An adequate supply of diatoms during the weaning stage (generally 5 - 10 mm shell length (SL)) is one of the primary constraints to the commercial culture of the South African abalone, Haliotis midae. Because of the seriousness of the problem, a project aimed at the development of an artificial weaning diet was initiated. Initially, the chemical composition (proximate composition, amino acid, fatty acid and mineral element profile) of juvenile H. midae was analyzed, as a general lack of such information was identified in a review. Due to the lack of knowledge on the nutritional requirements of H. midae, the formulation of the weaning diet was based on the essential amino acid (EAA) pattern of the shucked tissue, and the known nutrient requirements of haliotids. Subsequently, a water stable gel and pellet form of the diet were developed. The best water stability of a gel was obtained with a 1:3 agar/gelatine mixture which retained 70.7 ± 2.7 % of its dry weight after 24 h. Starch based pellets, however, retained 89.0 ± 0.6 % of their dry weight after 24 h. In a comparative growth trial, pellets produced a significantly better increase in SL and weight than gels after only 15 days. This was probably due to the better water stability of pellets, which resulted in a better nutritional quality than in gels. The feeding behaviour on both forms of the diet did not differ. Activity patterns were exclusively nocturnal and feeding frequency was consistently low. The percentage composition of the pelleted weaning diet, on a dry weight basis, was 5 % casein, 15 % gelatine, 15 % fish meal, 10 % Spirulina spp., 2.5 % fish oil, 2.5 % sunflower oil, 21.0 % dextrin, 23.0 % starch, 4.0 % of a mineral and 2.0 % of a vitamin mixture. The correlation coefficient between the EAA pattern of H. midae and the dietary EAA pattern was r⁷= 0.8989. Pellets were fed to juveniles in a 30 day growth trial to study the effect of photoperiod (12, 16, 20 and 23 hours of darkness) on growth and general nutritional parameters. A comparative experiment feeding diatoms was conducted under a 12hL: 12hD light regime at the same time. The SL and weight of the juveniles did not increase significantly with an increase in hours of darkness. The growth of juveniles fed on pellets did not differ significantly from those fed on diatoms. Percentage feed consumption (PFC), percentage feeding rate (PFR), feed conversion ratio (FCR), protein efficiency ratio (PER) and percentage protein deposited (PPD) were determined for the animals fed on pellets. None of the parameters were significantly affected by photoperiod. However, there were trends in that PFC increased with longer periods of darkness, while PPD decreased. The FCRs (0.44 ± 0.04 to 0.60 ± 0.19) and PERs (5.06 ± 1.74 to 6.64 ± 0.77) indicated that juveniles used the feed, and in particular the protein, very efficiently. Photoperiod did not have an effect on the specific activity of the digestive enzymes amylase, protease and lipase. The specific activity of amylase in the juveniles fed on diatoms was significantly higher than in the pellet fed groups. This was surprising as the main carbohydrate of diatoms is the ß-(l-3) glucan chrysolaminarin, and not starch, a ß-(l-4) glucan. Protease specific activity, on the other hand, was significantly higher in the pellet fed groups, indicating an ability to adapt to the high protein content in the artificial diet (35.48 %), compared to diatoms which had a protein content of 5 %. The specific activity of lipase did not differ significantly between groups, probably because of a similar lipid concentration (5 - 10 %) in diatoms and pellets. Finally, the effect of stocking density, ranging from 1250 to 10,000 juveniles/m2, on the growth of juveniles was evaluated. A model of hatchery productivity was developed based on this investigation. Hatchery productivity was defined as the number of juveniles per unit space reared through to the grow-out stage per unit time. The model predicted that maximum productivity would be achieved at a stocking density of 10,000 juveniles/m2. The results have shown that H. midae can be successfully weaned on an artificial diet, as the growth on the diet was not significantly different to growth obtained on diatoms. Long-term growth trials are needed to confirm these results. The importance of standardized experiments on the nutritional requirements and digestibility of abalone was emphasized. The importance of improved artificial diets, optimal culture conditions, as well as the application of biotechnological techniques to further abalone aquaculture was highlighted.

Polypteridae é um grupo de peixes de água doce e salobra que ocorre atualmente apenas em regiões tropicais da África. As 14 espécies viventes de polipterídeos estão distribuídas em dois gêneros, Polypterus (bichirs, 13 espécies) e Calamoichthys (o peixe-corda, C. calabaricus). O grupo atrai interesse especial dos pesquisadores devido à sua peculiar anatomia que combina características observadas em diferentes grupos viventes e extintos de vertebrados, com caracteres exclusivos, como a presença de um tipo único de nadadeira dorsal. Essa combinação singular de características dificulta o estabelecimento de sua posição filogenética, embora sejam considerados atualmente o grupo irmão de todos os peixes de nadadeiras raiadas viventes, ocupando uma posição filogenética chave entre os peixes ósseos. Nesse contexto, compreender em detalhes sua anatomia é fundamental para entender a história evolutiva dos vertebrados como um todo e particularmente dos peixes ósseos. O presente estudo consiste de uma revisão sobre a anatomia dos polipterídeos, enfatizando sistemas e complexos mofológicos pouco explorados, como os sistemas laterossensorial e musculoesquelético, em uma abordagem holística. Integramos a análise de espécimes vivos, espécimes preservados em coleções (preservados em etanol ou preparações secas do esqueleto), espécimes corados e dissecados, radiografias, e modelos tridimensionais gerados por tomografia computadorizada. A análise é focada no bichir do Senegal, Polypterus senegalus, mas inclui vários espécimes de diferentes tamanhos de todas as espécies de polipterídeos, incluindo espécimes-tipo de quase todas elas. Foram incluídas informações da ontogenia, com base em uma análise das séries de desenvolvimento de P. senegalus e de representantes dos demais grupos de peixes actinopterígios não-teleósteos (Acipenseriformes, Lepisosteiformes e Amiiformes). O estudo também inclui uma extensa revisão da literatura sobre a anatomia e relações filogenéticas dos polipterídeos e outros peixes ósseos basais. Várias novas interpretações sobre a anatomia dos polipterídeos e dos demais peixes ósseos são apresentadas, muitas dos quais são incorporadas em novas propostas de terminologia anatômica para Actinopterygii ou para Osteichthyes. Também é apresentada uma análise detalhada da variação intra- e interespecífica na anatomia externa dos polipterídeos, que será útil em futuras tentativas de desvendar sua taxonomia e inter-relações filogenéticas. O presente estudo demonstra que, mesmo considerando todos os esforços anteriores, ainda há muito a ser conhecido sobre a anatomia dos polipterídeos, bem como de outros grupos basais de peixes ósseos. Muitas dessas informações podem ser incorporadas em estudos filogenéticos, a fim de aperfeiçoar as hipóteses sobre as relações evolutivas entre os principais clados de Vertebrata, e também podem fornecer novas idéias sobre a anatomia e a história evolutiva dos vertebrados. / Polypteridae is a group of freshwater and brackish water fishes currently ocurring exclusively in tropical regions of Africa. The 14 extant species of polypterids are distributed in two genera, Polypterus (bichirs, 13 species) and Calamoichthys (the reedfish, C. calabaricus). The group attracts special interest of researchers due to their peculiar anatomy that combines features observed in different groups of living and extinct vertebrates with exclusive characters such as the presence of a unique type of dorsal fin. The singular combination of characteristics difficults establishing the phylogenetic position of polypterids, although they are considered nowadays the sister-group of all living ray-finned fishes, occupying a key phylogenetic position among the bony fishes. In this context, understanding in details their anatomy is crucial for understanding the evolutionary history of vertebrates as a whole and particularly of bony fishes. The present study consists of a revisionary investigation of the anatomy of polypterids, emphasizing underexplored mophological systems and complexes such as the laterosensory and musculoskeletal systems, on a holistic approach. We integrate the analysis of living specimens, specimens preserved in collections (ethanol-preserved and dry-skeleton preparations), stained and dissected specimens, radiographs, and tridimensional models generated by computadorized tomography. The analysis focuses on the Senegal Bichir, Polypterus senegalus, but includes several specimens of different sizes of all species of polypterids, including types of almost all of them. We include information from early ontogeny, with basis on an analysis of developmental series of P. senegalus and of representatives of the remaining groups of non-teleost actinopterygians (Acipenseriformes, Lepisosteiformes and Amiiformes). The study also includes an extensive revision of the literature on the anatomy and phylogenetic relationships of polypterids and other basal bony fishes. We provide several new interpretations about the anatomy of polypterids and other bony fishes, many of which are incorporated into new proposals of anatomical terminology for Actinopterygii or for Osteichthyes. We also provide a detailed analysis of the intra- and interspecific variation on the external anatomy of polypterids that will be useful in future attempts to unravel their taxonomy and phylogenetic interrelationships. The present study demonstrates that, even considering all the efforts by previous authors, there is still a lot to be known regarding the anatomy of polypterids, as well as of other basal groups of bony fishes. Much of this information can be incorporated into phylogenetic studies in order to improve our hypotheses of evolutionary relationships between the major clades of Vertebrata, and can also provide new ideas about the anatomy and evolutionary history of vertebrates.

O presente estudo busca reunir todo o conhecimento disponível acerca da diversidade e distribuição dos peixes amazônicos. A ictiofauna amazônica é composta por 2441 espécies válidas, 527 gêneros, 55 famílias e 16 ordens. Esses números tornam o Amazonas, por ampla margem, a bacia hidrográfica mais rica em diversidade de peixes do planeta. A presente tese é dividida em quatro capítulos, cada um explorando um diferente aspecto da biogeografia dos peixes amazônicos. O primeiro capítulo aborda o assunto a partir de uma perspectiva histórica, desde sua fundação com Louis Agassiz na metade do século XIX até os dias atuais, abrangendo diversas escolas de pensamento. O segundo capítulo descreve a assembléia de peixes amazônicos, incluindo diversos testes estatísticos sobre a riqueza, composição taxonômica e a distribuição geográfica dos peixes da Amazônia. Um dos resultados é que a ictiofauna amazônica é composta em torno de 4,000 a 12,000 espécies. O terceiro capítulo descreve todos os padrões de distribuição presentes entre os peixes da Amazônia, sendo apresentados diversos exemplos e todos esses são discutidos dentro dos contextos temporal e geomorfológico. O último capítulo implementa análises biogeográficas quantitativas e as topologias resultantes formam a base conceitual para discussões sobre áreas de endemismo, sobre os problemas de faunas reticuladas histórica e cronologicamente e sobre a relação entre a filogenia e a biogeografia. / The present study is an effort to assemble all available knowledge about the diversity and the distribution of Amazonian fishes. The Amazonian ichthyofauna is composed of 2441 valid species, 527 genera, 55 families and 16 orders. These numbers make the Amazon, by a wide margin, the richest basin of the world in fish diversity. The present thesis is divided into four chapters, each one exploring a different aspect of the biogeography of Amazonian fishes. The first chapter addresses the subject from a historical perspective, from its foundation by Louis Agassiz in the middle of the nineteenth century to the present day, covering several schools of thought. The second chapter describes the Amazonian fish assemblage, including several statistical tests of hypotheses about the richness, taxonomic composition and geographic distribution of Amazonian fishes. One of the results is that the Amazonian ichthyofauna is composed of somewhere between 4,000 and 12,000 species. The third chapter describes every distribution pattern present in Amazonian fishes, with numerous examples of each, and discusses them in temporal and geomorphological contexts. The last chapter offers quantitative biogeographic analyzes, and the resulting topologies form the basis for conceptual discussions about the nature of areas of endemism, about the problems of historical reticulation and chronologically hybrid faunas, and on the relationship between phylogeny and biogeography.

Engraulinae, uma sub-família de Engraulidae, inclui onze gêneros e cerca de 90 espécies com hábitos marinhos, estuarinos e dulcícolas, distribuídas nas américas do Sul, Central e do Norte, exceto Encrasicholina e Engraulis, o primeiro restrito ao Indo-Pacífico e o segundo com distribuição global. Anchoviella, um gênero de Engraulinae, que pertence ao grupo de manjubas do Novo Mundo, possui 15 espécies descritas, mas, como sugerido por diversos autores, a maioria das espécies do gênero apresenta problemas taxonômicos que necessitam ser revisados. O monofiletismo de Engraulinae é sustentado por quatro sinapomorfias relacionadas a morfologia geral do corpo, padrão de canais sensoriais cefálicos e características do esqueleto caudal e arcos branquiais. O presente estudo tem dois objetivos principais: i) elaborar a análise filogenética de Engraulinae com base na análise de dados morfológicos, a fim de evidenciar padrões de evolução dos grupos na sub-família, ii) elaborar a revisão taxonômica de Anchoviella. Foram elencados 103 caracteres de morfologia externa e interna de todos os gêneros pertencentes a Engraulinae. O monofiletismo de Engraulinae e Engraulini não foi corroborado no presente estudo, assim como o da maioria dos gêneros incluídos na subfamília, com exceção de Anchovia, que formou um clado monofilético com alto suporte de Bremer. Proposto como o mais derivado em Engraulinae em estudos filogenéticos anteriores, o gênero Encrasicholina foi incluído em um dos grandes clados da família obtidos no presente estudo, juntamente com espécies de Stolephorus, Engraulis e Anchoa. Pterengraulis atherinoides é o clado mais derivado em Engraulidae, com Lycengraulis grossidens e Anchoa spinifer também situados entre os táxons mais derivados da família. Além disso, a obtenção de um grande clado com espécies pertencentes a Amazonsprattus scintilla, Anchoviella e Anchoa reforça as hipóteses de relacionamento próximo entre Amazonsprattus scintilla e Anchoviella. A revisão taxonômica de Anchoviella revelou 13 espécies válidas e duas espécies dulcícolas não descritas. Entretanto, de acordo com o resultado obtido na análise filogenética, apenas três dessas espécies deveriam ser mantidas em Anchoviella enquanto as demais espécies formariam um novo gênero incluindo Amazonsprattus scintilla. / Engraulinae, a subfamily of Engraulidae, includes eleven genera and about 90 species with marine, estuarine and freshwater habits, distributed in South, Central and North America, except Encrasicholina and Engraulis, the first one restricted to the Indo-Pacific and the second, with a global distribution. Anchoviella, one genus of Egraulidae, that belongs to the New World Anchovies group, is represented by 15 described species but, according to many authors, most species of the genus are poorly described and in need of revision. The monophyly of Engraulinae is supported by four synapomorphies related to general morphology of the body, pattern of sensory cephalic canals and characteristics of the caudal skeleton and branchial arches. The present study has two main goals: i) to analyse the phylogenetic relationships within Engraulinae based on morphological data, aiming to highlight evolution patterns within the groups of the subfamily, ii) to perform the taxonomic revision of Anchoviella based on the analysis of 103 external and internal morphological characters of all the genera within Engraulinae. The monophyly of Engraulinae and Engraulini was not herein corroborated, as well as the monophyly of most of the genera within the subfamily, except Anchovia, that was included in a monophyletic clade with a strong Bremer support. Proposed as the most derived genus within the Engraulinae in previous studies, the genus Encrasicholina was herein included within one of the major clades of the family, together with species of Stolephorus, Engraulis and Anchoa. Pterengraulis atherinoides is the more derived taxon within the Engraulidae, together with Lycengraulis grossidens and Anchoa spinifer, also included within the more derived taxa of the family. Moreover, one major clade with species belonging to Amazonsprattus scintilla, Anchoviella and Anchoa was obtained, reinforcing the hypothesis of a close relationship among Amazonsprattus scintilla and Anchoviella and among Anchoa and Anchoviella. The taxonomic revision of Anchoviella revealed the existence of 13 valid species and two undescribed freshwater species. However, according to the results obtained through the phylogenetic analysis undertaken, only three among these species should be maintained within Anchoviella, while the other species would form a new genus including Amazonsprattus scintilla.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 2001. / Title from PDF title page (viewed on Apr. 2, 2005). Vita. Includes bibliographical references (p. 107-121).

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The Pitt Water Estuary is a shallow, barrier estuary, with typically normal marine salinity, which has been subject to considerable anthropogenic modification. Modern seafloor environments were described using the distribution of sedimentary facies and foraminiferal and ostracod assemblages, examined from surficial sediment samples. Ten sedimentary facies were identified by grouping sediment samples using particle-size distribution data and lithic sand content. Faunal assemblages were identified by cluster analysis, with twelve sample, and eight species associations defined by foraminifera, and eight sample, and six species associations defined by Ostracoda. The distribution of sedimentary facies varies, firstly, with the upstream change in relative current energy (tidal versus fluvial) as reflected by the relative proportion of quartzose to lithic sand in sediment; and, secondly, with the water depth variation in current strength, as reflected by the sand grain size and mud content. The distribution and composition of foraminiferal and ostracod assemblages is determined mainly by average salinity and pH. The position of species along the axis of the estuary correlates with the altered salinity profile inferred to occur during floods, with tolerance to lowered salinity being greater further upstream. Low pH conditions are widely distributed (due to the anoxia of stagnant, nutrient-enriched waters), causing calcareous test dissolution which, in some areas, totally excludes calcareous foraminifera and ostracods. Illumination is also important in controlling ostracod distribution, being lowest in widespread turbid waters. Additional factors controlling foraminiferal and ostracod distribution include: substrate mobility, nutrients, seagrass distribution, tidal exposure, and tolerance to varying temperature. Recent seafloor environments were described using the distribution of sediments, foraminifera and ostracods in short cores and previous spatial surveys. They have changed considerably since the late 19th century, mainly as a result of human activities which continue to affect the estuary. During periods of increased agricultural activity (1920’s-1940s; 1960’s-present), greater land clearance, cultivation and fertiliser usage within the catchment area lead to increased sediment and nutrient loading of fluvial waters entering the estuary. This lead to increased sedimentation, mud accumulation, turbidity, and lowered dissolved oxygen and pH within the estuary, causing the demise of dense clam and oyster beds, reduced distribution of ostracods and calcareous foraminifera, increased distribution of agglutinated foraminifera, and increased faunal abundance within nutrient-enriched sediments. Dam construction and irrigation activities during the 20th century, reduced rainfall over the last thirty years, and causeway construction during the 1870’s, have all contributed to increased water stagnation, reduced flushing, and more upstream penetration of the estuary by marine waters.