One of the main objectives of evolutionary biology is to understand the reasons behind the maintenance of individual differences in a multitude of traits that influence fitness such as locomotor performance and behaviour. Because locomotor performance sets an "envelope" within which behaviour is expressed, it is likely that a multitude of co-adaptations exists between these two suites of traits. In recent years, a growing number of studies have identified associations of different strength and directions between performance and behaviour. Two main hypotheses have received support, on one hand locomotor performance could be "co-specialized" with behaviour in a manner that behaviour reduces predation risk, such that shyer, less active, less explorative animals should be the best sprinters and the most endurant. On the other hand, locomotor performance could "compensate" for behaviours that lead to increased predation risk, in a way that bolder, more active and explorative animals should be able to sprint faster and for longer. In my thesis I provide a review of published studies that successfully identify associations between locomotor performance and behaviour and classify each association as supporting the co-specialization or compensation hypothesis respectively. I further elaborate on the importance of using repeated measurements and (co)variance partitioning when studying correlations between labile traits. I also discuss one of the main challenges that comes with studying locomotor performance, namely the importance of the variation in motivation, both methodologically, by using different performance tests, but also physiologically, by using blood corticosterone measurements as indicators of such variation.

The relative importance of deterministic processes versus chance is one of the most important questions in science. We analyze the success of variance partitioning methods used to explain variation in β-diversity and partition it into environmental, spatial, and spatially structured environmental components. We test the hypotheses that 1) the number of environmental descriptors in a study would be positively correlated with the percentage of β-diversity explained by the environment, and that the environment would explain more variation in β-diversity than spatial or shared factors in VP analyses, 2) increasing the complexity of environmental descriptors would help account for more of the total variation in β-diversity, and 3) studies based on functional groups would account for more of the total variation in β-diversity than studies based on taxonomic data. Results show that the amount of unexplained β-diversity is on average 65.6%. There was no evidence showing that the number of environmental descriptors, increased complexity of environmental descriptors, or utilizing functional diversity allowed researchers to account for more variation in β-diversity. We review the characteristics of studies that account for a large percentage of variation in β-diversity as well as explanations for studies that accounted for little variation in β-diversity.

A fundamental focus in ecology is understanding interactions between environmental heterogeneity and ecological community structure, both of which are currently undergoing unprecedented alterations due to global change. In particular, many freshwater phytoplankton communities are experiencing multiple global change stressors, altering phytoplankton community composition, biomass, and spatial distribution. I used multiple approaches to characterize the interactions between spatial distribution and community structure of phytoplankton and quantify uncertainty in predictions of phytoplankton temporal dynamics. First, I analyzed data from 51 lakes to determine the environmental drivers of phytoplankton vertical distributions across the water column for different phytoplankton groups. I show that the relative importance of environmental drivers varies according to the functional traits of each phytoplankton group. Second, I conducted whole-ecosystem experiments in a reservoir to assess phytoplankton responses to surface water mixing events, which may become more prevalent as storms increase under global change. My results demonstrate that aggregated phytoplankton biomass has inconsistent responses to mixing over the short term, but responses of morphology-based functional groups of phytoplankton to mixing are more predictable. Third, I conducted a long-term whole-ecosystem experiment to assess phytoplankton responses to changes in water column thermal gradients which are predicted to increasingly occur under global change. I found that phytoplankton depth distributions responded similarly to thermal gradient disturbance over multiple years, and changes in depth distributions were related to changes in community composition. Fourth, I produced weekly hindcasts of phytoplankton density in a lake for two years to determine the dominant sources of uncertainty in phytoplankton density predictions. I found that better estimation of current phytoplankton density improved representation of error in phytoplankton models, and incorporation of additional life history stages to model structure may improve phytoplankton predictions. Overall, my dissertation chapters demonstrate that the vertical distribution and community structure of phytoplankton are linked, and that the interaction of phytoplankton community structure with environmental heterogeneity is more predictable over longer-term (e.g., months to years) than shorter-term (e.g., days to weeks) scales. My research emphasizes that consideration of phytoplankton community dynamics and the uncertainty associated with phytoplankton predictions are needed for freshwater management under global change. / Doctor of Philosophy / Freshwater phytoplankton, which are microscopic primary producers, are experiencing many environmental changes in lakes and reservoirs due to global change. This includes changes in water temperature, which affects phytoplankton growth and the types of phytoplankton that are present in the water. As a result, phytoplankton communities are changing in ways that affect water quality. For example, phytoplankton may grow rapidly and form blooms which cause unsightly surface scums, clog filters at water treatment plants, or release toxins. My dissertation research uses ecosystem experiments, computer modeling, and large datasets from many lakes to study how the interactions between phytoplankton and their environment might change due to human activities. I found that it is difficult to predict how phytoplankton will respond to changes in water temperature over the short term (days to weeks), but that longer-term (months to years) responses to water temperature changes are more predictable. I also found that the types of phytoplankton present in the water vary across depth in response to light, temperature, and predation. Since the species of phytoplankton that are present determine a waterbody's water quality, my results indicate that water quality can vary substantially among different depths. Finally, I found that the greatest sources of uncertainty in predicting phytoplankton are due to the challenges in accurately measuring the amount of phytoplankton that are present in a lake and representing complex phytoplankton processes in computer models. My research demonstrates that it is important to think about multiple types of phytoplankton and how they interact with the environment, not just the total amount of phytoplankton present, when predicting how water quality will change due to global change. In addition, it is important to consider the uncertainty associated with predictions of phytoplankton when we make decisions about how to manage water quality.

Dados e análises de gradientes altitudinais em diversidade têm sido fundamentais para o desenvolvimento e avaliação de uma série de teorias gerais da biodiversidade. Esta proposta pretende contribuir para uma melhor compreensão dos padrões de diversidade das samambaias e licófitas ao longo de um gradiente de altitude no Sul do Brasil, abrangendo desde as formações florestais da planície, composta pela floresta de Terras Baixas, Submontana, como por formações florestais de altitude superiores, florestas Montana e Altomontana, e considerando a influência de fatores climáticos e de solo sobre as comunidades de plantas deste grupo. Assim, os objetivos deste estudo são: 1) verificar se a composição e riqueza de espécies varia ao longo do gradiente altitudinal; 2) se caso afirmativo, descrever em qual altitude podemos encontrar a maior diversidade; 3) analisar se existem diferenças ao longo do gradiente nos padrões de distribuição entre comunidade epifítica, terrícola e rupícola; 4) estabelecer quais são os fatores ambientais e de espaço que governam a distribuição das espécies de samambaias e licófitas, sua riqueza e sua cobertura na floresta brasileira ao sul do Atlântico; 5) investigar se espécies epifíticas e terrestres respondem igualmente aos condutores ambientais. Os resultados de um estudo detalhado, bem como de análises morfológicas, ecológicas, pedológicas e geográficas são: 1) a composição e riqueza de espécies variou significativamente ao longo do gradiente altitudinal; 2) riqueza e diversidade foram maiores nas formações superiores (Montana e Altomontana); 3) comunidades ecológicas distintas (epifítica, terrícola e rupícola) diferiram quanto ao padrão de distribuição observado ao longo do gradiente; 4) os fatores ambientais (tais como: insolação solar, precipitação, velocidade do vento, umidade relativa do ar relacionados ao clima e, concentração de matéria orgânica, alumínio, pH e profundidade, relacionados ao solo) apresentam maior importância na variação da distribuição de espécies ao longo do gradiente; 5) a variação da distribuição de espécies epífitas demostrou ser mais relacionada aos condutores ambientais relacionados aos fatores climáticos enquanto que as espécies terrestres, aos fatores edáficos. Processos de nicho (teoria de nicho) são os responsáveis por modular a distribuição e a abundância das espécies de samambaias e licófitas ao longo do gradiente altitudinal da Floresta Atlântica Sul Brasileira. Adicionalmente, é descrito novo registro de Stigmatopteris no Estado do Rio Grande do Sul, Brasil. / Data and analyses of elevational gradients in diversity have been central to the development and evaluation of a range of biodiversity general theories. This proposal seeks to contribute to a better understanding of the ferns and lycophytes diversity patterns along an elevation gradient in Southern Brazil, spanning from Lowland and Submontane to Montane and Upper Montane forest formations, and considering the influence of climatic factors and soil on communities of this group plants. The objectives of this study are: 1) to verify the composition and species richness varies along the altitudinal gradient; 2) if so, describe at what altitude we find the greatest diversity; 3) to analyze if there are differences along the gradient in the distribution patterns of epiphytic community, terrestrial and rupicolous; 4) establish what are the environmental and spatial factors that govern ferns and wealth lycophyte species and its coverage in the Brazilian forest at the South of the Atlantic; 5) investigate if epiphytic and terrestrial species also respond to environmental drivers. The results of a detailed study, as well as morphological, ecological, soil and geographical study are: 1) the composition and species richness varied significantly along the altitudinal gradient; 2) richness and diversity were higher in the Montane and Upper Montane formations; 3) distinct ecological communities (epiphytic, terrestrial and rupicolous) to differ on the distribution pattern observed along the gradient; 4) the environmental factors (such as solar insolation, precipitation, wind speed, relative humidity related to the climate, and concentration of organic matter, aluminum, pH and depth, related to soil) have greater importance in the variation species distribution along the gradient; 5) the variation of the distribution of epiphytes demonstrated to be more related to environmental drivers that are related to climatic factors, while terrestrial species are related to the soil factors. Niche processes (niche theory) are responsible for modulate distribution patterns and species abundance along elevational gradient in the Southern Brazilian Atlantic Forest. In addition, we present the new registration Stigmatopteris in the State of Rio Grande do Sul, Brazil.

To understand the processes affecting the abundance of wild populations is a fundamental goal of ecology and a prerequisite for the management of living resources. Variable abundance, however, makes the investigation of ecological processes challenging. Recruitment, the process whereby new individuals enter a given stage of a ?sh population, is a highly variable entity. I have confronted this issue by developing methodologies speci?cally designed to account for, and ecologically interpret, patterns of variability in recruitment. To provide the necessary context, Chapter 2 begins with a review of the history of recruitment science. I focus on the major achievements as well as present limitations, particularly regarding environmental drivers. Approaches that include explicit environmental information are contrasted with time-varying parameter techniques. In Chapter 3, I ask what patterns of variability in pre-recruit survival can tell us about the strength of density-dependent mortality. I provide methods to investigate the presence of density-dependent mortality where this has previously been hindered by highly variable data. Stochastic density-independent variability is found to be attenuated via density dependence. Sources of recruitment variability are further partitioned in Chapter 4. Using time-varying parameter techniques, signi?cant temporal variation in the annual reproductive rate is found to have occurred in many Atlantic cod populations. Multivariate state space models suggest that populations in close proximity typically have a shared response to environmental change whereas marked differences occur across latitude. Hypotheses that could result in consistent changes in productivity of cod populations are tested in Chapter 5. I focus on a meta-analytical investigation of potential interactions between Atlantic cod and small pelagic species, testing aspects of the cultivation-depensation hypothesis. The ?ndings suggest that predation or competition by herring and mackerel on egg and larval cod could delay recovery of depleted cod populations. Chapter 6 concludes with a critical re?ection on: the suitability of the theories employed, the underlying assumptions of the empirical approaches, and the quality of the data used in my thesis. Application of ecological insights to ?sheries management is critically evaluated. I then propose future work on recruitment processes based on methods presented herein.

Dados e análises de gradientes altitudinais em diversidade têm sido fundamentais para o desenvolvimento e avaliação de uma série de teorias gerais da biodiversidade. Esta proposta pretende contribuir para uma melhor compreensão dos padrões de diversidade das samambaias e licófitas ao longo de um gradiente de altitude no Sul do Brasil, abrangendo desde as formações florestais da planície, composta pela floresta de Terras Baixas, Submontana, como por formações florestais de altitude superiores, florestas Montana e Altomontana, e considerando a influência de fatores climáticos e de solo sobre as comunidades de plantas deste grupo. Assim, os objetivos deste estudo são: 1) verificar se a composição e riqueza de espécies varia ao longo do gradiente altitudinal; 2) se caso afirmativo, descrever em qual altitude podemos encontrar a maior diversidade; 3) analisar se existem diferenças ao longo do gradiente nos padrões de distribuição entre comunidade epifítica, terrícola e rupícola; 4) estabelecer quais são os fatores ambientais e de espaço que governam a distribuição das espécies de samambaias e licófitas, sua riqueza e sua cobertura na floresta brasileira ao sul do Atlântico; 5) investigar se espécies epifíticas e terrestres respondem igualmente aos condutores ambientais. Os resultados de um estudo detalhado, bem como de análises morfológicas, ecológicas, pedológicas e geográficas são: 1) a composição e riqueza de espécies variou significativamente ao longo do gradiente altitudinal; 2) riqueza e diversidade foram maiores nas formações superiores (Montana e Altomontana); 3) comunidades ecológicas distintas (epifítica, terrícola e rupícola) diferiram quanto ao padrão de distribuição observado ao longo do gradiente; 4) os fatores ambientais (tais como: insolação solar, precipitação, velocidade do vento, umidade relativa do ar relacionados ao clima e, concentração de matéria orgânica, alumínio, pH e profundidade, relacionados ao solo) apresentam maior importância na variação da distribuição de espécies ao longo do gradiente; 5) a variação da distribuição de espécies epífitas demostrou ser mais relacionada aos condutores ambientais relacionados aos fatores climáticos enquanto que as espécies terrestres, aos fatores edáficos. Processos de nicho (teoria de nicho) são os responsáveis por modular a distribuição e a abundância das espécies de samambaias e licófitas ao longo do gradiente altitudinal da Floresta Atlântica Sul Brasileira. Adicionalmente, é descrito novo registro de Stigmatopteris no Estado do Rio Grande do Sul, Brasil. / Data and analyses of elevational gradients in diversity have been central to the development and evaluation of a range of biodiversity general theories. This proposal seeks to contribute to a better understanding of the ferns and lycophytes diversity patterns along an elevation gradient in Southern Brazil, spanning from Lowland and Submontane to Montane and Upper Montane forest formations, and considering the influence of climatic factors and soil on communities of this group plants. The objectives of this study are: 1) to verify the composition and species richness varies along the altitudinal gradient; 2) if so, describe at what altitude we find the greatest diversity; 3) to analyze if there are differences along the gradient in the distribution patterns of epiphytic community, terrestrial and rupicolous; 4) establish what are the environmental and spatial factors that govern ferns and wealth lycophyte species and its coverage in the Brazilian forest at the South of the Atlantic; 5) investigate if epiphytic and terrestrial species also respond to environmental drivers. The results of a detailed study, as well as morphological, ecological, soil and geographical study are: 1) the composition and species richness varied significantly along the altitudinal gradient; 2) richness and diversity were higher in the Montane and Upper Montane formations; 3) distinct ecological communities (epiphytic, terrestrial and rupicolous) to differ on the distribution pattern observed along the gradient; 4) the environmental factors (such as solar insolation, precipitation, wind speed, relative humidity related to the climate, and concentration of organic matter, aluminum, pH and depth, related to soil) have greater importance in the variation species distribution along the gradient; 5) the variation of the distribution of epiphytes demonstrated to be more related to environmental drivers that are related to climatic factors, while terrestrial species are related to the soil factors. Niche processes (niche theory) are responsible for modulate distribution patterns and species abundance along elevational gradient in the Southern Brazilian Atlantic Forest. In addition, we present the new registration Stigmatopteris in the State of Rio Grande do Sul, Brazil.

Dados e análises de gradientes altitudinais em diversidade têm sido fundamentais para o desenvolvimento e avaliação de uma série de teorias gerais da biodiversidade. Esta proposta pretende contribuir para uma melhor compreensão dos padrões de diversidade das samambaias e licófitas ao longo de um gradiente de altitude no Sul do Brasil, abrangendo desde as formações florestais da planície, composta pela floresta de Terras Baixas, Submontana, como por formações florestais de altitude superiores, florestas Montana e Altomontana, e considerando a influência de fatores climáticos e de solo sobre as comunidades de plantas deste grupo. Assim, os objetivos deste estudo são: 1) verificar se a composição e riqueza de espécies varia ao longo do gradiente altitudinal; 2) se caso afirmativo, descrever em qual altitude podemos encontrar a maior diversidade; 3) analisar se existem diferenças ao longo do gradiente nos padrões de distribuição entre comunidade epifítica, terrícola e rupícola; 4) estabelecer quais são os fatores ambientais e de espaço que governam a distribuição das espécies de samambaias e licófitas, sua riqueza e sua cobertura na floresta brasileira ao sul do Atlântico; 5) investigar se espécies epifíticas e terrestres respondem igualmente aos condutores ambientais. Os resultados de um estudo detalhado, bem como de análises morfológicas, ecológicas, pedológicas e geográficas são: 1) a composição e riqueza de espécies variou significativamente ao longo do gradiente altitudinal; 2) riqueza e diversidade foram maiores nas formações superiores (Montana e Altomontana); 3) comunidades ecológicas distintas (epifítica, terrícola e rupícola) diferiram quanto ao padrão de distribuição observado ao longo do gradiente; 4) os fatores ambientais (tais como: insolação solar, precipitação, velocidade do vento, umidade relativa do ar relacionados ao clima e, concentração de matéria orgânica, alumínio, pH e profundidade, relacionados ao solo) apresentam maior importância na variação da distribuição de espécies ao longo do gradiente; 5) a variação da distribuição de espécies epífitas demostrou ser mais relacionada aos condutores ambientais relacionados aos fatores climáticos enquanto que as espécies terrestres, aos fatores edáficos. Processos de nicho (teoria de nicho) são os responsáveis por modular a distribuição e a abundância das espécies de samambaias e licófitas ao longo do gradiente altitudinal da Floresta Atlântica Sul Brasileira. Adicionalmente, é descrito novo registro de Stigmatopteris no Estado do Rio Grande do Sul, Brasil. / Data and analyses of elevational gradients in diversity have been central to the development and evaluation of a range of biodiversity general theories. This proposal seeks to contribute to a better understanding of the ferns and lycophytes diversity patterns along an elevation gradient in Southern Brazil, spanning from Lowland and Submontane to Montane and Upper Montane forest formations, and considering the influence of climatic factors and soil on communities of this group plants. The objectives of this study are: 1) to verify the composition and species richness varies along the altitudinal gradient; 2) if so, describe at what altitude we find the greatest diversity; 3) to analyze if there are differences along the gradient in the distribution patterns of epiphytic community, terrestrial and rupicolous; 4) establish what are the environmental and spatial factors that govern ferns and wealth lycophyte species and its coverage in the Brazilian forest at the South of the Atlantic; 5) investigate if epiphytic and terrestrial species also respond to environmental drivers. The results of a detailed study, as well as morphological, ecological, soil and geographical study are: 1) the composition and species richness varied significantly along the altitudinal gradient; 2) richness and diversity were higher in the Montane and Upper Montane formations; 3) distinct ecological communities (epiphytic, terrestrial and rupicolous) to differ on the distribution pattern observed along the gradient; 4) the environmental factors (such as solar insolation, precipitation, wind speed, relative humidity related to the climate, and concentration of organic matter, aluminum, pH and depth, related to soil) have greater importance in the variation species distribution along the gradient; 5) the variation of the distribution of epiphytes demonstrated to be more related to environmental drivers that are related to climatic factors, while terrestrial species are related to the soil factors. Niche processes (niche theory) are responsible for modulate distribution patterns and species abundance along elevational gradient in the Southern Brazilian Atlantic Forest. In addition, we present the new registration Stigmatopteris in the State of Rio Grande do Sul, Brazil.

Lagoas costeiras são ecossistemas dinâmicos caracterizados por uma alta biodiversidade, e podem ser vistos como manchas de hábitats na paisagem. Potencialmente, as características das comunidades em lagoas podem ser explicadas por teorias ecológicas (Biogeografia de Ilhas e Ecologia de Metacomunidades), onde o grau de isolamento e a heterogeneidade do hábitat em escala da paisagem são fatores importantes na determinação da comunidade. O objetivo deste trabalho foi verificar a influência destes fatores sobre diferentes descritores da comunidade (abundância, diversidade alfa e beta) de peixes em lagoas costeiras, utilizando métricas de paisagem. A área de estudo localiza-se no sistema do rio Tramandaí, RS (50,14°O; 29,98°S), possui 41 lagoas com diferentes graus de conexão e comunica-se com o mar através do estuário de Tramandaí. As variáveis de paisagem foram obtidas através de sistemas de informação geográfica (imagens Spot e Landsat-TM5) e foram divididas entre variáveis estruturais (área, forma, distância do mar, coeficiente de variação da área, conectividade primária e conectividade estuarina) e variáveis de uso e cobertura da terra (buffer de 50, 100, 250 e 500 m). Dados de ictiofauna foram obtidos através de amostragem padronizada com rede de espera e de arrasto em 38 lagoas. Nossos resultados mostram que diferentes descritores da comunidade respondem a diferentes variáveis de paisagem. Quando considerada a composição de assembleias que habitam diferentes porções do corpo d’água observamos que 18% da variação nas assembleias de margens rasas são explicadas pelas variáveis estruturais e de uso e cobertura; já assembleias que habitam margens mais profundas respondem apenas as variáveis estruturais, as quais explicam 7% da variação nessa assembleia. Ambas as assembleias possuem partição de variância equilibrada entre variáveis que representam o isolamento e a heterogeneidade da paisagem. No entanto, quando consideramos outros descritores da comunidade como diversidade alfa e beta, observamos que as variáveis estruturais e de uso e cobertura da terra são mais importantes para explicar a diversidade dentro do corpo d’água (alfa), não sendo significantes para predizer a diversidade entre corpos d’água (beta). Esses resultados nos sugerem que as assembleias de peixes de lagoas costeiras podem estar estruturadas dentro de uma metacomunidade onde o efeito de massa pode ser o paradigma que melhor explica os padrões observados. / Coastal lagoons are dynamics ecosystems characterized by high levels of biodiversity, and they can be envisaged as discrete patches immersed in the landscape. Community patterns observed in coastal lagoons can be explained by ecological theories, such as, Island Biogeography and Metacommunity Ecology. These theories emphasize that the degree of isolation and habitat heterogeneity, in the landscape scale, are important factors defining community patterns. Our aim was to investigate the influence of these factors on different community descriptors (species composition, alpha and beta diversity) of fish communities in coastal lagoons, using landscape metrics. Our study area is located in the Tramandaí river system, RS (50,14°O; 29,98°S). This system communicates with the ocean through the Tramandaí estuary, and it encompasses 41 lagoons with different degrees of connection. We quantified landscape variables using geographic information systems (Spot and Landsat-TM5 images). These variables were grouped in two categories; structural variables (area, shape, distance to the ocean, coefficient of variation of area, primary connectivity and estuarine connectivity) and land use/land cover variables (using buffers of 50, 100, 250 and 500 m). Ichthyofauna data were obtained through standardized sampling, using gillnets and trawls in 38 lagoons. Our results show that different community descriptors respond to different landscape variables. Altogether, structural and land use/land cover variables explain 18% of the variation of fish composition (abundance) of shallow margins; while structural variables explain 7% of the total variation of fish composition inhabiting deeper banks. Both assemblages exhibit a balanced partition of variation among variables representing landscape isolation and heterogeneity. However, when considering other community descriptors, such as, alpha and beta diversity, we observed that landscape variables are more important in explaining the diversity within each lagoon (alpha), but they are not significant in predicting diversity between lagoons (beta). These results suggest that fish assemblages of coastal lagoons can be structured within a metacommunity, and that the mass effect may be the paradigm that better explains the observed patterns.

Lagoas costeiras são ecossistemas dinâmicos caracterizados por uma alta biodiversidade, e podem ser vistos como manchas de hábitats na paisagem. Potencialmente, as características das comunidades em lagoas podem ser explicadas por teorias ecológicas (Biogeografia de Ilhas e Ecologia de Metacomunidades), onde o grau de isolamento e a heterogeneidade do hábitat em escala da paisagem são fatores importantes na determinação da comunidade. O objetivo deste trabalho foi verificar a influência destes fatores sobre diferentes descritores da comunidade (abundância, diversidade alfa e beta) de peixes em lagoas costeiras, utilizando métricas de paisagem. A área de estudo localiza-se no sistema do rio Tramandaí, RS (50,14°O; 29,98°S), possui 41 lagoas com diferentes graus de conexão e comunica-se com o mar através do estuário de Tramandaí. As variáveis de paisagem foram obtidas através de sistemas de informação geográfica (imagens Spot e Landsat-TM5) e foram divididas entre variáveis estruturais (área, forma, distância do mar, coeficiente de variação da área, conectividade primária e conectividade estuarina) e variáveis de uso e cobertura da terra (buffer de 50, 100, 250 e 500 m). Dados de ictiofauna foram obtidos através de amostragem padronizada com rede de espera e de arrasto em 38 lagoas. Nossos resultados mostram que diferentes descritores da comunidade respondem a diferentes variáveis de paisagem. Quando considerada a composição de assembleias que habitam diferentes porções do corpo d’água observamos que 18% da variação nas assembleias de margens rasas são explicadas pelas variáveis estruturais e de uso e cobertura; já assembleias que habitam margens mais profundas respondem apenas as variáveis estruturais, as quais explicam 7% da variação nessa assembleia. Ambas as assembleias possuem partição de variância equilibrada entre variáveis que representam o isolamento e a heterogeneidade da paisagem. No entanto, quando consideramos outros descritores da comunidade como diversidade alfa e beta, observamos que as variáveis estruturais e de uso e cobertura da terra são mais importantes para explicar a diversidade dentro do corpo d’água (alfa), não sendo significantes para predizer a diversidade entre corpos d’água (beta). Esses resultados nos sugerem que as assembleias de peixes de lagoas costeiras podem estar estruturadas dentro de uma metacomunidade onde o efeito de massa pode ser o paradigma que melhor explica os padrões observados. / Coastal lagoons are dynamics ecosystems characterized by high levels of biodiversity, and they can be envisaged as discrete patches immersed in the landscape. Community patterns observed in coastal lagoons can be explained by ecological theories, such as, Island Biogeography and Metacommunity Ecology. These theories emphasize that the degree of isolation and habitat heterogeneity, in the landscape scale, are important factors defining community patterns. Our aim was to investigate the influence of these factors on different community descriptors (species composition, alpha and beta diversity) of fish communities in coastal lagoons, using landscape metrics. Our study area is located in the Tramandaí river system, RS (50,14°O; 29,98°S). This system communicates with the ocean through the Tramandaí estuary, and it encompasses 41 lagoons with different degrees of connection. We quantified landscape variables using geographic information systems (Spot and Landsat-TM5 images). These variables were grouped in two categories; structural variables (area, shape, distance to the ocean, coefficient of variation of area, primary connectivity and estuarine connectivity) and land use/land cover variables (using buffers of 50, 100, 250 and 500 m). Ichthyofauna data were obtained through standardized sampling, using gillnets and trawls in 38 lagoons. Our results show that different community descriptors respond to different landscape variables. Altogether, structural and land use/land cover variables explain 18% of the variation of fish composition (abundance) of shallow margins; while structural variables explain 7% of the total variation of fish composition inhabiting deeper banks. Both assemblages exhibit a balanced partition of variation among variables representing landscape isolation and heterogeneity. However, when considering other community descriptors, such as, alpha and beta diversity, we observed that landscape variables are more important in explaining the diversity within each lagoon (alpha), but they are not significant in predicting diversity between lagoons (beta). These results suggest that fish assemblages of coastal lagoons can be structured within a metacommunity, and that the mass effect may be the paradigm that better explains the observed patterns.

Lagoas costeiras são ecossistemas dinâmicos caracterizados por uma alta biodiversidade, e podem ser vistos como manchas de hábitats na paisagem. Potencialmente, as características das comunidades em lagoas podem ser explicadas por teorias ecológicas (Biogeografia de Ilhas e Ecologia de Metacomunidades), onde o grau de isolamento e a heterogeneidade do hábitat em escala da paisagem são fatores importantes na determinação da comunidade. O objetivo deste trabalho foi verificar a influência destes fatores sobre diferentes descritores da comunidade (abundância, diversidade alfa e beta) de peixes em lagoas costeiras, utilizando métricas de paisagem. A área de estudo localiza-se no sistema do rio Tramandaí, RS (50,14°O; 29,98°S), possui 41 lagoas com diferentes graus de conexão e comunica-se com o mar através do estuário de Tramandaí. As variáveis de paisagem foram obtidas através de sistemas de informação geográfica (imagens Spot e Landsat-TM5) e foram divididas entre variáveis estruturais (área, forma, distância do mar, coeficiente de variação da área, conectividade primária e conectividade estuarina) e variáveis de uso e cobertura da terra (buffer de 50, 100, 250 e 500 m). Dados de ictiofauna foram obtidos através de amostragem padronizada com rede de espera e de arrasto em 38 lagoas. Nossos resultados mostram que diferentes descritores da comunidade respondem a diferentes variáveis de paisagem. Quando considerada a composição de assembleias que habitam diferentes porções do corpo d’água observamos que 18% da variação nas assembleias de margens rasas são explicadas pelas variáveis estruturais e de uso e cobertura; já assembleias que habitam margens mais profundas respondem apenas as variáveis estruturais, as quais explicam 7% da variação nessa assembleia. Ambas as assembleias possuem partição de variância equilibrada entre variáveis que representam o isolamento e a heterogeneidade da paisagem. No entanto, quando consideramos outros descritores da comunidade como diversidade alfa e beta, observamos que as variáveis estruturais e de uso e cobertura da terra são mais importantes para explicar a diversidade dentro do corpo d’água (alfa), não sendo significantes para predizer a diversidade entre corpos d’água (beta). Esses resultados nos sugerem que as assembleias de peixes de lagoas costeiras podem estar estruturadas dentro de uma metacomunidade onde o efeito de massa pode ser o paradigma que melhor explica os padrões observados. / Coastal lagoons are dynamics ecosystems characterized by high levels of biodiversity, and they can be envisaged as discrete patches immersed in the landscape. Community patterns observed in coastal lagoons can be explained by ecological theories, such as, Island Biogeography and Metacommunity Ecology. These theories emphasize that the degree of isolation and habitat heterogeneity, in the landscape scale, are important factors defining community patterns. Our aim was to investigate the influence of these factors on different community descriptors (species composition, alpha and beta diversity) of fish communities in coastal lagoons, using landscape metrics. Our study area is located in the Tramandaí river system, RS (50,14°O; 29,98°S). This system communicates with the ocean through the Tramandaí estuary, and it encompasses 41 lagoons with different degrees of connection. We quantified landscape variables using geographic information systems (Spot and Landsat-TM5 images). These variables were grouped in two categories; structural variables (area, shape, distance to the ocean, coefficient of variation of area, primary connectivity and estuarine connectivity) and land use/land cover variables (using buffers of 50, 100, 250 and 500 m). Ichthyofauna data were obtained through standardized sampling, using gillnets and trawls in 38 lagoons. Our results show that different community descriptors respond to different landscape variables. Altogether, structural and land use/land cover variables explain 18% of the variation of fish composition (abundance) of shallow margins; while structural variables explain 7% of the total variation of fish composition inhabiting deeper banks. Both assemblages exhibit a balanced partition of variation among variables representing landscape isolation and heterogeneity. However, when considering other community descriptors, such as, alpha and beta diversity, we observed that landscape variables are more important in explaining the diversity within each lagoon (alpha), but they are not significant in predicting diversity between lagoons (beta). These results suggest that fish assemblages of coastal lagoons can be structured within a metacommunity, and that the mass effect may be the paradigm that better explains the observed patterns.