Assessment of the Aquacultural Potential of the Portuguese Oyster Crassostrea Angulata

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Assessment of the Aquacultural Potential of the Portuguese Oyster Crassostrea Angulata Assessment of the aquacultural potential of the Portuguese oyster Crassostrea angulata Frederico Miguel Mota Batista Dissertação de doutoramento em Ciências do Meio Aquático 2007 Frederico Miguel Mota Batista Assessment of the aquacultural potential of the Portuguese oyster Crassostrea angulata Dissertação de Candidatura ao grau de Doutor em Ciências do Meio Aquático submetida ao Instituto de Ciências Biomédicas de Abel Salazar da Universidade do Porto. Orientador – Doutor Pierre Boudry Categoria – Investigador Afiliação – “Institut Français de Recherche pour l’Exploitation de la Mer” Co-orientador – Professora Doutora Maria Armanda Henriques Categoria –Professora catedrática Afiliação – Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto. ACKNOWLEDGEMENTS First of all, I would like to thank Dr. Pierre Boudry for accepting to supervise this work, for your commitment and for providing me all conditions that made possible this work. Thank you also for your guidance and at the same time for giving me the freedom to make my own decisions which helped me to become a more independent researcher. Gostaria de agradecer à minha co-orientadora, a Professora Doutora Maria Armanda Henriques por me ter aceite como seu aluno de doutoramento e pela disponibilidade. Gostaria de agradecer ao Dr. Carlos Costa Monteiro por ter permitido a realização de parte deste trabalho na estação experimental de moluscicultura de Tavira do Instituto Nacional de Investigação Agrária e das Pescas (INIAP/IPIMAR). Gostaria também de agradecer-lhe pela disponibilidade e incentivo durante o desenrolar do doutoramento. Je remercie Dr. Philippe Goulletquer et Dr. Tristan Renault pour m’avoir accueillie au sein du Laboratoire de Génétique et Pathologie de la Station de La Tremblade de l’Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER). I would like to acknowledge the Portuguese Foundation for Science and Technology for a PhD grant that made this work possible. This work was also made possible by a Marie Curie Training fellowship. Gostaria de agradecer ao Dr. Francisco Ruano pelo seus preciosos ensinamentos de patologia, pelas várias conversas sobre a ostra Portuguesa, disponibilidade, interesse, camaradagem e incentivo durante todo o desenrolar do doutoramento. Je tiens à exprimer toute ma gratitude à Dr. Tristan Renault pour m’avoir donné goût à la Pathologie et pour son implication au cours de ce travail. Il a toujours été disponible pour passer du temps avec moi malgré ses nombreuses activités. Merci également à Sylvie Lapègue et à Serge Heurtebise pour leurs nombreux conseils de génétique et son aide quotidienne. Merci à l'équipe de la station de La Tremblade pour votre aide quotidienne: Delphine L ., Christopher, Véronique, Isabelle, Maeva, Céline, Florence R. (merci pour toute l’ biblio), Pascal (le vrai Dr. des larve), Bruno, Raphaël, Christophe, Patrick, Jean-François, Helen, Jean-Cristophe, Nicole, Stéphanie, Florence C., Stéphanie, Jean-Pierre, Laurence et Martine. Gostaria de agradecer às várias pessoas que tive o prazer de conhecer no IPIMAR e na Universidade do Algarve, nomeadamente: ao Maurício Teixeira por tudo o que me ensinou, pela sua camaradagem e ajuda constante; ao Dr. Luís Cancela da Fonseca pelo interesse e incentivo; ao Radhouan pelo interesse e ajuda no tratamento estatístico; à Sandrinha pela simpatia e apoio; à Senhora Augusta e à Senhora Graça pela simpatia e ajuda no laboratório; ao João, Ana, Tânia, Paula, Victor e Zé pelo apoio e bons momentos que passamos juntos. Je voudrais adresser mes sincères remerciements à Sylviane et Albert Gass pour son accueil, amitié et extrême gentillesse. Thank you Nicolas for your continuous encouragements, suggestions, and discussions during our coffee brakes. Thank you also and your family for helping me to settle and discover your marvellous country. But I would like to thank you most of all for your friendship. Thank you Tim for your patience to answer my never ending questions, inspiration and friendship. Thank you also for sharing with me your passionate vision of science. Un grand merci à toi Stéphane pour ton soutien, bonne humeur et extrême gentillesse. Muito obrigado Alexandra e Teresa pela vossa amizade, camaradagem, generosidade e apoio constante. Merci aux personnes rencontrées à La Tremblade, avec lesquels j’ai partagé de vrais instants d’amitié: Maeva, Delphine L ., Christopher, Véronique, Isabelle, Jean-Luc, Aude, Noélia, Adeline, Jean-Côme, Doris, Lionel, Céline, Béatrice, Christophe, Niklas, Gaelle, Delphine R., Karine, Yohann et Pascal. Um agradecimento especial aos meus amigos de sempre Costa, Garcia, Mário, Paulo, Pedro e Tiago por me terem sempre apoiado. Gostaria de agradecer aos meus avós e sogros pelo apoio e incentivo. E como não podia deixar de ser, gostaria de agradecer ao meu pai e irmão pelo apoio, paciência e encorajamento permanente. E por fim gostaria de agradecer à pessoa que mais me ajudou, à Vera, a minha companheira, por tudo, e ao fruto do nosso amor, o pequenino Daniel, por me alegrar os dias. RESUMO A ostra Portuguesa Crassostrea angulata teve uma elevada importância comercial na Europa até finais de 1970, altura em que praticamente desapareceu devido a elevadas mortalidades. Actualmente a produção de ostras na Europa baseia-se sobretudo numa única espécie, a ostra Japonesa C. gigas, que foi introduzida para substituir a ostra Portuguesa. No entanto, algumas populações de C. angulata, localizadas sobretudo no Sul de Europa, resistiram à mortalidade massiva dos anos 70 bem como à introdução de C. gigas. O objectivo principal desta tese foi avaliar o potencial aquícola destas populações de C. angulata numa perspectiva comparativa com C. gigas e com os híbridos dos dois taxa. A composição genética de duas populações de C. angulata (situadas no Rios Mira e Sado, Portugal) foi analisada através da utilização de um marcador de ADN mitocondrial. Os resultados obtidos confirmaram que C. gigas não foi introduzida nas duas populações estudadas, podendo estas ser consideradas como populações “puras” de C. angulata. Efectuaram-se cruzamentos factoriais entre C. angulata (Rio Sado) e C. gigas (Rio Seudre, França) de modo a obter descendências puras e híbridos, tendo-se procedido ao seu cultivo na Ria Formosa (Portugal). Observou-se uma sobrevivência e taxa de crescimento superiores na descendência de C. gigas comparativamente com a descendência de C. angulata. Os híbridos tiveram uma performance intermédia, logo não se observou vigor dos híbridos para este dois parâmetros. A análise da proporção de cromossomas em falta e células aneuploides revelou níveis mais elevados em C. angulata do que em C. gigas, tendo-se observado valores intermédios nos híbridos. Verificaram-se igualmente diferenças na morfologia e pigmentação da concha entre C. angulata e C. gigas. A análise do recrutamento de indivíduos do género Crassostrea na Ria Formosa através de marcadores de ADN mitocondriais e nucleares sugere que existe uma sobreposição no padrão temporal de recrutamento de C. angulata e C. gigas. Os resultados obtidos sugerem igualmente que houve recrutamento de híbridos durante o mesmo período. No entanto, observaram-se diferenças nas frequências de haplotipos e alelos em diferentes períodos da época de recrutamento o que sugere que existe um isolamento reprodutivo parcial entre C. angulata e C. gigas. Verificou-se um surto de herpesvirus 1 de ostra associado a elevadas taxas de mortalidade durante o cultivo larvar de C. angulata, C. gigas e híbridos. Por seu turno, análises zoosanitárias em adultos demonstraram uma maior infestação parasitária (protozoários e metazoários) na descendência de C. angulata quando comparada com a de C. gigas. Observou-se nos híbridos infecções bacterianas e alterações citológicas associadas a infecções virais. Os resultados obtidos são discutidos numa perspectiva de desenvolvimento sustentável do cultivo de ostras em Portugal e preservação de populações de C. angulata. ABSTRACT The Portuguese oyster Crassostrea angulata was a species of major economic importance in Europe up to the early 1970's, when mass mortalities almost led to its disappearance. Nowadays, the European oysters farming industry is mainly based on the production of C. gigas that was introduced to replace C. angulata. However, there are still a few populations of C. angulata in southern Europe that manage to survive and recuperate from the mass mortalities observed in the 1970’s. Moreover, it is thought that C. gigas was not introduced in these C. angulata populations and hence they may constitute important genetic resources. The main objective of this work was to assess the aquacultural potential of C. angulata in comparison with C. gigas and their hybrids. The genetic composition of two C. angulata populations (from Mira and Sado Rivers, Portugal) was analyzed using a mitochondrial marker to confirm that C. gigas had not been introduced in these populations. The analyses showed that these two populations can be regarded as being “pure” C. angulata populations. Experimental crosses were carried out between C. angulata and C. gigas broodstocks to produce pure and hybrid progenies. Oysters from the different groups were grown in Ria Formosa (Portugal). A higher growth rate and survival was observed in the C. gigas progeny in comparison with the C. angulata progeny. Their reciprocal hybrids had an intermediate performance and hence no heterosis was observed for these traits. A higher proportion of aneuploid cells and missing chromosomes were recorded
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