In Saanich Inlet, a fjord located in southern Vancouver Island, British Columbia, dense aggregations of euphausiids exhibit diel vertical migration behavior and their capability of generating turbulence has been suggested. Despite decades of research on diel vertical migration of zooplankton, its variability has not been well studied. In addition, the physical oceanographic environment in Saanich Inlet has not been thoroughly quantified, which raises the possibility of previously observed turbulent bursts of O(10^-5 – 10^-4 W kg^-1) having physical (rather than biological) origin. This work characterizes variability of diel vertical migration behavior using a moored 200-kHz echosounder, complemented by plankton sampling. Physical properties such as barotropic, baroclinic and turbulent signals are described, and the relationship between turbulence and internal waves/scattering layer examined. A two-year high-resolution biacoustic time-series provided by the Victoria Experimental Network Under the Sea (VENUS) cabled observatory allowed quantification of the seasonal variability in migration timing of euphausiids. During spring – fall, early dusk ascent and late dawn descent relative to civil twilight occur. During winter, late dusk ascent and early dawn descent occur. Factors regulating the seasonal changes in migration timing are light availability at the daytime depth of the scattering layers, and size-dependent visual predation risk of euphausiids. Instead of the traditional view of diel vertical migration timing correlated solely with civil twilight, euphausiids also adapt their migration timing to accommodate changes in environmental cues as well as their growth. The pre-spawning period (February – April) is an exception to this seasonal pattern, likely due to the higher energy demands for reproduction. Turbulence and internal waves in Saanich Inlet are characterized based on a one-month mooring deployment. Average dissipation rates are nearly an order of magnitude larger than previously reported values and higher dissipation rates of O(10^-7 – 10^-6 W kg^-1) are occasionally observed. A weak correlation is observed between turbulent dissipation rates and baroclinic velocity/shear. To examine the possibility of biological generation of turbulence, an echosounder at the VENUS cabled observatory is used to simultaneously measure the intensity of the euphausiid scattering layer and its vertical position. Turbulent bursts of the sort previously reported are not observed, and no relation between diel vertical migration and turbulent dissipation rates is found. Physical forcing at the main channel remains as a possible cause of the turbulent bursts. / Graduate / 0416 / 0415

This thesis is focused on the fish spatial distribution and its changes mainly during the diel cycle. In the first part, I described the fish spatial distribution in the tropical lake ecosystem of Lake Turkana. The second part deals with the fish spatial distribution in a temperate reservoir on the different spatial scales from in/offshore habitats over the fine-scale to the level of individuals. The linkage of fish distribution patterns with selected environmental variables was also evaluated.

Made available in DSpace on 2014-12-17T15:14:54Z (GMT). No. of bitstreams: 1 ManoelSV_DISSERT.pdf: 1448096 bytes, checksum: 866dbf446f607cd2166e9d64dab483ef (MD5) Previous issue date: 1995-07-14 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Neste trabalho investigamos o espectro de polariton de plasmons (modos de volume e superf?cie) assim como o espectro ?ptico (reflect?ncia e transmit?ncia) em uma estrutura quasi-peri?dica, que obedece uma sequ?ncia de Cantor. O sistema quasi-peri?dico de multi-camadas de Cantor ? criado quando duas camadas diferentes, de materiais distintos A e B, s?o dispostos de acordo com a seguinte rela??o de recorr?ncia: C1 = ABA;C2= C1B2C1;...;Cn= Cn-1BnCn-1 Onde Bn ? o mesmo meio da camada B mas com diferente espessura. O aparatus experimental mais simples para medir estes espectros, consiste em posicionar a super-rede tipo Cantor na forma de um filme embebido no v?cuo. Usando o m?todo da matriz-transfer?ncia, para simplificar a ?lgebra, ? poss?vel determinar-se a rela??o de dispers?o dos polaritons (modos de superf?cie e volume), assim como as express?es te?ricas de reflect?ncia e transmit?ncia. H? uma s?rie de resultados interessantes nestes espectros, os quais discutiremos em detalhes neste trabalho

Despite the potential benefits of modifying behaviour according to changing ecological conditions, many populations comprise individuals that differ consistently in behaviour across situations, contexts and points in time (i.e. individuals show personality). If personalities are adaptive, the balance between consistency and flexibility of behavioural traits should reflect the ability of individuals to detect and respond to changing conditions in an appropriate and timely manner and, thus, depend upon the pace and predictability of changing conditions. We investigated the balance between individual consistency and flexibility in the subsocial spider Anelosimus studiosus by assaying boldness across the diel cycle and correlating these data with patterns of prey and threat abundance in the natural habitat. We found significant diel flexibility in boldness correlating with drastic and predictable changes in prey availability. Moreover, the strength of within-individual flexibility in boldness was comparable to the strength of rank-order consistency among individuals. We also found evidence that mean boldness level and among-individual variation in boldness are correlated with reproductive status. These data emphasize the interplay between behavioural consistency and flexibility and suggest that temporal characteristics of ecological conditions may be vital in assessing the strength, stability and adaptive value of animal personalities.

Small- and fine-scale biological and oceanographic processes may have a measurable electromagnetic signature. These types of processes inherently involve turbulence and three-dimensional dynamics. Traditional models of the electromagnetic signature of oceanographic processes are of an analytical nature, do not account for three-dimensional boundary layer dynamics or turbulence, self-inductance, and may not describe the variety of the environmental conditions occurring in the ocean. In order to address this problem, I have implemented magnetohydrodynamic (MHD) computational fluid dynamics (CFD) tools, which has allowed for the evaluation of the electromagnetic signature of a number of small- and fine-scale biological and oceanographic processes in the ocean. The suite of computational tools has included the commercial models ANSYS Fluent, coupled with the MHD module, and ANSYS Maxwell. These computational tools have been well-established in fluid and electromagnetic engineering. The application of CFD and MHD tools in oceanography is new but is undergoing rapid development. In this work, substantial effort was made toward the CFD, MHD, and magnetostatic model verification and identification of model limitations. Verifications of the CFD, MHD, and magnetostatic models were conducted by successfully comparing their results with the field measurements and laboratory experiments. Comparison with the traditional (analytical) models for surface and internal waves, has revealed their limitations related to bottom boundary layer physics, effect of self-inductance, and, to a lesser extent, the magnetic permeability difference at the air-sea interface. These limitations become important for shallow water internal waves. As a result, the traditional models significantly overestimate the magnetic signature of internal waves observed at the Electromagnetic Observatory. After model verification with the field and laboratory data, the computational models were then applied to evaluate the magnetic signature of diel vertical migration (DVM) of zooplankton, surface waves, internal wave solitons, freshwater lens spreading, and Langmuir circulation. The quantitative estimates have been made for typical environmental conditions. In other environmental conditions, their magnetic signature may be somewhat different. The suite of computational models developed in this dissertation work allows for the estimation of the magnetic signature of fine- and small-scale oceanographic processes in virtually any environmental conditions (e.g., in oil emulsions). I anticipate the result of this study will have Naval, environmental, and oil exploration applications.

Quantifying individual differences in behavior and the extent that behavior is influenced by circadian control is of paramount importance in behavioral ecology. In addition, the proximate mechanisms underlying behavior are also critical in order to obtain a more complete picture of how behavior evolves. Biogenic amines (BAs) are simple nitrogenous compounds derived from amino acids and have been consistently and extensively linked to behavior. For this study, we analyzed temporal patterns of BAs in relation to the antipredator (boldness) and aggressive behavior in female Agelenopsis pennsylvanica, a funnel-web spider. Using HPLC-ED, we compared behavioral responses to temporal patterns of octopamine and serotonin, two BAs known to influence behavior in invertebrates. Our results suggest that, while there was a clear diel cycling pattern of both aggression and boldness, BAs do not follow this same pattern, suggesting that oscillations in absolute levels of BAs are not the underpinnings of behavioral oscillations.

Shrinking alpine glaciers alter the geochemistry of sensitive mountain streams by exposing reactive freshly-weathered bedrock and releasing decades of atmospherically-deposited trace elements from glacier ice. Changes in the timing and quantity of glacial melt also affect discharge and temperature of alpine streams. To investigate the effects of glacier ice melt on the geochemistry and hydrology of proglacial streams in the arid Intermountain West, we sampled supraglacial meltwaters and proglacial streams in the Dinwoody Creek watershed in the Wind River Range, Wyoming during late summer 2015, when the contributions of glacier meltwater were highest. Supraglacial meltwater was enriched in 8 trace elements (Cd, Co, Cu, MeHg, Mn, Pb, THg, Zn) relative to proglacial meltwaters. Concentrations of major ions (Mg2+, K+, Na+, Ca2+, SO42-) and the remaining 30+ analyzed trace elements were enriched in proglacial streams relative to supraglacial meltwater. To evaluate the diurnal effects of glacial meltwater on the chemistry and hydrology of proglacial streams, we collected hourly water samples of Dinwoody Creek and deployed loggers to monitor water depth, temperature, and specific conductance (SPC) at 15-min intervals over a 1-week period. The influx of glacial meltwater between 10:00 and 20:00 diluted solute concentrations and affected the relative enrichment/depletion of highly soluble elements (major ions, alkaline earth elements), less than REEs. Stable isotopes of H and O (δD, δ18O) in Dinwoody Creek were more depleted during peak runoff (10:00 – 20:00) than base flow, reflecting contributions from isotopically depleted glacial meltwaters. Looping hysteresis patterns were observed between water depth versus DO, pH, temperature and SPC in glaciated streams. Hysteresis patterns were affected by changes in weather and varied depending on the type of stream (glaciated versus non-glaciated) and the distance to glacier toe. Combination of multiple hydrologic tracers (solute concentrations, high frequency logger data, stable isotopes) shows strong potential to improve estimates of glacial meltwater contributions to Dinwoody Creek. Our results suggest that elevated concentrations of heavy metals in glacier ice melt across the Intermountain West may negatively impact sensitive alpine streams.

A distribuição da biomassa do plâncton é a chave para o entendimento de vários processos inclusive a compreensão da migração vertical diurna. Entender a fototaxia positiva, como responsável por esta distribuição, com enfoque na qualidade espectral da luz é uma campo vasto a ser explorado. Investigamos a percepção espectral luminosa do mesozooplâncton marinho através da quantificação de capturas em uma nova arte de coleta com armadilha de luz. Estas armadilhas foram testadas com tratamentos luminosos na cor vermelha, verde, azul e branco. Elas foram fundeadas na enseada do Flamengo e de Ubatuba (Ubatuba-SP) no fim do verão e outono de 2015 durante a lua cheia e lua nova em três noites consecutivas. Foram avaliadas as associações de exposição (fase lunar, local de coleta e esquema de randomização dos tratamentos) baseada nos dados de captura através de gráficos NMDS, teste PERMANOVA e tabelas de contingência de Chi-quadrado. Os táxons mais abundantes nas capturas foram dois gêneros de copépodes Calanoida (Acartia sp e Temora sp) seguidos pela família Podonidae e Brachyura. Demonstramos que os organismos capturados do zooplâncton marinho expressaram seleção espectral induzidos pela fototaxia positiva. O tratamento luminoso verde exerceu maior atração nos organismos em detrimento ao tratamento luminoso vermelho. A influência das fases lunares ou dos esquemas de randomização dos tratamentos luminosos dependem da sensibilidade espectral de cada táxon. Porém local não implicou em diferenças entre as coletas. Estas particularidades da fototaxia positiva seletiva podem explicar a variação vertical da biomassa do zooplâncton marinho na coluna d\'água inclusive no entendimento da MVD. / The distribution of plankton biomass is the key for understanding many processes including diel vertical migration (DVM). Understand the positive phototaxis, as responsible for this distribution, with a focus on spectral quality of light is a vast field to be explored. We investigate the spectral light perception of the marine mesozooplankton through quantification of catches in a new art with light trap. These traps were tested with light treatments in red, green, blue and white. They were anchored in the Flamengo and Ubatuba bay (Ubatuba-SP) in late summer and autumn of 2015 during the full moon and new moon on three consecutive nights. Exposure associations were evaluated (lunar phase, site and treatment randomization scheme) based on the data capture through NMDS graphics, PERMANOVA test and Chi-square contingency tables. Most abundant taxa catched were two kinds of copepods Calanoida (Acartia sp and Temora sp) followed by Podonidae and Brachyura. We have demonstrated that the captured marine zooplankton showed spectral selection induced by positive phototaxis. The green light treatment exerted biggest attraction in organisms over the red light treatment. The influence of lunar phases or randomization schemes of bright treatments depend on the spectral sensitivity of each taxon. But location did not result in differences between collections. These specifics of selective phototaxis may explain the vertical variation of marine zooplankton biomass in water column including the understanding of DVM.

A distribuição da biomassa do plâncton é a chave para o entendimento de vários processos inclusive a compreensão da migração vertical diurna. Entender a fototaxia positiva, como responsável por esta distribuição, com enfoque na qualidade espectral da luz é uma campo vasto a ser explorado. Investigamos a percepção espectral luminosa do mesozooplâncton marinho através da quantificação de capturas em uma nova arte de coleta com armadilha de luz. Estas armadilhas foram testadas com tratamentos luminosos na cor vermelha, verde, azul e branco. Elas foram fundeadas na enseada do Flamengo e de Ubatuba (Ubatuba-SP) no fim do verão e outono de 2015 durante a lua cheia e lua nova em três noites consecutivas. Foram avaliadas as associações de exposição (fase lunar, local de coleta e esquema de randomização dos tratamentos) baseada nos dados de captura através de gráficos NMDS, teste PERMANOVA e tabelas de contingência de Chi-quadrado. Os táxons mais abundantes nas capturas foram dois gêneros de copépodes Calanoida (Acartia sp e Temora sp) seguidos pela família Podonidae e Brachyura. Demonstramos que os organismos capturados do zooplâncton marinho expressaram seleção espectral induzidos pela fototaxia positiva. O tratamento luminoso verde exerceu maior atração nos organismos em detrimento ao tratamento luminoso vermelho. A influência das fases lunares ou dos esquemas de randomização dos tratamentos luminosos dependem da sensibilidade espectral de cada táxon. Porém local não implicou em diferenças entre as coletas. Estas particularidades da fototaxia positiva seletiva podem explicar a variação vertical da biomassa do zooplâncton marinho na coluna d\'água inclusive no entendimento da MVD. / The distribution of plankton biomass is the key for understanding many processes including diel vertical migration (DVM). Understand the positive phototaxis, as responsible for this distribution, with a focus on spectral quality of light is a vast field to be explored. We investigate the spectral light perception of the marine mesozooplankton through quantification of catches in a new art with light trap. These traps were tested with light treatments in red, green, blue and white. They were anchored in the Flamengo and Ubatuba bay (Ubatuba-SP) in late summer and autumn of 2015 during the full moon and new moon on three consecutive nights. Exposure associations were evaluated (lunar phase, site and treatment randomization scheme) based on the data capture through NMDS graphics, PERMANOVA test and Chi-square contingency tables. Most abundant taxa catched were two kinds of copepods Calanoida (Acartia sp and Temora sp) followed by Podonidae and Brachyura. We have demonstrated that the captured marine zooplankton showed spectral selection induced by positive phototaxis. The green light treatment exerted biggest attraction in organisms over the red light treatment. The influence of lunar phases or randomization schemes of bright treatments depend on the spectral sensitivity of each taxon. But location did not result in differences between collections. These specifics of selective phototaxis may explain the vertical variation of marine zooplankton biomass in water column including the understanding of DVM.

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2018-10-02T13:28:26Z No. of bitstreams: 1 2013 - Leonardo Mitrano Neves.pdf: 2710150 bytes, checksum: e76a622435676fcc3b2281358ce93865 (MD5) / Made available in DSpace on 2018-10-02T13:28:27Z (GMT). No. of bitstreams: 1 2013 - Leonardo Mitrano Neves.pdf: 2710150 bytes, checksum: e76a622435676fcc3b2281358ce93865 (MD5) Previous issue date: 2013-04-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPQ / Rocky reef fish assemblages change along extreme environmental conditions gradients; both spatial (across gradients of distance from the river mouths) and short term temporal (diel cycle of light intensity). Moreover, changes in connection to habitat heterogeneity can occur, even for tropical rocky reefs with a more homogenous habitat structure. Knowledge of the way that fish assemblages respond to these changes is fundamental to identify the variables that determine spatial patterns and to predict how impacts in great or low intensity can affect diversity. The main aims of this study were: (1) to determine influence of physical (distance from river mouth and wave exposure), biological (benthic cover) and structural (substratum height and number of shelters) variables in structuring fish assemblages, species richness, abundance, biomass and trophic groups diversity; (2) to assess diel changes in composition and structure of fish assemblages; (3) to relate changes in species composition (beta diversity) with habitat heterogeneity for a small scale (among transects in a given area), and the relationship between beta and alfa diversity (species richness, richness estimation and Shannon diversity). Subaquatic visual census were carried out in Ilha Grande coastal reefs, encompassing (1) islands distributed along a spatial gradient of distance from river mouth; (2) six different time periods, i.e., sunrise (06:00h), morning (08:30h), afternoon (14:00h), sunset (17:30h), early night (19:30h) and night (21:00h) in two shallow coastal reef; and (3) in transect in four areas to assess beta biodiversity. Habitat structure (benthic cover and topographic complexity) assessment was performed (objectives 1 and 3). The distance from river mouth explained from 12.4% to 38.2% of the estimated components of variation (ECV) of PERMANOVA for all analyzed response variables, playing a major role in determining spatial patterns of fish assemblages. Differences between reefs close and far from river mouth reached a maximum of 4.5x for richness, 11x for biomass and 10x for abundance. The substrate height was positively related to fish abundance, species richness and trophic groups diversity (ECV between 7.3 % and 17.4%), whereas the number of shelters was positively associated to small-sized species abundance such as Stegastes fuscus, Emblemariopsis signifer and Scartella cristata. Benthic cover had significant influence to determine spatial pattern in fish assemblage structure and diversity of trophic groups (ECV = 8% and 10%, respectively), but not in species richness, biomass and fish abundance. Wave exposure had significant influence on fish assemblage structure only (ECV = 10%). The fish assemblage changes drastically along diel cycle. Species richness and fish abundance were at the highest during the period of the day with intermediary values at twilight periods, and at the lowest during the night. The highest difference in assemblage structure was found between the periods of the day and the night. The families Sciaenidae, mainly represented by Pareques acuminatus, and Pempheridae represented by Pempheris schomburgkii were more abundant during the night, whereas Haemulidae Haemulon steindachneri, Pomacentridae Abudefduf saxatilis, Chaetodondidae Chaetodon striatus, and Labrisomidae Malacoctenus delalandii were more abundant during the day. The twilight periods were similar in assemblage structure, and had as characteristics species of the day (H. steindachneri, M. acutirostris) and the night (P. acuminatus), reflecting a transitional period. Significant positive relationship was detected between habitat heterogeneity and beta diversity. The area with more ix homogeneous habitat and low variation in fish assemblage was dominated by little threedimensionally complex organisms (zoanthids), while areas that had fleshy algae, turf and zoanthids with a more even percentage cover had higher heterogeneity and beta diversity. For all measures of examined alfa diversity, the area with more heterogeneous habitat and with the highest beta diversity had the highest alfa diversity compared with areas with more homogenous habitat e lowest beta diversity. However, positive relationship between alfa and beta diversity was significant for species richness, but not for estimate of richness and Shannon index. This study demonstrated that changes in assemblages in spatial and short term (from transects to 10 km, and diel cycle) scales may be attributed to changes in local habitat structure, both composition of dominant benthic organisms and habitat heterogeneity and can be associated to behavioral characteristics mainly related to strategies of food acquirement and protection against predation / As assembleias de peixes recifais variam atrav?s de gradientes de mudan?as extremas nas condi??es ambientais, tanto espaciais (ao longo de gradientes de dist?ncia da foz de rios) quanto em escalas temporais curtas (ao longo do ciclo di?rio de intensidade luminosa). Al?m disto, varia??es em resposta ao n?vel de heterogeneidade do habitat tamb?m podem ocorrer, mesmo entre recifes rochosos situados fora de intensos gradientes ambientais. Entender como as assembleias de peixes respondem a tais mudan?as ? fundamental para identificar vari?veis determinantes dos padr?es espaciais e predizer como impactos de grande e pequena intensidade podem afetar os padr?es de diversidade. Os principais objetivos deste estudo foram: (1) determinar a influ?ncia de vari?veis f?sicas (dist?ncia da foz do rio e exposi??o a ondas), biol?gicas (cobertura b?ntica) e estruturais (altura do substrato e n?mero de ref?gios) na estrutura??o das assembleias de peixes, riqueza de esp?cies, abund?ncia, biomassa e diversidade dos grupos tr?ficos; (2) avaliar as mudan?as ao longo do ciclo di?rio na composi??o e estrutura da assembleia de peixes recifais; (3) relacionar a varia??o na composi??o de esp?cies (beta diversidade) com a heterogeneidade do habitat, para uma pequena escala (entre transectos de uma mesma ?rea), e as rela??es entre a beta diversidade e medidas de diversidade alfa (riqueza de esp?cies, estimativa da riqueza e diversidade de Shannon). Para tal, censos visuais subaqu?ticos foram realizados (1) em cost?es rochosos da ba?a da Ilha Grande, em ilhas localizadas atrav?s de um gradiente de dist?ncia da foz de rios; (2) em seis diferentes hor?rios, compreendendo o amanhecer (06:00h), manh? (08:30h), tarde (14:00h), anoitecer (17:30h) e in?cio da noite (19:30h) e noite (21:00h) em dois recifes rochosos rasos; e (3) em transectos de quatro ?reas para avaliar diversidade beta. Avalia??es da estrutura do habitat (cobertura b?ntica e complexidade topogr?fica) foram realizadas (para objetivos 1 e 3). A dist?ncia da foz do rio explicou entre 12,4% a 38,2% da estimativa dos componentes de varia??o (ECV) da PERMANOVA de todas as vari?veis respostas analisadas, desempenhando um papel principal nos padr?es espaciais da assembleia de peixes. Diferen?as entre recifes pr?ximos e distantes da foz atingiram um m?ximo de at? 4,5x para a riqueza, 11x para a biomassa e 10x para a abund?ncia. A altura do substrato foi positivamente relacionada com a abund?ncia de peixes, riqueza de esp?cies e diversidade dos grupos tr?ficos (ECV entre 7,3% a 17,4%), enquanto o n?mero de ref?gios foi associado positivamente com a abund?ncia de esp?cies de pequeno porte, como Stegastes fuscus, Emblemariopsis signifer e Scartella cristata. O efeito da cobertura b?ntica foi significativo em determinar os padr?es espaciais da estrutura da assembleia de peixes e da diversidade dos grupos tr?ficos (ECV = 8% e 10%, respectivamente), por?m n?o foram observadas influ?ncias significativas da cobertura b?ntica na riqueza de esp?cies, biomassa e abund?ncia. A exposi??o ?s ondas teve um efeito significativo apenas para a estrutura da assembleia de peixes (ECV = 10%). As assembleias de peixes variaram drasticamente ao longo do ciclo di?rio. A riqueza de esp?cies e a abund?ncia de peixes foram maiores durante os hor?rios do dia, com valores intermedi?rios nos hor?rios crepusculares e atingiram os menores valores durante a noite. Maiores diferen?as na estrutura da assembleia foram observadas entre o per?odo diurno e noturno. Durante a noite, as fam?lias Sciaenidae, representado por Pareques acuminatus, e Pempheridae vii representado por Pempheris schomburgkii foram mais abundantes, enquanto Haemulidae Haemulon steindachneri, Pomacentridae Abudefduf saxatilis, Chaetodondidae Chaetodon striatus, e Labrisomidae Malacoctenus delalandii foram abundantes durante o dia. Os hor?rios crepusculares foram semelhantes entre si, sendo caracterizados por esp?cies tanto dos hor?rios do dia (H. steindachneri, M. acutirostris) quanto da noite (P. acuminatus), refletindo esse per?odo de transi??o. Rela??es positivas significativas foram detectadas entre a heterogeneidade do habitat e a beta diversidade. A ?rea com habitat mais homog?neo e de menor varia??o na composi??o da assembleia foi dominada por organismos tridimensionalmente pouco complexos (zoant?deos), enquanto a ?reas que apresentaram algas frondosas, matriz de algas epil?ticas (MAE) e zoant?deos com uma percentagem de cobertura mais equitativa, tiveram a maior heterogeneidade do habitat e beta diversidade. Para todas as medidas de diversidade alfa utilizadas, a ?rea com habitat mais heterog?neo e com maior beta diversidade, apresentou uma diversidade alfa maior do que a ?rea com habitat mais homog?neo e de menor beta diversidade. Entretanto, as rela??es positivas entre a beta diversidade e a diversidade alfa foram significativas apenas para a riqueza de esp?cies, e n?o para a estimativa da riqueza e a diversidade de Shannon. Este estudo demonstrou que varia??es nas assembleias em escalas espaciais e temporais curtas (desde entre transectos at? 10 km, e ao longo do ciclo di?rio) podem ser atribu?das a mudan?as na estrutura dos habitats locais, tanto na composi??o dos organismos bent?nicos dominantes quanto na heterogeneidade do habitat e podem ser associadas a caracter?sticas comportamentais principalmente associadas a estrat?gias de obten??o de alimento e prote??o contra preda??o