D.Phil. / The entire Olifants . River Catchment is subjected to increasing afforestation, agricultural, domestic, mining, industrial, irrigation and urbanisation activities. These activities have a profound effect on the water quality of the river and its tributaries. This is cause for concern for the water users in the upper catchment, and because the Kruger National Park, one of its downstream water users, is extremely dependent on water of a satisfactory quality to sustain its various ecosystems. It is therefore vitally important to determine to what extent activities in the Upper Catchment of the Olifants River (Mpumalanga), especially in the Witbank and Middelburg areas, influence the water quality of the river. Point sources of pollution in the upper reaches include mining and industrial activities as well as water care works located at various points along the river. These were addressed in a Water Research Commission Project (No. 608/1/97) titled "Lethal and sublethal effects of metals on the physiology of fish: An experimental approach with monitoring support". Although sixteen localities were chosen for the initial project, this study only focussed around the metal ecotoxicology at two localities (Steenkool Spruit and Witbank Dam) in the upper catchment and the effect of metals (copper and zinc) on fish blood physiology. In aquatic ecosystems water quality is an important variable and full assessment of water quality, of Steenkool Spruit (locality 3) and Witbank Dam (locality 7), included evaluation of the chemical, physical and biological characteristics at each of the localities. Water and sediment samples were collected seasonally during the study period, February 1994 to May 1995, and the chemical and physical water quality variables were measured. During the study period three metal bioaccumulation indicator species, Labeo umbratus, Clarias gariepinus and Labeo capensis, were captured from which tissue (gills, liver, muscle and skin) samples were collected. These samples as well as water and sediment samples, were analysed for aluminium, chromium, copper, iron, manganese, nickel, lead and zinc concentrations, using atomic absorption spectrophotometry. In the past routine monitoring of chemical and physical water quality characteristics left scientists and managers with a sizeable pool of data which is often difficult but not impossible to interpret. To standardise and summarise this collection of data an aquatic toxicity index (ATI), WATER2 was developed by Wepener et at (1992). The present study attempted to expand and refine WATER2, which has resulted in the establishment of a new ATI, RAUWater.

M.Sc. (Zoology) / Please refer to full text to view abstract

M.Sc. (Zoology) / Please refer to full text to view abstract

M.Sc. / Hydrocynus vittatus, commonly known as the tigerfish, plays an important role in riverine ecology. It is a top predator which roams the open waters of most larger river systems in southern Africa. Their presence in a freshwater ecosystem has a dramatic impact on the fish community structure. It is known that dams and weirs have a negative effect on the migration of the tigerfish. It is also evident that tigerfish do not occur in certain areas in some of the rivers where they have been present historically. The Olifants and Letaba Rivers in the Kruger National Park (KNP) are two of a few rivers within South Africa where tigerfish do occur. The KNP represents the edge of the most southern distribution of tigerfish in southern Africa. It was therefore expected that the tigerfish do not function optimal in the Olifants and Letaba Rivers as they are subjected to waters with high concentrations of silt and low flow which influences migration and successful breeding. Breeding migrations does however take place during the summer months after which the tigerfish returns to the Massingire Dam in Mozambique to avoid the colder winter temperatures in the rivers. Gonad development coincide with the yearly summer rainfall patterns. A deviation of the expected 1:1 male:female sex ratio to favour the males was experienced in both rivers, which may be the result of over population. Females were found to grow to a larger size than the males and were extremely fecund. Although H. vittatus is believed to be mainly piscivorous, other food items such as invertebrates, played an important role in the diet of small and large tigerfish in both the Olifants and Letaba Rivers. Invertebrates were mostly preyed upon which implies that optimal feeding conditions for the tigerfish does not prevail in these systems and that they have to adapt to satisfy their feeding requirements. Tigerfish is more abundant in the Olifants than in the Letaba River. The overall growth performance or phi prime (4)) values for H. vittatus in the Olifants River was determined and compares well to the overall growth performance of tigerfish in the Okavango River and Lake Kariba. However the maximum length calculated for tigerfish in the Olifants River (Lco = 52.40 cm ) is smaller than the Lco values (56.06 cm) for the Okavango River. The mortality rate of tigerfish in the Olifants River exceeds those in the Letaba River which means that the life expectancy is longer in the Letaba as opposed to the Olifants River. Successful artificial spawning revealed some of the secrets of the reproduction strategy of this species. Tigerfish has semi pelagic eggs, are very small (0.65 mm), negatively buoyant and slightly adhesive for bentic and epibiotic incubation, and it is expected that tigerfish would spawn in open water, on a sandy substrate in the vicinity of aquatic vegetation. First hatching took place at 22h 30 min after fertilization. Vertical movement of the larvae lasts for two days, which allows for downstream movement and dispersement of the larvae. It was found that tigerfish replace their teeth on a regular basis as they grow larger. Transition from conical to functional dentition takes place 45 days after hatching. Replacement of sets of teeth occurs during all phases of its lifespan. It is a quick proses of three to six days during which all teeth are replaced in both the upper and lower jaws.

The Dinaric karst region in the Balkans is one of the hot spots of biodiversity with a high number of endemic freshwater fish. The major cause of the high degree of endemism are numerous paleoclimatic and geological events that have affected the formation of the entire area. Flows of karst poljes represent a specific ecosystem to which some fishes have adapted. The poljes have been periodically flooded and these floods may activate different underground channels, which lead to interconnection of poljes. These fish species spend a part of the year in surface water and a part in groundwater and they may use the underground flows between poljes for migration. The aim of this thesis is to evaluate the genetic variability of two endemic fish species of the genus Telestes living in karst poljes in the region of eastern Herzegovina, and to detect a possible current gene flow between populations of these species due to the connection of underground flows. For this purpose, the DNA from 102 individuals from five different localities was isolated. The mitochondrial marker cytochrom b and 16 microsatellite loci were used for the analyses. The results point to very low variability between species and populations. Based on mitochondrial marker analysis, no link between populations of the species was detected,...

Ma Wing-chi, Joyce. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 131-148). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgement --- p.vi / Contents --- p.viii / Abbreviation --- p.xii / List of Tables --- p.xiii / List of Figures --- p.xv / Chapter 1. --- Introduction --- p.1 / Chapter 2. --- Literature review --- p.5 / Chapter 2.1 --- Fisheries in Hong Kong --- p.5 / Chapter 2.2 --- Flavor of seafood --- p.6 / Chapter 2.2.1 --- Lipid-derived volatile aroma compounds --- p.7 / Chapter 2.2.2 --- "Alcohols, aldehydes and ketones" --- p.8 / Chapter 2.2.3 --- Enzymatic conversion of sulfur- and nitrogen-containing precursors --- p.9 / Chapter 2.2.4 --- Thermally generated compounds --- p.9 / Chapter 2.2.5 --- Bromophenols --- p.10 / Chapter 2.2.5.1 --- General properties of bromophenols --- p.11 / Chapter 2.2.5.2 --- Threshold of bromophenols --- p.14 / Chapter 2.2.5.3 --- Toxicity of bromophenols --- p.17 / Chapter 2.2.5.4 --- Previous studies about bromophenols --- p.19 / Chapter 2.2.5.5 --- Bromophenols in aquacultured seafood --- p.20 / Chapter 2.2.5.6 --- Possible dietary sources of bromophenols --- p.20 / Chapter 2.2.5.7 --- Possibility of increasing bromophenol content in aquacultured fish --- p.23 / Chapter 2.3 --- Criteria for selecting experimental fish model --- p.24 / Chapter 3. --- Distribution of Bromophenols in selected Hong Kong seafoods --- p.27 / Chapter 3.1 --- Introduction --- p.27 / Chapter 3.2 --- Materials and methods --- p.28 / Chapter 3.2.1 --- Sample collection and preparation --- p.28 / Chapter 3.2.2 --- Simultaneous steam distillation-solvent extraction (SDE) --- p.30 / Chapter 3.2.3 --- Gas chromatography / mass spectrometry (GC/MS) --- p.30 / Chapter 3.2.4 --- Compound identification and quantification --- p.31 / Chapter 3.2.5 --- Recoveries --- p.33 / Chapter 3.2.6 --- Moisture determination --- p.34 / Chapter 3.2.7 --- Statistical analysis --- p.34 / Chapter 3.3 --- Results and discussion --- p.34 / Chapter 3.3.1 --- Distribution of bromophenols in seafoods --- p.34 / Chapter 3.3.1.1 --- Bromophenols in marine fishes --- p.49 / Chapter 3.3.1.2 --- Bromophenols in mollusks --- p.49 / Chapter 3.3.1.3 --- Bromophenols in crustaceans --- p.50 / Chapter 3.3.2 --- Seasonal variations of TBCs --- p.51 / Chapter 3.3.3 --- Bromophenols in diet contents --- p.52 / Chapter 3.3.4 --- Bromophenol contents of freshwater fish --- p.53 / Chapter 3.3.5 --- Relationship between the living habitats and bromophenol contents --- p.56 / Chapter 3.3.6 --- Bromophenols as flavor compounds in seafoods --- p.58 / Chapter 3.4 --- Conclusion --- p.59 / Chapter 4. --- Distribution of Bromophenols in selected Hong Kong seaweeds --- p.61 / Chapter 4.1 --- Introduction --- p.61 / Chapter 4.2 --- Materials and methods --- p.62 / Chapter 4.2.1 --- Sample collection and preparation --- p.62 / Chapter 4.2.2 --- Simultaneous steam distillation-solvent extraction (SDE) --- p.63 / Chapter 4.2.3 --- Gas chromatography / mass spectrometry (GC/MS) --- p.64 / Chapter 4.2.4 --- Compound identification and quantification --- p.65 / Chapter 4.2.5 --- Recoveries --- p.66 / Chapter 4.2.6 --- Moisture determination --- p.67 / Chapter 4.3 --- Results and discussion --- p.67 / Chapter 4.3.1 --- Distribution of bromophenols in marine algae --- p.67 / Chapter 4.3.2 --- Seasonal variations --- p.76 / Chapter 4.3.3 --- Functions of bromophenols in marine algae --- p.79 / Chapter 4.3.4 --- Marine algae as sources of bromophenols in marine environment --- p.80 / Chapter 4.4 --- Conclusion --- p.81 / Chapter 5. --- Enhancement of bromophenol contents in aquacultured fish by the development of bromophenol-rich fish feeds --- p.83 / Chapter 5.1 --- Introduction --- p.83 / Chapter 5.2 --- Materials and methods --- p.85 / Chapter 5.2.1 --- Preparation of fish feeds --- p.85 / Chapter 5.2.2 --- Storage conditions of fish feeds --- p.88 / Chapter 5.2.3 --- Experimental animals --- p.88 / Chapter 5.2.4 --- Solvent and chemicals --- p.90 / Chapter 5.2.5 --- Extraction and quantification of bromophenols --- p.90 / Chapter 5.2.5.1 --- Simultaneous steam distillation-solvent extraction (SDE) --- p.90 / Chapter 5.2.5.2 --- Gas chromatography / mass spectrometry (GC/MS) --- p.91 / Chapter 5.2.5.3 --- Compound identification and quantification --- p.92 / Chapter 5.2.5.4 --- Recoveries --- p.93 / Chapter 5.2.6 --- Moisture determination --- p.94 / Chapter 5.2.7 --- Statistical analysis --- p.94 / Chapter 5.2.8 --- Sensory test --- p.95 / Chapter 5.3 --- Results and discussion --- p.96 / Chapter 5.3.1 --- Bromophenol contents in wild-harvested and aquacultured fish --- p.96 / Chapter 5.3.2 --- Development of bromophenol-rich fish feed --- p.99 / Chapter 5.3.3 --- Effect of feeding the fish with the fish feed developed --- p.105 / Chapter 5.3.4 --- Sensory evaluation on the flesh of the fish fed with different fish feeds --- p.121 / Chapter 5.3.5 --- Growth of the fish fed with different fish feeds --- p.124 / Chapter 5.4 --- Conclusion --- p.126 / Chapter 6. --- General conclusion and significance of the study --- p.128 / References --- p.131

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: In this study, the Fish Assemblage Integrity Index (FAll) was applied on three rivers within the southwestern Cape. This index uses fish as indicators of biological aquatic integrity and is based on indigenous species expected to be present in biological fish habitats. Fish integrity classes were calculated for each of the sites in the three rivers studied. Sites 2 and 4 within the Lourens River were rated as Class C, whereas sites 1 and 3 were rated as Class F and Class D respectively. Sites 1, 2 and 4 within the Palmiet River were rated Class F, whereas sites 3 and 5 were rated as Class E and Class D respectively. Site 1 within the Hout Bay River was rated as a Class F site, in addition to sites 2 and 3 been rated as Class A. It is however, suggested that the FAll needs to be adjusted to accommodate the general low species richness experienced in the southwestern Cape. In addition to the FAll been applied, the effects of long-term exposure to subtle water quality changes associated with human activities, specifically potential estrogenic compounds in fish from the Lourens River were also investigated. The production of the yolk precursor lipoprotein complex, vitellogenin (Vtg) produced in the liver under estrogen control was employed as biomarker for environmental estrogen exposure. Male fish from the Lourens River were studied using SDS-PAGE gel electrophoresis. Results indicated that 60% of male fish showed the presence of Vtg in their plasma. Abnormal gonad morphology in male and female fish were also assessed using standard histological procedures. Results from this study indicated no observed abnormalities in either male or female gonads. The immediate presence of endocrine disrupters with estrogen activity was investigated by screening water samples from the Lourens, Palmiet and Hout Bay Rivers for estrogen activity. Results indicated that none of the samples appeared to be cytotoxic. In addition, estrogen activity of water samples was also investigated by in vitro culturing of water samples with frog, Xenopus laevis, liver slices. Results indicated that none of the water samples from the three rivers studied indicated estrogenic activity. Although cytotoxicity and estrogen activity results were negative, the production of Vtg in male fish suggests further research regarding the presence of estrogenic substances in these rivers. / AFRIKAANSE OPSOMMING: In die huidige studie is die 'Fish Assemblage Integrity Index' (FAIl) toegepas op drie rivere in die suidwes Kaap. Hierdie indeks gebruik visse as bioindikatore van biologies akwatiese integriteit en is gebasseer op die inheemse visspesies wat verwag word in biologiese vishabitatte. Integriteitsklasse is bepaal vir elke studieterrein in die drie rivere wat ondersoek is. 'n Klas C is bepaal vir studieterreine 2 en 4 in die Lourensrivier. Klas F en Klas D is bepaal vir studieterreine 1 en 3 in die rivier onderskeidelik. 'n Klas F is bepaal vir studieterreine 1, 2 en 4 en Klas E en Klas D bepaal vir studieterreine 3 en 5 in die Palmietrivier onderskeidelik. 'n Klas F is bepaal vir studieterrein 1 in die Houtbaairivier waar 'n Klas A bepaal is vir studieterreine 2 en 3. Dit word egter voorgestel dat die FAII aangepas moet word om die algemene lae spesierykheid wat ervaar word in die suidwes Kaap te akkomodeer. Die reaksie van visse, afkomstig van die Lourensrivier, op die langtermyn blootstelling aan estrogeniese stowwe is ook bestudeer. Spesifieke reaksies van endokriene versteuring, soos vitellogeen (Vtg) produksie in manlike visse is ondersoek deur middel van SDS-PAGE gel elektroforese. Resultate toon dat in 60% van die manlike visse Vtg in die plasma teenwoordig was. 'n Ondersoek na abnormale gonade morfologie in manlike en vroulike visse van die Lourensrivier is deur standard histologiese prosedures gedoen. Resultate hiervan dui op geen sigbare abnormaliteite in die gonades nie. Die onmiddelike teenwoordigheid van endokriene versteurders is bestudeer deur die sitotoksisiteit van watermonsters afkomstig van die Lourens, Palmiet en Houtbaai riviere te bepaal. Resultate dui aan dat geen monsters sitotoksies was nie. Die estrogeenaktiwiteit van die watermonsters is ook ondersoek deur van in vitro kulture van watermonsters saam met padda, Xenopus leavis, lewersnitte gebruik te maak. Geen estrogeniese aktiwiteit is in die watermonsters gevind nie. Al is die sitotoksisiteit en estrogeenaktiwiteit resultate negatief, dui die produksie van Vtg in manlike visse op die noodsaaklikheid van verdere navorsing ten opsigte van die teenwoordigheid van estrogeniese stowwe in drie riviere.

M.Sc. (Aquatic Health) / Yellowfish and specifically Labeobarbus marequensis are a charismatic species targeted by anglers throughout South Africa. Their population are limited to the north-western parts of the country including the lower reaches of the Crocodile River that flows through the Kruger National Park (KNP). Despite conservation efforts the Crocodile River in the KNP is still highly impacted. The effect of these impacts on the ecosystem is largely unknown. The main aim of the study was to determine the influence of changing water quantity and quality in the Crocodile River on adult L. marequensis. This was achieved by evaluating altered flows (discharge) on the behaviour of adult L. marequensis in the Crocodile River using biotelemetry over a two year period. The influence of altered water quality was assessed using metal bioaccumulation as an indicator of metal exposure in L. marequensis, Clarias gariepinus and Hydrocynus vittatus in the Crocodile and Sabie Rivers during a high and low flow season. Biotelemetry was used on 16 L. marequensis and 12 H. vittatus to determine the habitat use and movement responses of the species. Fish were tagged with Advanced Telemetry Systems (ATS) and Wireless Wildlife (WW) tags and tracked remotely and manually. Home ranges were determined using Arc GIS ®, Habitat uses were analyzed using Windows Excel (© 2011, Microsoft inc.). Environment variables recorded were scored as primary and secondary and then combined with a weighting variable 2:1 ratio (primary variable: secondary variable). A mixed-model analysis of variance (ANOVA) approach with a random co-efficients model and Akaike’s information criteria (AIC) were used to test for significance. Analyses were conducted using SAS version 9 (SAS institute, Cary, NC)...

Murray cod Maccullochella peelii peelii is an iconic freshwater angling species that has suffered declines in abundance and is now listed as a nationally vulnerable species. Despite recognition of the need for biological knowledge to provide future management directions, little is known of its ecology. This thesis examines that ecology to provide new knowledge and recommendations for improved conservation management. (For complete abstract open document)

Made available in DSpace on 2016-06-02T20:20:30Z (GMT). No. of bitstreams: 1 3078.pdf: 3949929 bytes, checksum: 0375aaec7134412a51147cc0d80c7620 (MD5) Previous issue date: 2010-05-21 / The State of Maranhão is considered as a transitional area between northeastern semiarid and amazonian rainforest. Various perennial rivers such as the rivers Parnaíba, Itapecuru, Mearim, Pindaré and Gurupi are found in Maranhão. Distribution patterns analysis indicated the region as an endemism area for Neotropical freshwater fishes. However, only few studies have been performed in the region. Therefore the relationships between the hidrographic set and the respective neighbour areas are not fully comprehended. One complication is the insufficient cientific knowledge about the endemism level in the region due to insufficient establishment of taxonomic bounds for several species in the area. This study examines the hypothesis that freshwater fishes from Maranhão rivers are valid taxonomic unities, and whether its hydrographic set can be considered as an endemism area for Neotropical fishes. The study is focused on the analsis of genetic differentiation of Hoplias malabaricus and Prochilodus lacustris. The geographic variation of H. malabaricus was studied using sequences of the DNAmt control region as well by geometric morphometrics. Besides the mitochondrial marker, the variation analyses of P. lacustris employed sequences of the S7 intron 1. Both species exhibited high genetic variability which may be related to its own ecological features. The genetic diversity of H. malabaricus, a sedentary species, is influenced by drainage architeture. On the other hand, the migratory behavior of P. lacustris and the results obtained had suggested that the variability found was influenced by historical factors. Because the most resolution of the P. lacustris data, the molecular clock hypothesis was tested and divergence times between populations sampled were estimated. These estimates matching with geological informations enabled us to identify several putative events that may play an important role in differentiation of the maranhense ichthyofauna. Under the taxonomic point of view, the hypothesis that H. malabaricus is a species complex was reinforced and the analyses suggested that putative criptic species occur in the region. The P. lacustris specimens constitute a taxonomic unit, but did not support the hypothesis that the species is endemic for the Parnaíba and Mearim rivers. Considering these results, we suggest that the most closely indication of endemism areas could be the ecoregions established by Secretaria de Recursos Hídricos from Ministério do Meio Ambiente. / O Estado do Maranhão é geralmente considerado uma área de transição entre o semiárido nordestino e a floresta amazônica, onde está localizado um conjunto de rios perenes, tais como, Parnaíba, Itapecuru, Mearim, Pindaré e Gurupi. Análises baseadas em padrões de distribuição têm indicado que a região constitui uma área de endemismo para peixes neotropicais. No entanto, devido ao reduzido número de estudos, as interrelações desse conjunto hidrográfico com áreas vizinhas são pouco compreendidas. Uma das dificuldades que surge do esquálido conhecimento científico é a identificação do nível de endemismo que a região abriga, uma vez que há problemas na definição dos limites taxonômicos de várias espécies com ocorrência registrada na área. Assim, este trabalho teve como objetivo testar as hipóteses de que as espécies de peixes dos rios do Maranhão são unidades taxonômicas válidas e, consequentemente, o conjunto hidrográfico pode ser considerado uma área de endemismo. O estudo foi centrado na análise de diversidade genética das espécies Hoplias malabaricus e Prochilodus lacustris. Em H. malabaricus a variação geográfica foi estudada usando sequências da região controle do DNAmt e através de morfometria geométrica. Além do marcador mitocondrial, na análise da variação em P. lacustris foram utilizadas sequências do íntron 1 do gene S7. Ambas as espécies apresentaram alta variabilidade genética que parece estar associada às características ecológicas de cada uma. H. malabaricus, sendo sedentária, teve sua diversidade genética influenciada por arquitetura de drenagem. Por outro lado, dado o comportamento migratório de P. lacustris, os resultados sugeriram que a variabilidade observada foi influenciada por fatores históricos. A maior resolução dos dados em P. lacustris permitiu testar a hipótese de relógio molecular e estimar tempos de divergências entre as populações amostradas. Estas estimativas foram combinadas com informações geológicas disponíveis, possibilitando a identificação de vários eventos que provavelmente exerceram papéis importantes na diferenciação da ictiofauna maranhense. Do ponto de vista taxonômico, as análises reforçaram a hipótese de que H. malabaricus é um complexo de espécie, sugerindo a possibilidade de ocorrência de espécies crípticas na área. As amostras de P. lacustris, por sua vez, constituem uma unidade taxonômica, mas não são consistentes com a hipótese de que a espécie é endêmica para os rios Parnaíba e Mearim. Diante dos resultados obtidos, sugerimos que a indicação mais aproximada de áreas de endemismo seja a de ecorregiões definidas pela Secretaria de Recursos Hídricos do Ministério do Meio Ambiente.