No description available.

Hurricanes can temporarily disrupt seasonal patterns of fish assemblage change or result in permanent changes in fish assemblages. I studied the effects of two hurricanes on fish assemblages at the Chandeleur Islands and the possible influence that storm-generated tidal channels may have on the composition of local fish assemblages. I also compared recently collected data to historic ichthyofaunal survey data collected over thirty years ago at the Chandeleur Islands. Near shore fish assemblages changed the most after hurricanes but changes in species composition were primarily due to increases in abundance and diversity. During July 2007 there was no significant difference between fish assemblages in channel and seagrass habitats, although significant differences among wash-over channels existed. Loss of habitat and the increased intensity and frequency of recent storms may explain why current fish assemblages at the Chandeleur Islands are less diverse (as measured by taxonomic distinctness) than assemblages collected during 1969-1971.

The spatial and population dynamics of avian scavengers are poorly understood. This information is key for management and conservation interventions that guarantee long-term species conservation. My goal in this dissertation is to fill information gaps on the movement ecology of New World vultures using the Turkey Vulture (Cathartes aura) as a model species. I used a continental-wide satellite telemetry dataset to study the migration ecology, space-use, and demography of the three North American breeding populations of Turkey Vultures wintering in the Neotropics during a 17-year period. I found that primary productivity, but not weather, triggered Turkey Vulture migratory behavior, migration initiated when primary productivity dropped at the end of the breeding and non-breeding season. Migratory connectivity was high at the species level (0.85, 95% CI: 0.74–0.94). However, I found evidence of intrapopulation segregation during the non-breeding season demonstrated by lower values of migratory connectivity in each population. I investigated how seasonality interacted with human disturbance, landscape composition and configuration to mediate patterns of geographic and environmental space-use, and annual and seasonal survival probabilities. Environmental space-use was best explained by landscape configuration. Geographic space-use exhibited a quadratic response to landscape configuration metrics, suggesting that Turkey Vultures maximize space-use in landscape with intermediate disturbance. Human disturbance, but not but not landscape composition and configuration, influenced survival rates in space and time. Overall annual survival averaged 0.87 (95% CI = 0.74 – 0.98). Mortality risk was low in western and central populations but was 3.7 times greater for vultures in the eastern population. Risk of mortality for all vulture populations increased with road density, and this was greater during the non-breeding and return migration seasons. My results suggest that spatial and population dynamics are affected at a continental scale by the energy landscape, intermediate disturbance and human disturbance. My dissertation emphasizes the importance of an integrative empirical-modeling approach to address questions on effects of resources availability and search efficiency in the spatial and population dynamics of avian scavengers.

No description available.

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / Environmental changes resulting from climatic conditions may limit the reproductive activity of anurans. The calling activity is an important indicator of the temporal patterns of anuran activity, which may be regulated by several factors. Reproductive strategies, including the period of calling activity, time of tadpole and juvenile recruitment, and the larval rate of development, can be used for minimizing the adverse influence of environmental variables. Moreover, local environmental changes may generate disturbances (e.g., flooding, grazing, climatic events) and alter the availability of resources in the environment, which may lead to either a reduction or an increase in the local species diversity. In this context, the intermediate disturbance hypothesis (IDH) predicts that the species diversity would be higher at intermediate levels of disturbance. In freshwater systems, for instance, water bodies with intermediate hydroperiods (temporary ponds) would have higher species diversity because they would have fewer predators in relation to permanent ponds, and more resources availability in relation to ephemeral ponds. Thus, we aimed to determine the environment abiotic effects on the calling activity of an anuran community from the temperate wetlands of the extreme southern Brazil. We identified the reproductive patterns of species considering the periods of tadpole and juvenile recruitment, the larval development rate, and the influence of environmental variables on the species activity seasonality. We also established the disturbance frequency, duration and extent in water bodies, through the investigation of the relationship between the disturbance levels, the hydroperiod and the diversity of anurans. Data were collected over 17 months in coastal wetlands of the extreme portion of southern Brazil. Between December 2012 and April 2014 we registered 11 active species, distributed in the families Hylidae, Leptodactylidae, and Bufonidae. The calling activity of the community was positively related to water temperature and rainfall. The recruitment of tadpoles occurred during the rainy period, regardless of variation in the measured abiotic variables. The recruitment of juveniles also occurred during the rainy period and was related to increased water temperature. Our results indicate a link between the frequency and duration of the disturbance with the hydroperiod, as well as with tadpole richness and abundance. Overall, much of the species abiotic dependence was linked to the patterns of reproductive behavior and phylogeny; the occurrence of many species was also linked to the hydrological regime of water bodies. Also, our study demonstrates the direct effect of a disturbance event and the IDH on the studied anuran community, in which temporary water bodies presented a richest anuran community than ephemeral or permanent ones. / As variações ambientais decorrentes do clima representam um limitador para a atividade reprodutiva em anuros. A atividade de vocalização, por exemplo, é um importante indicativo do padrão de atividade diária e sazonal dos anuros e pode ser regulada por diversos fatores. As estratégias reprodutivas, tais como períodos de vocalização, época de recrutamento de girinos e juvenis, são utilizadas para amenizar a influência dessas variáveis. Adicionalmente, as variações climáticas podem refletir na forma de distúrbios sobre uma comunidade. Os distúrbios (e.g. alagamentos, pastejo, eventos climáticos) agem no ambiente alterando a disponibilidade de recursos, podendo causar o declínio ou aumento da diversidade de espécies. Nesse contexto a hipótese do distúrbio intermediário (HDI) prediz que em níveis intermediários de distúrbio a diversidade de espécies seria máxima. Em sistemas dulcícolas, por exemplo, corpos d água com hidroperíodos intermediários (temporários) apresentariam maior diversidade, por possuir menor número de predadores em relação aos permanentes e mais recursos disponíveis em relação aos efêmeros. Dessa forma, objetivamos averiguar os efeitos de fatores abióticos sobre a atividade de vocalização em uma comunidade de zona úmida temperada no extremo sul do Brasil. Identificamos os padrões reprodutivos das espécies, através do período de recrutamento de girinos e juvenis e tempo de desenvolvimento larval, bem como a influência de variáveis abióticas sobre a sazonalidade das espécies. Por fim, estabelecemos os atributos frequência, duração e extensão de distúrbio em corpos d água continentais, verificando a relação dos níveis de distúrbio com o hidroperíodo e diversidade de espécies de anuros. Os dados foram coletados ao longo de 17 meses em campos úmidos costeiros no extremo sul do Brasil. Foram registradas 11 espécies ativas de dezembro de 2012 a abril de 2014, distribuídas em três famílias: Hylidae, Leptodactylidae e Bufonidae. A atividade de vocalização sazonal da comunidade foi relacionada com a temperatura da água e pluviosidade, havendo respostas diferentes quando consideradas as espécies separadamente. O recrutamento de girinos ocorreu no período de chuvas, sendo independente das variáveis abióticas. O recrutamento de juvenis também ocorreu no período de chuvas e foi relacionado ao aumento da temperatura da água. Observamos, também, uma ligação entre os níveis dos atributos frequência e duração de distúrbio com o hidroperíodo, bem como com a abundância e riqueza de espécies de girinos presentes nesses ambientes. De uma forma geral, os resultados adquiridos mostram que grande parte da dependência abiótica apresentada pela atividade das espécies esteve ligada à filogenia e padrões comportamentais reprodutivos, onde a ocorrência de muitas espécies está ligada ao regime hídrico dos corpos d água. Por fim, os resultados encontrados no presente estudo demonstram a ação direta de um evento de distúrbio, bem como da HDI, sobre a comunidade de anuros, onde corpos d água temporários, com níveis intermediários de distúrbio, apresentam um maior número de espécies que efêmeros ou permanentes.

Dissertação (mestrado)-Universidade Federal do Rio Grande, Programa de Pós-Graduação em Biologia de Ambientes Aquáticos Continentais, Instituto de Ciências Biológicas, 2012. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2014-01-13T17:21:35Z No. of bitstreams: 1 0000010065.pdf: 2640072 bytes, checksum: 684c38e9d51f045a0f7b69cc99781e58 (MD5) / Approved for entry into archive by cristiane soares (krikasoares@live.com) on 2014-02-23T02:02:19Z (GMT) No. of bitstreams: 1 0000010065.pdf: 2640072 bytes, checksum: 684c38e9d51f045a0f7b69cc99781e58 (MD5) / Made available in DSpace on 2014-02-23T02:02:19Z (GMT). No. of bitstreams: 1 0000010065.pdf: 2640072 bytes, checksum: 684c38e9d51f045a0f7b69cc99781e58 (MD5) Previous issue date: 2012 / Esta dissertação teve como objetivo descrever a composição e estrutura da assembleia de Chironomidae durante um período de 10 anos e sua resposta frente a mudança de estados alternativos em um lago raso. Buscou-se também verificar se a estrutura das plantas aquáticas tem influência sobre esta assembleia em quatro diferentes lagos. Para verificar a semelhança quanto à composição dos gêneros entre os anos foi realizada similaridade de Jaccard e Nonmetric Multidimensional Scaling (NMDS, distância de Bray Curtis) para verificar a similaridade entre os anos com base nas abundâncias dos gêneros. A contribuição das variáveis ambientais para a distribuição dos gêneros de Chironomidae ao longo dos anos foi avaliada através da Análise de Correspondência Canônica (CCA). No estudo que analisou a influência da complexidade das plantas e características ambientais entre quatro lagos foi realizado a similaridade de Jaccard para verificar a semelhança quanto à composição dos gêneros entre os lagos e a composição em relação as plantas, MANOVA para testar se existe diferença entre os lagos e entre as plantas em relação às abundâncias médias dos gêneros, MANOVA entre os lagos em função dos grupos tróficos funcionais (GTFs) e entre as plantas em função dos GTFs. Os resultados do estudo a longo prazo no lago eutrófico demonstraram mudanças na riqueza, densidade e estrutura trófica de Chironomidae, com as alterações na qualidade de água e estrutura do ecossistema, confirmando nossa hipótese de que esta assembleia pode ser utilizada como indicadora nos estados alternativos e estado trófico em lagos rasos subtropicais. Os resultados indicam que as mudanças de estados alternativos podem corresponder a distúrbios de moderada intensidade no ecossistema. A assembleia de Chironomidae respondeu com maior riqueza e diversidade nos períodos de transição, sugerindo que este grupo responde a hipótese do distúrbio intermediário. Os resultados referentes ao estudo sobre a complexidade de plantas indicam que a complexidade da estrutura das plantas aquáticas em ambientes lênticos subtropicais rasos, influencia na composição dos gêneros de Chironomidae. Embora não tenhamos encontrado diferença significativa entre os lagos em relação a abundância desses gêneros, com a categorização em grupos funcionais obtivemos uma resposta desses organismos em relação as características ambientais de cada lago. / This study aims to describe the composition and structure of the assembly of chironomids for a period of 10 years and its response to change of alternative states in a shallow eutrophic lake. It also sought to verify that the structure of aquatic plants has an influence on this assembly in four different lakes. To check the similarity in the composition of the genera was performed between the years Jaccard similarity and Nonmetric Multidimensional Scaling (NMDS, Bray Curtis distance) to verify the similarity between the years based on the abundances of the genera. The contribution of environmental variables for the distribution of Chironomidae genera over the years was evaluated by Canonical Correspondence Analysis (CCA). In the study examined the influence of the complexity of plants and environmental characteristics of four lakes was conducted Jaccard similarity to verify the similarity in the composition of the genera among the lakes and composition in relation to plants, MANOVA to see if there are differences between the lakes and among plants in relation to the average abundances of the genera, MANOVA between lakes depending on the functional trophic groups (GTFs) and among plants depending on the GTFs. The results of longterm study in eutrophic lake showed changes in density, richness and trophic structure of Chironomidae with changes in water quality and ecosystem structure confirming our hypothesis that this assembly can be used as an indicator in the alternative states and trophic state in subtropical shallow lakes. The results indicate that changes in alternative states may correspond to moderate disturbances in the ecosystem. The assembly of chironomids responded with greater richness and diversity in transition periods, suggesting that this group responds to the intermediate disturbance hypothesis. The results for the study of the complexity of plants indicate that the complexity of the structure of aquatic plants in lentic shallow subtropical influences the composition of the genera of Chironomidae. Although we found no significant difference between the lakes relative abundance of these genera, as categorized into functional groups obtained a response of these organisms in relation to environmental characteristics of each lake.

Les cervidés, animaux mobiles et herbivores, peuvent influencer les distributions, assemblages et dynamiques d'espèces végétales. L'objectif de cette thèse est d'évaluer le rôle joué par les cervidés sur la composition, stratification et dynamique de la végétation forestière. Le ré-échantillonnage de relevés couplant composition et abroutissement de la flore, implantés en 1976 en Forêt d'Arc-en-Barrois (52) a permis d'identifier (i) des espèces ligneuses préférées (Cornus sp., Rosa arvensis) ou au contraire évitées par les cervidés qui sélectionnent les espèces arbustives et à bois dense et (ii) le niveau trophique et la pression d'abroutissement comme gradients structurant la végétation et déterminant les dynamiques des espèces et des communautés. Nous analysons plus précisément le rôle des cervidés dans la progression spectaculaire de Cynoglossum germanicum, espèce rare, épizoochore et toxique.A partir d'un réseau national d'enclos/exclos suivis sur 10 ans, nous montrons que les cervidés limitent la croissance des arbustes et des espèces compétitrices, ce qui profite à la richesse spécifique de la strate herbacée. La valeur écologique et patrimoniale des espèces en progression est discutée. A l'aide de données de chasse, nous tentons d'isoler les rôles des différentes espèces d'ongulés dans ces dynamiques.Ces résultats exposent la complexité et la diversité des effets des cervidés sur la végétation forestière. Enfin, ce travail met l'accent sur la nécessité des suivis temporels intégrant toutes les composantes de l'écosystème forestier pour mieux appréhender les changements en cours. / This thesis aims at assessing the impacts of deer on forest vegetation composition, stratification and dynamics.We resampled a network of relevés coupling vegetation and browsing surveys, settled in 1976 in the national forest of Arc-en-Barrois. We identified (i) ligneous species that are either preferred (Cornus sp., Rosa arvensis) or avoided by deer, which tend to select shrubs species with dense wood and (ii) trophic level and browsing pressure as gradients that determine plant communities structures and dynamics. Then, we highlight the roles of deer in the spectacular expansion of Cynoglossum germanicum, a rare, epizoochorous and toxic species. According to a national network of exclosures, monitored for over 10 years, we show that deer limit shrubs and competing species growth, which in turn benefits to the herbaceous species richness probably through an increased light availability. Ecological and patrimonial value of the benefitting species is discussed. Using hunting statistics, we try to isolate the role of the various ungulate species in these dynamics.These results provide evidence for the diversity and complexity of deer impacts on forest vegetation. Finally, we demonstrate the need for long term monitoring programs, including all the forest ecosystem components so that we could better appreciate the forces driving the current changes