Testing the suitability of local seaweeds and formulated feed as a food source for abalone (Haliotis midae Linnaeus) in an Integrated Land-based Aquaculture System

Magister Scientiae - MScThe direct methanol fuel cell or DMFC is emerging as a promising alternative energy source for many applications. Developed and developing countries, through research, are fast seeking a cheap and stable supply of energy for an ever-increasing number of energyconsuming portable devices. The research focus is to have DMFCs meet this need at an affordable cost is problematic. There are means and ways of making this a reality as the DMFC is found to be complementary to secondary batteries when used as a trickle charger, full charger, or in some other hybrid fuel cell combination. The core functioning component is a catalyst containing MEA, where when pure platinum is used, carbon monoxide is the thermodynamic sink and poisons by preventing further reactions at catalytic sites decreasing the life span of the catalyst if the CO is not removed. Research has shown that the bi-functional mechanism of a platinum-ruthenium catalyst is best because methanol dehydrogenates best on platinum and water dehydrogenation is best facilitated on ruthenium. It is also evident that the addition of other metals to that of PtRu/C can make the catalyst more effective and increase the life span even further. In addition to this, my research has attempted to reduce catalyst cost for DMFCs by developing a low-cost manufacturing technique for catalysts, identify potential non-noble metal catalytic systems and develop a basic process to combine various non-noblel, less expensive metallic systems to form binary, ternary and quaternary catalysts. The initial research focused on the identification of a suitable Pt/C preparation method, and characterization of the resulting catalysts by electrochemical methods (including voltammetry), elemental analysis (by EDS), and morphological characterization (by TEM). Once the preparation method for Pt/C had been established, binary (Pt–M/C), ternary (Pt–M1M2 /C) and quaternary (Pt–M1M2M3 /C) catalysts were prepared by modifying the initial Pt/C preparation method. These multi-metallic catalysts primarily function in preventing CO poisoning and allowing MeOH oxidation at the anode. To determine the effectiveness of the in-house multi-metallic catalysts the catalysts were then compared to the commercially available bench mark JM commercially available catalyst. Cyclic voltammetric and chronoamperommetric analysis revealed that the in-house catalysts electrochemical catalytic activity were similair to that of the commercially available catalysts. The Fuel application testing revealed similair trends to that of the EC activity at 0,5V (Ag/AgCl) test results, with the quaternary catalyst proving to be the most active anode catalyst producing the highest power density. The quaternary catalysts proved to be superior with its increased mass activity and high surface area (80% of the catalytic particles < 3nm).South Afric

Optimization of gene transfer in Haliotis midae by means of polyplex mediation

Thesis (MSc (Genetics))--Stellenbosch University, 2010.ENGLISH ABSTRACT: Haliotis midae is the most important aquaculture species in South Africa, with abalone farming contributing 80% of the Rand value of the aquaculture industry. Although genetic research has benefited the abalone industry, several issues still hinder increases in abalone production. Progress towards an increase in H. midae growth rate by utilizing conventional genetic studies and selective breeding has been relatively slow. Gene transfer has therefore become a plausible option to address this problem. Genes that code for certain desirable traits, such as increased growth rate, could be incorporated into the genome of commercial abalone. The current study undertook the optimization of a chemically-mediated gene transfer technique using Polyethylenimine (PEI) as transfection reagent and fluorescent proteins as reporter genes. Before gene transfer could be undertaken, several complementary studies also needed to be undertaken due to the novel nature of the study. The auto fluorescence of H. midae, the suitability of several H. midae tissues as targets for gene transfer and the cytotoxic effect of transfection reagents and selection antibiotics were assessed before gene transfer optimization could be attempted. Also, genes linked to an increase in growth rate were characterized for differential expression in different abalone age-groups to determine the suitability of these genes for incorporation into a homologous gene construct in future transfection studies. The auto fluorescence of ova, embryos and larvae were found to be comparable to that of the fluorescent reporter genes, EGFP and DsRed. A PCR-based transfection validation method was therefore employed to confirm the presence of internalized transgenes. It was established that sperm, ova, larvae and haemocyte cell culture were the most suitable target tissues for transfection. The transfection reagents, a 25kDa PEI and ExGen 500, were not cytotoxic to sperm, embryos and haemocyte cell cultures. The minimum lethal concentration of the selection antibiotics, neomycin and zeocin, was determined for larvae and haemocytes. After transfection treatment of sperm and fertilization of untreated ova, the presence of internalized transgenes could be verified for larvae. The presence of internalized transgenes could not be detected after transfection treatment of ova and larvae. Fluorescent flow cytometry and microscopy analysis of haemocytes could not detect the expression of the fluorescent reporter genes. Expression of two of the growth related genes was found to differ between age-groups. The perlustrin gene was upiv regulated in older animals, while the insulin related peptide receptor gene was down regulated in older animals. The third gene, a thrombospondin-1 precursor was stably expressed in all age-groups. This study represents the first report of transfection studies carried out on H. midae. Future studies will benefit from the groundwork established in H. midae transfection.AFRIKAANSE OPSOMMING: Haliotis midae is die belangrikste akwakultuur spesie in Suid-Afrika met perlemoen boerdery wat 80% van die Rand waarde van die akwakultuur industrie bydrae. Alhoewel genetiese studies die perlemoen industrie ‘n hupstoot gegee het, is daar steeds sekere struikelblokke wat verdere toename in produksie verhoed. Vooruitgang ten opsigte van ‘n toename in H. midae se groei tempo deur gebruik te maak van konvensionele genetiese studies en selektiewe teling was tot dusver relatief stadig. Genetiese transformasie het daarom ‘n wesenlike alternatief geword wat moontlik hierdie probleem kan oplos. Gene wat kodeer vir sekere eienskappe, soos ‘n toename in groeitempo, kan in die genoom van kommersiële perlemoen inkorporeer word. Die huidige studie het onderneem om ‘n chemies-gemedieerde genetiese transfeksie tegniek te optimiseer en van Polyethylenimine (PEI) as transfeksie reagens en fluoresserende proteine as verklikkers gebruik te maak. As gevolg van die oorspronklikheid van die studie moes verskeie bykomende ondersoeke ook aangepak word voordat genetiese transfeksie uitgevoer kon word. Die outofluoressensie van H. midae, die geskiktheid van verskeie H. midae teiken weefsels en die sitotoksiese effek van die transfeksie reagense en seleksie antibiotika is ondersoek voordat transfeksie uitgevoer is. Gene gekoppel aan ‘n toename in groeitempo is ook gekarakteriseer vir verskille in uitdrukking in verskillende perlemoen ouderdoms-groepe om te bepaal of hierdie gene moontlik in ‘n homoloë geen konstruk ingesluit kan word vir toekomstige transfeksie studies. Dit is gevind dat die outofluoressensie van ova, embrios en larwes vergelykbaar is met die fluoressensie van die verklikker proteïene, EGFP en DsRed. ‘n PKR-baseerde metode om die internalisering van die transgeen te kontroleer is daarom gebruik. Dit is vasgestel dat sperm, ova, larwes en haemosiete die mees geskikte teiken vir transfeksie sou wees. Die transfeksie reagense, ‘n 25kDa PEI en Exgen 500, is nie sitotoksies vir sperm, embrios of haemosiete nie. Die minimum dodelike konsentrasie van die seleksie antibiotika, neomycin en zeocin, is bepaal. Na transfeksie behandeling van sperm en bevrugting van onbehandelde ova, kon die teenwoordigheid van internaliseerde transgene bevestig word vir larwes. Die teenwoordigheid van internaliseerde transgene kon nie bevestig word na transfeksie behandeling van ova en larwes nie. Fluoressente vloei sitometrie en mikroskopiese analise kon nie die uitdrukking van die fluoressente verklikker gene bevestig in haemosiete nie. Die uitdrukking van twee van die gene gekoppel aan groei het verskil tussen ouderdomsgroepe. Die perlustrin geen is meer uitgedruk in ouer diere terwyl die insulien geassosieerde peptied reseptor geen minder uitgedruk is in ouer diere. Die thrombospondin-1 voorloper geen is stabiel uitgedruk in al die ouderdomsgroepe. Hierdie studie verteenwoordig die eerste verslag van transfeksie studies uitgevoer op H. midae. Toekomstige studies sal baat vind by die grondslag wat deur hierdie projek gelê is

Bacteria Recovered from Aquaculture in Oman, with emphasis on Aeromonas Spp.

Aquaculture is being seriously considered as a promising sustainable industry in the Sultanate of Oman. Fish farming commenced in Oman in 1986, but it was only in 2011 that it became a more commercially driven sector. While worldwide aquaculture production is expected to rise to meet the shortage in capture fisheries, there is a parallel requirement to identify potential threats to the health and welfare of existing aquatic farmed stocks and to take appropriate steps to mitigate them. As aquaculture in Oman is in an early stage of development, it is important to acquire baseline data on the existence and prevalence of aquatic diseases and pathogens to help the Government make policy decisions to develop health management regimes applicable for Omani aquaculture. Therefore, this study was conducted to evaluate current farming practices of tilapia in Oman, to investigate the bacterial species composition and distribution from different sites in some of the economically important fish species, and to study the characteristics and pathogenicity of Aeromonas species. The current practices were studied for 9 Nile tilapia (Oreochromis niloticus) farms from four areas (Al Batinah, Ad Dhahirah, Ad Dakhiliyah and Ash Sharqiyah North) during the period of September to November 2012 by using questionnaires and interviews with the farm owners and staff. In total 417 fish representing 5 target species were chosen on the basis of the commercial importance and their potential for aquaculture in Oman, including red spot emperor (Lethrinus lentjan), king soldier bream (Argyrops spinifer), white spotted rabbit fish (Siganus canaliculatus), abalone (Haliotis mariae) and tilapia (Oreochromis niloticus). The fish were collected from 5 main sampling areas in Oman (Muscat, Mudhaibi, Manah, Sohar and Salalah) based on the Atlas of suitable sites for aquaculture in Oman to investigate the bacterial species composition and distribution. The animals were examined for clinical signs of disease prior to routine bacteriology. Bacterial isolates were recovered using traditional methods and identified to species level using phenotypic and molecular approaches using 16S rDNA, 16S rDNA RFLP and 16S rDNA sequencing. Experimental fish challenge studies were also conducted using both live bacterial cells and ECP protein to investigate the pathogenicity of Aeromonas isolates. In addition, the presence of some virulence factors was investigated using both phenotypic and genotypic methods. The results of this study showed that, the most farms in the Oman follow very similar farming practices. The major proportion of the tilapia is consumed within the local communities. A number of farmers have experienced mortalities, which were considered to be attributable to poor water quality, overcrowding or due to excessive feeding. Farmers facing fish mortalities tended not to record the problems due to a lack of understanding of the concept of fish farm management. There is a regulation about aquaculture and related quality control, but it has not yet been implemented in an appropriate manner in Oman. From the diverse group of bacteria recovered from wild and farmed fish, 83% of the total isolates comprised Gram negative, rod-shaped bacteria. The most frequently isolated groups from marine and cultured fish were Aeromonas spp., Vibrio spp., Sphingobacterium spp., Micrococcus spp. and Staphylococcus spp., with Aeromonas spp. being the predominant group representing 25% of the isolates recovered in this study. Identification of the Aeromonas spp. showed 57% agreement between the results of phenotypic and genotypic methodologies, and determined 6 species as the dominant organisms, i.e. A. veronii, A. jandaei, A. caviae, A. trota, A. encheleia and A. salmonicida. 65% of the iso-lates shared 99% 16S rDNA sequence similarity with the closest sequences in GenBank, and the dominant species was A. veronii. In conclusion, the Aeromonas isolates recovered from fish with clinical signs of disease showed heterogeneity in their identification profiles and their pathogenicity

Diseases in Asian Aquaculture VII

Proceedings of the Seventh Symposium on Diseases in Asian Aquaculture 20-26 June 2008 Taipei, Taiwan

Risk Assessment of Impacts of Climate Change for Key Marine Species in South Eastern Australia. Part 2: species profiles

[Extract] Blacklip and greenlip abalone form the basis of valuable fisheries in Tasmania, Victoria, South Australia and New South Wales (Figure 1.1). The Tasmanian abalone fishery is the largest wild abalone fishery in the world, producing more than 25% of the global catch (Miller et al. 2009). In 2008, the fishery had a gross landed value of $ 90 million. Blacklip abalone (BA), Haliotis rubra, is the predominant species harvested in Tasmania with 2461 t landed in 2008, compared to only 122 t of greenlip abalone (GA), H. laevigata (Tarbath and Gardner 2009). Since 2003, the BA fishery has been divided into five zones: Eastern, Western, Northern, Bass Strait, and Central West (Tarbath and Gardner 2009). The GA fishery is restricted to the north of the state and is managed by regions and separately from the BA fishery. In Victoria, approximately 1,200 t was landed in 2007/08, however, the current TAC is 774 t (2010/11). Catches are dominated by BA (96%) and the fishery is structured into three zones: Western, Central and Eastern. The South Australian fishery harvests approximately 880 t of abalone each year, about 60% of this is BA with the remainder comprising GA. Like Victoria, the South Australian fishery is divided into the Southern, Central and Western zones. Current annual catches in NSW were less than 75 t in 2009/10 and consist exclusively of BA. The commercial fisheries are assessed on a variable combination of commercial catch, effort and size-composition data, fishery-independent surveys and length-structured models. In Tasmania, 105,500 abalone were taken by recreational fishers in 2006/07, weighing an estimated 49 t. The number of recreational licenses has tripled since 1995, with 12,500 recreational diving licenses issued in 2007/08 (Lyle 2008). Recreational catches in SA are small, probably less than 1% of the TACC (Jones, 2009)

Risk Assessment of Impacts of Climate Change for Key Marine Species in South Eastern Australia. Part 2: species profiles

[Extract] Blacklip and greenlip abalone form the basis of valuable fisheries in Tasmania, Victoria, South Australia and New South Wales (Figure 1.1). The Tasmanian abalone fishery is the largest wild abalone fishery in the world, producing more than 25% of the global catch (Miller et al. 2009). In 2008, the fishery had a gross landed value of $ 90 million. Blacklip abalone (BA), Haliotis rubra, is the predominant species harvested in Tasmania with 2461 t landed in 2008, compared to only 122 t of greenlip abalone (GA), H. laevigata (Tarbath and Gardner 2009). Since 2003, the BA fishery has been divided into five zones: Eastern, Western, Northern, Bass Strait, and Central West (Tarbath and Gardner 2009). The GA fishery is restricted to the north of the state and is managed by regions and separately from the BA fishery. In Victoria, approximately 1,200 t was landed in 2007/08, however, the current TAC is 774 t (2010/11). Catches are dominated by BA (96%) and the fishery is structured into three zones: Western, Central and Eastern. The South Australian fishery harvests approximately 880 t of abalone each year, about 60% of this is BA with the remainder comprising GA. Like Victoria, the South Australian fishery is divided into the Southern, Central and Western zones. Current annual catches in NSW were less than 75 t in 2009/10 and consist exclusively of BA. The commercial fisheries are assessed on a variable combination of commercial catch, effort and size-composition data, fishery-independent surveys and length-structured models. In Tasmania, 105,500 abalone were taken by recreational fishers in 2006/07, weighing an estimated 49 t. The number of recreational licenses has tripled since 1995, with 12,500 recreational diving licenses issued in 2007/08 (Lyle 2008). Recreational catches in SA are small, probably less than 1% of the TACC (Jones, 2009)

Vibrio tubiashii en France : description d’isolats pathogènes affectant des mollusques et étude de leurs mécanismes de virulence

The oyster farming constitutes one of the major components of the global aquaculture. However, this sector is facing abnormal mortalities outbreaks that affect diploid and triploid oyster at their different life stages, in the hatcheries and in the field. During bivalve molluscs mortality events in France, bacteria initially classified into Harveyi group, were regularly isolated along with herpes virus, V. splendidus or V. aestuarianus. In order to fine tune the taxonomic affiliation of those isolates, a genotypic and phenotypic approach was used. The bacterial isolates, initially misclassified into the Harveyi clade, were shown to be genetically closed to V. tubiashii strains already recognized as the main causative agents of larvae and juvenile mollusc mortalities in America and in England. A diagnostic tool was developed to evaluate its spread in mortality events since 2007, supporting this first description of V. tubiashii in France. Moreover, the virulence of isolates and the toxicity of their extracellular products (ECPs) were confirmed on C. gigas larvae and juveniles by experimental infections. Using in vitro assays, French V. tubiashii ECPs revealed their ability to alter some hemocytes immune defense probably through the degradation of matrix structural proteins. Finally, proteomic and transcriptomic analyses revealed the conjunction of multiples virulence factors including metalloproteases in the virulence of the French V. tubiashii strains.L’ostréiculture constitue l'une des principales composantes de l’aquaculture. Cependant, ce secteur est confronté à des épisodes de mortalités anormales survenant aussi bien en écloseries que dans le milieu naturel, affectant les huîtres diploïdes et triploïdes et à différents stades de leur vie. Pendant les épisodes de mortalité des mollusques bivalves en France, des bactéries, initialement classées dans le groupe de V. harveyi, ont été régulièrement isolées à coté des virus de type herpès, V. splendidus ou de V. aestuarianus. Afin d'affiner l’affiliation taxonomique de ces isolats, une caractérisation génotypique et phénotypique a été réalisée. Les isolats bactériens, initialement classés dans le groupe de V. harveyi, se sont révélés génétiquement plus proches de souches du groupe V. tubiashii, reconnues comme agents pathogènes affectant larves et juvéniles de mollusques aux Etats-Unis et en Angleterre. Des outils de diagnostic ont été élaborés pour évaluer la propagation de cette espèce lors des périodes de mortalité depuis 2007, supportant cette première description de V. tubiashii en France. La virulence des isolats et la toxicité de leurs produits extracellulaires (ECPs) ont été confirmés par infections expérimentales sur des larves et des juvéniles de C. gigas. Les essais in vitro ont révélé la capacité des ECPs de V. tubiashii à perturber des fonctions immunitaires hémocytaires probablement via la dégradation de certaines protéines structurales. Finalement, des analyses protéomiques et transcriptomiques ont révélé la conjonction de multiples facteurs de virulence, y compris les métalloprotéases dans la virulence des souches françaises de V. tubiashii

Evaluation of the intra and interspecific variability in the genus Perkinsus. Proteomic analysis of the parasite and its interaction with the host

Clam culture industry is rising every year worldwide. The most produced species is the Manila clam Ruditapes philippinarum. China is the main producer country followed by Italy, South Korea, USA and Spain. The introduction of the Manila clam in Europe was between 1970 and 1980. R. philippinarum is well adapted and grows faster than native species R. decussatus, for this, is the most produced species in Europe. The production of venerids in Galicia is a very important socio-economic resource. The production of Manila clam in Galicia rose in the last years and now is the most produced species too. The infection by Perkinsus olseni is one of the most serious diseases affecting clams. The parasite is highly distributed worldwide and affect to a large list of molluscs. Mortality of R. decussatus and R. philippinarum was associated with P. olseni infection in south Europe as well as with R. philippinarum mortality in several Asian countries. Two species of the genus Perkinsus, P. olseni and P. marinus, are included in the list of notifiable diseases of the World Organization for Animal Health, which indicates the interest to stop the expansion of the disease. The knowledge of P. olseni is very scarce in comparison with P. marinus which provokes massive mortalities in oysters Crassostrea virginica in USA. The economic transcendence of the perkinsosis justifies the research for a better knowledge of the disease and minimizes their effects. With this purpose, this study was developed in order to know (1) the variability of P. olseni along the Spanish coast, with the emphasis in virulence variability among populations, and (2) the modulation of the Manila clam protein expression due to P. olseni infection, with emphasis in the search of protein markers of resistance to the disease. The study of the variability was done analyzing the genetic population structure as well as the proteome of P. olseni clons derived from several regions of the Spanish coast. Furthermore, the proteome of P. olseni was compared with the proteome of two species of the genus, P. marinus and P. chesapeaki, in order to amplify the perspective of the variability of P. olseni. The analysis of the modulation of the Manila clam protein expression due to P. olseni infection was focused in haemocytes and haemolymph. The effect of the exposition to P. olseni in clams was measured at short time and a long time with the aim in the modulation of the immune response of the clam to the parasite

Estudio proteómico del sistema inmunitario de la Ostra Plana Ostrea edulis y su interacción con parásitos Bonamia spp.

Desde finales del siglo XIX, la sobrepesca combinada con brotes de enfermedades, especialmente los de bonamiosis, llevaron a las poblaciones de la ostra plana Europea, Ostrea edulis, a una reducción dramática, con consecuencias ecológicas y económicas de gran transcendencia. La recuperación de las poblaciones de esta especie requiere abordar la mortalidad causada por los parásitos protozoarios del género Bonamia spp., la principal amenaza patológica actual para Ostrea edulis en el litoral atlántico europeo. El presente trabajo se centra en el estudio proteómico de la hemolinfa y los hemocitos de O. edulis por ser las principales células implicadas en el sistema inmunitario de la ostra y el blanco de la infección por parásitos del género Bonamia spp. El objetivo final es profundizar en el conocimiento del sistema inmune de la ostra plana para entender mejor los mecanismos de defensa del bivalvo, identificar marcadores moleculares de resistencia y poder combatir así las enfermedades a las que están expuestas las ostras