Thèses sur le sujet « Intertidal gastropods »
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Al-Mazrouai, Ahmed Mohammed. « Phenotypic plasticity in marine intertidal gastropods ». Thesis, University of Plymouth, 2008. http://hdl.handle.net/10026.1/1973.
Moisez, Emilie. « A step forward in the understanding of behavioural and thermal ecology of intertidal gastropods ». Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR010.
Intertidal organisms inhabit highly variable and complex environments and are submitted to a large range of stimuli and stresses. Recently, new insights into the sensory abilities of intertidal gastropods and their subsequent ability to navigate through topographically complex landscapes demonstrated that the behavioural repertoire of intertidal gastropods is much wider than previously thought. In this context, the present thesis first aimed to ameliorate our knowledge in the thigmotactic behaviour of Littorina littorea. Specifically, thigmotactic behaviour was tested in experimental containers of different sizes and shapes. This approach allowed individuals to encounter two-dimensional and three-dimensional discontinuities in order to understand how the topographical complexity of their environment can modify this behaviour. Thigmotaxis was further tested under decreasing salinity concentrations to understand how salinity can modify gastropods behaviour, since they are typically submitted to large salinity variations during emersion periods. During emersion, intertidal organisms are also submitted to large temperature variations (up to 20°C). Thus, this work also investigated the thermal behaviour of intertidal gastropods by studying body temperature of L. littorea and Patella vulgata and their microhabitat temperature on a rocky platform on the French coasts of the eastern English Channel. Temperatures were investigated on four sunny days from June to December to test the microhabitat choice of these two intertidal gastropods species under temperature conditions typically experienced through a seasonal cycle on the Opal Coast. Aggregation behaviour in L. littorea and the associated thermal benefits previously found in gastropods literature were also investigated, (i) in situ under a moderate heat wave and (ii) ex situ under an extreme heat wave simulated under laboratory-controlled conditions. Specifically, the body temperature of individuals inside and at the edge of aggregates were investigated to assess the importance of the position within aggregates.Taken together, the results of this thesis suggest that the thigmotactic behaviour can be one of the major taxes involved in intertidal gastropods orientation. Indeed, even under unfavourable conditions (e.g. low salinity conditions), the thigmotactic behaviour is still observed in L. littorea. This work also highlighted macrohabitat preference in L. littorea and P. vulgata for biogenic structures which allow to reduce both desiccation and thermal stresses. Within a macrohabitat, intertidal organisms are able to take advantage of the thermal mosaic encountered in intertidal environment and select microhabitat. This microhabitat selection in gastropods, is species- temperature- and habitat-dependent and allows individuals to maintain their body into their optimal range of temperatures. Finally, this work stressed the absence of thermal benefits of being aggregated in L. littorea under heat stress conditions. Specifically, under extreme heat wave, body temperature of individuals inside the aggregate is higher than for individuals at the edge of the aggregate. This result raised the rather unexpected and still unresolved question to understand the mechanisms driving aggregation behaviour in L. littorea. These results nevertheless contribute to the growing evidence that studying behaviour in intertidal gastropods is critical to understand how they move, how they perceive their environment and how they cope with raising temperature under global warming. This work also highlighted the importance of a better understanding of the thermoregulatory behaviour in intertidal organisms, for a better estimation of the impact of global warming in their ecology
Muteveri, Tinashe. « Effect of pleistocene climatic changes on the evolutionary history of South African intertidal gastropods ». Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79791.
ENGLISH ABSTRACT: Historical vicariant processes due to glaciations, resulting from the large-scale environmental changes during the Pleistocene (0.012-2.6 million years ago, Mya), have had significant impacts on the geographic distribution of species, especially also in marine systems. The motivation for this study was to provide novel information that would enhance ongoing efforts to understand the patterns of biodiversity on the South African coast and to infer the abiotic processes that played a role in shaping the evolution of taxa confined to this region. The principal objective of this study was to explore the effect of Pleistocene climate changes on South Africa′s marine biodiversity using five intertidal gastropods (comprising four rocky shore species Turbo sarmaticus, Oxystele sinensis, Oxystele tigrina, Oxystele variegata, and one sandy shore species Bullia rhodostoma) as indicator species. Sequence data obtained from partial segments of the mitochondrial cytochrome oxidase c subunit 1 (COI), and the nuclear ribosomal DNA (encompassing part of 5.8S, second Internal Transcribed Spacer and part of 28S, hereinafter called ITS2; or comprising part of the first Internal Transcribed Spacer, 5.8S, second Internal Transcribed Spacer and part of 28S, hereinafter called ITS), were used as genetic markers to construct phylogeographic patterns and to investigate demographic histories of the taxa. Population structure was investigated using haplotype network analyses, pairwise ΦST statistics, analysis of molecular variance (AMOVA), isolation by distance analyses, Bayesian analysis of population structure (BAPS) and coalescent analysis of gene flow. Demographic history was analysed through Fu′s Fs tests, mismatch distributions, and Bayesian skyline plots. Demographic analyses suggest that all five intertidal gastropods studied experienced demographic expansions dating to the late Pleistocene. The sandy shore direct developer B. rhodostoma began expansion after the LGM (c. 15 kya) whereas for the four rocky shore broadcast spawners (T. sarmaticus, O. sinensis, O. tigrina, and O. variegata) the onset of expansion coincided with or preceded the LGM (c. 25, 60, 50, 40 kya, respectively). Consistent with recent range expansions and gene flow patterns, the population genetic structure in all species was characterised by shallow or a lack of population differentiation. Oxystele variegata was an exception as it showed a deep disjunction, of late Pleistocene origin, between individuals in the west coast Namaqua Bioregion and those in the south coast Agulhas Bioregion. These results provide strong evidence of the vital role that Pleistocene climatic changes and current regimes played in shaping the nature and distribution of biodiversity on the South African coast. In addition, gene flow in all species, except O. tigrina, was remarkably asymmetrical with the regions around Cape Infanta and Port Elizabeth acting as source populations. Considering the generally weak population genetic structure and gene flow patterns detected for most gastropod species studied here, it is recommended that T. sarmaticus, O. sinensis, O. tigrina and B. rhodostoma be managed as panmictic populations, and that the region encompassing Cape Infanta, and Port Elizabeth should be prioritised for conservation as it appears to harbour source populations. Oxystele variegata was the only species showing distinct population structure and in this instance, species specific conservation efforts should recognize this divergence by treating the two genetic assemblages as distinct management units.
AFRIKAANSE OPSOMMING: Historiese vikariante prosesse kan toegeskryf word aan glasiasie, en het tot gevolg gehad dat grootskaalse veranderinge in die omgewing plaasgevind het tydens die Pleistoseen (,012 - 2.6 miljoen jaar gelede, Mjg). Dit het 'n beduidende impak gehad op die geografiese verspreiding van spesies, veral ook in die mariene stelsels. Die motivering vir hierdie studie was om nuwe data te voorsien wat sal bydrae tot die voortgesette pogings om die patrone van biodiversiteit langs die Suid-Afrikaanse kus te verstaan. Dit sou ook help om die abiotiese prosesse af te lei wat 'n rol gespeel het in die evolusie van taksa wat in hierdie streek voorkom. Die hoofdoel van hierdie studie was om die effek van die Pleistoseen klimaatsveranderinge op Suid-Afrika se mariene biodiversiteit te bepaal deur gebruik te maak van vyf intergety slak spesies as indikatore (vier wat in rotsagtige gebiede voorkom: Turbo sarmaticus, Oxystele sinensis, Oxystele tigrina, Oxystele variegata en 'n sanderige strand spesies: Bullia rhodostoma). Volgorde data verkry vanaf gedeeltelike segmente van die mitochondriale sitochroom oksidase c subeenheid 1 (COI), en die kern ribosomale DNA (bestaande uit 'n deel van 5.8S, tweede interne getranskribeerde spasieërders en 'n deel van 28S), hierna genoem ITS2 is gebruik as genetiese merkers om filogeografiese patrone te dokumenteer en ook om die demografiese geskiedenis van die spesies te ondersoek. Bevolking struktuur is ondersoek deur gebruik te maak van haplotipe netwerk analise, paarsgewyse ΦST statistiek, analise van molekulêre variansie (AMOVA), isolasie deur afstand analise, Bayesiaanse analise van die bevolking struktuur (BAPS) en analise van gene vloei. Demografiese geskiedenis is ontleed deur Fu se Fs toetse, misparing verdelings, en Bayesiaanse luglyn kurwes. Demografiese ontleding dui daarop dat al vyf die intergety slakke wat ondersoek is demografiese uitbreidings ervaar het wat terugdateer tot die einde van die Pleistoseen. Die sanderige strand direkte ontwikkelaar, B. rhodostoma, het die uitbreiding begin na die LGM (c. 15 Kya), terwyl vir die vier rotsagtige kusbewoners wat eiers oor 'n uitgebreide gebiede versprei (T. sarmaticus, O. sinensis, O. tigrina, en O. variegata) het die aanvang van die bevolkings uitbreiding saamgeval met die laaste galsiasie of dit voorafgegaan (c. 25, 60, 50, 40 Kya, onderskeidelik). In ooreenstemming met die onlangse reeks bevolkings uitbreidings, is die bevolking genetiese struktuur in alle spesies gekenmerk deur weinig differensiasie. Oxystele variegata was 'n uitsondering en het 'n ontwrigting van laat Pleistoceen oorsprong getoon tussen individue langs die weskus Namaqua Biostreek en dié in die suid kus Agulhas biostreek. Hierdie resultate voorsien sterk bewyse van die belangrike rol wat die Pleistoseen klimaatsveranderinge gespeel het in die vorming en verspreiding van biodiversiteit langs die Suid-Afrikaanse kus. Daarbenewens, geen vloei in alle spesies, behalwe O. tigrina, was merkwaardig asimmetries. Kaap Infanta en Port Elizabeth verteenwoordig moontlik die bron bevolkings. Met inagneming van die geringe bevolking genetiese struktuur en geenvloei patrone wat waargeneem is vir die meeste slak spesies wat bestudeer is, word dit aanbeveel dat T. sarmaticus, O. sinensis, O. tigrina en B. rhodostoma bestuur word as 'n panmiktiese bevolking, en dat die streek wat Kaap Infanta en Port Elizabeth insluit geprioritiseer moet word vir bewaring. Oxystele variegata was die enigste spesie wat duidelike bevolking struktuur getoon het en in hierdie geval, moet spesie spesifieke bewaringspogings aangewend word.
Waung, I.-Hui. « Effect of patch-size and habitat-edges on intertidal distributions of microgastropods ». Thesis, The University of Sydney, 2006. https://hdl.handle.net/2123/28116.
Chin, I.-mei, et 錢綺微. « Variation in monodonta labio among different intertidal habitats in Hong Kong ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244087.
in, John Kevin John. « The status and ecology of the intertidal gastropod littorina neglecta bean ». Thesis, University of Leeds, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510013.
Jones, Helen Lucy. « The reproductive and larval ecology of the intertidal nudibranch mollusc Adalaria proxima (Alder & ; Hancock) (Gastropoda : Opisthobranchia) ». Thesis, University of St Andrews, 1996. http://hdl.handle.net/10023/14633.
Cooper, Erin Elaine 1981. « Population biology and reproductive ecology of Chlorostoma (Tegula) funebralis, an intertidal gastropod ». Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10916.
The trochid gastropod Chlorostoma (Tegula) funebralis is found in rocky intertidal habitats along the west coast of North America from Baja California to Vancouver Island. Size-frequency distributions of populations were analyzed along a latitudinal gradient from northern Oregon to Baja California. Populations in California and southern Oregon were dominated by individuals in the juvenile size classes (0.1g-2g). Along the Oregon coast, populations dominated by juveniles were correlated with coastline topography, with protected areas having large numbers of juveniles and exposed areas dominated by larger size classes. The largest size classes (>9g) were rarely present in southern populations. The seasonality of reproduction was investigated in a southern California population and an Oregon population to determine whether continuous reproduction in southern populations increases recruitment success over the year and decreases inter-annual variation in reproductive success. Constant recruitment may cause populations to have a large number of juveniles, the observed pattern in southern populations. Although individuals capable of reproduction were found year-round in both populations, the southern population experienced multiple spawning events over the year, while the northern population experienced only one such event. Constant recruitment may be a strategy to compensate for shorter life spans and smaller sizes of individuals in southern California. To investigate whether variations in predation rates on large adult C. funebralis affect the size structure of populations, the main predators and predation rates for different populations in Oregon were identified. All observed predation events were by the intertidal seastar Pisaster ochraceus . Predation pressure by P. ochraceus varied significantly with site and between sampling dates but did not remove enough C. funebralis from the adult population to have a significant effect on population size structure. To determine the connectivity between populations and the maximum dispersal potential, the mitochondrial gene COI was sequenced from individuals from nine populations ranging from southern California to northern Oregon. Although haplotype diversity was high, no genetic structure was found between populations. Rather than an indication of high dispersal potential and a panmictic species, the lack of isolation by distance may be a result of range expansion following the last glacial maximum.
Committee in charge: Patrick Phillips, Chairperson, Biology; Alan Shanks, Advisor, Biology; Craig Young, Member, Biology; Richard Emlet, Member, Biology; Jon Erlandson, Member, Anthropology; Gregory Retallack, Outside Member, Geological Sciences
McNeill, Myndee. « Predation Avoidance Response Behaviors, Oviposition and Distribution of the Intertidal Gastropod Lirularia succincta ». Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11491.
The small trochid gastropod
Committee in charge: Dr. Craig M. Young, Chair; Dr. Richard B. Emlet, Member; Dr. Alan L. Shanks, Member
Roman-Pena, Rodrigo R. « Does Bioregionalisation Really Reflect Differences in Biodiversity ? A Test of the Marine Bioregional Boundaries of Australia Using Gastropod Assemblages ». Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17224.
English, Tamara Erica. « Differential gene expression in response to freezing and anoxia in the intertidal marine gastropod, Littorina littorea ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ59357.pdf.
English, Tamara Erica Carleton University Dissertation Biology. « Differential gene expression in response to freezing and anoxia in the intertidal marine gastropod, littorina littorea ». Ottawa, 2000.
Melatunan, Sedercor. « Biochemical, metabolic and morphological responses of the intertidal gastropod Littorina littorea to ocean acidification and increase temperature ». Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1009.
Kim, Dohong. « Seasonality of marine algae and grazers of an Antarctic rocky intertidal, with emphasis on the role of the limpet Nacella concinna Strebel (Gastropoda : Patellidae) / ». Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2001. http://www.gbv.de/dms/bs/toc/331661446.pdf.
Literaturverz. S. 94 - 108.
Matumba, Tshifhiwa Given. « Genetics and thermal biology of littorinid snails of the genera Afrolittorina, Echinolittorina and Littoraria (Gastropoda : Littorinidae) from temperate, subtropical and tropical regions ». Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001953.
(9779363), Leonie Barnett. « Cercariae of intertidal nassariid gastropods : Taxonomy, specificity and ecology ». Thesis, 2012. https://figshare.com/articles/thesis/Cercariae_of_intertidal_nassariid_gastropods_Taxonomy_specificity_and_ecology/13436015.
Gemelli, F. « The influence of phenotypic variation in a habitat-forming seaweed on intertidal gastropod communities ». Thesis, 2019. https://eprints.utas.edu.au/31722/1/Gemelli_whole_thesis.pdf.
Puturuhu, Louise [Verfasser]. « Ecological studies on intertidal dog whelks (Gastropoda : Nassariidae) off Northern Minahasa, Sulawesi, Indonesia / vorgelegt von Louise Puturuhu ». 2004. http://d-nb.info/972118381/34.
Silva, Daniela Nobre da. « Limites de distribuição vertical da espécie Patella depressa : padrões e processos ». Master's thesis, 2015. http://hdl.handle.net/10400.1/8190.
Foi realizado um trabalho com o intuito de compreender os padrões associados aos limites de distribuição vertical de lapas da espécie Patella depressa e analisar processos possivelmente associados a estes padrões. Para tal, realizaram-se diversos estudos relacionados com o gradiente de alturas de distribuição e com a ecologia desta espécie. A execução prática deste trabalho decorreu na zona intertidal rochosa da Praia da Oliveirinha (sudoeste de Portugal), onde é abundante a espécie em estudo. Foram efetuadas observações relativas aos limites de distribuição vertical assim como à abundância e aos padrões de movimento em dois níveis verticais de ocorrência da espécie. Também se executaram experiências manipulativas in situ para testar a variação da sobrevivência, do crescimento e da condição fisiológica das lapas em diferentes níveis verticais da zona intertidal. Observou-se um decréscimo dos limites superior e inferior de distribuição da espécie na transição do inverno para o verão. A abundância de lapas foi em geral superior no nível de maré médio comparativamente ao nível superior. Ocorreram mais deslocações no nível superior comparativamente ao nível médio. A sobrevivência e condição ecofisiológica de lapas adultas não variou entre os níveis médio e superior. Verificou-se que os indivíduos junto ao limite superior têm a capacidade de percorrer grandes distâncias e que a diminuição da altura deste limite poderá ser devido a deslocações das lapas para locais de refúgio. A mortalidade de lapas grandes no nível superior pode ser em parte influenciada pela temperatura ambiental, sugerindo a existência de estratégias de regulação de temperatura corporal possivelmente eficazes na manutenção das funções vitais destas lapas. Apesar de ter havido um particular interesse nos potenciais efeitos da temperatura na distribuição vertical da espécie há que ter em conta que outros fatores poderão estar associados às reações observadas (e.g., a humidade e disponibilidade de alimento).
Silva, Mariana Oliveira. « Diet and feeding activity of Olivella minuta (Link, 1807) (Mollusca, Gastropoda, Olividae) along the intertidal - subtidal zone of a dissipative sandy beach in the north coast of São Paulo - Brazil ». Master's thesis, 2013. http://hdl.handle.net/10400.1/7441.
The present study aimed to investigate the diet and feeding activity of a sandy-mud snail, Olivella minuta along the gradient subtidal-intertidal of a dissipative morphodynamic beach: Barequeçaba (southeast coast of Brazil). Locomotor behavior of the species was also evaluated in laboratory conditions. The sampling was carried out in March, April and May, 2013 in the intertidal zone during low and high tide and in the subtidal zone during low tide, to further comparisons if these organisms change their diet according to the variation of the tide. Thirty specimens from 7 mm of length were caught in each situation and stomach contents were analyzed by means of qualitative (richness, diversity, evenness and Simpson) and quantitative indexes (numeric importance (NI) and frequency of occurrence (FO)). Also, the index of stomach repletion was calculated to complement the analysis of the feeding diet of this gastropod. A total of 49 items was registered in the digestive tracts of O. minuta being the most frequents: macroalgaes (48%), microalgaes (15%), artropodes (12%) and foraminiferans (12%). The remaining items had frequency of occurrence lower than 10%. The results of the diet composition of the individuals did not differ along the tidal range of the beach, suggesting that the species does not possess a preference for a single food resource, and the variation on NI e FO in all studied situations can be merely consequences of the dynamics of each food items during the tidal cycle. The results of the stomach repletion suggest that this snail feed in all studied situations, but with higher intensity when emerged during low tide and the results of locomotor behavior tested experimentally, reinforce this idea and still suggests that during the day this organisms have a higher feeding activity rather than at night, since a lesser movement was displayed in these conditions.
As praias arenosas são dos ambientes mais hostis para as comunidades de organismos bentónicos. Estas áreas estão sujeitas a uma enorme intensidade de factores que as moldam morfologicamente ao longo do tempo e que, consequentemente, afectam a distribuição e o comportamento dos organismos que nelas ocorrem. O dinamismo ambiental, resultado da variação de parâmetros abióticos, tais como regime de ventos, ondas, correntes e marés, com consequentes alterações na morfodinâmica da praia, leva os organismos intertidais a desenvolverem adaptações morfológicas, fisiológicas e comportamentais que os permitem suportar o dinamismo do ambiente costeiro. Dito isto, acredita-se que a estrutura de comunidades e populações em praias arenosas é determinada pela morfodinâmica, na qual os factores físicos são predominantes. De acordo com a Hipótese de Severidade Ambiental (HSA) para praias arenosas, as populações de praias reflectivas deverão exibir menor abundância, crescimento, fecundidade e maior esforço reprodutivo e maior taxa de mortalidade quando comparadas a populações de praias dissipativas, uma vez que o impacto de facotes abióticos em praias dissipativas é considerado reduzido, fornecendo aos organismos estabilidade para o seu estabelecimento nestes ambientes. O conhecimento sobre como a interacção de factores bióticos e abióticos pode modular a distribuição de uma espécie, são fundamentais para entender a dinâmica e ecologia da população em um ecossistema de praia. Além disso, a análise da dieta, através da análise do conteúdo do estômago, é uma ferramenta importante para a compreensão da ecologia de uma comunidade, pois além de nos fornecer dados de como as espécies se sobrepõem no uso de recursos alimentares, a interacção dos mecanismos biológicos das espécies em uma comunidade também é observada. Deste modo, a análise do conteúdo estomacal, torna-se uma ferramenta importante para validar a importância da posição trófica de um predador particular no fluxo de energia de um ecossistema, bem como determinar a estratégia de alimentação e da composição de alimentação. Gastrópodes têm uma grande quantidade de hábitos alimentares, podendo ser detritívoros, necrófagos, predatórios, herbívoros, e muitos são omnívoros. Em muitos fundos moles, as suas actividades alimentares são conhecidas por afectar a estrutura da comunidade, especialmente macro e meiofauna. Por outro lado, são esperadas variações dentro das populações desde que os recursos tornam-se fonte de heterogeneidade na distribuição e abundância dos organismos. Assim sendo, neste estudo foram avaliados quais os efeitos dos ciclos de maré bem como diurno/nocturno, na dieta alimentar e actividade locomotória do gastrópode Olivella minuta, numa praia arenosa de baixa energia dissipativa, Praia de Barequeçaba, localizada no Litoral Norte do Estado de São Paulo (Brasil), tendo como base, a HSA. As amostragens foram realizadas tanto em condições de submersão, (na zona intertidal durante maré alta e no subtidal durante maré baixa) com o auxilio de um puçá, bem como quando sujeitos à exposição do ar (no intertidal durante maré baixa), através das marcas sinuosas deixadas por este predador no sedimento. Trinta indivíduos com comprimento de concha igual a 7 mm foram amostrados em cada situação e os seus conteúdos estomacais foram analisados tanto por métodos quantitativos (importância numérica (NI) e frequência de ocorrência (FO)), bem como por meio de análises qualitativas, através da determinação dos índices de diversidade de Shannon, equitabilidade de Pielou, dominância de Simpson e Riqueza de espécies. O índice de repleção estomacal mostrou actividade alimentar desta espécie em todas as situações, com um acentuado pico de actividade quando exposta a períodos de maré baixa. Um total de 49 itens alimentares foi registado no trato digestivo de O. minuta, sendo macroalgas (48%), microalgas (15%), artrópodes (12%) e foraminíferos (12%) os recursos mais consumidos por este gastrópode. Itens alimentares com proporções inferiores a 10% também foram identificados nos estômagos deste gastrópode, tal como itens indeterminados (7%), Porífera (3%), vermes (2%) e moluscos e ciliados ambos com 1% de NI. Bactérias foram também identificadas na dieta alimentar de O. minuta mas não apresentaram importância significativa na composição alimentar deste gastrópode. A maré não mostrou ser factor chave na selectividade alimentar de O. minuta, dado que a composição alimentar destes organismos não se mostrou significativamente variável entre as três situações estudadas (Intertidal durante maré alta, intertidal durante maré baixa e zona subtidal), onde macroalgas e foraminíferos foram os itens alimentares mais abundantes nos estômagos deste organismo em cada situação particular estudada. Os resultados sugerem que a espécie não possui uma preferência por uma única fonte de alimento, e a variação dos valores de NI e FO ao longo das situações pode ser meramente consequências da dinâmica de cada um dos itens alimentares face ao ciclo das marés. Também a fase de maré não se mostrou relevante na actividade locomotora de O. minuta. Por outro lado, o ciclo dia / noite simulado em condições de laboratório mostrou grande significância, onde menores percursos foram observados nos tratamentos sujeitos a períodos de dia. Estudos prévios realizados em gastrópodes sobre o seu comportamento locomotor associado a alimentação, leva-nos a reforçar a hipótese proposta neste estudo, em que o comportamento locomotor de O. minuta é influenciado pela disponibilidade de recursos alimentares no ambiente. Os resultados do nosso experimento laboratorial reforçam a ideia de que estes organismos quando emersos e durante períodos de maré baixa apresentam uma maior actividade alimentar, essencial para a manutenção dos seus recursos vitais, tais como crescimento e reprodução. Também o enterramento em profundidade no sedimento durante o dia, como foi observado em laboratório, pode ser um mecanismo de defesa contra a dessecação e predação. Os resultados deste estudo vão de acordo com a hipótese da severidade ambiental para praias protegidas, morfodinâmicamente dissipativas, como foi modelo deste estudo, praia de Barequeçaba. Neste extremo dissipativo, a influência de factores abióticos (neste caso o ciclo de marés), não mostrou ser o factor mais importante nas funções vitais (alimentação e deslocamento) deste gastrópode. O seu comportamento (diurno e enterramento no sedimento) sugere uma possível adaptação destes organismos de forma a evitar a predação bem como uma forma de maximizar a qualidade ou quantidade de alimento disponível no local quando expostos ao ar e á luz em ambientes arenosos.