Data/hora: 27/07/2024 01:41:09

Provedor de dados: 	5	
País: 	France	
Título: 	La sensibilité des larves de pectinidés aux conditions d’élevage : le flux ouvert comme alternative aux mortalités massives	
Autores: 	Holbach, Marine.	
Data: 	2014-12-19	
Ano: 	2014	
Palavras-chave: 	Pectinidés; Pecten maximus; Écloserie; Élevage larvaire; Flux ouvert; Contamination bactérienne; Prophylaxie; Physiologie larvaire; Indices de stress.; Pectinids; Pecten maximus; Hatchery; Larval rearing; Flow-through; Bacterial contamination; Prophylaxis; Larval physiology; Stress index.	
Resumo: 	In many countries, aquaculture of pectinids depends on the success of artificial spat production in hatchery. This production is always unpredictable due to the variability of hatching rate and larval survival. Flow-through larval rearing systems were developed in Norway for the King scallop Pecten maximus and showed promising results. Unfortunately the system needs to be optimized since the larval yields and the densities used are still relatively low. In France, a small-scale (5 L) and high-density (≤ 300 larva mL-1) flow-through larval rearing system was successfully developed for oysters. First trials in such system and in similar conditions with P. maximus failed as we registered slower growth and high mortality rate in only a few days. It is known that pectinids larvae are more sensitive to environmental conditions than the oyster Crassostrea gigas, for example. Nowadays, it is important to identify and to understand the phenomena disturbing larval development in flow-through system to improve larval quality and production yields. In this context, this thesis focuses on (1) controlling the sanitary quality of the early life stage of P. maximus and (2) understanding the sensitivity of larvae in flow-through larval rearing. This document is divided into 3 chapters based on 4 experiments. First, we verified the influence of sediment used during P. maximus broodstock conditioning. This work has shown that using broodstock conditioning without sediment could reduce contamination of gametes and D-larvae by Vibrio. Furthermore, both treatments led to similar fatty acids profiles in oocytes and resulting larvae, suggesting that broodstock conditioning was physiologically similar with or without sediment. The larvae obtained from broodstocks conditioned without sediment had the highest survival rates when reared in a static system. Secondly, we tried to determine the influence of aeration on larval physiology. Larval performances and stress index as antioxidant defenses (catalase and superoxide dismutase) and energetic metabolism (citrate synthase) enzyme activities were examined. Whatever the intensity of aeration tested, the larval growth was lesser than in control condition with a higher and earlier mortality. These results could be related to the rapid decrease of larval food uptake after the set up of the aeration. Lastly, two experiments were conducted to have a better understanding of the influence of tank shape, seawater renewal and aeration on scallop larval development. In the first experiment, we compared the influence on larvae of circular and rectangular flat-bottomed tanks. Larvae reared in flat-bottomed rectangular tanks exhibited the best overall performances with survival and competency rates higher than any other results obtained in the flow-through rearing system for oysters. In the second experiment, flow-through larval rearing was conducted in rectangular tanks to study the influence of the water renewal on larval development and physiology with the same stress indexes mentioned above. No differences in larval development and physiology were detected between the two intensities of water inflow (¼ tank renewal h-1 and ½ tank renewal h-1). Aeration associated to flowthrough induced massive mortalities. This variable appeared to be the most deleterious for scallop development. This doctoral project provided some indications how improving P. maximus flowthrough rearing system while limiting the use of antibiotic through a better understanding the physiological mechanisms involved in the larval response to a stressful environment	
Tipo: 	Text	
Idioma: 	Francês	
Identificador: 	http://archimer.ifremer.fr/doc/00259/37000/35491.pdf

http://archimer.ifremer.fr/doc/00259/37000/	
Editor: 	Université de Bretagne Occidentale	
Relação: 	info:eu-repo/grantAgreement/EC/FP7/245119/EU//REPROSEED	
Formato: 	application/pdf	
Fonte: 	2014 UBO

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