists that some aspects of the current research can be adapted to be applicable in other abalone species and even in other aquaculture species. / AFRIKAANSE OPSOMMING: Die eerste suksesvolle aanteel van die Suid-Afrikaanse perlemoen Haliotis midae in gevangeskap is in die 1980’s gerapporteer, waarna ‘n suksesvolle akwakultuur industrie ontwikkel het met ‘n geskatte produksievermoë van 500 tot 800 ton en kapitaalbelegging van US$ 12 miljoen in 2001. Suid-Afrika is tans die grootste perlemoen-produserende land wat buite Asië geleë is. Die ontwikkeling van ‘n geskikte alternatiewe voedselbron vir natuurlike kelp (tans die algemeenste voedselbron wat gebruik word in die kweek van perlemoen), sowel as verbeterde siektebestryding word tans gesien as die hooffaktore wat verdere uitbreiding in die Suid-Afrikaanse industrie beperk. Perlemoen het verder baie stadige groeitempo’s en enige verbetering in hierdie verband sal produksietye verkort en dus produsente bevoordeel. Siektes in akwakultuur word tradisioneel bestry deur gebruik te maak van antibiotiese behandeling (terapeutiese bestryding) of van voorkomende behandeling (profilaktiese bestryding). In gewone diereproduksie-sisteme (bv. varke en hoenders) word antibiotika ook gebruik as groeistimulante. Die gebruik van antibiotika in akwakultuur het onlangs die bekommernis laat ontstaan dat sekere menslike en dierepatogene weerstand kan ontwikkel teen sommige middels, wat die behoefte laat ontstaan het om siektebestryding sonder die gebruik van antibiotika te ontwikkel. Alternatiewe strategieë fokus grootliks daarop om die samestelling van die mikrobiese bevolking van die gasheer te manipuleer en sodoende ‘n voordelige bevolking in die gasheer te vestig, wat dan siektes voorkom. Daar is ondersoek ingestel na die rol van organiese sure en hul soute as groeistimulante en manipuleerders van die mikrobiese bevolking in die Suid-Afrikaanse perlemoen Haliotis midae. Drie verskillende behandelings is getoets en vergelyk met beide ‘n negatiewe- en positiewe kontrole (wat 30 dele per miljoen van ‘n kommersiële antibiotiese groeistimulant bevat het). Die drie formulasies het onderskeidelik bestaan uit ‘n mengsel van 1% etanoëen 1% metanoësuur (behandeling AF), 1% bensoë- en 1% sorbiensuur (behandeling BS) en 1% natriumbensoaat en 1% kaliumsorbaat (behandeling SBPS). Om die effekte van hierdie formulasies te toets, is daar 3 proewe gedoen. Een proef is gedoen onder temperatuurbeheerde toestande teen ‘n optimum watertemperatuur van 16.5ºC terwyl ‘n ander gedoen is onder onbeheerde, praktiese produksie-omstandighede. ‘n Verdere beheerde proef is gedoen teen ‘n watertemperatuur van 20.5ºC om die effek van die verskillende formulasies te toets wanneer die diere aan temperatuur-spanning blootgestel word. Die samestelling van die mikrobiese bevolking in die dunderm van die perlemoen is deurentyd gemonitor in ‘n poging om die meganisme vas te stel waarvolgens die sure en soute hul effek het, indien daar enige effek waargeneem word. Daar is gevind dat die onderskeie sure en suursoute die groeitempo van Haliotis midae met ‘n gemiddelde lengte van 23 mm tot 33 mm beduidend kan verhoog in vergelyking met die groeitempo’s van beide kontroles. Daar is gevind dat die antibiotiese groeistimulant geen effek het op die groei van die diere nie en dat geen behandelings ‘n beduidende effek op voeromsetting, voerkoste of voerinname gehad het nie. Daar kon nie bewys word dat enige van die formulasies of die antibiotika ‘n effek gehad het op die mikrobes in die spysverteringskanaal van die perlemoene in die sisteem nie, alhoewel die gebrek aan ‘n effek moontlik toegeskryf kan word aan die onakkurate en onvoldoende mikrobiologiese metodes wat gebruik is tydens die studie. Die meganisme waarvolgens die sure werk kon nie vasgestel word nie. Daar is verder gevind dat die diere in die temperatuur-beheerde eksperiment aanvaklik deur ‘n aanpassingsperiode gegaan het, wat tot gevolg gehad het dat die spesifieke groeitempo, voeromsetting en voerkoste verbeter het met die verloop van die eksperiment. Daar is groot verskille gevind in die voeromsetting van beheerde optimale toestande en onbeheerde produksietoestande, wat impliseer dat daar nog baie ruimte en geleenthede is om metodes te ontwikkel wat beter voeromsetting bewerkstellig tydens perlemoenproduksie. Spesifieke groeitempo, voeromsetting en voerkoste is nadelig beïnvloed toe die watertemperatuur verhoog is vanaf 16.5ºC na 20.5ºC. Die samestelling van die mikrobiese bevolking in die spysverteringskanaal van die perlemoen het ook beduidende veranderinge ondergaan tydens hierdie temperatuur verhoging. Dit wil voorkom asof die lengtegroei van die dop en die toename in massa verskillend reageer op ‘n verandering in watertemperatuur en hierdie effek word weerspieël in die verandering in Fulton-kondisiefaktor. ‘n Verwantskap tussen totale doplengte en totale gewig van Haliotis midae kon vasgestel word vir diere tussen 15 mm en 47 mm en daar is gewys dat H. midae nie ‘n isometriese groeipatroon volg nie. Hierdie verwantskap kan aangewend word tydens produksiebestuur om produksie te verbeter en daardeur ook winsgewendheid te verhoog. Verskeie mikrobes is tydens die verloop van die proef geïsoleer, maar die rol van en interaksie tussen hierdie mikrobes en die Suid-Afrikaanse perlemoen is nie duidelik nie. Sekere bakterieë het die mikrobiese bevolking in die spysverteringskanaal van die perlemoen in hierdie proef oorheers tydens sekere groeiperiodes. Die huidige navorsing het duidelik aangetoon dat organiese sure en hul soute as groeistimulante kan optree in die Suid-Afrikaanse perlemoen Haliotis midae, met toepassings in die plaaslike akwakultuur- en voervervaardigins-industrieë. Dit beskik verder oor die potensiaal om aangepas te word sodat dit toepaslik is in ander perlemoenspesies en selfs ander akwakultuur organismes.

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 (PhD (Genetics))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: South African abalone, Haliotis midae, has been the subject of major concern regarding its survival and conservation over the last decade or more. Being the only one of five endemic species with commercial value, there is considerable interest and urgency in genetic management and improvement of this species. Limited genetic information and the increasing conservation concern of this species are considered the key motivations for generating information on the micro- and macro-evolutionary processes of H. midae, the overall objective of this study. This study reported the first microsatellite and Single Nucleotide Polymorphism (SNP) markers developed specifically for Haliotis midae. Both these marker types were applied to elucidate the degree of gene flow in nine natural abalone populations whilst testing for two contrasting hypotheses; panmixia versus restricted gene flow. Data was analysed using a series of methodological approaches ranging from traditional summary statistics to more advanced MCMC based Bayesian clustering methods with and without including spatial information. Using only microsatellite data, the historical demography of the species was also examined in terms of effective population size and population size fluctuations. Finally, the evolutionary positioning and origin of Haliotis midae with regards to other Haliotis species was investigated based on mitochondrial and nuclear sequence data. Both microsatellite and SNP data gave evidence for subtle differentiation between West and East coast populations that correlates with a hydrogeographic barrier in the vicinity of Cape Agulhas. Population substructure was supported by AMOVA, FCA and Bayesian clustering analysis. Clustering utilizing spatial information further indicated clinal variation on both sides of the proposed barrier with a region in the middle coinciding with a secondary contact zone, indicating possible historical isolation during glacial periods. Overall, the similar degree of substructure observed with both microsatellites and SNPs supported the existence of contemporary and/or historical factors with genome-wide effect on gene flow. The population expansion measured with the microsatellites was inconsistent with the known recent decline but taking the species’ life cycle and large effective population size into account, a shrinkage in population size will probably only be apparent in a few generations time. On a macro-evolutionary scale, this study presents the first classification of South African abalone as a monophyletic group within the Haliotidae family. The topology based on the combined mitochondrial and nuclear dataset is highly suggestive of a relatively recent radiation of the SA species from the Indo-Pacific basin. The study concludes by describing the most likely factors that could have affected overall population structure and makes suggestions on how the given genetic information should be incorporated into strategies aimed towards the effective management and conservation of Haliotis midae. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse perlemoen, Haliotis midae, is oor die laaste dekade of meer die onderwerp van groot bekommernis betreffende die spesie se oorlewing en bewaring. Aangesien dit die enigste van vyf endemiese SA spesies is met kommersiёle waarde, is daar besonderse belang en erns in die genetiese beheer en verbetering van die spesie. Beperkte genetiese inligting en ‘n toenemende behoefte om die spesie te bewaar is die hoof motivering agter die generering van informasie rakende mikro- en makro-evolusionêre prosesse in Haliotis midae en is die oorhoofse doel van hierdie studie. Hierdie studie beskryf die eerste mikrosatelliete en enkel basispaar polimorfismes wat ontwikkel is spesifiek vir Haliotis midae. Beide tipe merkers is aangewend om die mate van gene vloei in nege wilde perlemoen populasies te ondersoek terwyl twee hipoteses ondersoek is; panmiksie versus beperkte gene vloei. Data is geanaliseer deur gebruik te maak van ‘n reeks metodieke benaderings wat wissel van tradisionele opsommings statistieke tot meer gevorderde MCMC gebasseerde groeperings metodes met of sonder die gebruik van geografiese data. Mikrosatelliet data is ook aangewend om die historiese demografie van die spesie te bepaal in terme van effektiewe populasie grootte asook veranderinge in populasie groottes. Laastens is die evolusionêre posisionering en oorsprong van Haliotis midae teenoor ander Haliotis spesies ondersoek deur gebruik te maak van mitokondriale en nukleêre DNA volgorde data. Beide mikrosatelliet en enkel basispaar polimorfisme data lewer bewys van ‘n subtiele genetiese verskil tussen wes en ooskus populasies wat verband hou met ‘n hidrografiese skeiding in die omgewing van Kaap Agulhas. Populasie struktuur is ondersteun deur die analise van molekulêre variansie (AMOVA), faktoriale komponente analise asook Bayesiese groeperings analise. Groeperings analise wat geografiese informasie insluit dui klinale genetiese variasie aan beide kante van die skeiding aan met ‘n area in die middel wat ooreenstem met ‘n sekondêre kontak gebied. In totaal, ondersteun die soortgelyke mate van struktuur verkry met beide die mikrosatelliete en enkel basispaar polimorfismes die bestaan van hedendaagse en/of historiese faktore met genoom wye invloed op gene vloei. Die toename in populasie grootte vasgestel deur die mikrosatelliet data stem nie ooreen met die onlangse afname waargeneem in die spesie nie, maar met inagneming van Haliotis midae se lewenssiklus en groot effektiewe populasie grootte, sal die afname in populasie grootte moontlik eers oor ‘n paar generasies na vore kom. Op ‘n makro-evolusionêre skaal lewer hierdie studie die eerste klassifikasie van Suid-Afrikaanse perlemoen as ‘n monofiletiese groep binne die Haliotidae familie. Die topologie gebaseer op ‘n gesamentlike mitkondriale en nukleêre datastel is hoogs aanduidend van ‘n relatiewe onlangse verspreiding van die Suid-Afrikaanse spesies uit die Stille-Indiese Oseaan. Die studie sluit af deur die mees algemene faktore te bespreek wat populasie struktuur kon beïnvloed het en maak voorstelle op watter wyse hierdie genetiese inligting aangewend kan word vir die effekiewe beheer en bewaring van Haliotis midae.

Graduation date: 2003

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)--University of Stellenbosch, 2008. / ENGLISH ABSTRACT: The five leading abalone producers in South Africa have initiated a genetic enhancement program for Haliotis midae in a collaborative effort to improve economically valuable traits. Several independent objective-specific studies were initiated, including the establishment of a Performance Recording Scheme (PRS), utilised in this study, and necessary to monitor the ongoing performance of individuals as the move from mass-selection to marker assisted selection (MAS) is implemented. The primary objective of this study was parentage assignment of F1 offspring mass-selected for size at approximately one year and allocated to either a “faster” or a “slower” growth group. Nine microsatellite markers were used to genotype juveniles and potential parents, with assignment completed using CERVUS 2.0. Average growth results for Abagold and HIK were comparable for both growth groups. Slight environmental effects, although not statistically significant, were evident as growth advantages for juveniles within the faster growth group at two of the five locations and for juveniles within the slower growth group at one of the five rearing locations. Despite measures to standardise environmental influences, variables are difficult to control within the reality of a production environment; and potential genotype x environment interactions may require further investigation and factoring into future breeding programs. The additional costs associated with MAS often make the technology prohibitive to most aquaculture operations, despite the significant genetic gains to be realised from its implementation. Cost-optimising routine processes such as DNA extractions may be one approach to reduce these additional costs. Chelex®100 appears to be a suitable alternative to the CTAB method – being quick and cost-effective to perform. Applying this method in combination with the high throughput of a robotic platform warrants further evaluation. For the microsatellite development, 50% of positive recombinant clones contained inserts. Sequencing of these clones produced 16% perfect repeats and 47% imperfect repeats for which 52 primer sets were designed and tested. In total, 31 polymorphic microsatellite loci of different motifs and composition were developed. Sixty-one percent of sequenced clones were deemed redundant and pre-screening for both uniqueness and the presence of microsatellites would reduce unnecessary sequencing thus improving the efficiency of the FIASCO method and reducing costs. Nine loci were selected for parentage assignments. Null alleles were present for all the selected markers; however, frequencies were below the critical level of 5%. Parentage yielded 91% and 90% successful assignment for Abagold and HIK respectively; however, observations indicate that a measure of relatedness may exist between breeders. Recommendations with regards to future family breeding include, for both Abagold and HIK, retaining selected breeders based on their respective contributions to the F1 progeny while reassessing the potential of remaining breeding stock under more controlled breeding conditions. No obvious trends were observed for growth with most individuals producing both faster and slower growing offspring. Juveniles will be reassessed at two years to determine whether the size advantage or disadvantages were maintained and to ascertain whether growth advantages/disadvantages may be gender specific. / AFRIKAANSE OPSOMMING: Die vyf mees toonaangewende perlemoen produseerders in Suid Afrika het „n genetiese verbeteringsprogram vir Haliotis midae geinisieer in „n gesamentlike poging om ekonomiese belangrike eienskappe te verbeter. Verskeie onafhanklike fokus-spesifieke studies is geinisieer, insluitend die totstandkoming van „n groeiprestasie aantekenstelsel, soos gebruik in hierdie studie, en wat noodsaaklik is om die aaneenlopende prestasie van individue te moniteer soos daar beweeg word van massa seleksie tot merker bemiddelde seleksie. Die primêre fokus van hierdie studie was die ouerskapsbepaling van F1 nageslag wat massa geselekteer is op ouderdom 1 jaar vir grootte en as of “vinniger” of “stadiger” groeiers geklassifiseer is. Nege mikrosatelliet merkers is gebruik om jong perlemoen individue en moontlike ouers te genotipeer, met die ouerskapstoekenning bereken deur CERVUS 2.0. Groei resultate vir Abagold en HIK was vergelykbaar vir beide groei groepe op drie van die lokaliteite. Geringe omgewingseffekte, alhoewel nie statisties betekenisvol nie, was sigbaar as „n groei voordeel vir jong individue op twee van die vyf lokaliteite. Ongeag maatstawe om omgewingsinvloede te standardiseer, is varieerbares moeilik om te beheer in die produksie omgewing en genotipe x omgewings interaksies mag verdere navorsing vereis en behoort in ag geneem te word in toekomstige telingsprogramme. Die onkoste wat met merker bemiddelde seleksie geassosieer word, maak die tegniek soms onaantreklik vir die meeste akwakultuur operasies; nie teen staande die genetiese voordele wat die gebruik daarvan veroorsaak. Die koste-optimiseering van roetine prosesse, soos byvoorbeeld, DNA ekstraksies, is dalk een aanslag om die addisionele koste te verminder. Chelex®100 blyk „n geskikte alternatief tot die CTAB metode te wees – die tegniek is vinnig en koste-effektief om uit te voer. Die gebruik van hierdie metode in kombinasie met die hoë deurvloei van ‟n robotiese sisteem behoort verder ondersoek te word. Vir die mikrosatelliet ontwikkeling het slegs 50% van die positiewe rekombinante klone invoegings bevat. Nukleotiedvolgorde bepaling van hierdie klone het 16% perfekte herhalings en 47% onderbroke herhalings bevat waaruit 52 inleierstelle ontwikkel en getoets is. In totaal is 31 polimorfiese mikrosatelliet loki van verskillende motiewe en samestelling ontwikkel. Een-en-sestig persent van die volgorde bepaalde klone is oortollig geag en vooraf sifting vir beide uniekheid en die teenwoordigheid van mikrosatelliete sal onnodige volgorde bepaling verhoed, die effektiwiteit van die FIASCO tegniek verhoog sowel as addisionele koste verminder. Nege loki is geselekteer vir ouerskapsbepaling. Nul allele was teenwoordig vir al die geselekteerde merkers, maar die frekwensies was egter laer as die 5% kritieke waarde. Ouerskap is 91% en 90% suksesvol bepaal vir Abagold en HIK onderskeidelik. Waarnemings dui egter daarop dat daar verwantskappe mag wees tussen van die broeidiere. Voorstelle in terme van toekomstige familie teling sluit is, vir beide Abagold en HIK, om geselekteerde broei diere te behou gebaseer op hulle onderskeie bydraes tot die F1 nageslag asook die herevaluaring van die potensiaal van die oorblywende broei diere onder meer beheerde teling toestande. Geen voor-die-handliggende tendense is waargeneem vir groei nie met die meeste individue wat beide vinniger en stadiger groeiende nageslag geproduseer het. Jong individue moet geherevalueer word op tweejarige ouderdom om te bepaal of die groei voordeel of nadele behou is en om te bepaal om groei voordele/nadele geslagspesifiek is.

Thesis (MSc (Genetics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The South African abalone, Haliotis midae, is the only endemic species of commercial value. Aquaculture remains the only avenue for expanding the industry, since the closure of the fishery. The current focus is on implementing a molecular breeding programme; thus the development of molecular markers for linkage mapping and QTL analysis is a priority. Various markers, mainly anonymous, have been developed for H. midae; however emphasis is being placed on the development of gene-linked type I molecular markers. The present study investigates and demonstrates the use of public sequence collections to develop type I markers for a species with limited genomic resources, via three strategies: Surveying anonymous H. midae microsatellite markers’ flanking regions to find homology to gene sequences in public databases, cross-species marker transfer of anonymous markers from H. rubra and H. discus hannai demonstrating putative gene associations and lastly EST marker mining (SNP and microsatellites) from various Haliotids and testing transfer to the target species. Approximately 17% of H. midae anonymous markers showed significant similarity to genes. The current study also reports higher cross-species transferability from both H. rubra and H. discus hannai to H. midae (39% and 20.5%, respectively) than previously demonstrated and 15 EST-microsatellites and 16 EST-SNPs were successfully mined. Furthermore, the non-random distribution of microsatellites and high nucleotide diversity in the H. midae genome was confirmed. This is a low cost and time effective method for marker development and presents a continuous and dynamic resource that could be used for future marker development and characterisation as sequence information in public databases grow exponentially. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse perlemoen, Haliotis midae, is die enigste van vyf inheemse spesies van kommersiële waarde. Na die noodgedwonge sluiting van die vissery, is akwakultuur die mees praktiese oplossing om die perlemoen industrie uit te brei. Die huidige fokus is gerig op die implementering van ‘n molekulêre teel-program en dus is die ontwikkeling van molekulêre merkers vir genetiese kartering en kwantitatiewe kenmerk lokus analise, van uiterste belang. Tipe II merkers is voorheen vir die perlemoen ontwikkel, maar huidige tendense lê klem op die ontwikkeling van geen-gekoppelde tipe I merkers. Die huidige studie ondersoek die gebruik van publieke databasisse vir die ontwikkeling van tipe I molekulêre merkers vir ‘n spesie met beperkte genomiese bronne. Drie strategieë is geïmplementeer: Eerstens is ‘n opname gemaak van die homologie van perlemoen tipe II merker-vleuelende volgordes met geen volgordes in databasisse. Verder is die oordraagbaarheid van tipe II merkers vanaf H. rubra en H. discus hannai wat assosiasie met gene toon ondersoek. Laastens is ‘n Uitgedrukte Volgorde Merk (UVM) (Expressed Sequence Tag, EST) merker-ontginnings metode vanaf verskeie Haliotis spesies en toetsing van oordraagbaarheid na die teiken spesie uitgevoer. Ongeveer 17% van die tipe II H. midae merkers het geniese assosiasie getoon. ‘n Hoër tussen-spesie oordraagbaarheid vanaf beide H. rubra en H. discus hannai na H. midae (39% en 20.5%, onderskeidelik) word gerapporteer in vergelyking met vorige studies en 15 UVM-mikrosatelliete en 16 UVM-enkel nukleotied polimorfismes (single nucleotide polimorphism, SNP) is ontwikkel. Verder bevestig die studie die nie-lukrake verspreiding van mikrosatelliete en hoë nukleotied diversiteit in die perlemoen genoom. Die gebruik van publieke databasise vir die ontwikkeling en karakterisering van tipe I molekulêre merkers is tyd- en koste-besparend en bied ‘n volgehoue en dinamiese bron vir toekomstige gebruik.