Thesis (Ph. D.)- -Gótebourg University, 2006. / Includes bibliographical references.

Methods were developed for the successful artificial fertilization and rearing of the eggs and larvae of the Pacific herring, Clupea pallasii Cuvier. Effects of various constant and changing conditions of salinity (0 ‰ to 34.28 ‰) on the development, mortality and hatching of eggs and on the mortality of larvae were studied. Evidence of an optimum salinity, 11.55 ‰ to 16.24 ‰, for development and survival of eggs is presented, although a wide salinity tolerance, 6.06 ‰ to 34.28 ‰ for both eggs and larvae is evident. Eggs transferred to pond water (0 ‰ salinity) during the first few days of development, perish within a few hours, but if transferred at a later stage, they will survive for at least two days. No apparent correlation exists between survival of eggs and magnitude of salinity change. The presence of two critical stages during embryonic development, the first at blastopore closure, the second prior to and during hatching, have been shown. An optimum survival of eggs was obtained on egg slide sections containing from 75 to 125 eggs. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M. Sc. (Zoology and Entomology))--Rhodes University, 2006.

Phylogeographic patterns of coastal organisms with different life histories and breeding strategies may reveal patterns not consistent with the current delineation of the biogeographic provinces around South Africa. The subdivision of the South African coastline into these three main climatological or biogeographic regions: namely the cool temperate west coast, the warm temperate south coast and the subtropical east coast, is based on average seawater temperatures and hydrological conditions. Genealogies of two estuarine fish species Atherina breviceps, a marine breeder, and Gilchristella aestuaria, an estuarine spawner, were reconstructed using mitochondrial DNA (mtDNA) control region sequences. The study comprised two components, an assessment of a small dataset of both fish species to compare their population structure along the South African coastline and a more comprehensive investigation of the phylogeography of G. aestuaria collected from 21 estuaries around the coast. The comparative study of A. breviceps and G. aestuaria indicate different population distribution patterns along the South African coastline. Results of the A. breviceps analysis demonstrate substantial gene flow due to the random mixing of alleles, while the comparative G. aestuaria dataset indicates a more structured population and considerably less gene flow. The G. aestuaria population demonstrates geographic separation into four groups, namely the west coast (Great Berg), Bot (south coast), Seekoei (south coast) and east coast (Bushmans, Kasouga and Cefane). Results from the larger G. aestuaria dataset indicate that the phylogeographic patterns observed during this study do not conform to existing biogeographic boundaries along the southern African coastline. The delineation identified during this study between the warm temperate and subtropical regions is further south than originally perceived and this southward extension can be ascribed to the prevailing hydrology. The life history patterns and ecology of these two estuarine fish species appears key to understanding their population structure. These factors interact with environmental characteristics such as physical oceanography and the distribution of estuaries (along the coastline) to explain the observed distribution patterns and population structure of A. breviceps and G. aestuaria.

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2011. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-10-09T17:25:09Z No. of bitstreams: 1 Evandro.pdf: 2513898 bytes, checksum: 56564f2ddd5a85095a4f342776ac7ec9 (MD5) / Approved for entry into archive by Sabrina Andrade (sabrinabeatriz@ibest.com.br) on 2013-10-17T03:06:55Z (GMT) No. of bitstreams: 1 Evandro.pdf: 2513898 bytes, checksum: 56564f2ddd5a85095a4f342776ac7ec9 (MD5) / Made available in DSpace on 2013-10-17T03:06:55Z (GMT). No. of bitstreams: 1 Evandro.pdf: 2513898 bytes, checksum: 56564f2ddd5a85095a4f342776ac7ec9 (MD5) Previous issue date: 2011 / Os padrões associados às condições ambientais e a distribuição espaço-temporal dos estágios iniciais da savelha, B. pectinata, e de seu desenvolvimento no estuário da Lagoa dos Patos foram investigados através de dados históricos. Dois outros experimentos complementares foram realizados: um para avaliar as técnicas de medição (tradicional e por imagem) em larvas de peixes; e, outro, para investigar o efeito dos principais conservantes (álcool 70 % e formaldeído 3,6%) sobre as larvas de savelha. Diferença significativa na medição de larvas de peixes entre ambas as técnicas não foi observada, e os coeficientes de variação foram similares, o que sugere que as técnicas produzem o mesmo resultado médio, apesar do ganho de precisão pela técnica de análise por imagem. Um encolhimento significativo foi observado para ambos os conservantes, e os fatores de correção para as larvas de B. pectinata em formaldeído foi CP vivo = 1,0799 × CP pós-conservação, e em álcool foi CP vivo = 1,1415×CP pós-conservação. No período de 1975 a 2009, um total de 10479 ovos e 14066 larvas e juvenis foram coletados através de amostragens planctônicas, e também amostrados parâmetros da água (salinidade e temperatura). As larvas foram medidas e classificadas de acordo com seu estágio de desenvolvimento. Cada estágio de desenvolvimento foi caracterizado pelo seu intervalo de tamanho, onde a menor larva em estágio vitelínico mediu 2,16 mm, e o maior juvenil teve 43,25 mm. As análises dos padrões de distribuição indicam desova fora da Lagoa dos Patos, em salinidade mais elevada, sendo importantes períodos sazonais para os ovos o inverno, primavera e início de verão, e posteriormente ocorre um transporte para dentro da região estuarina nos estágios mais iniciais de desenvolvimento, associados a valores menores de salinidade e temperatura. A distribuição dos juvenis indicou um retorno para a região costeira, e neste estágio o outono foi um período muito importante. Estes resultados são importantes para o conhecimento desta espécie, e serão úteis para o planejamento no gerenciamento deste recurso. / Patterns associated to environmental conditions and to the spatial and temporal distributions of the early stages of Argentine menhaden, B. pectinata, and of its development in the Patos Lagoon estuary were investigated using historical records. Two other complementary experiments were performed: one to evaluate the measurement techniques (traditional and image) in larval fishes; and, other, to investigate the effect of main conservatives (alcohol 70 % and formaldehyde 3.6 %) over Argentine menhaden larvae. Significant difference in the measurement of fish larvae between techniques was not observed, and the coefficients of variation were similar, suggesting that these two techniques produce the same average result, despite the gain in precision by image analysis technique. A significant shrinkage was observed for both preservatives, and the correction factors for B. pectinata larvae in formaldehyde was SL live= 1.0799 × SL post-conservation, and in alcohol was SL live= 1.1415 × SL post-conservation. From 1975 to 2009 a total of 10479 eggs and 14066 fish larvae and juveniles were collected at plankton surveys, and sampled water parameters (salinity and temperature), too. Larvae were measured and classified according to their developmental stage. Each development stage was characterized by its size range, which the smallest yolk-sac larvae measured 2.16 mm, and the largest juveniles had 43.25 mm. Analysis of the distributional pattern indicate spawning outside the Patos Lagoon, in high salinities, being important seasonal period for the eggs the winter, spring and early summer, and after occur a transport to the inner estuarine region in the earlier developmental stages, associated to lesser temperature and salinity values. Distribution of juveniles indicated a return to the coastal region, and in this stage the autumn was a very important period. These results are important for knowledge this specie, and will be useful for planning the management of this resource.