Orientadores: Luiz Francisco Lembo Duarte, Vera Nisaka Solferini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T12:02:47Z (GMT). No. of bitstreams: 1 Aranha_TiagoPorto_M.pdf: 851406 bytes, checksum: 8a0e698a85700d7b59721c4e8167d63f (MD5) Previous issue date: 2010 / Resumo: A quantidade de espécies envolvidas, a amplitude geográfica e a freqüência de ocorrência das invasões biológicas não conhecem precedentes. Atualmente as invasões são consideradas um processo composto de múltiplos estágios, dinâmico no espaço e no tempo. As populações invasoras podem estacionar em determinados estágios e até regredir a estágios anteriores antes de atingir a fase de clímax. As invasões são consideradas uma das grandes causas da extinção de espécies no planeta, desta forma, a compreensão dos mecanismos e fatores que influenciam o sucesso das invasões e o entendimento de seus efeitos em comunidades nativas é fundamental. O objeto de estudo do presente trabalho é o bivalve invasor Isognomon bicolor em costões rochosos do sudeste do Brasil. No capítulo I, padrões de distribuição e dominância de populações localizadas no litoral norte de São Paulo foram documentados. A situação atual da invasão de I. bicolor foi avaliada frente às populações de organismos nativos da área. No capítulo II, padrões de variabilidade e estruturação genética de populações de I. bicolor no litoral sudeste foram descritos e comparados com aqueles para populações do bivalve nativo Brachidontes solisianus. A combinação dessas duas abordagens permitiu uma maior compreensão do processo de invasão de I. bicolor e das conseqüências dessa invasão sobre as espécies nativas. Atualmente I. bicolor apresenta-se amplamente distribuído no litoral norte de São Paulo, entretanto, ao contrário de estudos anteriores, suas populações apresentam baixas porcentagens de cobertura nos costões onde ocorre. Tal fato deve-se a um evento de mortaliade em massa pelo qual a espécie passou recentemente. A alta variabilidade e baixa estruturação genética observada, semelhante à encontrada para o bivalve nativo B. solisianus, são indícios de um processo de invasão costituido por múltiplos episódios de introdução e da grande capacidade de dispersão do invasor. Esses resultados são preocupantes pois sugerem que as populações de I. bicolor estão relativamente estáveis e conectadas entre si, tornando sua exitinção na costa sudeste do Brasil improvável, mesmo após a ocorrência do evento de mortalidade em massa / Abstract: The species number, geographic scale and frequency of biological invasions are unparalleled. Currently, invasions are considered as a several stages process, dynamic in space and time. The invasive populations can remain at some stage or return to earlier stages before reaching the invasion climax. Invasions are considered one of the major causes of species extinction on the planet and thus. Understanding mechanisms and factors that influence invasion success and its effects on native communities is of primary imporatance. The present work studied the invasive Isognomon bicolor populations along the southeastern coast of Brazil. In Chapter I, the distribution and the dominance patterns of I. bicolor were documented along the northern coast of São Paulo. The population attributes of the invasive species I. bicolor were evaluated and compared to the population attributes of native organisms in the sampled area. In Chapter II, the genetic variability and the structure patterns of four I. bicolor populations on southeastern Brazilian Coast were analyzed and compared with those of the native Brachidontes solisianus populations. The combination of these two approaches has enabled a better understanding of I. bicolor invasion process and its consequences for native species. Currently, I. bicolor has become widely distributed in the northern coast of São Paulo, however, unlike previous studies, I.bicolor is not dominant in the rocky shores. This fact may be caused by a recent mass mortality event. The high variability and low genetic structure observed, similar to the genetic attibutes of the native bivalve B. solisianus populations, are evidences of an invasion process with multiple introduction events and of the large invader dispersal ability. These results are concerning as they suggest that I.bicolor populations are relatively stable and connected to each other, making its extinction in the southeastern coast of Brazil unlikely, even after the occurrence of a mass mortality event / Mestrado / Ecologia / Mestre em Ecologia

A Actuopaleontologia é o ramo da Paleontologia que visa aperfeiçoar as interpretações paleoambientais e paleoecológicas através das assinaturas tafonômicas, principalmente aquelas presentes em conchas bivalves. Tais estudos tafonômicos com bivalves marinhos têm sido conduzidos em ambientes sedimentares do Holoceno, porém, no Brasil, investigações similares são ainda incipientes, tendo sua predominância no litoral norte do Estado de São Paulo. O Complexo Estuarino de Paranaguá (CEP), situado na porção centro-norte do litoral do Paraná, possui feições fisiográficas distintas das encontradas no litoral norte do Estado de São Paulo. Com o objetivo de gerar dados comparativos entre os diferentes ambientes da costa brasileira, este estudo pretende caracterizar tafonomicamente as associações de moluscos bivalves em 11 pontos de coleta ao longo do CEP. Foram coletados oito litros de sedimento com a utilização de pegador de fundo tipo Petersen, em parceria com o Laboratório de Oceanografia Geológica (LOGeo CEM/UFPR). As assinaturas tafonômicas analisadas, podendo ser de origem química, física e/ou biológica, foram: articulação, tipo de valva, fragmentação, modificação da margem da concha, corrasion, perióstraco, brilho, cor, bioerosão, incrustação e predação. A ação dessas assinaturas pode resultar em outra assinatura tafonômica aqui analisada, a alteração da textura da superficial da concha. Foram analisados 150 bioclastos de cada um dos pontos de coleta, e cada assinatura tafonômica foi classificada individualmente. Os bioclastos foram peneirados em malhas de 2 mm para que as menores classes de tamanho não fossem excluídas das análises tafonômicas. Além dos bioclastos, foram coletadas amostras da água junto ao fundo dos locais amostrados, para registro de pH, salinidade, temperatura e turbidez. Ao total, 1.438 bioclastos foram utilizados nas análises tafonômicas e, das 11 estações de coleta, apenas duas não apresentaram o n mínimo de 150 conchas. Os dados abióticos não apresentaram grandes diferenças nas diferentes estações de coleta. A análise de cluster foi feita levando-se em consideração todas as assinaturas tafonômicas estudadas, e um dendograma geral relacionou os 9 pontos de coleta em que obteve-se o mínimo de 150 bioclastos. O dendograma gerado nesta análise mostrou quais as acumulações de moluscos bivalves e seus respectivos pontos de coleta estão mais semelhantes. Há um primeiro grupo formado pelas estações 683, 336, 482, 696 e 32. Com exceção da estação 32, as estações reunidas no primeiro grupo são os pontos de coleta mais próximos às desembocaduras do CEP, região de maiores profundidades e fortes correntes de marés. O segundo grupo é formado pelas estações 607, 152, 645 e 472, sendo pontos de coleta mais internos na área do CEP, próximos a ilhas, manguezais e bancos de areia. As assinaturas alteração da cor, brilho, modificação da margem, perióstraco e corrasion não parecem ser assinaturas úteis na identificação ou para uma possível caracterização dos diferentes ambientes do CEP. Isto porque elas não são variáveis entre esses diferentes ambientes. Houve predominância de desarticulação e fragmentação das valvas em todos os ambientes estudados, sendo possível que a fragmentação esteja sobre maior influência dos danos biológicos. Bioerosão e incrustação não apareceram em frequências expressivas, porém, apenas as estações de coleta próximas a desembocadura do CEP apresentaram bioeorosão, enquanto incrustação apareceu em todas as estações. A textura superficial da concha correlacionou-se positivamente com as assinaturas corrasion e bioerosão. / Actuopaleontology is the branch of Paleontology that aims to enhance paleoecological and paleoenvironmental interpretations, through the taphonomic signatures, especially those in bivalve shells. Such taphonomic studies with marine bivalves have been conducted in sedimentary Holocene environments, however, in Brazil, similar investigations are still incipient, having its predominance in the northern coast of São Paulo. The Paranaguá Estuarine Complex (CEP), situated in the north central portion of the Paraná coast, has different physiographic characteristics of those found in the north coast of São Paulo. In order to generate comparative data between different environments of the Brazilian coast, this study aims to characterize the taphonomy of bivalve mollusk associations from 11 collection stations along the CEP. Eight liters of sediment were collected with background catcher Petersen, in partnership with the Laboratory of Geological Oceanography (LOGeo - CEM/UFPR). The taphonomic signatures analyzed, which may be of chemical, physical and/or biological origin, were: articulation, valve type, fragmentation, edge modification, corrasion, periostracum, brightness, color, bioerosion, encrustation and predation. The action of these signatures may result in other taphonomic signature analyzed here, the alteration of shell superficial texture. 150 bioclasts were analyzed from each collection point and each taphonomic signature was individually classified. The bioclasts were sieved through mesh of two millimeter, so that classes of smaller size were not excluded from the taphonomic analyzes. In addition, water samples were collected at the bottom of each station for analysis of pH, salinity, temperature and turbidity. In total, 1,438 bioclasts were used in the taphonomic analysis and only two stations did not show the minimum n of 150 shells. Abiotic data showed no great differences in the different sampling stations. The cluster analysis was performed taking into account all studied taphonomic signatures, and a general dendrogram listed the collection points that showed the minimum of 150 bioclasts. The dendrogram generated in this analysis showed which accumulations of bivalve molluscs and their respective collection points are more similar. There is a first group formed by the stations 683, 336, 482, 696 and 32. With the exception of station 32, the stations on the first group are the closest to the mouths of the CEP, region of greater depths and strong tidal currents. The second group is formed by stations 607, 152, 645 and 472, being the more internal collection points, near islands, mangroves and sandbanks. The signatures color, brightness, edge modification, periostracum and corrasion do not seem to be useful in identifying or for a possible characterization of the different environments of the CEP, because they are not variable between these different environments. There was predominance of disarticulation and fragmentation of the valves in all study sites, being possible that the fragmentation was influenced more by biological damages. Bioerosion and encrustation did not appear in expressive frequencies, however, only the stations near the mouth of the CEP presented bioeorosão, while encrustation appeared in all stations. The surface texture of the shell was correlated positively with the sigantures corrasion and bioerosion.

Orientador: Flávio Dias Passos / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-23T04:53:16Z (GMT). No. of bitstreams: 1 Machado_FabrizioMarcondes_M.pdf: 6179757 bytes, checksum: 5fb73eff92075fe6ed70b1ce5dbb75f0 (MD5) Previous issue date: 2013 / Resumo: A conservação da biodiversidade marinha e o pouco conhecimento sobre a ecologia das espécies que habitam regiões mais profundas são temas atuais e amplamente discutidos. Com o objetivo geral de conhecer as espécies e a ecologia dos organismos marinhos bentônicos da Bacia de Campos - RJ, foi implantado o programa HABITATS- "Avaliação da Heterogeneidade Ambiental da Bacia de Campos". Apoiado pela Petrobras S.A./CENPES, o programa HABITATS foi realizado no período de fevereiro/2009 a julho/2009 e foi composto por nove transectos perpendiculares a linha da costa, localizados principalmente entre a Plataforma e o Talude Continental, totalizando 149 estações de coleta em faixas batimétricas que variaram de 25 a 3.000 metros de profundidade. O presente trabalho se baseia em espécimes obtidos a partir desse programa e tem como objetivos principais, o registro de duas famílias de bivalves (Cyamiidae e Spheniopsidae) para o Brasil, além da análise taxonômica e da descrição de três novas espécies de microbivalves. Após cerca de dois anos de triagens mais de 5.000 espécimes de bivalves provindos da Plataforma Continental foram analisados. Desse total foram identificadas 180 espécies, agrupadas em 47 famílias. Nesse trabalho foram descritas três novas espécies de microbivalves: Cyamiocardium sp. n. pertencente à família Cyamiidae; Grippina sp. n. e Spheniopsis sp. n. pertencentes à família Spheniopsidae. Ambas, devido ao tamanho diminuto (1,75 - 4,5 mm de comprimento), não puderam ter a sua anatomia descrita apenas por técnicas manuais de dissecção, sendo submetidas então a um processo de descalcificação e posteriormente a microscopia eletrônica de varredura e a histologia. Foram analisados 356 indivíduos de Cyamiocardium sp. n. sendo 25 destes com parte mole e coletados em uma faixa de 26-75m de profundidade. Para as espécies de Spheniopsidae, foram analisados 58 indivíduos de Grippina sp. n. sendo 20 com parte mole e coletados entre 21-53 m de profundidade e 189 indivíduos de Spheniopsis sp. n. sendo 2 com parte mole e coletados entre 17-148 m de profundidade. Para a família Cyamiidae cujas espécies eram até então distribuídas somente em águas australianas, neozelandesas, antárticas, subantárticas e magelânicas, o presente trabalho ampliou sua distribuição, fazendo o primeiro registro da família para águas brasileiras, além de descrever uma nova espécie. Já para a família Spheniopsidae além de um novo registro e da descrição de duas novas espécies, foi realizada a primeira descrição anatômica do grupo além de uma discussão sobre sua posição filogenética dentre os Anomalodesmata / Abstract: The conservation of marine biodiversity and little knowledge about the ecology of the species inhabiting deeper regions are current topics widely discussed. With the overall aim of knowing the species and ecology of benthic marine organisms in the Campos Basin, Rio de Janeiro, was implemented the HABITAT program "Assessment of Environmental Heterogeneity in the Campos Basin. Supported by Petrobras SA / CENPES, HABITAT program was conducted from February/2009 to July/2009 and was composed of nine transects perpendicular to shoreline, located mainly between the shelf and the continental slope, totaling 149 sampling stations in bathymetric ranges that varied from 25 to 3.000 meters deep. This study is based on specimens obtained from that program and aims general registration of two new families of bivalves (Cyamiidae and Spheniopsidae) for Brazil, besides the taxonomic analysis and description of three new species of microbivalves. After two years of triage, more than 5.000 specimens of bivalves from Continental Shelf were analyzed, of these about 180 species were identified and grouped into 40 families. In this work three new species of microbivalves were described: Cyamiocardium n. sp. belonging to the family Cyamiidae; Grippina n. sp. and Spheniopsis n. sp. belonging to the family Spheniopsidae. Because of their small size (1.75 - 4,5 mm in length), both not have their anatomy described by classical techniques of dissection and then subjected a process of descalcification and subsequent to scanning electron microscopy and histology. Were analyzed 356 individuals of Cyamiocardium n. sp. with 25 of these being soft part and collected in a range of 26-75 meters deep. To species Spheniopsidae, 58 individuals were analyzed Grippina n. sp. with 20 the soft part and collected between 21-53 meters deep and 189 individuals of Spheniopsis n. sp. with two the soft part and collected between 17-148 meters depth. For family Cyamiidae whose species were previously distributed only in Australian, New Zealand, Antarctic, Subantarctic and Magelanic waters, this study has expanded its distribution by making the first record of the family to Brazilian waters, and describe a new species. Already to the family Spheniopsidae addition of a new record and description of two new species, was held the first anatomical description of the group as well as a discussion of its phylogenetic position among Anomalodesmata / Mestrado / Ecologia / Mestre em Ecologia

An 80 Probestellen im Flusssystem der Vereinigten Mulde zwischen Trebsen/Sachsen und der Landesgrenze zu Sachsen-Anhalt wurden in den Untersuchungsjahren 2007 und 2008 insgesamt 157 lebende Muscheln und zahlreiche Schalenreste gefunden. Unter den Großmuschelarten fand sich am häufigsten die Malermuschel. Weiterhin gelang der Fund der Gewöhnlichen Teichmuschel und der Schwanenmuschel. Erstmals wurde auch die in Sachsen vom Aussterben bedrohte Große Flussmuschel (Unio tumidus) gefunden. Wasseruntersuchungen zeigten, dass die Gewässer einen ausreichenden Sauerstoffgehalt aufweisen und als Lebensraum für Großmuscheln und andere Wassertiere gut geeignet sind. Muscheln und andere Weichtiere bilden eine nicht ersetzbare Artengruppe in den Seen und Flüssen und tragen als Filtrierer wesentlich zur Qualität von Gewässern bei. Sie sind daher wichtige Bioindikatoren für den Erhaltungszustand von Fließgewässern. 73 Prozent der in sächsischen Gewässern vorkommenden Muschelarten sind in ihrem Bestand gefährdet oder sogar ausgestorben (vgl. Rote Liste Mollusken Sachsens, SCHNIEBS et al. 2006).

A behavioral model for acute responses in bivalves, was developed using time series analysis for use in a real-time biomonitoring unit. Stressed bivalves closed their shell and waited for the stressful conditions to pass. Baseline data showed that group behavior of fifteen bivalves was periodic, however, individuals behaved independently. Group behavior did not change over a period of 20 minutes more than 30 percent, however, following toxic exposures the group behavior changed by more than 30 percent within 20 minutes. Behavior was mathematically modeled using autoregression to compare current and past behavior. A logical alarm applied to the behavior model determined when organisms were stressed. The ability to disseminate data collected in real time via the Internet was demonstrated.

Growth of mussels under laboratory conditions was examined under various food regimes in different water types and temperatures. Growth was less than would be useful as an indicator and comparisons with field exposures were of minimal value. The effects of organophosphates on bivalves were examined via toxicity tests, tissue concentration, and by controlling exposure through the use of physical constraints. Upper temperature tolerance of both bivalve species was examined with respect to different acclimation temperatures and organophosphate exposures. Deviations from control exposures occurred at some temperatures. Copper effectively lowered the mean heat coma temperatures of C. fluminea at some concentrations, however, chlorine exposures did not alter heat coma temperature.

No description available.

La consommation des mollusques peut comporter des risques et ceux-ci peuvent transmettre des agents infectieux d'origine alimentaire tels que les virus entériques, dont les conséquences peuvent être très néfastes pour la santé. Les norovirus (NoV) et le virus de l'hépatite A (VHA) semblent être la cause première des maladies imputables aux mollusques bivalves. Cette étude visait à évaluer la contamination virale dans des mollusques provenant de la Gaspésie et à établir des traitements thermiques permettant une réduction complète de ces virus dans les mollusques. Les résultats ont montré que l'inactivation complète du NoV murin substitut du NoV humain et du VHA a été atteinte respectivement à une température 90°C pendant une période de 3 minutes et 5 minutes avec (5,47 logs de réduction) dans des pots de vene et à une température de 90 °C pendant une période de 3 minutes dans des sacs de plastique pour le VHA.

La mitochondrie est un organite intracellulaire permettant la production d’énergie nécessaire à la survie de la cellule. Sa singularité passe par le fait qu’elle possède son propre génome (ADN mitochondrial ou ADNmt) distinct du génome nucléaire (ADNnu). Aussi, contrairement à l’ADNnu qui est transmis par les deux parents, l’ADNmt est lui hérité seulement par la mère chez les animaux. Exceptionnellement, un seul système connu va à l’encontre de cette « loi » d’hérédité. Il s’agit du système de double hérédité uniparentale (Doubly Uniparental Inheritance ou DUI) retrouvé chez plusieurs espèces de bivalves. Les espèces concernées possèdent ainsi 2 lignées d’ADNmt distinctes : une d’origine paternelle (ADNmt M) transmise seulement de pères en fils, et une d’origine maternelle (ADNmt F) transmise par la mère à la fois aux filles et fils. L’hypothèse privilégiée pour expliquer le maintien du système DUI au cours de l’évolution l’engage dans la détermination sexuelle chez les bivalves mais la vérification de cette hypothèse repose entre-autre sur une étude plus élargie de différents systèmes DUI. Jusqu’à maintenant, le DUI a été trouvée chez 46 espèces de bivalves, mais sa distribution chez ce groupe est certainement plus vaste étant donné le nombre d’espèces vivantes estimé à >20000. L’objectif de ce projet est d’étudier (et d’élargir) la distribution taxonomique du système DUI au sein du groupe des mollusques afin d’obtenir les prérequis indispensables à une meilleure compréhension de sa fonction mais également pour en retracer l’origine. Les résultats suggèrent l’absence du système DUI chez cinq espèces de gastéropodes et confirment sa découverte chez deux nouvelles espèces et familles de bivalves [i.e. Scrobicularia plana (Semelidae) et Yoldia hyperborea (Yoldiidae)]. En s’appuyant sur les résultats phylogénétiques, nous favorisons l’hypothèse d’une origine unique pour ce système. Finalement, la nouvelle distribution taxonomique proposée ici confirme la présence du système DUI chez 103 espèces de bivalves appartenant à 12 familles. / Mitochondria are semi-independent organelles, mostly known for their role in energy production necessary for cell survival. Several characteristics make them unique: they have their own genome, the mitochondrial DNA (mtDNA), and contrary to the nuclear genome (nuDNA), they are inherited uniparentally by Strict Maternal Inheritance (SMI) in animal species. Exceptionally, one model of mitochondrial inheritance found in some Bivalvia goes against the rule of SMI. It is called the Doubly Uniparental Inheritance (DUI) system. The species concerned possess two distinct mitochondrial lineages: one transmitted by the male (M mtDNA) to his sons only, and the other by the female to both sons and daughters. The most likely hypothesis to explain the retention of the DUI system in evolution involves him in sexual determination in bivalves but a widened study on different DUI systems is needed to verify this hypothesis. Until now, the DUI system has been described in 46 bivalve species but its distribution in this group might be broader given the total number of living species estimated to >20000. This project aimed to study (and broaden) taxonomic distribution of DUI within mollusks as a necessary prerequisite to a better understanding of its function and its origin. The results suggest the absence of DUI in five gastropods species and confirm its discovery in two new bivalves species and families [i.e. Scrobicularia plana (Semelidae) and Yoldia hyperborea (Yoldiidae)]. Based on phylogenetic data, we favor the hypothesis of a single origin of DUI. Finally, the new taxonomy proposed here confirms the presence of the DUI system in 103 bivalves species belonging to 12 families.

L’objectif de ce travail de thèse vise à analyser les effets de quelques pesticides et d’un adjuvant sur des organismes marins, représentatifs de quatre niveaux trophiques, à savoir des micro-algues, un échinoderme, des bivalves et un poisson. L’analyse de la pollu-sensibilité est basée sur l’utilisation de différents bio-essais existants ou adaptés au contexte de cette étude.Les tests de toxicité ont permis d’évaluer la sensibilité de trois espèces phytoplanctoniques (Chaetoceros calcitrans, Isochrysis aff. Galbana et Tetraselmis suecica) vis-à-vis d’un fongicide l’époxiconazole (pur et en formulation commerciale Opus) et de l’adjuvant nonylphénol. D’une manière générale, la croissance de C. calcitrans et I. aff. Galbana s’avère plus sensible à l’action des contaminants étudiés. Ainsi, en utilisant pour C. calcitrans un milieu reproduisant les conditions naturelles du Golfe de Gabès, des valeurs de CE50 de 2 ,31 mg/L et 2,9 μg/l sont obtenues respectivement avec la substance active époxiconazole, et le produit formulé. Ces résultats montrent l’importance des adjuvants dans la toxicité et que les micro-algues peuvent être sensibles aux effets non-cibles d’un fongicide triazole.En outre, l’âge des cellules, les conditions d’éclairement et de composition des milieux de culture induisent des changements de sensibilité au fongicide, suggérant que la densité cellulaire est un paramètre important dans les tests de toxicité.L’analyse de quelques paramètres physiologiques montre que les contaminants utilisés induisent une augmentation du volume cellulaire, des échanges gazeux, de la teneur en pigments et en ATP. Il apparaît ainsi que les toxiques utilisés réduisent la vitesse de croissance, prolongeant le cycle cellulaire, sans affecter la production de nouveaux matériaux, nécessaires à la construction de nouvelles cellules.Par ailleurs, une étude réalisée en microcosmes lors d’un bloom de l’algue toxique Karenia selliformis dans le golfe de Gabès, montre que les différents contaminants chimiques (époxiconazole, chlorpyriphos-éthyl, nonylphénol) produisent des modifications drastiques de la structure des communautés phytoplanctoniques, fonction de la nature et de la concentration du contaminant.La toxicité des différents contaminants a été étudiée sur des animaux marins, aux stades embryo-larvaire (oursin, huître, palourde), métamorphose des larves (palourde) et survie des larves (turbot). Les résultats montrent que les larves du turbot sont les plus sensibles à l’action des contaminants avec des CE50 allant de 2,78 à 492 μg/L selon le toxique et que chez la palourde, la métamorphose est le stade le plus sensible parmi les trois stades de développement étudiés. Les contaminants utilisés produisent des anomalies du développement et des malformations embryonnaires qui peuvent induire une réduction de la production naturelle en agissant i) directement sur le développement embryo-larvaire et ii) indirectement sur la qualité et la biodisponibilité de l’aliment à travers la variation de la biomasse phytoplanctonique. Ces résultats soulignent la nécessité d’appliquer les toxiques à différents organismes marins présentant des organisations différentes pour apprécier pleinement leur impact. / This work aims to study the effects of a few pesticides and one adjuvant on marine organisms, representatives of four trophic levels : micro-algae, echinoderm, bivalves and fish. Analysis of the pollu-sensitivity was based on the utilisation of existing bio-assays or adapted to this study.Phytotoxic assessments were conducted on three phytoplanktonic species (Chaetoceros calcitrans, Isochrysis aff. Galbana et Tetraselmis suecica) using the fungicide epoxiconazole and the adjuvant nonylphenol. Sensitivity to these toxicants of C. calcitrans and I. aff. Galbana was high. Thus, when C. calcitrans was grown in a medium simulating pre-winter conditions in Gabès Gulf, EC50 values were respectively, 2.31 mg/L and 2.9 μg/L for epoxiconazole active ingredient and epoxiconazole-formulated. These results questioned the use of ecotoxicological data obtained solely using active molecules of pesticides rather the complete formulation and show that non-target micro-algae may be affected by a triazole fungicide.Moreover, cell age, light and nutrient composition induced changes in epoxiconazole sensitivity, suggesting that cellular density is an important parameter in toxicity tests.Analysis of a few physiological parameters show that contaminants used in this study induce an increase of pigment content, ATP synthesis, and rates of oxygen exchanges while the cell volume enlarges. Consequently, the toxicants might reduce the growth rate, by a prolongation of the cell cycle without affecting the production of new material for the construction of new cells.Bioassays were conducted using microcosms during a bloom of the toxic algae Karenia selliformis in the Gulf of Gabès. The different toxicants (epoxiconazole, chlorpyrifos-éthyl, nonyphenol) produced drastic changes in the phytoplankton communities, depending on the type and concentration of the contaminant.Phytotoxic assessments were conducted on marine animal models, using different developmental stages: embryo-larval development (sea urchin, oyster, and clam), metamorphosis larvae (clam) and larvae survival (turbot). Results show that turbot larvae are most sensitive to the action of contaminants with EC50 values ranging from 2.78 to 492 μg/L depending on the toxic and that the metamorphosis is the stage the most sensitive of the three stages of development of clam studied.The pollutants produced developmental and embryonic abnormalities that might induce a reduction in the natural production by acting i) directly on the development of the marine organisms and ii) indirectly on the quality and bioavailability of food through the variation of phytoplankton biomass.These results underline the need to study pollutant effects on marine organisms having different organizations to evaluate their full impact.