Dissertations / Theses on the topic 'Abalone'
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Godfrey, Brian Peter. "The potential of abalone stock enhancement in the Eastern Cape Province of South Africa." Thesis, Connect to this title online, 2003. http://eprints.ru.ac.za/23/.
Full textLyon, Robert Gary. "Aspects of the physiology of the South African abalone, Haliotis Midae L., and implications for intensive abalone culture." Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005069.
Full textLambrechts, Daneel. "Molecular analysis of genetic variation and relationships amongst abalone (Haliotis midae) at the I&J abalone hatchery at Danger Point, Gansbaai, R.S.A." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52943.
Full textENGLISH 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.
Britz, P. J. (Peter Jacobus) 1959. "The nutritional requirements of Haliotis midae and development of a practical diet for abalone aquaculture." Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005152.
Full textJackson, Daniel John. "Applied and molecular approaches to improving the cultivation of the tropical abalone Haliotis asinina Linnaeus /." St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17413.pdf.
Full textSlabbert, Ruhan. "Molecular analysis of genetic variation and relationships within the population of abalone (Haliotis midae) at the Sea Plant Products abalone hatchery, Hermanus, R.S.A." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50027.
Full textENGLISH 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.
Gray, Michael. "Morphometrics and reproduction of Terebrasabella heterouncinata (Polychaeta:Sabellidae), infesting abalone (Haliotis midae) from different culture environments." Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1018231.
Full textYearsley, Rowan David. "Water quality, abalone growth and the potential for integrated mariculture on a South African abalone Haliotis midae L. farm." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1005180.
Full textGreen, Alistair John. "The protein and energy requirements of the South African abalone, Haliotis midae." Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1008261.
Full textKnauer, Jens. "Development of an artificial weaning diet for the South African abalone, Haliotis midae (Haliotidae: Gastropoda)." Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1004099.
Full textHancock, Andrew. "The biology and fishery of Roe's abalone Haliotis roei Gray in south-western Australia, with emphasis on the Perth fishery /." Connect to this title, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0068.
Full textGoosen, Neill Jurgens. "Organic acids as potential growth promoters in abalone culture." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/16416.
Full textAFRIKAANSE 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.
Vlok, Arnoldus Christiaan. "Genetic assessment of five breeding populations of abalone (Haliotis midae) through a comparative Performance Testing Scheme." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96870.
Full textENGLISH ABSTRACT: Cultured abalone in South Africa is undomesticated. For the local industry to remain competitive on the international markets it is essential to improve production. This study is part of a selective breeding component of a larger genetic programme that aims to enhance productivity of the local industry by genetic improvement of growth rates. Selective breeding programmes are based on genetic variation and correlations. Molecular studies proved genetic differentiation exist between the broodstock- and offspring populations and among the offspring populations used in this study. Five commercial abalone farms from the Walker bay region each entered 3000 randomly selected animals obtained from synchronised mass spawning of conditioned broodstock into a Performance Recording Scheme (PRS). Microsatellite marker analysis proved these broodstock populations to be representative of the wild populations. The five cohorts were assessed over the five locations represented by three replicates per location with 200 randomly assigned animals per replicate. The average growth rate was used as growth performance parameter by measuring shell length and body weight at three month intervals over a period of 24 months. Interaction was observed between cohort and location effects when analysing the full data set. This was unexpected as the cohorts were constructed from parent stick that was randomly sampled from the same geographical area, the larger Walker bay. The factors suspected of causing this observed interaction were considered in a stepwise analysis. Initial and progressive tag loss, differences in initial size of animals entered into the study and on-farm management errors were considered as possible causes of the observed interaction in a stepwise analysis. Statistically significant differences were observed between the five cohorts and between the five locations in terms of length and weight growth rates. Based on these findings it is advised that a central facility is used to effectively compare the growth rates of different cohorts or populations. Any future research in selective breeding to follow this study should involve the integration of molecular techniques and biotechnologies.
AFRIKAANSE OPSOMMING: In Suid-Afrika is gekweekte perlemoen wild. Vir die plaaslike bedryf om op die internasionale markte kompeterend te bly, is dit noodsaaklik om produksie te verbeter. Hierdie studie vorm deel van ’n selektiewe telingskomponent van ‘n groter genetiese program met die doel om die produktiwiteit van die plaaslike bedryf deur die genetiese verbetering van groeitempo’s te verbeter. Selektiewe teelprogramme word gebaseer op genetiese variasie en korrelasies. Molekulêre studies het bewys dat daar genetiese differensiasie bestaan tussen die teel- en nageslagpopulasies en onder die nageslagpopulasies wat in hierdie studie gebruik is. Vyf kommersiële perlemoenplase in die Walkerbaaistreek het elk 3000 ewekansig geselekteerde diere vanaf gesinkroniseerde massa broei van gekondisioneerde teelpopulasies aan ‘n Performance Recording Scheme (PRS) bygedra. Mikrosatelliet merker-analise het bewys dat hierdie teelpopulasies verteenwoordigend is van die wilde populasies. Die vyf kohorte is oor die vyf liggings geassesseer, elkeen waarvan verteenwoordig is deur drie replikate bestaande uit 200 ewekansig toegedeelde diere per replikaat. Die gemiddelde groeitempo is gebruik as die groeiprestasieparameter deur skulplengte en liggaamsgewig elke drie maande oor ‘n tydperk van 24 maande te meet. Daar is interaksie waargeneem tussen kohort- en liggingseffekte toe die volledige datastel geanaliseer is. Hierdie was onverwags, aangesien die kohorte gekonstrueer is uit teelouers waarvan monsters ewekansig vanuit dieselfde geografiese gebied, naamlik die groter Walkerbaai, geneem is. Die faktore wat vermoedelik hierdie waargenome interaksie veroorsaak het, is in ‘n stapsgewyse analise beskou. Aanvanklike en progressiewe merkerverlies, verskille in die aanvanklike grootte van die diere wat in die studie ingesluit is en bestuursfoute op die plaas is as moontlike oorsake van die waargenome interaksie voorgestel. Statisties betekenisvolle verskille is tussen die vyf genotipes en tussen die vyf liggings in terme van lengte en gewigsgroeitempo’s waargeneem. Op grond van hierdie bevindings word daar voorgestel dat ‘n sentrale fasiliteit gebruik word om die groeitempo’s van die verskillende genotipes of populasies doeltreffend te vergelyk. Enige toekomstige navorsing oor selektiewe teelt wat op hierdie studie sou volg, moet die integrasie van molekulêre tegnieke en biotegnologieë behels.
Lin, Albert Yu-Min. "Structural and functional biological materials abalone nacre, sharp materials, and abalone foot adhesion /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3307734.
Full textTitle from first page of PDF file (viewed July 28, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 192-202).
Hancock, Andrew T. "The biology and fishery of Roe's abalone Haliotis roei Gray in south-western Australia, with emphasis on the Perth fishery." Connect to this title online, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0068/.
Full textDonovan, Deborah Anne. "Energetics of activity in the abalone, Haliotis kamtschatkana." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ27132.pdf.
Full textDe, Beer Mathilde. "Induction of triploidy in the South African abalone, Haliotis midae, by the use of hydrostatic pressure." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16299.
Full textENGLISH 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.
Dixon, Mark Geoffrey. "The effect of temperature and photoperiod on the digestive physiology of the South African abalone Haliotis midae." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005120.
Full textMakhande, Emmanuel Denis. "Growth of the South African abalone (Haliotis Midae) on three diets, under commercial conditions." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/755.
Full textWhite, Hermien Ilse. "Anaesthesia in abalone, Haliotis midae." Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005059.
Full textRiddin, Nicholas Alwyn. "Growth and gonad size in cultured South African abalone, Haliotis midae." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001651.
Full textGruenthal, Kristen Marie. "Conservation genetics of California abalone species." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3268587.
Full textTitle from first page of PDF file (viewed September 4, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
Swanson, Willie J. "The molecular evolution of abalone fertilization proteins /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9907825.
Full textGerber, Maria Elizabeth (Mariette). "Quantitative assessment of yield traits between family groups of the cultured abalone, Haliotis midae, during the process of canning." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80085.
Full textENGLISH ABSTRACT: The species Haliotis midae is of great commercial value to the South African abalone industry and is mainly exported to Asian markets, specifically China. Up to 50% is sold as canned products with H. midae registering an average canning yield of approximately 35%. The species is presently genetically undomesticated and breeding programmes are being introduced to improve a range of production traits of which growth and yield is of primary importance. The objective of the study was to determine genetic parameters such as heritability, genotypic and phenotypic correlations of yield-related traits to assess the potential genetic improvement through selective breeding. A series of yield-related parameters were identified that is of relevance to the standard abalone canning procedure. Low to moderate heritabilities where recorded for most traits, including pre-shuck/live weight (0.20 ± 0.06), post-shuck weight (0.15 ± 0.05), post-gut weight (0.15 ± 0.05), post-brine weight (0.19 ± 0.06), pre-canning weight (0.19 ± 0.06), post-canning weight (0.21 ± 0.06), shell weight (0.16 ± 0.05), canning yield percentage (0.08 ± 0.03) and shell weight to post-gut weight ratio (SW: PGW) (0.09 ± 0.04). Weight related parameters are phenotypically highly correlated (0.86 ≤ r ≤ 0.99) but show negative correlation with canning yield percentage (-0.38 ≤ r ≤ 0.04). The nett yield of abalone shows a relatively strong positive correlation with the live weight (r = 0.66). Shell length is highly heritable (h2 ≈ 0.48) and show a strong positive correlation with live weight (r = 0.94). Shell weight is also highly correlated with live weight (r = 0.80) and the SW: PGW ratio does not show a significant correlate with live weight (r = 0.03). Weight-related traits show heritability values ranging from 0.15 to 0.20 that could allow a positive genetic response. Shell length (as a linear growth parameter) shows a high heritability (h2 ≈ 0.48) and a strong positive correlation with live weight (r = 0.94) which also makes it suitable for use as a selection criterion in breeding programmes for improved growth rate. Direct selection for canning yield is compromised by the destructive nature of measurement and the low heritability (h2 < 0.10). The negative correlations between yield as a percentage and growth traits (-0.38 ≤ r ≤ 0.04) further complicate its use as a direct breeding objective. Although the canning yield as a percentage shows a decrease with an increase in live weight, the nett canning yield increases (r = 0.66) with the live weight. It is therefore recommended to use shell length as a criterion for selection for increased growth rate and nett yield, thereby optimising profitability.
AFRIKAANSE OPSOMMING: Die spesie Haliotis midae is van groot kommersiёle waarde tot die Suid-Afrikaanse perlemoenindustrie en word meestal uitgevoer na markte in Asiё, spesifiek China. Tot 50% van die perlemoen wat in Suid-Afrika geproduseer en uitgevoer word, word verblik en huidiglik is die verblikkingsopbrengspersentasie ongeveer 35%. Haliotis midae is tans geneties onderontwikkeld en die gebruik van teelprogramme word nou geimplementeer met die doel om 'n verskeidenheid eienskappe te verbeter, waarvan groei en opbrengs van primêre belang is. Die doelwit van die studie was om genetiese parameters soos oorerflikheid en ook die genotipiese en fenotipiese korrelasies van obrengsverwante eienskappe te bepaal om sodoende die potensiёle genetiese verbetering as gevolg van selektiewe teeling te assesseer. 'n Reeks obrengsverwante eienskappe is geidentifiseer wat relevant is binne bestaande en standaard kommersiёle perlemoenverblikkingsprotokolle. Lae tot matige oorerflikheidswaardes is waargeneem en sluit in lewende, of voor-ontskulpingsgewig (0.20 ± 0.06), na-ontskulpingsgewig (0.15 ± 0.05), na-oopvlekkingsgewig (0.15 ± 0.05), na-pekelgewig (0.19 ± 0.06), voor-verblikkingsgewig (0.19 ± 0.06), na-verblikkingsgewig (0.21 ± 0.06), skulpgewig (0.16 ± 0.05), verblikkingsopbrengspersentasie (0.08 ± 0.03) en 'n skulpgewig tot na-oopvlekkingsgewig verhouding (SW: PGW) (0.09 ± 0.04). Gewigsverwante parameters is fenotipies hoogs gekorreleerd met mekaar (0.86 ≤ r ≤ 0.99) maar toon 'n negatiewe korrelasie met die verblikkingsopbrengspersentasie (-0.38 ≤ r ≤ 0.04). Die netto opbrengs van perlemoen dui op 'n relatiewe sterk positiewe korrelasie met lewende gewig (r = 0.66). Skulplengte is hoogs oorerflik (h2 ≈ 0.48) en toon 'n sterk positiewe korrelasie met lewende gewig (r = 0.94). Skulpgewig is ook hoogs gekorreleerd met lewende gewig (r = 0.80) en die SW: PGW verhouding toon geen beduidende korrelasie met lewende gewig nie (r = 0.03). Gewigsverwante eienskappe toon oorerflikheidswaardes wat varieer tussen 0.15 en 0.20 en kan 'n moontlike genetiese respons lewer. Skulplengte (as 'n liniêre groeiparameter) toon 'n hoё oorerflikheid (h2 ≈ 0.48) en 'n sterk positiewe korrelasie met lewende gewig (r = 0.94) wat dit gepas maak vir gebruik as 'n seleksiekriterium in 'n teelprogram met verbeterde groeitempo as doel. Direkte seleksie in terme van verblikkingsopbrengs word ingeboet danksy die destruktiewe natuur van die metingsmetodiek asook 'n lae oorerflikheid (h2 < 0.10). Die negatiewe korrelasies tussen verblikkingsopbrengs (uitgedruk as 'n persentasie) en groeieienskappe (-0.38 ≤ r ≤ 0.04) dien as 'n verdere komplikasie in die gebruik van dié eienskap as direkte teeldoelwit. Alhoewel die verblikkingopbrengs 'n afname toon soos lewende gewig toeneem, is daar steeds 'n positiewe korrelasie tussen die netto verblikkingsopbrengs en die lewende gewig (r = 0.66). Dit word dus aangeraai om skulplengte as seleksiekriterium vir verbeterde groeitempo en netto opbrengs te gebruik om sodoende wins te maksimaliseer.
Dlaza, Thembinkozi Steven. "Growth of juvenile abalone under aquaculture conditions." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&.
Full textSimon, Carol Anne. "The life history patterns of the polychaete, Terebrasabella heterouncinata, a pest of cultured abalone." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1005632.
Full textRagg, Norman Lawrence Charles. "Respiratory circulation in the abalone Haliotis iris." Thesis, University of Canterbury. Biological Sciences, 2003. http://hdl.handle.net/10092/1753.
Full textJames, Darren Stuart, and mikewood@deakin edu au. "Environmental site assessment for abalone ranching on artificial reef." Deakin University. School of Biological and Chemical Sciences, 2005. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20060914.100744.
Full textDale, Kuys Ruth. "Linkage disequilibrium in the South African abalone, Haliotis midae." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97991.
Full textENGLISH ABSTRACT: Linkage disequilibrium (LD) is defined as the non-random association of alleles at two or more loci within a population. It is sensitive to a variety of locus-specific- and demographic factors, and can thus provide much insight into the micro-evolutionary factors that have shaped species of interest. It can also be exploited to identify the genomic regions determining complex traits of interest, which can then be applied as performance evaluation markers in marker-assisted selection (MAS). The South African abalone, Haliotis midae, supports a rapidly developing aquaculture production industry, in which genetic improvement potential is high. This species also represents an opportunistic model for studying the effects of early domestication in a shellfish species. The aim of this study was therefore to quantify and characterise levels of genome-wide LD within the South African abalone, and to demonstrate its utility within population genetic investigations and the characterisation of complex traits. Estimates of LD between 112 mapped microsatellite markers within wild and cultured H. midae revealed that levels of LD in abalone are high relative to other aquaculture species. This was attributed primarily to small effective population sizes produced by a combination of natural- and anthropogenic factors. The decay of LD with genetic distance was evident in both cultured cohorts, but almost absent in wild cohorts, likely reflecting the differences in size, age and sampling of wild populations relative to cultured. Putative evidence for the effects of recombination, selection, and epistasis were also evident in distinctive locus-specific patterns of LD on some of the linkage groups, many of which could represent the effects of domestication. The effects of selection associated with the domestication event were further investigated using a candidate locus LD mapping approach to determine the proportion of candidate loci under selection associated with artificial selection for faster growth rate in cultured abalone. Two loci (15%) were found to be significantly associated with differences in size of individual animals, both of which could be linked with genes potentially involved in growth and development. These markers could therefore find application in MAS programmes for abalone. Several promising candidates for natural selection were also identified based on similarity with known genes. As the latter represented the majority, natural selection, rather than artificial selection, appears to be predominant during the early stages of domestication in abalone. While some conclusions within the current study were speculative, both the direct and indirect applications of LD were clearly demonstrated. Linkage disequilibrium data can provide a unique perspective on many of the commonly used population genetic estimates, and is therefore of great value in population genetic investigations. Furthermore, these results also highlighted the effectiveness of the candidate locus approach in species with both limited molecular resources and extensive LD.
AFRIKAANSE OPSOMMING: Koppelingsonewewig (KO) word gedefinieer as die nie-lukrake assosiasie van allele by twee of meer lokusse binne 'n populasie. Koppelingsonewewig is sensitief vir 'n verskeidenheid van lokus-spesifieke- en demografiese faktore, en kan dus insiggewend wees m.b.t. mikro-evolusionêre faktore wat spesies van belang beïnvloed het. Dit kan ook benut word om die genoom-gebiede onderligend tot komplekse eienskappe te bespeur; wat dan aangewend kan word vir prestasie-evaluering m.b.v. merkerbemiddelde seleksie (MBS). Die Suid-Afrikaanse perlemoen, Haliotis midae, ondersteun 'n vinnig ontwikkelende akwakultuur produksie bedryf, waarin genetiese verbeteringspotensiaal hoog is. Hierdie spesie verteenwoordig ook 'n opportunistiese model vir die bestudering van die gevolge van vroeë domestiseering in 'n skulpvis spesie. Die doel van hierdie studie was dus om vlakke van genoom-wye KO binne die Suid-Afrikaanse perlemoen te kwantifiseer en te karakteriseer, en om die toepassing hiervan binne populasiegenetiese ondersoeke en die karakterisering van komplekse eienskappe te demonstreer. Ramings van KO tussen 112 gekarteerde mikrosatelliet-merkers binne wilde en gekultiveerde H. midae het aan die lig gebring dat die vlakke van KO in perlemoen hoog was, in vergelyking met ander akwakultuur spesies. Dit word hoofsaaklik toegeskryf aan klein effektiewe populasiegroottes wat deur 'n kombinasie van natuurlike- en antropogeniese faktore teweeg gebring word. Die verval van KO met genetiese afstand was duidelik waarneembaar in gekultiveerde kohorte, maar amper afwesig in die wilde kohorte, waarskynlik a.g.v. verskille in populasiegrootte, ouderdom, en streekproef-neemings metodieke van die verskeie populasies. Vermeende bewyse vir die gevolge van rekombinasie, seleksie en epistase kon ook gesien word a.g.v. lokus-spesifieke patrone van KO op sommige van die koppelingsgroepe, moontlik ‘n gevolg van domestisering. Die gevolge van seleksie wat verband hou met die domestiseringsgebeurtenis is verder ondersoek m.b.v 'n kandidaat-lokus KO karteringsbenadering om die verhouding van kandidaat lokusse wat geassosieer is met kunsmatige seleksie (vir vinniger groeikoers in perlemoen) te bepaal. Twee lokusse (15%) was beduidend geassosieer met verskille in grootte tussen individuele diere. Beide van die lokusse was gekoppel met gene wat potensieel betrokke is by groei en ontwikkeling. Hierdie merkers kan dus moontlik aangewend word in MBS programme vir perlemoen. Verskeie belowende kandidaat lokusse vir natuurlike seleksie is ook geïdentifiseer gebaseer op ooreenkoms met bekende gene. Gegewe dat die laasgenoemde die meerderheid van die merkers verteenwoordig, kan daar afgelei word dat natuurlike seleksie, eerder as kunsmatige seleksie, oorheersend is in die vroeë stadia van domestisering in perlemoen. Terwyl sommige gevolgtrekkings binne die huidige studie spekulatief was, is beide die direkte en indirekte toepassings van KO duidelik gedemonstreer. Koppelingsonewewig-data kan 'n unieke perspektief gee op baie van die algemeen gebruikte populasie genetiese skattings, en is dus van groot waarde in populasie genetiese ondersoeke. Verder demonstreer hierdie resultate ook die doeltreffendheid van die kandidaat lokus benadering in spesies met beide beperkte molekulêre hulpbronne en uitgebreide KO.
Mohamed, Riaaz. "Abalone nutrition – growth performance of Haliotis midae in relation to variable artificial feeds." University of Western Cape, 2020. http://hdl.handle.net/11394/7860.
Full textAbalone are among the most expensive and sought-after seafood subjects. In South Africa, Haliotis midae is the only commercially significant abalone species and it has become increasingly sold on the global market. The importance of abalone as a mariculture subject has triggered extensive research into maximizing production, with particular emphasis on optimizing growth rates. This study aimed to assess the growth performance of Haliotis midae relative to 1) standard pelleted feed, and 2) kelp-inclusive pelleted feed. I assessed feed stability of the dietary treatments and growth parameters associated with abalone weight gain. Temperature and time of feed submersion were found to significantly affect feed stability. Although there were no significant differences in water stability between feeds, the kelp-inclusive feed produced significantly lower total suspended solids (TSS) than the standard pelleted feed at upper time-temperature combinations.
Naylor, Matthew Aubrey. "Water quality dynamics in an experimental serial-use raceway and its effects on growth of South African abalone, Haliotis midae." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1005181.
Full textSchoonbee, Lize. "The effect of triploidy on the growth and survival of the indigenous abalone, Haliotis midae, over a 24 month period under commercial rearing conditions." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/20859.
Full textENGLISH 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.
Van, der Merwe Elizabeth. "Toward best management practices for the growth of the abalone Haliotis midae Linnaeus on a commercial South African abalone farm." Thesis, University of the Western Cape, 2008. http://hdl.handle.net/11394/2745.
Full textSales, James. "Nutrient digestibility in South African abalone (Haliotis Midae L.)." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1005150.
Full textBritz, Peter Jacobus 1959. "Adventures with abalone : aquaculture, poaching, and fishery restoration." Rhodes University, Grahamstown, 2011. http://hdl.handle.net/10962/d1018943.
Full textWill, Margaret. "Genetic variation in New Zealand abalone, Haliotis iris." Thesis, University of Canterbury. School of Biological Sciences, 2009. http://hdl.handle.net/10092/4418.
Full textVisser-Roux, Adelle. "Reproduction of the South African abalone, Haliotis midae." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18111.
Full textENGLISH ABSTRACT: Currently, South African aquaculture is dominated by the cultivation of Haliotis midae, which is estimated as the most lucrative sector of the industry, with 934 t being export in 2008, totalling an income of ZAR 268 million (40 million USD) in 2008. This represents 81% of the total rand value of the aquaculture sector. Abalone was the highest aquaculture commodity exported during the last two years from South Africa, representing 24% of the total tonnage exported. Employment in the aquaculture sector increased by approximately 80% between 2005 and 2008, and was highest in the abalone sector where the number of people employed increased by 234%. Despite these high production rates, no hatchery procedures have been developed specifically for H. midae. Most procedures and protocols currently used in South African abalone hatcheries have been adopted from cultivation methods used for foreign species. Although certain aspects of reproduction are universally conserved between abalones, it is important to consider the physiology and the origin of the species studied. To date, no scientific research has been conducted on the reproduction of H. midae, except for a few studies in the early 1990s, which focused on the basic reproduction of this species. No further studies have been done on H. midae reproduction under intensive culture. Currently, hatch-out rates obtained by most abalone farms in South Africa averages 80%, with a 50% settlement rate, and a final hatchery output of only 30%. This study reports on various aspects of H. midae reproduction that can influence its commercial culture. A detailed histological characterisation of gametogenesis was developed. Findings indicated that cultured H. midae reaches 50% sexual maturity at a shell width of between 25 mm and 30 mm. During fertilisation trials, a sperm concentration of 50 000 sperm mL-1 and egg concentrations lower than 50 eggs mL-1 produced the highest hatch-out rates. Whilst fertilisation volume did not influence fertilisation success, fertilisation potential of the eggs did decrease with time. Eggs older than 100 minutes showed a lower fertilisation potential than eggs fertilised earlier. A larval stress test was developed to evaluate larval resistance against chemical stress. It was determined that 50% of resultant larvae would exhibit morphological abnormalities after fertilised eggs were incubated in 0.7% dimethyl sulfoxide (Me2SO) for a 24 hour period. If larvae exhibited fewer abnormalities at this concentration, it could be deduced that the larvae had a high resistance to the negative effect of the toxicant, and could thus be seen as good quality larvae. When evaluating hybridisation potential between H. midae and H. spadicea, it was found that it was possible to fertilise spawned H. midae eggs with biopsied H. spadicea sperm. By incorporating the results obtained from the present study into current hatchery systems on South African abalone farms, higher hatchery yield could be achieved, which in turn would lead to an increase in commercial revenue.
AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse akwakultuur sektor word tans oorheers deur die produksie van Haliotis midae, en word gereken as die mees winsgewendste bedryf in die industrie, met 934 t uitgevoer in 2008, na-raming „n inkomste van ZAR 268 miljoen (40 miljoen Amerikaanse doller). Dit verteenwoordig sowat 81% van die totale rand waarde in die akwakultuur bedryf. Perlemoen was ook die grootste uitvoer kommoditeit gedurende die laaste twee jaar, en het tot sowat 24% van die totale uitvoer vanuit akwakultuur bygedra. Werksgeleenthede in die akwakultuur sektor het tussen 2005 en 2008 met ongeveer 80% gegroei, waarvan die hoogste groeisyfer in die perlemoen bedryf was, waar die aantal werknemers met 234% toegeneem het. Ten spyte van hierdie hoë produksie omset, is daar tans geen protokolle wat spesifiek vir die produksie van H. midae ontwerp is nie. Meeste van die tegnieke wat huidiglik gebruik word op Suid-Afrikaanse plase, is gebaseer op, en aangepas vanaf metodes daargestel in die internasionale bedryf vir uitheemse spesies. Alhoewel sekere aspekte van reproduksie tussen perlemoen spesies verband hou, is dit belangrik om die fisiologie en oorsprong van die spesie van belang, in ag te neem. Wetenskaplike navorsing gedoen op die reproduksie van H. midae is beperk tot studies in die vroeë 1990s, wat die basiese beginsels van die spesie se reproduksie ondersoek het. Daar is geen verdere studies op die reproduksie van H. midae, veral onder intensiewe teel toestande, gedoen nie. Tans toon die meeste perlemoen plase in Suid-Afrika „n produksie persentasie van ongeveer 80% larwes vanaf bevrugting, met „n afname na 50% met vestiging en „n gevolglike uitset van slegs 30%. Hierdie studie doen verslag oor verskeie reproduksie aspekte van H. midae wat die teel doeltreffendheid van perlemoen op kommersiële plase kan beïnvloed. „n Gedetaileerde histologiese karakterisering van gametogenese is ontwikkel. Daar is gevind dat geteelde perlemoen 50% geslagsrypheid bereik met „n skulp wydte van tussen 25 mm en 30 mm. Tydens bevrugting eksperimente is bepaal dat 50 000 sperm mL-1 en „n eier konsentrasie van laer as 50 eiers mL-1, die optimale gameet konsentrasies is vir effektiewe bevrugting. Alhoewel die volume water waarin bevrugting plaasvind nie „n invloed getoon het op bevrugtingsukses nie, is daar wel gevind dat die eiers se potensiaal om bevrug te word, afneem met verloop van tyd. Eiers ouer as 100 minute het „n verlaagde bevrugtingspotentiaal getoon teenoor eiers wat vroeër bevrug is. „n Larwale stres toets is ontwikkel om larwale weerstand teen chemiese stres te bepaal. Daar is gevind dat 50% van geproduseerde larwes morfologiese abnormaliteite sal toon indien bevrugte eiers vir „n periode van 24 uur in 0.7% dimetiel sulfoksied (Me2SO) geïnkubeer word. Indien larwes minder abnormaliteite toon by hierdie konsentrasie, beteken dit dat hierdie larwes meer weerstand kan bied teen die negatiewe effek van die toksiese middel, en dus beskou kan word as goeie kwaliteit larwes met hoë lewensvatbaarheid. Met die evaluering van hibridisasie potensiaal tussen H. midae en H. spadicea, is gevind dat dit moontlik is om vrygestelde H. midae eiers te bevrug met H. spadicea sperm wat verkry is deur „n biopsie. Die implementering van hierdie studie se bevindinge in kommersiële H. midae produksiesisteme sal daadwerklik bydra tot die optimisering van bestuurspraktyke en „n verhoging in die totale produksie doeltreffendheid van sulke sisteme.
Tiravanit, Kanit. "Supply chain design for abalone farming in Thailand." Online version, 2003. http://www.uwstout.edu/lib/thesis/2003/2003tiravanitk.pdf.
Full textDanckert, Nathan Peter. "Characterising the intestinal microbiome of Australian aquacultured abalone." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21643.
Full textAyres, Devin William Philip. "Effect of diet and sex-sorting on growth and gonad development in farmed South African abalone, Haliotis midae." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1010856.
Full textShipton, Thomas A. "The protein requirements of the South African abalone, Haliotis midae." Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1005159.
Full textGerber, Werner Hugo. "Enhancing the competitive advantage of the South African cultivated abalone industry." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49946.
Full textENGLISH 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.
Stepto, Nigel Keith. "Triploid induction in the South African abalone, Haliotis midae." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/9669.
Full textAn investigation was undertaken to determine whether triploidy could be induced and improve the growth rate of the South African abalone, Haliotis midae. From the polar body counts at 17 °C the release times of polar body 1 and 2 were found to be at 12 - 15 min. post insemination (pi.) and 33-36 min. pi. respectively. Cytochalasin B (CB) (0.5mg. 1-¹ seawater) and elevated temperature (30 °C) were used as stresses to induce triploidy. CB induced 48.4% polar body 1 and 70.9 % polar body 2 triploid larvae at 20 hrs pi. At 120 hrs pi. induction rates were 55.5% and 62.4% respectively. Temperature induction was more successful, producing 92.9% polar body 1 and 86.4% polar body 2 triploid larvae at 20 hrs pi. This success was still evident at 120 hrs pi, where 71.1 % polar body 1 and 62.5% polar body 2 triploid larvae were produced. In the CB induction, where polar body 1 was retained, there was a pronounced production of tetraploid larvae (34. 2%). It appeared that CB affected the ova's resistance to polyspermy, which was found to be dependent on both CB concentration and the amount of excess sperm present. At 0.4 mg 1-¹ CB in seawater, 86.5% triploids and 0% tetraploids were produced. However, on the addition of sperm, 25.4% triploids and 69% tetraploids resulted. CB (0.5 mg 1-¹ ) in seawater produced 42.6%> tetraploids which, after the addition of sperm, increased even further to 50. l % pentaploids. Larval survival was found to be low overall with only 17% and 22% of control (diploid) animals surviving the rearing period, in the temperature and CB treatments respectively. The survival rates of the polar body 2 treatment were 11 % and 15% whilst those of the polar body 1 treatment were 7% and 11 %. Although these percentages indicated a difference in survival rates between the CB and temperature inductions, the actual numbers of larvae surviving were the same. The polar body 1 triploid larval survival was significantly less than both control and polar body 2 triploid animals.
Henderson, Ray Arthur. "Mitigation methods for Terebrasabella heterouncinata, a problematic sabellid polychaete, populations within an abalone (Haliotis midae) production system." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1580.
Full textT. heterouncinata is a sabellid polychaete endemic to South Africa and found primarily in the shells of the abalone Haliotis midae. With the intensification of abalone aquaculture around the world, T. heterouncinata has become a problematic pest by causing shell deformities, reducing abalone growth rates and, in some instances, high abalone mortalities. The problem of this sabellid was first noticed in Californian in the early 1980’s in Red abalone (Haliotis rufescens) production facilities. Many mitigation methods have been tested over the years and this paper investigates another two methods; a reduction in particulate load in the tank to reduce the food source of the sabellid which perhaps will reduce fecundity, and to use ultrasound as a possible mitigation method. This study found that filtration and reduction in suspended particles did not have a significant effect, but that ultrasound did have a significant effect in reducing T. heterouncinata populations.
Difford, Gareth Frank. "Critical assessment of the “internal reference” method to eliminate non-genetic effects within a Combined Family Selection program on the abalone species (Haliotis midae)." Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85658.
Full textENGLISH ABSTRACT: The aim of this study was to critically assess the implementation of the internal reference method within the most recent 173 full-sibling growth trial of the Innovation Fund Abalone Breeding Project. The trial was conducted over two locations for a period of five years, with minimal replication for the majority of test families and a single full-sibling family was entered into each experimental unit (basket) as an internal reference group. The primary focus was firstly, to validate the performance of the internal reference group as a control for comparisons and correction of environmental variation in test family performances. Secondly, to identify areas of weakness and either make recommendations to remedy areas of weakness or justify devoting resources to alternative methods of reducing extraneous environmental variance with limitations on replication. The efficiency and statistical power associated with utilising internal reference information as a covariate and for manual correction respectively were examined for the 6 full-sibling test families that were replicated. This study reports on the evaluation of factors which are potential sources of bias in the internal reference method, the first of which, tag loss, was found to be significant after 6- 12 months. However, it was not found to bias internal reference group performances as the factors which contribute to tag loss were found to act randomly. Variability in size ratio of internal reference to test family at co-stocking proved a significant source of bias, as reference groups smaller than their test family counterparts had reduced performances. Testing for genotype by environment interactions was precluded due to the inherent lack of replication and the subsequent confounding of genotype effects with inter-rearing structure effects at one of the locations. However, significant differences were detected for both traits of interest of the internal reference group over the two locations. Significant antagonistic interactions were detected and identified as a source of bias for average daily weight gain of replicate test families. The evaluation of average daily length gain for the efficiency of adjustment when the internal reference is a covariate and the change in statistical power when the internal reference is used for a manual correction, yielded conflicting results. The latter shows a decrease in statistical power and the former shows an increase in efficiency, both resulting in poor goodness of fit in the respective models. There was however evidence that when no antagonistic interactions occurred “between replicate variance” decreased and therefore the internal reference method has statistical merit provided all critical success factors are satisfied. Recommendations were made for future implementation of the internal reference method to facilitate adequate statistical testing for sources of bias and the prevention thereof. Additionally, an alternative method which may have merit in decreasing environmental variance and the need for replication, is discussed.
AFRIKAANSE OPSOMMING: Die doel van die studie was om die gebruik van ʼn interne verwysingsgroep te ontleed, soos toegepas tydens die evaluering van 173 volsib families as deel van die Innovasiefonds Perlemoen Teelprogram. Die evaluering is gedoen op twee lokaliteite oor 'n tydperk van vyf jaar, met minimale replikasie van die toets families en die gebruik van ‘n enkele volsib familie as 'n interne verwysingsgroep in elke eksperimentele eenheid (mandjie). Die primêre fokus was eerstens om die gebruik van die interne verwysingsgroep vir die korreksie van omgewingsvariasie in die toets familie optredes te evalueer. Tweedens, om spesifieke gebreke te identifiseer ten opsigte van die gebruik van die interne verwysingsgroep en aanbevelings maak dit reg te stel en om die meriete van alternatiewe metodes te oorweeg. Die doeltreffendheid en statistiese onderskeidingsvermoë van die gebruik van interne verwysingsgroep as 'n kovariaat is ondersoek met betrekking tot die 6 volsib groepe wat oor voldoende replikasies beskik het. Die studie doen voorts verslag oor die evaluering van potensiële oorsake van sydigheid ten opsigte van die gebruik van die interne verwysingsgroep, insluitend die beduidende verlies van identifikasie vanaf 6 tot 12 maande. Geen aanduiding van sydigheid is egter gevind en die aanleidende oorsake van verlies van identifikasie blyk van ʼn ewekansige aard te wees. Verskille in die grootte tussen die interne verwysingsgroep en toets-families met aanvang van evaluering blyk 'n belangrike bron van sydigheid te wees, waar die kleiner groepering aan verminderde prestasie gekoppel word. Bepaling van genotipe-omgewing-interaksies kon nie uitgevoer word nie as gevolg van die inherente gebrek van replisering oor lokaliteite. Beduidende verskille is egter waargeneem tussen interne verwysingsgroepe oor die twee lokasies ten opsigte van die beide groei eienskappe. Beduidende antagonistiese interaksies is waargeneem en geïdentifiseer as 'n bron van sydigheid ten opsigte van die gemiddelde daaglikse gewigstoename van replikaat toetsfamilies. Die evaluering van gemiddelde daaglikse lengtetoename met die interne verwysingsgroep as is 'n kovariaat en die verandering in statistiese ontledingsvermoë tydens die gebruik van die interne verwysingsgroep het teenstrydige resultate opgelewer. Laasgenoemde toon 'n afname in statistiese ontledingsvermoë en die eersgenoemde toon 'n toename in doeltreffendheid, met beide swak passing op die onderskeie modelle. In die afwesigheid van antagonistiese interaksies tussen replikasies het variansie afgeneem en beskik die interne verwysingsgroep oor die nodige statistiese meriete indien daar aan al die kritiese vereistes voldoen word. Aanbevelings is gemaak ten opsigte van die toekomstige implementering van die interne verwysingsmetode met verwysing na voldoende statistiese toetsing vir bronne van sydigheid en die voorkoming daarvan. 'n Verdere metode wat oor die nodige meriete beskik om die omgewingsvariasie en die noodsaaklikheid vir replikasie te verminder, word bespreek.
Nicholson, Gareth Hurst. "Towards understanding the effects of stocking density on farmed South African abalone, Haliotis Midae." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1015646.
Full textNeethling, Karin. "An investigation of the implications of the decision to close the abalone fishery and the impacts on abalone rights holders in Kleinmond, South Africa." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4787.
Full textInludes bibliographical references (leaves 159-172).
The overall aim of this dissertation is to investigate the implications of the decision toclose the abalone fishery and the impacts of this decision on abalone rights holders inthe Kleinmond community in the Western Cape Province of South Africa. This dissertation also looked at the role that marine resources play in the livelihoods of fishers and the impact of the closure on the livelihoods of rights holders. Potential opportunities and constraints associated with alternative livelihoods options for fishers were also identified.
Greeff, Mariska R. "The development, optimisation and evaluation of molecular methods to diagnose abalone tubercle mycosis (ATM) caused by Halioticida Noduliformans in South African abalone, Haliotis Midae." Thesis, University of the Western Cape, 2012. http://hdl.handle.net/11394/4033.
Full textLand-based abalone aquaculture in South Africa started in the early 1990s and is based on the local species Haliotis midae. This industry expanded with great success over the last decade. In 2006 abalone exhibiting typical clinical signs of tubercle mycosis was discovered for the first time in South African abalone culture facilities,posing a significant threat to the industry. Halioticida noduliformans, a fungus belonging to the Peronosporomycetes (formerly Oomycetes), has been identified as the causative agent of abalone tubercle mycosis (ATM). While diagnoses of this disease are currently done by gross observation and histopathology, these methods fail to be sensitive enough to identify the causative agent accurately and reliably.Molecular confirmation could provide for quicker more accurate diagnostic information. The aim of this study was to develop a DNA based molecular diagnostic test. Polymerase chain reaction (PCR) has been used to rapidly detect, characterise and identify a variety of organisms. Nucleotide sequences of the smalland large-subunit ribosomal ribonucleic acid (rRNA) and mitochondrial cytochrome oxidase subunit II (cox2) genes of H. noduliformans were compared with closely related Peronosporomycete gene sequences to identify potential PCR primer sites. H. noduliformans specific real-time quantitative PCR (Q-PCR) primer sets were designed and optimised for each of the selected genes. Results indicate that, although all tested primers sets could amplify fungal DNA, only the LSU and cox2 primer sets - v -demonstrated no cross-amplification with the closely related Peronosporomycete and non-fungal DNA tested in the present study. The H. noduliformans specific LSU primer set was chosen for further analysis and used for all subsequent real-time PCR assays. The lowest detection limit for the LSU primer set was evaluated by running Q-PCR on serial dilutions of known quantities of extracted H. noduliformans DNA.Serial dilutions were made in PCR grade water as well as in an abalone tissue matrix.The sensitivity of the Q-PCR reaction was determined to be 266 pg of H.noduliformans DNA per 25 μL reaction volume. However, inclusion of a nested PCR step, utilising universal fungal outer primers, followed by Q-PCR with the H.noduliformans LSU specific primers improved sensitivity to 0.266 pg of H.noduliformans DNA per 25 μL reaction volume. This equates to approximately 2.4spores per 25 μL reaction volume. DNA extraction protocols were optimised to ensure efficient and repeatable extraction of high quality fungal DNA from pure fungus and tissue samples spiked with known quantities of fungal DNA. PCR amplification efficiency and potential inhibition were examined for each extraction method. Results suggest that real-time PCR has great potential in monitoring and quantifying H. noduliformans on abalone culture facilities in South Africa.
Steynberg, Leander Duvan. "Characterisation and desalination of typical South African abalone farm effluent sea water." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71601.
Full textENGLISH 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.
Zeeman, Susanna Catharina Franzina. "Influences of the abalone Haliotis midae on subtidal benthic communities." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/12230.
Full textThe South African abalone Haliotis midae is a commercially exploited species that is seriously threatened by overfishing and poaching. This not only affects the species itself but also the integrity and functionng of the ecosystem through associated changes in community structure. I assessed the influence of abalone on the ecosystem by a combination of (a) dietary studies, (b) comparisons of communities living on shell versus surrounding rock substratum, and (c) removal experiments using field exclusion/inclusion plots.