Made available in DSpace on 2014-06-12T23:00:59Z (GMT). No. of bitstreams: 2 arquivo8098_1.pdf: 15805362 bytes, checksum: c88cc6e0670419e5cc67f42878b30f55 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2002 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Informa-se o resultado dos estudo sistemático, ecológico e biogeográfico dos Mollusca, Gastropoda, Turbonillinae, presentes na Margem Continental do Nordeste do Brasil. Os espécimens analisados foram adquiridos através das coleções do Museu de Malacologia Rosa de Lima Silva Mello/Departamento de Pesca da Universidade Federal Rural de Pernambuco e do Laboratório de Bentos/Departamento de Oceanografia da Universidade Federal de Pernambuco. Esse material é proveniente de coletas manuais, mergulho autônomo e através de dragagens realizadas por Navios Oceanográficos e Barcos Pesqueiros. Os exemplares coligidos foram submetidos em laboratório a triagem em microscópio estereoscópico e identificados com a comparação da série-tipo e fotointepretação dos mesmos em alguns casos, e da literatura malacológica. Foram analisados 1025 espécimens em 133 amostras que resultou na identificação de 45 espécies, sendo elas: T. abrupta Bush, 1899, T. atypha Bush, 1899, T. fasciata (Orbigny, 1840), T. multicostata (C. B. Adams, 1850), T. brasiliensis Clessin, 1900, T. coomansi Aartsen, 1994, T. pupoides Orbigny, 1842, T. penistoni Bush, 1899, T. arnoldoi Jong & Coomans, 1988, confirmadas para o Nordeste do Brasil, Turbonilla deboeri ?, T. anira P. Barstch in Dall, 1927, T. protracta Dall, 1892, T. rhabdota Watson, 1886, T. krebsii Jong & Coomans, 1988, são reportadas pela primeira vez para a região, T. aff. obsoleta 1, T. aff. obsoleta 2, T. aff. rhabdota, T. aff. unilirata, T. aff. micans, T. atypha 1, T. atypha 2, T. aff. pilsbry, T. aff. myia, T. aff. rushii, T. sp. A, T. sp. B, T. sp. C, T. sp. D, T. sp. E, T. sp. F, T. sp. G, T. sp. H, T. sp. I, T. sp. J, T. sp. K, T. sp. L, T. sp. M, T. sp. N, T. sp. O., T. sp. P, T. sp. Q., T. sp. R, T. sp. S, T. sp., T. sp. U, T. sp. V, T. sp. X, confirmam a grande abundância específica presente na margem Continental. O estudo ainda mostrou que o Estado de Pernambuco foi o que apresentou maior abundância com 40 espécies. A região de talude mortrou-se um pouco mais abundante (29 espécies) que a região de plataforma (26 espécies). As espécies com maior distribuição geográfica foram T. coomansi (6 estados) e T. deboeri (5 estados)

In any circulatory system, the mechanical properties of the walls of the arteries will have significant effects on the dynamics of blood flow. The distensibi1ity of the artery wall is important in determining the wave propagation characteristics of the system, as well as contributing a pulse smoothing effect on the intermittant flow of blood from the heart. These properties are well studied in mammalian circulatory systems, but have never been directly investigated in any invertebrate animal. This study examines the structure and mechanical properties of the major artery in a cephalopod mollusc, Octopus dofleini, and relates these properties to cardiovascular dynamics in the living animal. The dorsal aorta of cephalopods is the large blood vessel through which blood flows from the systemic heart. The walls of this artery are comprised of thick layers of circularly and longitudinally oriented muscle cells. Outside the muscle layers is a loose collagenous adventitia. Innermost, adjacent to the lumen is a layer of elastic fibres, analogous to vertebrate elastin fibres. In addition, these fibres extend throughout the artery wall as a network of extracellular connective tissue. The elastic fibres have been isolated from the octopus aorta and subjected to direct mechanical and chemical tests. These fibres are composed of a protein which has rubber-like properties, that is, the material has high extensibility and a modulus of elasticity, G (= 4.65 X 10⁵ N/m² ), which is similar to a rubber. Chemical and optical properties of this unusual protein suggest that the molecular structure is one of covalently crosslinked, random coil, kinetically free chains. This interpretation is consistent with the thermoelastic data for these protein fibres which fit closely the predictions of the kinetic theory of entropic elasticity in rubbers. In vitro mechanical tests on the octopus aorta showed that this vessel is a highly distensible, resilient elastic tube which, like mammalian arteries, becomes much less compliant as it is extended. The tangential elastic modulus in the circumferential direction (Ec) ranged from 9X10³ to 2X10⁵ N/m² over the normal resting range of physiological pressures (20 to 50 cm of water), while the elastic modulus in the longitudinal direction (El) was always about one-half of Ec. Hysteresis in quasi-static inflations was about 25%. The dynamic modulus of elasticity increased continuously with frequencies from 0.1 Hz to 10Hz. Tan d varied from about 0.10 to 0.15 over the physiologically relevant range of frequencies in this animal (0.1 to 1.0 Hz). These results show that this artery can function as an elastic, pulse smoothing component in the octopus circulation. Further, it appears that the elastic properties of the intact artery can be attributed largely to the rubber-like protein found in the wall. In vivo measurements of blood pressure and flow in the octopus show an impedance spectrum which is similar to what has been observed in turtles and frogs, that is, the arterial circulation of this invertebrate is adequately described by a simple Windkessel model. Pulse wave velocity measured in vivo appeared to be greater than 10 m/sec, although the velocity predicted from the elastic properties of the aorta was less than 5 m/sec. These anomalies arise because, due to the low heart rate of the octopus, the length of the aorta is less than 5% of the wavelength of the significant frequencies in the pressure pulse. The arterial system of the octopus is one which is dominated by strong wave reflections, but does not exhibit other transmission effects such as peaking and distortion of the travelling pressure wave. These results may have general application to other cephalopods, but it will be interesting to examine species, such as pelagic squids, which presumably have higher blood pressure and heart rates. / Science, Faculty of / Zoology, Department of / Graduate

Hatching larvae of neritimorph gastropods have a bilateral set of both larval and pedal retractor muscles, which is unique among gastropod molluscs. Adults also display a novel connection (“shortcut”) between the two pleural ganglia. To reconstruct the evolution of the novel shortcut between pleural ganglia and its functional role, I studied the development of the central nervous system and muscle innervation in three distinct larval and one post-metamorphic stages of Nerita melanotragus using light and transmission electron microscopy and surface-rendered three-dimensional reconstructions. My results revealed that the novel shortcut is derived from an ancestral nerve connective, which establishes an unconventional link between the ganglia that generate motor output to the bilateral set of larval and pedal retractor muscles to coordinate activity of these muscles. The unique characteristics of the shell, muscles and nervous system in N. melanotragus represent secondarily derived characteristics that co- evolved as an integrated functional unit. / Graduate / 0472

Cephalopods first appeared around 500 million years ago. Since then they have developed from the external shelled ammonites, belemnites and nautiloid's to the soft bodied organisms we find today. By becoming soft bodied, protection which would have been provided by the shell was lost and a different approach to predator avoidance was adopted. Modern day cephalopods such as octopus, squid and cuttlefish frequently use camouflage techniques to avoid detection. In addition to countershading, which is an often used camouflage technique by aquatic species, the presence of chromatophores allow a versatile and rapid response in relation to stimuli. Cuttlefish expression of these chromatic responses can be categorised into chromatic components. It is the intensity and combination of the expression which makes them an interesting organism to study, when looking at how the environment influences camouflage decisions. In this thesis, I present six experiments looking at how external environmental factors influence camouflage in Sepia officinalis. The first experimental chapter looks at how 3D objects and proximity play a role in not only camouflage, but behavioural responses. The first set of experiments discuss how factors such as contrast and size of an object may elicit different responses both behaviourally and chromatically. The proximity of the cuttlefish to the object was then investigated to determine if visual input was a possible cause for the differences. Size of the object, proximity and contrast produced a differing response to that of a cuttlefish on a uniform background. The two subsequent chapters look at differing light information and whether cuttlefish treat these differences similar to that of low contrast. Reaction to turbid and low light levels show similar responses in camouflage, suggesting that similar mechanisms are employed when there is reduced light and high scatter information. In respect to luminance versus reflectance, cuttlefish seem to be able to differentiate between a projected and reflected image where they appear to treat projected images like a lower contrast value. The last experimental chapter investigates motion camouflage in respect to predation. Prey and distance had a large effect on behaviour and how camouflage was expressed. Over greater distances behavioural variance reduced. Darkening of the head region and arm waving was also present over a greater distance. Camouflage varied in relation to background with a more uniform background producing reduced expression when moving. Stationary predation therefore elicits a different response than that of motion camouflage in cuttlefish.

Endogenous nitric oxide (NO) produced by the enzyme NO synthase (NOS) has an important role in a variety of physiological processes. However, NO becomes noxious to cells if produced in excess. Therefore, the production of NO is tightly regulated. A particularly exciting and novel aspect of the regulation of NO signalling is the possibility that the expression of NOS genes is controlled by unconventional mechanisms that depend on the presence of natural antisense transcripts (NATs). In this thesis I investigate the important properties of two distinct NOS-related NATs: Lym-antiNOS2 and Mm-antiNOS1. I show that Lym-antiNOS2 RNA is widely expressed in the CNS of the pond snail Lymnaea stagnalis. Furthermore, I demonstrate that the expression of Lym-antiNOS2 is differentially regulated by training leading to long-term memory formation. Moreover, my results indicate that Lym-antiNOS2 RNA is subjected to peripheral trafficking in neurons. As for Mm-antiNOS1, I find that its expression is restricted to embryonic brain tissue and is almost undetectable in the adult brain of Mus musculus.

A presente tese trata da Tafonomia de tanatocenoses compostas por conchas de moluscos bivalves e braquiópodes [Bouchardia rosea (Mawe)], variando em idade, desde recentes até 23.820 anos A.P. A abordagem envolveu a tafonomia comparada, a tafonomia experimental e a paleobiologia de B. rosea, a fim de cumprir os seguintes objetivos: (1) estabelecer um protocolo metodológico comparável aos disponíveis na literatura; (2) investigar comparativamente a tafonomia das tanatocenoses analisadas, (3) compreender o comportamento de decantação de conchas de B. rosea; (d) reconhecer e entender as interações bióticas (e.g., predação e parasitismo), registradas em B.rosea, comparando-as com as dos moluscos bivalves simpátricos. As tanatocenoses provêm das enseadas de Ubatuba e Picinguaba, na costa norte do Estado de São Paulo e da plataforma interna adjacente. Trinta estações de coleta, com fundo siliciiclástico ou bioclástico foram amostradas (e.g., Van Veen com 31 x 40cm), em gradiente batimétrico, desde a praia até 45 metros de profundidade. Quatro ambientes sedimentares foram informalmente reconhecidos: (a) ambiente praial, (b) enseada de fundo argiloso, (c) enseada de fundo arenoso e (d) plataforma de fundo arenoso. As coletas forneceram 5204 conchas de braquiópodes e 9137 de moluscos bivalves. Os resultados das análises tafonômicas indicaram que, quando realizadas para cada fração granulométrica (frações .8mm,.6 mm e .2 mm), independentemente, os bioclastos de diferentes frações registram, de maneira complexa e não uniforme, a atuação de processos bioestratinômicos distintos e, portanto, o tamanho da partícula tem influência na distribuição das assinaturas tafonômicas. Análises de agrupamentos para distribuição das assinaturas tafonômicas das assembléias de bivalves mostraram que o grau de similaridade é distinto, entre as estações, segundo as frações consideradas, sugerindo que concentrar as análises tafonômicas na fração granulométrica maior (.8mm) não é, necessariamente, a melhor estratégia metodológica a ser adotada. Desse modo, a metodologia mais adequada é aquela fundamentada na fração total. Diversos exemplos de generalizações e modelos tafonômicos, disponíveis na literatura, não são aplicáveis aos dados tafonômicos obtidos para os bioclastos das enseadas de Ubatuba e Picinguaba, contribuindo para a convicção de que, em Tafonomia, cada caso é um caso. Assinaturas como articulação, fragmentação, corrosão, modificação da margem, bioerosão, incrustação, alteração da cor, perda do brilho e perióstraco apresentaram-se homogeneamente distribuídas entre os ambientes estudados, indicando que, no caso desse estudo, essas não são sensíveis às condições ambientais, sendo pouco informativas à caracterização ambiental e paleoambiental. A assinatura textura superficial da concha mostrou potencialidade para interpretações ambientais mais fidedignas e utilização na definição de tafofácies. Quanto àTafonomia Experimental, a velocidade e o padrão de decantação de conchas de B. rosea foram experimentalmente estudadas, para entendimento de seu comportamento hidrodinâmico e potencial para seleção por processos hidráulicos. Vinte valvas (10 dorsais e 10 ventrais) e três conchas articuladas, compreendendo a variação de tamanho de B. rosea, foram selecionadas. A média de velocidade de decantação foi de 15,35 cm/s, 16,65 cm/s, e 26,48 cm/s, para as valvas ventrais, dorsais e articuladas, respectivamente. Velocidade de decantação mais baixa para valvas ventrais indica que essas permanecem por tempo mais prolongado em suspensão na coluna d\'água, estando mais susceptíveis ao transporte. As dorsais, com seu formato menos convexo e velocidade de decantação mais rápida, estão menos sujeitas ao transporte, podendo formar depósitos residuais. Assim sendo, fragmentação diferencial das valvas não é o único processo responsável pela proporção desigual de valvas dorsais/ventrais, em depósitos sedimentares atuais ou nas assembléias fósseis. Mais de 14.000 espécimes de bivalves e braquiópodes foram analisados quanto à predação. Perfurações parabólicas, circulares a sub-circulares ocorrem nas conchas de bivalves e braquiópodes. Essas são comparáveis entre si, quanto à morfologia e o diâmetro médio, indicando decorrem de ataques de um mesmo organismo perfurador. Perfurações nos braquiópodes são raras (0,4%), embora nos moluscos bivalves a frequência seja de até cinqüenta vezes maior. Contudo, as taxas de perfuração nos bivalves das enseadas de Ubatuba e Picinguaba são baixas, se comparadas às freqüências típicas cenozóicas. As baixas freqüências de perfuração nos braquiópodes estão de acordo com as obtidas em estudos recentes, tanto em ambientes atuais, como no registro sedimentar. As perfurações podem sugerir predação: (a) por gastrópodes naticídeos/muricídeos, (b) por outros predadores, (c) predação acidental ou decorrerem de parasitismo. Finalmente, observações em braquiópodes vivos permitiram identificar traços de bioerosão do tipo Caulostrepsis Clarke (1908) e identificar o organismo produtor do traço. Das 1616 conchas examinadas (vivas e mortas), 292 mostraram traços de Caulostrepsis (18%). As freqüências dos traços variaram, segundo as estações de coleta, o tamanho dos bioclastos e o tipo de valva. Caulostrepsis não foi encontrado nos moluscos bivalves simpátricos. Todos os braquiópodes vivos com Caulostrepsis apresentaram-se infestados por Polydora (Polychaeta, Spionidae). Portanto, Caulostrepsis resulta do parasitismo por essas poliquetas. / In this study the taphonomy of bivalve mollusks and brachiopod shells [Bouchardia rósea (Mawe)], ranging from Recent to 23,820 years B.P. was analysed. The main goals are; (1) the establishment of a methodological protocol comparable to the previously available in the literature; (2) the comparative taphonomy between brachiopod and bivalve mollusk shells; (3) the understanding of the setting behavior of B. rosea shells, and the (d) identification of the biotic realtionships (e.g., predation and parasitism), recorded on B. rosea shells, comparing them with the occurrences in the sympatric bivalve shells. The studied thanathocoenosis were sampled in the Ubatuba Bay and Pinciguaba Bay, northern cost of São Paulo State, and in the inner platform, as well. Thirty collecting stations, characterized by siliciclastic or bioclastic bottoms were sampled via Van Veen grab sampler (31 x 40cm), along a bathymetric gradient, ranging from zero (beach) to 45 meters of depth. Four sedimentary environments were informally recognized: (a) beach, (b) muddy bottom bay, (c) sandy bottom bay, and (d) inner shelf with sandy bottom. Bulk samples yielded 5204 brachiopod and 9137 bivalve mollusk shells. The results indicate that, when independently analysed to each sieve ( .8mm, . 6mm e . 2mm), shells of different sieve sizes record the biostratinomic processes in a complex and non-random way. Thus, the sieve size plays a role in the taphonomic analysis. Cluster analysis performed for the distribution of the taphonomic signatures on bivalves shells showed that the similarity among the clusters vary according to the considered sieve size. This suggests that concentrating the taphonomic analysis in one class (e.g., the largest sieve size, . 8mm) is not, necessarily, the better methodological decision. Hence, the total data (all sieves included) is more accurate in the taphonomic analysis. Several examples of taphonomic generalizations and models, available in the literature, are neither applicable nor comparable to our results. This enhances the conviction that, in taphonomy we may avoid generalizations to seek laws and models that are applicable to all cases without restrictions. Taphonomic signatures such as articulation, fragmentation, corrosion, edge modification, bioerosion, encrustation, color alteration, luster, and lost of periostracum were homogeneously distributed, among the studied sedimentary environments, indicating that these taphonomic signatures are not sensible to the environmental conditions. On the other hand, shell texture showed high potential to environmental interpretations and seems to be usefull as a tool in taphofacies analysis. The setting velocity and falling patterns of B. rosea shells, were experimentally performed to understand the hydrodynamic behavior and potential for sorting by hydraulic processes. Twenty valves (10 dorsals and 10 ventrals) and three articulated shells were selected, encompassing the size range of B. rosea shells. The obtained average settling velocities are: 15.35 cm/s, 16.65 cm/s, and 26.48 cm/s, respectivelly, for ventral, dorsal and articulated valves. The lower average settling velocities of ventral shells indicate that they can be transported to greater distances, than the less convex dorsal valves. This can be explained, in part, by the fact that ventral valves have greater cross-sectional areas than dorsal ones of the same weight. Hence, differential fragmentation of brachiopod valves is not the unique process likely to produce bias between dorsal and ventral valves, observed in some modern deposits, and many fossil concentrations. Over 14,000 bivalve and brachiopod specimens were studied for predation. Beveled (countersunk) circular-to-subcircular borings were found in bivalve and brachiopod shells that are comparable in their morphology, and average diameter, indicating attacks by a single type of a drilling organism. Drill holes in brachiopods were rare (0.4%). Drilling frequency in bivalves was up to 50 times as high as in brachiopods. However, the average drilling frequency was low on bivalves from the Ubatuba Bay and Picinguaba Bay, comparing to the frequencies typically observed in Cenozoic mollusks. Low drilling frequency in brachiopods is consistent with other recent reports, both in the fossil record as well as in recent habitats. Drilling may record (a) naticid/muricid predation, (b) predation by some other drillers, (c) mistaken and/or opportunistic attacks, and (c) parasitic drillings. Finally, the observations of infested live specimens of brachiopods allowed identifying one type of common bioerosional traces, named Caulostrepsis Clarke (1908). The identity of the trace producer was also recorded. Out of 1616 examined shells (both living and dead brachiopod shells), 292 shells showed traces referable to Caulostrepsis (18%). Infestation rates vary by collecting site, shell size, and valve type. Nome of sympatric bivalve shells showed similar traces. All shells collected alive yielding Caulostrepsis traces were infested by Polydora (Polychaeta, Spionidae), indicating a parasitic relationship between spionids and brachiopods.

Information was gathered regarding all aquarium and already introduced alien snail species (Gastropods), which are being imported to Europe. For the integrity of the research non-native and aquarium clams (Bivalve) were also included. Profiles of species were created based on collected information and the data were subsequently used for creating questionnaires. Questionnaires of each species were processed by FI - ISK, version 1.19 screening tool. Score of invasiveness risk potential was evaluated for each species individually. Surveyed taxa were divided into three groups according to their scores: low risk, medium risk and high risk. Celetaia persculpta was evaluated as aquarium snail (Gastropods) with the lowest risk for native fauna of Czech Republic. According to the results, Pomacea maculata and Pomacea canaliculata are the aquarium snails (Gastropods) with the highest invasiveness risk potential. The riskiest introduced species is Potamopyrgus antipodarum. Scabies crispata and Hyriopsis bialata are clams (Bivalve) with the least risk for the native fauna of Czech Republic. Corbicula fluminea and Dreissena polymorpha were analyzed as clams (Bivalve) with the highest invasiveness risk potential. By comparing aquarium species with species that were already introduced into Czech nature, I conclude that the aquarium snails (clams) do not represent similar risk like the alien species that were introduced without the share of aquarists.

A presente tese trata da Tafonomia de tanatocenoses compostas por conchas de moluscos bivalves e braquiópodes [Bouchardia rosea (Mawe)], variando em idade, desde recentes até 23.820 anos A.P. A abordagem envolveu a tafonomia comparada, a tafonomia experimental e a paleobiologia de B. rosea, a fim de cumprir os seguintes objetivos: (1) estabelecer um protocolo metodológico comparável aos disponíveis na literatura; (2) investigar comparativamente a tafonomia das tanatocenoses analisadas, (3) compreender o comportamento de decantação de conchas de B. rosea; (d) reconhecer e entender as interações bióticas (e.g., predação e parasitismo), registradas em B.rosea, comparando-as com as dos moluscos bivalves simpátricos. As tanatocenoses provêm das enseadas de Ubatuba e Picinguaba, na costa norte do Estado de São Paulo e da plataforma interna adjacente. Trinta estações de coleta, com fundo siliciiclástico ou bioclástico foram amostradas (e.g., Van Veen com 31 x 40cm), em gradiente batimétrico, desde a praia até 45 metros de profundidade. Quatro ambientes sedimentares foram informalmente reconhecidos: (a) ambiente praial, (b) enseada de fundo argiloso, (c) enseada de fundo arenoso e (d) plataforma de fundo arenoso. As coletas forneceram 5204 conchas de braquiópodes e 9137 de moluscos bivalves. Os resultados das análises tafonômicas indicaram que, quando realizadas para cada fração granulométrica (frações .8mm,.6 mm e .2 mm), independentemente, os bioclastos de diferentes frações registram, de maneira complexa e não uniforme, a atuação de processos bioestratinômicos distintos e, portanto, o tamanho da partícula tem influência na distribuição das assinaturas tafonômicas. Análises de agrupamentos para distribuição das assinaturas tafonômicas das assembléias de bivalves mostraram que o grau de similaridade é distinto, entre as estações, segundo as frações consideradas, sugerindo que concentrar as análises tafonômicas na fração granulométrica maior (.8mm) não é, necessariamente, a melhor estratégia metodológica a ser adotada. Desse modo, a metodologia mais adequada é aquela fundamentada na fração total. Diversos exemplos de generalizações e modelos tafonômicos, disponíveis na literatura, não são aplicáveis aos dados tafonômicos obtidos para os bioclastos das enseadas de Ubatuba e Picinguaba, contribuindo para a convicção de que, em Tafonomia, cada caso é um caso. Assinaturas como articulação, fragmentação, corrosão, modificação da margem, bioerosão, incrustação, alteração da cor, perda do brilho e perióstraco apresentaram-se homogeneamente distribuídas entre os ambientes estudados, indicando que, no caso desse estudo, essas não são sensíveis às condições ambientais, sendo pouco informativas à caracterização ambiental e paleoambiental. A assinatura textura superficial da concha mostrou potencialidade para interpretações ambientais mais fidedignas e utilização na definição de tafofácies. Quanto àTafonomia Experimental, a velocidade e o padrão de decantação de conchas de B. rosea foram experimentalmente estudadas, para entendimento de seu comportamento hidrodinâmico e potencial para seleção por processos hidráulicos. Vinte valvas (10 dorsais e 10 ventrais) e três conchas articuladas, compreendendo a variação de tamanho de B. rosea, foram selecionadas. A média de velocidade de decantação foi de 15,35 cm/s, 16,65 cm/s, e 26,48 cm/s, para as valvas ventrais, dorsais e articuladas, respectivamente. Velocidade de decantação mais baixa para valvas ventrais indica que essas permanecem por tempo mais prolongado em suspensão na coluna d\'água, estando mais susceptíveis ao transporte. As dorsais, com seu formato menos convexo e velocidade de decantação mais rápida, estão menos sujeitas ao transporte, podendo formar depósitos residuais. Assim sendo, fragmentação diferencial das valvas não é o único processo responsável pela proporção desigual de valvas dorsais/ventrais, em depósitos sedimentares atuais ou nas assembléias fósseis. Mais de 14.000 espécimes de bivalves e braquiópodes foram analisados quanto à predação. Perfurações parabólicas, circulares a sub-circulares ocorrem nas conchas de bivalves e braquiópodes. Essas são comparáveis entre si, quanto à morfologia e o diâmetro médio, indicando decorrem de ataques de um mesmo organismo perfurador. Perfurações nos braquiópodes são raras (0,4%), embora nos moluscos bivalves a frequência seja de até cinqüenta vezes maior. Contudo, as taxas de perfuração nos bivalves das enseadas de Ubatuba e Picinguaba são baixas, se comparadas às freqüências típicas cenozóicas. As baixas freqüências de perfuração nos braquiópodes estão de acordo com as obtidas em estudos recentes, tanto em ambientes atuais, como no registro sedimentar. As perfurações podem sugerir predação: (a) por gastrópodes naticídeos/muricídeos, (b) por outros predadores, (c) predação acidental ou decorrerem de parasitismo. Finalmente, observações em braquiópodes vivos permitiram identificar traços de bioerosão do tipo Caulostrepsis Clarke (1908) e identificar o organismo produtor do traço. Das 1616 conchas examinadas (vivas e mortas), 292 mostraram traços de Caulostrepsis (18%). As freqüências dos traços variaram, segundo as estações de coleta, o tamanho dos bioclastos e o tipo de valva. Caulostrepsis não foi encontrado nos moluscos bivalves simpátricos. Todos os braquiópodes vivos com Caulostrepsis apresentaram-se infestados por Polydora (Polychaeta, Spionidae). Portanto, Caulostrepsis resulta do parasitismo por essas poliquetas. / In this study the taphonomy of bivalve mollusks and brachiopod shells [Bouchardia rósea (Mawe)], ranging from Recent to 23,820 years B.P. was analysed. The main goals are; (1) the establishment of a methodological protocol comparable to the previously available in the literature; (2) the comparative taphonomy between brachiopod and bivalve mollusk shells; (3) the understanding of the setting behavior of B. rosea shells, and the (d) identification of the biotic realtionships (e.g., predation and parasitism), recorded on B. rosea shells, comparing them with the occurrences in the sympatric bivalve shells. The studied thanathocoenosis were sampled in the Ubatuba Bay and Pinciguaba Bay, northern cost of São Paulo State, and in the inner platform, as well. Thirty collecting stations, characterized by siliciclastic or bioclastic bottoms were sampled via Van Veen grab sampler (31 x 40cm), along a bathymetric gradient, ranging from zero (beach) to 45 meters of depth. Four sedimentary environments were informally recognized: (a) beach, (b) muddy bottom bay, (c) sandy bottom bay, and (d) inner shelf with sandy bottom. Bulk samples yielded 5204 brachiopod and 9137 bivalve mollusk shells. The results indicate that, when independently analysed to each sieve ( .8mm, . 6mm e . 2mm), shells of different sieve sizes record the biostratinomic processes in a complex and non-random way. Thus, the sieve size plays a role in the taphonomic analysis. Cluster analysis performed for the distribution of the taphonomic signatures on bivalves shells showed that the similarity among the clusters vary according to the considered sieve size. This suggests that concentrating the taphonomic analysis in one class (e.g., the largest sieve size, . 8mm) is not, necessarily, the better methodological decision. Hence, the total data (all sieves included) is more accurate in the taphonomic analysis. Several examples of taphonomic generalizations and models, available in the literature, are neither applicable nor comparable to our results. This enhances the conviction that, in taphonomy we may avoid generalizations to seek laws and models that are applicable to all cases without restrictions. Taphonomic signatures such as articulation, fragmentation, corrosion, edge modification, bioerosion, encrustation, color alteration, luster, and lost of periostracum were homogeneously distributed, among the studied sedimentary environments, indicating that these taphonomic signatures are not sensible to the environmental conditions. On the other hand, shell texture showed high potential to environmental interpretations and seems to be usefull as a tool in taphofacies analysis. The setting velocity and falling patterns of B. rosea shells, were experimentally performed to understand the hydrodynamic behavior and potential for sorting by hydraulic processes. Twenty valves (10 dorsals and 10 ventrals) and three articulated shells were selected, encompassing the size range of B. rosea shells. The obtained average settling velocities are: 15.35 cm/s, 16.65 cm/s, and 26.48 cm/s, respectivelly, for ventral, dorsal and articulated valves. The lower average settling velocities of ventral shells indicate that they can be transported to greater distances, than the less convex dorsal valves. This can be explained, in part, by the fact that ventral valves have greater cross-sectional areas than dorsal ones of the same weight. Hence, differential fragmentation of brachiopod valves is not the unique process likely to produce bias between dorsal and ventral valves, observed in some modern deposits, and many fossil concentrations. Over 14,000 bivalve and brachiopod specimens were studied for predation. Beveled (countersunk) circular-to-subcircular borings were found in bivalve and brachiopod shells that are comparable in their morphology, and average diameter, indicating attacks by a single type of a drilling organism. Drill holes in brachiopods were rare (0.4%). Drilling frequency in bivalves was up to 50 times as high as in brachiopods. However, the average drilling frequency was low on bivalves from the Ubatuba Bay and Picinguaba Bay, comparing to the frequencies typically observed in Cenozoic mollusks. Low drilling frequency in brachiopods is consistent with other recent reports, both in the fossil record as well as in recent habitats. Drilling may record (a) naticid/muricid predation, (b) predation by some other drillers, (c) mistaken and/or opportunistic attacks, and (c) parasitic drillings. Finally, the observations of infested live specimens of brachiopods allowed identifying one type of common bioerosional traces, named Caulostrepsis Clarke (1908). The identity of the trace producer was also recorded. Out of 1616 examined shells (both living and dead brachiopod shells), 292 shells showed traces referable to Caulostrepsis (18%). Infestation rates vary by collecting site, shell size, and valve type. Nome of sympatric bivalve shells showed similar traces. All shells collected alive yielding Caulostrepsis traces were infested by Polydora (Polychaeta, Spionidae), indicating a parasitic relationship between spionids and brachiopods.

El cultivo de mejillón en la Argentina es un recurso de alta potencialidad productiva y económica. Una de las principales limitantes para la expansión de esta actividad se encuentra en la provisión de juveniles para la cría y engorde, comúnmente denominados “semilla”. En el golfo San Jorge, Chubut, existe una serie de iniciativas productivas que enfrentan el interrogante de si es posible la captación natural de juveniles de mejillón en colectores artificiales. Hasta el momento, la semilla utilizada en los emprendimientos que se ubicaron en esta área geográfica proviene de criadero o de la recolección de la región del intermareal rocoso de los alrededores de los sitios en producción, como así también de otros sitios ubicados en la costa argentina. En esta investigación se trabajó en dos sitios de estudio cercanos entre sí, pero de características de exposición y morfología costera diferentes. Ambos sitios se hallan en las cercanías de la ciudad de Comodoro Rivadavia. El objetivo general fue conocer si existía el fenómeno de captación en la región central costera del golfo San Jorge. Para ello se instaló en el mar una serie de colectores de remplazo bimestral que dieron como resultado la existencia de un pulso de captación principal a fines del verano-comienzo del otoño. También se estudió el ciclo sexual del mejillón, inferido a partir de las variaciones de su peso seco, obteniendo dos posibles periodos de desove, el primero a fines de primavera-principios de verano y el segundo de ellos, a comienzos del otoño. Otro objetivo específico de esta tesis fue el monitoreo de variables ambientales durante el periodo de estudio y, a partir de los datos obtenidos, desarrollar un modelo estadístico predictivo para la captación, que contemplara las variables que resultaran más relevantes. Dicho modelo presentó como variables predictoras la temperatura como factor de mayor influencia, la concentración de materia orgánica en el agua de mar y la variación del peso seco de los mejillones con un corrimiento de un mes. Asimismo se evaluó también el posible efecto de la morfología costera sobre el fenómeno de asentamiento postlarvario. Para ello se seleccionaron dos sitios a distinta distancia de geoformas costeras; el sitio Belvedere fue seleccionado por su menor exposición y por su cercanía a una prolongación del continente hacia el mar, y el sitio Km 3, por su mayor exposición y por su lejanía a geoformas costeras. Los resultados indicaron que en Belvedere se encontraron mayores captaciones que en Km 3, indicando que la geomorfología costera tendría un efecto sobre la captación. Se efectuó un análisis de las corrientes marinas locales en ambos sitios, observándose diferencias en el comportamiento de las direcciones de las corrientes. Por otro lado se analizó el efecto de la profundidad sobre la densidad de individuos captados, colocando colectores a tres profundidades diferentes; no se detectaron variaciones significativas en la densidad de individuos captados por efecto de la profundidad, pero sí en el tamaño de los mismos, que presentaron tallas mayores a profundidades menores. Se identificaron las postlarvas captadas mediante diferentes técnicas que resultaron satisfactorias, encontrándose un criterio clasificatorio distintivo para las postlarvas de mejillón. Por último, se realizó una determinación de la epibiosis hallada en los colectores durante el estudio, con la finalidad de reconocer especies competidoras y facilitadoras del asentamiento de postlarvas.

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