Lors des efflorescences de micro-algues productrices de toxines paralysantes (PST), les bivalves filtreurs peuvent bioaccumuler une grande quantité de toxines et devenir à leur tour toxiques, notamment pour l’homme. La quantité de toxines PST accumulée d’un individu à l’autre s’avère être très variable au sein même d’une population de bivalves. Ainsi, dans nos conditions expérimentales, la quantité de PST accumulées par des huîtres creuses, Crassostrea gigas, d’un même lot, exposées au dinoflagellé toxique Alexandrium minutum, variait d’un facteur 450. L’origine de cette variabilité est inconnue jusqu’alors mais l’une des hypothèses pour l’expliquer serait l’existence de plusieurs formes de canaux sodium voltage-dépendant (NaV), cible des PST, qui confèreraient aux bivalves des sensibilités différentes aux PST. L’objectif principal de cette thèse était de comprendre s’il existe une sensibilité individuelle aux PST différente entre les huîtres et si cette variabilité pouvait être due à des formes différentes de NaV.Une première partie a permis de caractériser le NaV chez C. gigas par une approche de biologie moléculaire. Deux gènes NaV ont été mis en évidence chez C. gigas : CgNaV1, codant un canal sodium et CgNaV2 codant un canal potentiellement sélectif du sodium et du calcium. L’épissage alternatif de CgNaV1 produits trois variants (A, B et C) avec des profils d’expression différents : au niveau des jonctions neuromusculaires pour CgNaV1A, dans les cellules nerveuses pour CgNaV1B et dans les deux pour CgNaV1C. L'acide aminé Q, observé dans le site de liaison aux PST (domaine II) de la séquence CgNaV1 pour les 3 variants et chez tous les individus des 4 populations étudiées, pourrait conférer aux huîtres une certaine résistance aux PST. Ainsi, les variants issus du génotypage/épissage de CgNaV1 ne seraient donc pas le point déterminant du niveau de bioaccumulation des huîtres.Une deuxième partie a permis d’étudier la sensibilité aux PST des nerfs de l’huître creuse C.gigas en relation avec l’accumulation de PST par une approche d’électrophysiologie. La sensibilité à la STX des nerfs cérébroviscéraux d'huîtres a été évaluée en étudiant leur potentiel d'action (CNAP).Il a été montré que les nerfs de C. gigas possédaient une sensibilité à la STX de l’ordre du micromolaire, ce qui leur confère une sensibilité intermédiaire parmi les bivalves. Cette sensibilité des nerfs peut varier selon la période à laquelle les huîtres ont été prélevées et potentiellement selon leur condition physiologique. Une pré-exposition des huîtres à A. minutum semble augmenter la résistance des nerfs à la STX. Cependant, aucune corrélation significative n'a été observée entre la sensibilité nerveuse à la STX et la charge en PST dans la glande digestive des huîtres.Il apparait donc que la variabilité de l’accumulation des PST par les huîtres résulterait plutôt d’une plasticité physiologique, en terme de filtration, d’ingestion et d’assimilation, que d’une sensibilité différentielle des NaV. / During bloom of microalgae producing paralytic shellfish toxins (PST), filtering bivalves can bio-accumulate a large quantity of toxins and become toxic for human consumption. The amount of accumulated PST can greatly vary from one individual to another within a bivalve population. Indeed, under our experimental conditions, the amount of accumulated PST by Pacific oysters, Crassostrea gigas, exposed to the toxic dinoflagellate Alexandrium minutum, varied by a factor of 450. To explain such variability we hypothesized the existence of several forms of voltage-gated sodium channel (NaV), target of the PST, resulting in different sensitivities to PST. The main objective of this thesis was to understand whether there are relationships between nerve sensitivity to PST, the different forms of NaV and the amount of accumulated PST.The NaV was first characterized in C. gigas by a molecular biology approach. Two NaV genes were reported in C. gigas: CgNaV1, encoding a sodium channel and CgNaV2 encoding a channel potentially selective for sodium and calcium. Alternative splicing of CgNaV1 produced three variants (A, B and C) with different expression profiles: at the neuromuscular junctions for CgNaV1A, in the nerve cells for CgNaV1B and in both for CgNaV1C. The amino acid Q observed in the binding site of PST (domain II), of the sequence CgNaV1 for the 3 variants and in all individuals from the 4 studied populations possibly provide some PST resistance to oysters. Thus, the variants resulting from the genotyping/splicing of CgNaV1 would not therefore be the determining factor of the level of bioaccumulation in oysters.A second part allowed studying the nerve sensitivity to PST of C. gigas oyster in relation to the accumulation of PST by an electrophysiology approach. The sensitivity to saxitoxin (STX, a PST) of the cerebro-visceral nerves from oysters was assessed by studying their action potential (CNAP). C.gigas nerves have been shown to have sensitivity to STX of the micromolar range, which gives them intermediate sensitivity among bivalves. This nerve sensitivity may vary depending on the period at which the oysters were collected and potentially according to their physiological condition. A preexposure of oysters to A. minutum appears to increase nerve resistance to STX. However, there was no significant correlation between STX nerve sensitivity and PST content in the oyster digestive gland.Overall, it appears that the variability of the PST accumulation by oysters would result rather from a physiological plasticity, in terms of filtration, ingestion and assimilation, than from a differential sensitivity of the NaV.

L'huître creuse du Pacifique constitue une part importante de la production aquacole mondiale, avec 555 913 tonnes produites en 2013. La France est le quatrième producteur mondial d'huîtres et Crassostrea gigas est la principale espèce cultivée dans le bassin d'Arcachon. Cependant, ces dernières années, des problèmes de recrutement et de captage des naissains de certaines cohortes d’huîtres sont survenus. L'augmentation de la fréquence de ces événements peut être révélatrice de changements dans la qualité du milieu. Dans ce contexte de crise, ces travaux se sont intéressés à l’impact de deux polluants, le cuivre et le S-métolachlore, majoritairement retrouvés dans les eaux du Bassin d’Arcachon sur le développement embryo-larvaire des larves D de l’huître creuse (24h post -fécondation). Dans un contexte de changement climatique, une approche multifactorielle a été adoptée afin d’étudier les effets combinés des polluants et de l’accroissement des températures ou des changements de salinité susceptibles d’altérer le développement et la survie des embryons et des larves en période estivale. Dans un premier temps, les effets embryo-toxiques d’une pollution par le cuivre ou le S-métolachlore couplés ou non à la salinité ou à différentes températures ont été étudiés sur des huîtres en provenance d’une écloserie. Pour cela le test embryo-larvaire a été utilisé, et ses limites d’application précisées. Dans un deuxième temps, les effets des polluants couplés ou non à des températures et salinités environnementales ont été analysés sur les embryons provenant d’huîtres sauvages ou cultivées prélevées directement dans le milieu en différents sites du Bassin d’Arcachon. Le pourcentage de malformations ainsi que l’expression différentielle de gènes cibles ont été déterminés chez les larves tandis que la bioaccumulation du cuivre et du S-métolachlore et le pourcentage d’occupation gonadique ont été analysés chez les géniteurs. Ces résultats ont ensuite été comparés afin de déterminer la capacité des huîtres d’écloserie à représenter un modèle alternatif aux huîtres autochtones. Dans l’objectif d’étudier les impacts liés au changement climatique, des conditions un peu plus extrêmes ont été testées, à savoir des températures supérieures de 26 °C, des salinités inférieures de 24 u.s.i et des concentrations en polluants supérieures aux conditions actuelles du bassin. La mise au point d’un logiciel d’analyse du comportement natatoire des larves D a également été réalisée. Nos résultats indiquent une bioaccumulation plus grande du Cu et S-métolachlore dans les huîtres cultivées par rapport aux huîtres sauvages. Par ailleurs cette étude indique clairement que les larves issues des huîtres autochtones (sauvages et cultivées) sont sensibles à des concentrations environnementales en cuivre et en S-métolachlore. Cependant, il a été montré que les gènes impliqués dans divers mécanismes de défense sont surexprimés, avec une plus grande capacité de défense des larves issues des huîtres sous l’influence des tributaires mais également des huîtres sauvages par rapport aux cultivées. En présence de concentrations environnementales de Cu comme de S-métolachlore, une augmentation des trajectoires erratiques circulaires a été constatée. De plus, les larves, bien que capables de se développer normalement dans une gamme de températures allant de 22 °C à 26 °C, sont sensibles à l’action combinées des hautes/basses températures et des polluants. De la même manière, elles sont sensibles aux effets combinés de la dessalure et de l’exposition aux polluants. Les huîtres d’écloserie se sont révélées être une bonne alternative à l’utilisation des huîtres autochtones. Finalement, au vu des prédictions concernant l’évolution du climat, nos résultats indiquent qu’il faut s’attendre à un accroissement des malformations larvaires et donc à une diminution du recrutement des naissains dans les années futures dans le Bassin d’Arcachon. / The Pacific oyster represents an important part of the aquaculture production, with 555 913 tons produced in 2013. France is the fourth world producer of oysters and Crassostrea gigas is the principal cultivated species in the Arcachon bay. However, in recent years, problems of recruitment, capture and mortality of juvenile or adult oysters occurred. The increased frequency of these events can be indicative of changes in the global quality of the Arcachon bay. In this context of crisis, this work has been focused on the impact of two pollutants, copper and S-metolachlor, mostly found in the waters of the Arcachon bay, on D-larvae embryo-larval development of the Pacific oyster (24h post -fecundation). In a context of global climate change, a multifactorial approach was adopted to study the combined effects of pollutants and increase temperature or salinity changes that could affect the development and survival of embryos and larvae during reproduction season. First, the embryo-toxic effects of copper or S-metolachlor coupled to salinity or different temperatures were studied with oysters from hatchery. For this, the embryo-larval test was used, and its application limits specified. Secondly, the effects of pollutants combined or not to environmental temperature and salinity were analyzed on embryos from wild or cultivated oysters harvested directly on different sites of the Arcachon bay. The percentage of abnormalities and the differential expression levels of target genes were determined in larvae while the Cu and S-metolachlor bioaccumulation and the percentage of gonadal occupation were measured in genitors. These results were then compared to determine the ability of oyster from hatchery to represent an interesting alternative model to indigenous oysters. With the objective to study the impacts of climate change, somewhat more extreme conditions were tested, namely temperatures of 26 ° C, lower salinity of 24 u.s.i and higher concentrations of pollutants compared to current conditions in the lagoon. A software able to analyze swimming behavior of D-larvae was also developed. Our results indicate higher bioaccumulation of Cu and S-metolachlor in cultivated oysters compared to wild oysters. Furthermore this study clearly indicates that larvae from indigenous oysters (wild and cultivated) are sensitive to environmental concentrations of copper and S-metolachlor. However, it has been demonstrated that genes involved in various defense mechanisms are overexpressed with higher larval defense capacity of oysters under the influence of the tributaries but also wild oysters in comparison to cultivated oysters. In the presence of environmental concentrations of Cu or S-metolachlor, an increased erratic circular trajectory was found. In addition, larvae, although able to grow normally in a temperature range of 22 ° C to 26 ° C, are sensitive to the action of the combined high / low temperatures and pollutants. Similarly, they are sensitive to the combined effect of low salinity and exposure to pollutants. Oyster’s hatchery have proved to be a good alternative to the use of indigenous oysters. Finally, given the predictions of climate change, our results indicate that one can expect an increase in larval abnormalities and thus a decrease in the recruitment of spat in future years in the Arcachon bay.

L’objectif de cette thèse était de caractériser les éléments appartenant à la voie de signalisation énergétique AMP-activated protein kinase chez l’huître creuse Crassostrea gigas afin de comprendre son implication dans la gestion de l’énergie, en particulier en réponse à des conditions physiologiques qui sollicitent de l’énergie telles que la reproduction, ou à des stress environnementaux comme l’hypoxie ou le jeûne. Au niveau génomique, les trois sous-unités constitutives du trimère AMPK ainsi que plusieurs éléments impliqués dans cette voie de signalisation et dans les métabolismes glucidiques et lipidiques, potentiellement cibles de l’AMPK, ont été décrits. Au niveau protéique, plusieurs anticorps hétérologues ciblant les isoformes de la sous-unité α et la phosphorylation du résidu thréonine 172 de la sous-unité α, témoin indirect de l’activité AMPK, ont été utilisés. Deux sous-unités α tronquées dans le domaine kinase ont été caractérisées principalement dans les tissus musculaires suggérant leurs implications dans la fonction musculaire. Au cours d’un stress hypoxique, une augmentation significative des quantités de sous-unités α tronquées a été observée dans le muscle lisse. Ce résultat suggère que pendant une durée d’au moins 6 h, ces protéines tronquées sont nécessaires au maintien du métabolisme aérobie dans le muscle lisse, lui permettant ainsi de remplir son rôle de fermeture statique des valves. Nous avons suggéré une hypothèse indiquant que l’accumulation in vivo de ces sous-unitésα tronquées pourrait exercer un rôle de modulation ou de transdomination négative de l’activité de la sous-unité α entière. Dans la gonade, nous avons observé une activation de l’AMPK tout au long du processus de gamétogénèse afin de supporter les processus cataboliques de création de gamètes. Une diminution de cette activation a été observée lors du stade anabolique de mise en réserve des ovocytes. Enfin, lors d’un conditionnement en milieu contrôlé, une approche physiologique par privation de nourriture et une approche pharmacologique par injection d’AICAR ont été réalisées pour provoquer une modulation de l’AMPK. Les analyses ont montré que ni le jeûne ni l’AICAR n’ont induit une augmentation de la phosphorylation de la sous-unité α. Cependant, plusieurs changements liés à l’injection de l’AICAR ont été observés sur la physiologie de l’huître : la modification du rapport AMP:ATP chez les huîtres nourries en comparaison aux huîtres à jeun, et une mortalité dépendante de la dose injectée d’AICAR chez les huîtres mises à jeun. La caractérisation de l’AMPK chez C. gigas ouvre de nombreuses perspectives exigeant des études fonctionnelles poussées afin de démontrer le rôle pivot de cette kinase dans la gestion de l’énergie, comme démontré chez de nombreuses espèces de vertébrés, et ainsi décrypter le métabolisme énergétique de l’huître. / The objective of this thesis was to characterize elements implicated in the energypathway of the AMP-activated protein kinase of the Pacific oyster Crassostrea gigas. Thecharacterization of the elements was performed in the scope of understanding their involvementin energy management, particularly in response to physiological conditions requiring energy, asreproduction or environmental stress, such as hypoxia or fasting.At genomic level, the three subunits of AMPK trimer and several elements involved inAMPK signaling pathway and in carbohydrate and lipid metabolism, supposedly under AMPKcontrol, were described. Additionally, at proteomic level, several heterologous antibodiestargeting AMPKα subunit isoforms and threonine 172 phosphorylation site of AMPKα subunit,indirect witness of AMPK activity, were assayed. Two truncated α subunits in the kinase domainwere characterized essentially in muscles, suggesting their involvement in muscle function.During a hypoxic stress, a significant increase of truncated α subunits protein amount wasobserved in smooth muscle. These results suggest that, for a period of at least 6 h, thesetruncated subunits are necessary for the maintenance of aerobic metabolism in smooth muscle ofC. gigas, allowing it to fulfill its static closing valves. We suggested that in vivo accumulation oftruncated AMPKα could serve as modulator or as transdominant negative regulator of the fulllengthAMPKα activity. In the gonad, AMPK appeared to be activated through the process ofgametogenesis, in order to support the catabolic processes of gametes creation. During theanabolic phase, when oocyte reserves were created, a signal disruption was observed. Finally,during controlled experiment, a physiological approach by food deprivation and apharmacological approach using AICAR injections were performed to modulate AMPK signal.This analysis showed that neither fasting nor AICAR induced an increase of AMPKphosphorylation, as expected. Although, several changes related to AICAR injection wereobserved in oysters physiology, such as the change of the AMP:ATP ratio in fed oysters and aAICAR dose-related mortality in fasting oysters. AMPK characterization in C. gigas opens newperspectives demanding extensive functional studies to establish the key role of AMPK in energymanagement, as demonstrated in vertebrates’ species, in order to understand the oyster’s energymetabolism.

published_or_final_version / Zoology / Master / Master of Philosophy

Native oysters have been promoted as a means to improve water quality in Chesapeake Bay. This project added important insights into the potential of oyster aquaculture to process and remove nutrients from Bay waters. Results clarified that nutrient removal of nitrogen (N), phosphorous (P), and carbon (C) through harvest of cultivated oyster biomass can be quantified and modeled with high levels of statistical confidence. A simple, yet accurate, method is now available for estimating the amount of nutrients removed via harvesting aquacultured oysters. Based on model estimates, 106 harvest sized oysters (76 mm TL) remove 132 kg TN, 19 kg TP, and 3,823 kg TC. Previous work suggested that potentially substantial quantities of N may be removed through enhancement of the coupled nitrification-denitrification pathway in sediments as a result of oyster biodeposition. Using 15N and N2/Ar methods to measure N2 production in sediments, encompassing direct denitrification (DNF), coupled nitrification- denitrification, and anaerobic ammonium oxidation (anammox) pathways, at two oyster aquaculture sites and two reference sites (no aquaculture), we found that oyster biodeposition did not accelerate sediment N removal. We estimate sediment N removal rates via N2 production at an oyster cultivation site producing 5 x 105 oysters (1750 m2) to range from 0.49-12.60 kg N yr-1, compared to 2.27-16.72 kg N yr-1 at a reference site of the same area; making the contribution of oyster cultivation to N removal via sediment N2 production inconsequential as a policy initiative for Chesapeake Bay eutrophication mitigation. Molecular approaches and direct abundance measures have improved our understanding of the sediment microbial community response to oyster biodeposition. Overall, sediments impacted by oyster biodeposition had a significantly different denitrifying community composition than sediments a few meters away or at the non-aquaculture reference sites. Bacterial abundance in sediments was determined by site rather than by oyster biodeposition. No apparent effects of oyster biodeposition were evident in nitrifying bacterial abundance patterns at either site, indicating that oyster biodeposition does not enhance coupled nitrification-denitrification by increasing the abundance of nitrifiers in sediments.

Thesis submitted in fulfilment of the requirements for the MTech: Oceanography in the Faculty of Applied Sciences at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2013 / The current status of metal pollution off the South African South coast is not well known. This study was the first to be undertaken in many years using Striostrea margaritacea as a subject species. The aims of the study were to determine the degree of metal contamination in the water, sediments, oyster tissues and oyster shells at sites selected in Witsand, Wilderness and Goukamma, as well as to establish if Striostrea margaritacea qualifies as a successful biomonitor when using lysosomal destabilization as a tool. Seasonal variations between sites were also considered. Other objectives, such as the potential of a Marine Protected Area (MPA) as a control site and the necessity of a monitoring program along the south coast were also included. Sites were sampled seasonally for one year at spring low tides. Ten oysters were collected from each individual site upon each visit. The Neutral Red Retention Time (NRRT) assay was used to determine lysosomal membrane integrity of oyster haemocytes, whereafter oysters were sacrificed for metal analyses. Metals that were analysed are aluminium (Al), copper (Cu), zinc (Zn) and iron (Fe). Metal analyses were done using an Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP- AES). All statistical analyses were performed using ANOVA on Ranks to determine if there were significant differences between sites and between sampling occasions. Aluminium concentrations found in the water column at all sites were considered as low. Iron, zinc and copper concentrations within the water column can on the other hand be considered as high when comparisons are drawn with other studies and data sets. Sediment concentrations for all the metals within the present study were considered to be low when compared to other studies and guidelines. There were not many significant differences recorded between sites and no seasonal patterns were present. Within the tissues of the oysters, the metal ranges are considered to be low when compared to other studies. No definite conclusion about the contamination status of the oyster tissue could be drawn due to the lack of comparative literature. A field study in conjunction with a laboratory experiment should yield more reliable results. There were also no seasonal trends present and very few differences between sites. The bioaccumulation factors were considered as being low with a few exceptions where they were moderate when oyster tissue data was compared to water and sediment data. Concentrations for Al, Zn and Cu in the shells could be considered low when comparisons are drawn, with the exception of Fe that was found to be high. The bioaccumulation factors were considered to be low when oyster shell concentrations were compared to water and sediment data. There were also no seasonal trends present and a prolonged sampling period is suggested to further investigate these findings. When a comparison was drawn between the tissue and shell data a clear pattern was evident. Al and Fe concentrations were highest within the shell where as Zn and Cu concentrations were highest within the tissues of the animal. The theory of mineralization is supported by these findings where bivalves will use their shell as a reservoir for micronutrients and other substances. The NRRT assay revealed that lysosomal membrane destabilization had occurred and that the animals appeared to be stressed for the duration of the sampling period. Site 3, within the MPA, had the longest retention time. The retention times that were recorded were short when compared to other studies. This assay did however show potential as a basic monitoring tool from which more thorough investigations can be initiated. In conclusion, the study sites along the south coast of South Africa does not seem to be contaminated by Al, Zn, Cu or Fe when data is compared to international and local water quality guidelines, sediment quality guidelines and other studies. Also, as concentrations between sites did not differ greatly, it is inconclusive whether or not the MPA can be used as a reliable references site for in situ studies. More vigorous and lengthy studies should be undertaken to contribute to current knowledge of our indigenous species, Striostrea margaritacea and to aid in the development of better management of this resource as well as an ongoing monitoring programme.

Submitted by (edna.saturno@ufrpe.br) on 2017-02-09T13:18:22Z No. of bitstreams: 1 Cybelle Pereira de Freitas Augusto.pdf: 260202 bytes, checksum: 9a7a4293ac15de6abd863a11cc2c2b0d (MD5) / Made available in DSpace on 2017-02-09T13:18:22Z (GMT). No. of bitstreams: 1 Cybelle Pereira de Freitas Augusto.pdf: 260202 bytes, checksum: 9a7a4293ac15de6abd863a11cc2c2b0d (MD5) Previous issue date: 2004-07-09 / The bivalve mollusks are filter feeders that have been used as natural biofilter with the purpose of minimizing the excess of nutritious coming of the liberation of effluent’s of the sea shrimp culture, considering that such a nutrients ones can cause serious problems to the aquatic environment. The native oyster Crassostrea rhizophorae has been used as natural biofilter in cultivations of sea shrimps. The present work, used the native oyster C. rhizophorae as natural biofilter, has the purpose to verify the efficiency of C. rhizophorae in the reduction of the tenors of Ammonia, Nitrite, Nitrate, Orthophosphate and Chlorophyll the one of the effluent’s in the cultivation of shrimps sea the (10, 20 and 30) meters of distance of the beds in relation to the drainage of effluent’s of the shrimp culture. The experiment was accomplished in the period of March to December of 2003, in the farm of sea shrimp (New Field), in the Municipal district of (Rio Formoso), coast South of Pernambuco. They were certain the tenors of nutrients through the collection of samples of water in three points of the farm: in the channel of provisioning-AB, nursery 1 (V1), drainage-D and (bed I, II and III, respectively. These were analyzed at the Laboratory of Limnology of the Department of Fishing of Universidade Federal Rural de Pernambuco - UFRPE. The maximum and minimum value registered for Ammonia corresponded to 113.267 and 0.000μg/L; for Nitrate 41.055μg/L and 0.008μg/L; for Nitrite 3.435μg/L and 0.297μg/L; for Orthophosphate 104.411μg/L and 1.339μg/L and for Chlorophyll to 105.035μg/L and 1.860μg/L respectively. The experiment randomic was used entirely, being the treatments represented by three different distances of the beds in relation to drainage floodgate the (10m, 20m and 30m), with densities of stock of 1500 semen/cam. Theused statistical analysis was the one of analysis of simple variance (ANOVA), associated to the test of grouping of averages (Test of Tukey) being this applied to the analyses of compositions nitrogen and Chlorophyll-a. With base in the results is possible to affirm that the native oyster reduces the chlorophyll tenors the, and the orthophosphate. / Os moluscos bivalves são organismos filtradores que vem sendo utilizados como biofiltro natural com a finalidade de minimizar o excesso de nutrientes provenientes da liberação de efluentes da carcinicultura marinha, considerando que tais nutrientes podem causar sérios problemas ao ambiente. A ostra nativa Crassostrea rhizophorae vem sendo empregada como biofiltro natural em cultivos de camarões marinhos. O presente trabalho, utilizou a ostra nativa C. rhizophorae como biofiltro natural, tendo como objetivo verificar a eficiência da C. rhizophorae na redução dos teores de Amônia, Nitrito, Nitrato, Ortofosfato e Clorofila a dos efluentes no cultivo de camarões marinho a (10, 20 e 30) metros de distância das camas em relação à drenagem de efluentes da carcinicultura. O experimento foi realizado no período de março a dezembro de 2003, na fazenda de camarão marinho (Campo Novo), no município de Rio Formoso, litoral Sul de Pernambuco. Foram determinados os teores de nutrientes através da coleta de amostras de água em três pontos da fazenda: no canal de abastecimento-AB, viveiro 1 (V1), drenagem-D e (cama I, II e III, respectivamente. Estas foram analisadas no Laboratório de Limnologia do Departamento de Pesca da UFRPE). O valor máximo e mínimo registrado para Amônia correspondeu a 113,267 e 0,0μg/L; para Nitrato 41,055μg/L e 0,008μg/L; para Nitrito 3,435μg/L e 0,297μg/L; para Ortofosfato 104,411μg/L e 1,339μg/L e para Clorofila a 105,035μg/L e 1,860μg/L respectivamente. O delineamento experimental utilizado foi inteiramente casualizado, sendo os tratamentos representados por três diferentes distâncias das camas em relação a comporta de drenagem a (10m, 20m e 30m), com densidades de estocagem de 1500sementes/cama. A análise estatística utilizada foi a de análise de variância simples (ANOVA), associado ao teste de agrupamento de médias (Teste de Tukey) sendo esta aplicada às análises de compostos nitrogenados e Clorofila a. Com base nos resultados é possível afirma que a ostra nativa reduz os teores de clorofila a, e esta o ortofosfato.

Submitted by (edna.saturno@ufrpe.br) on 2017-02-13T14:53:19Z No. of bitstreams: 1 Icaro Gomes Antonio.pdf: 478526 bytes, checksum: 6cf86e27d3379061fb9ff246ead16ad9 (MD5) / Made available in DSpace on 2017-02-13T14:53:19Z (GMT). No. of bitstreams: 1 Icaro Gomes Antonio.pdf: 478526 bytes, checksum: 6cf86e27d3379061fb9ff246ead16ad9 (MD5) Previous issue date: 2007-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The combined effect of salinity, storage density and water exchange time on growth and larval survival of Crassostrea rhizophorae were studied in two experiments corresponding to the period from day 1 to day 6 (experiment 1) and day 7 to day 14 (experiment 2) after Of D-véliger larvae. Two salinities (25 and 35) and three densities (3, 6 and 12 larvae.mL-1 - experiment 1) and (2, 4 and 8 larvae.mL-1 - experiment 2) were tested under three water exchange times (24, 48 and 72h). Response surface diagrams were generated for survival and larval growth data for estimation of optimal conditions. The salinity above 32.5 provided the highest larval survival in the first week (≥ 50%), but this was not different from the saline range between 25 and 31 with water changes above 70h. Between the 7th and 14th day of larvae survival was higher at salinities below 26 (≥ 14%). Growth was higher in the two experiments at salinities below 27. Water changes greater than 36 h increased growth and larval survival in the two experiments. All densities used in both experiments were not statistically different for growth (P> 0.05). However, survival was highest in experiment 1 at densities of 6 (32.56%) and 12 larvae.mL-1 (37.1%) and in the second all densities were statistically the same. Based on the results of this study, it is recommended that larvae of C. rhizophorae be cultivated at salinities of less than 27 and water changes above 36 h with densities of 12 mL-1 larvae and 8 mL-1 larvae, first and second week, respectively. / O efeito conjunto da salinidade, densidade de estocagem e tempo de troca de água no crescimento e sobrevivência larval da Crassostrea rhizophorae foram estudados em dois experimentos correspondentes ao período do 1º ao 6º dia (experimento 1) e 7º ao 14º dia (experimento 2) depois da formação da larva D-véliger. Duas salinidades (25 e 35) e três densidades (3, 6 e 12 larvas.mL-1 – experimento 1) e (2, 4 e 8 larvas.mL-1 – experimento 2) foram testadas sob três tempos de troca de água (24, 48 e 72h). Diagramas de superfície de resposta foram gerados para os dados de sobrevivência e crescimento larval para estimação das condições ótimas. A salinidade acima de 32,5 proporcionou a maior sobrevivência larval na primeira semana (≥ 50%), mas esta não foi diferente da faixa salina entre 25 e 31 com trocas de água acima de 70h. Entre o 7º e o 14º dia de larvicultura a sobrevivência foi maior em salinidades inferiores a 26 (≥ 14%). O crescimento foi superior nos dois experimentos em salinidades abaixo de 27. Trocas de água superiores a 36h aumentaram o crescimento e sobrevivência larval nos dois experimentos. Todas as densidades utilizadas em ambos experimentos não foram diferentes estatisticamente para o crescimento (P>0,05). No entanto, a sobrevivência foi maior no experimento 1 nas densidades de 6 (32,56%) e 12 larvas.mL-1 (37,1%) e no segundo todas as densidades foram estatisticamente iguais. Baseado nos resultados deste estudo é recomendado que as larvas de C. rhizophorae sejam cultivadas em salinidades inferiores a 27 e trocas de água acima de 36h com densidades de 12 larvas mL-1 e 8 larvas mL-1, primeira e segunda semana respectivamente.

Les effets de la micro-algue toxique, Alexandrium minutum, sur l'huître creuse, Crassostrea gigas, ont été analysés par une approche intégrative. Cette démarche a conduit à s'intéresser à différents aspects de la physiologie de l'huître, tels que le comportement, l'activité digestive, des activités cellulaires et la reproduction. Dans un premier temps, le statut physiologique de A. minutum a été abordé en utilisant la cytométrie en flux, la microscopie ainsi que des marqueurs fluorescents. Cela nous a permis de démontrer que certaines conditions expérimentales étaient susceptibles de perturber la physiologie de ce dinoflagellé. Les systèmes expérimentaux permettant d'exposer les huîtres ont donc été conçus afin de limiter les conditions stressantes pour la micro-algue toxique. Dans un second temps, les huîtres ont été exposées à A. minutum, en milieu contrôlé, au cours de plusieurs expérimentations, et comparées à des huîtres témoins nourries avec Isochrysis galbana ou Heterocapsa triquetra. L'exposition de C. gigas à A. minutum provoque chez les huîtres une réponse comportementale, se traduisant notamment par une augmentation du temps d'ouverture et de la fréquence des micro-fermetures des valves. Une corrélation positive entre le temps d'ouverture des valves et la quantité de toxines accumulée par les huîtres a été observée. De même, des pathologies du muscle adducteur des huîtres ont été constatées, ce qui pourrait expliquer les changements de comportement des huîtres. Le dinoflagellé toxique induit une activation des mécanismes de défense des huîtres. Ainsi, une augmentation de la production de mucus a été observée au niveau des branchies, de même qu'une importante réaction inflammatoire dans la glande digestive. Les paramètres hémocytaires ont également présenté des variations. Des différences, en terme d'activité de la phénoloxydase et de la production d'espèces réactives de l'oxygène dans les hémocytes, ont été observées entre les huîtres exposées à A. minutum et les témoins. Les variations des paramètres hémocytaires semblent liées au stade de maturité des huîtres et à la quantité de toxines accumulées, mais aussi à leur statut métabolique lors de l'exposition. Les contenus de la glande digestive en lipides sont également modifiés suite à l'exposition à A. minutum. Une réduction significative des contenus en monoglycérides (MG) et diglycérides (DG) ainsi qu'une importante diminution du contenu en phosphatidylcholine (PC) ont été observés. La diminution de la PC étant parallèle à celle des MG et DG, cela suggère une diminution de la synthèse des lipides liée à une altération des tissus de la glande digestive. Finalement, les spermatozoïdes produits par les huîtres exposées à A. minutum présentaient une réduction de leur activité (diminution de la mobilité et du contenu en ATP) en comparaison aux huîtres témoins. Cette altération de la physiologie des gamètes pourrait avoir des répercussions sur la reproduction des huîtres. Etant donné la subtilité de certains changements et l'interconnexion des paramètres mesurés, la mise en place d'une approche intégrative nous a permis d'obtenir une vision holistique de l'interaction A. minutum / C. gigas. La présente étude a mis en évidence des interactions peu ou mal connues entre des caractères comportementaux, morphologiques et physiologiques des huîtres. Cela nous a conduit à mieux comprendre les interactions entre les micro-algues toxiques et les bivalves, ainsi que les impacts écologiques potentiels.

The present study was undertaken to evaluate the effects of stress on crystalline style characteristics in bivalves of Crassostrea angulata, Meretrix lusoria, and Perna viridis. Firstly, the crystalline style morphological characteristics in normal submerged condition was examined. The presence percentage of crystalline styles in C. angulata collected from different months ranged from 0 to 73%. While, it was 100% in M. lusoria and P. viridis. Secondly, the crystalline style morphological characteristics were investigated under stresses of starvation, hypoxia and desiccation. In C. angulata, the crystalline styles were absent after treated with each of the unfavorable conditions for 1 hour. In M. lusoria, under starvation and hypoxia conditions for 72 hours, the presence percentage of crystalline styles was significantly decreased. Even more, the presence percentages of crystalline styles in M. lusoria reduced to 22% when treated with desiccation for 2 hours. In P. viridis, the presence percentage of crystalline styles was 100% under starvation and hypoxia for 72 hours. In contrast, the mussels were totally dead under desiccation for 72 hours. By comparison, desiccation had greater influence on the three bivalves than starvation and hypoxia based on the standardized crystalline style wet weight (crystalline style wet weight/ shell length). Additionally, the presence percentage of crystalline styles in C. angulata was also influence by fed. In all, among the three examined species, oyster C. angulata is the most sensitive one to unfavorable conditions.