Made available in DSpace on 2014-06-11T19:30:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-29Bitstream added on 2014-06-13T20:39:51Z : No. of bitstreams: 1 kurchevski_g_me_botib.pdf: 972112 bytes, checksum: 5ba514fc94cea9053e0327b1bda69630 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Diversos fatores são responsáveis pela estruturação das assembléias de peixes em ecossistemas aquáticos artificiais. As relações entre o ambiente e os padrões de abundância e composição são provenientes das escalas temporais e espaciais avaliadas. Nesse sentido, as construções de reservatórios modificam o ambiente de tal forma que ocorre uma reorganização das assembleias de peixes. Com esse enfoque, o presente estudo objetivou caracterizar a distribuição espaço-temporal da fauna de peixes do reservatório de Jurumirim, avaliar o status de conservação e as interferências da represa nos atributos dessas assembleias. Três compartimentos do reservatório foram amostrados (lótico, transição e lêntico), além de duas lagoas na região de desembocadura do rio Paranapanema na represa. Foram registrados 52 táxons, sendo 14 deles considerados novos registros para a área de influência do reservatório. Desses novos registros, quatro espécies são de origem não nativa (alóctone): Triphorteus nematurus, Hyphessobrycon eques, Metynnis maculatus, e Cichla monoculus e uma exótica: Tilapia rendalli. As análises dos atributos ecológicos demonstraram, mesmo que incipiente, existe influência das condições impostas pelo barramento nas estruturas das assembléias. Dos atributos analisado, apenas o comprimento padrão médios e riqueza de espécies apresentaram diferenças estatísticas entre os trechos e os meses estudados. O padrão de distribuição longitudinal de riqueza específica parece ser atribuído às características peculiares desse sistema: baixa frequência de espécies introduzidas, presença de importantes tributários e condição trófica. O reservatório de Jurumirim apresenta filtros ecológicos que promovem certa resistência à invasões biológicas. Ainda, pela idade... / Many factors are responsable for the structure of fish assemblages in artificial aquatic ecosystems. The relation between the environment and the patterns of abundance and composition come from temporal and spatial scales evaluated. Therefore, the constructions of reservoirs modify the environment leading to a reorganization of fish communities. The present study aimed to characterize the spatial-temporal distribution of fish fauna in Jurumirim Reservoir, determining the interferences of the dam in the fish community attributes, as well as evaluating the conservation status of fish assemblages in this artificial system. Three compartments of the reservoir were sampled (lotic, transition, lentic), as well as two lagoons in the mouth zone of Paranapanema River into the reservoir. 52 taxons were found, 14 of which considered new records. Of the new records, 4 species are alloctone species: Triphorteus nematurus, Hyphessobrycon eques, Metynnis maculatus and Cichla monoculus. The analysis of ecological attributes showed low influence of the conditions imposed by the dam in the fish assemblages. Only the average standard length and the species richness presented statistical differences between stretches and months. The pattern of longitudinal distribution of specific richness seems to happen due to the peculiar characteristics of that system: low frequency of introduced species, presence of the important tributaries and trophic condition. Jurumirim Reservoir presents ecological filters that promote some resistance to the progress of operational aspects of the invasions. Furthermore, because of reservoir’s age... (Complete abstract click electronic access below)

Approximately 65 vessel reefs have been deployed intentionally in Broward County, Florida since 1982. The purpose of these deployments was to enhance fish stocks for recreational fisheries and sport divers. The other main goal was to reduce pressure on heavily exploited natural reefs. Several studies have been conducted at both artificial and natural reef sites in the area; however, none of these have focused on nocturnal fish assemblages (Ferro et al., 2005; Arena et al., 2007). The goal of our study was to characterize nocturnal fish assemblages on vessel and natural reefs in Broward County. This data, in addition to the existing diurnal data, will provide a more comprehensive understanding of fish assemblage structure on artificial and natural reefs. Comparisons among vessel and natural nocturnal fish assemblages and previous diurnal studies were made. Abundance was greater on diurnal natural and vessel reefs when compared to nocturnal. Abundance was also greater on nocturnal vessel reefs than nocturnal natural reefs. The twilight period on vessel reefs was characterized by high abundance of piscivores and a significantly greater abundance of grunts than during the nocturnal period. The abundance of grunts supports their movement during this time to surrounding sand flats to feed. The vertical relief of the vessel reefs seemed to appeal to an abundance of pelagic fishes as well as planktivores. Distinctly different fish assemblages were seen between nocturnal natural and vessel reefs, as well as between diurnal and nocturnal natural reefs and vessel reefs. Fisheries-important fishes were more abundant during the day, but also more abundant on vessel reefs than natural reefs. Although vessel reefs do not mimic the natural reefs studied or support the same fish assemblages, they are providing habitat for diverse nocturnal fish assemblages.

Despite the increases in the intensity and frequency of disturbances on coral reefs in the Red Sea over the past decade, patterns of variability in fish communities are still poorly understood. This study aims to contribute to a better understanding of how fish communities vary along multiple spatial scales (10-100’ of kilometers) and to provide a baseline for future comparisons, fundamental to assess responses to climate change and other disturbances. Coral reefs along the Saudi Arabian Red Sea coast were surveyed from 2017 to 2019. The reefs ranged from 28° N to 18 °N and were categorized according their geographical location and grouped within three regions, namely north (24-28.5°N; 12 reefs), central (20.4-22.3°N; 11 reefs), and south (18.5-21.2°N; 30 reefs). The quantification of spatial patterns was conducted based on both taxonomic- and trait-based approaches. Considering the dependence of fish communities on the benthic habitat the relationship between different attributes of the fish assemblages and coral cover was also investigated. A consistent pattern of separation between assemblages of the northern and central region from the ones in the south was observed in nearshore reefs but was not evident for offshore reefs. The southern region supported higher densities, biomass, and species richness than the other two regions. The analysis showed that transect and reef scales contributed to the greatest variation in fish communities, suggesting higher levels of variability within small spatial scales. Several parameters of the fish community (total species, total density, total biomass, total functional entities, functional richness, functional redundancy) were positively correlated to coral cover, particularly in the northern region. Responses were not consistent across the Red Sea basin, suggesting that management plans should be regionally based. This study can be helpful to design management strategies as it provides a current baseline from both taxonomic and trait perspectives for Red Sea reefs that can be used to evaluate future changes due to natural and human-based disturbances.

Human alteration of the landscape for agricultural and urban land use has been linked to the degradation of streams and stream biota. Natural physical and climatic characteristics, or physiographic template, are important for determining natural land cover and constraining human land use, and are strongly related to stream habitat and stream biotic assemblages. Since the physiographic template differs among watersheds and is an important determinant of the processes being studied, it is important to account for these natural differences among watersheds so that the relationship between land cover and streams can be properly understood. The purpose of this thesis is to develop and assess the utility of a regional framework that classifies watersheds based on physical and climatic predictors of land cover. In Chapter 1, I identified physical and climatic predictors of land cover and classified watersheds into Land cover Distinguished Physiographic Regions (LDPRs) based on these predictors. I was able to identify and create classes based off eight climatic and landform characteristics that determined natural land cover and human land use patterns for both the Eastern and Western U.S. In Chapter 2, I utilized LDPRs to stratify a study region and investigated whether the relationships between land cover and stream fish assemblages varied between these regions. Five commonly used metrics covering trophic, reproductive and taxonomic groupings showed significant variation in their response to agricultural land use across LDPRs. The results suggest that the physiographic differences among LDPRs can result in different pathways by which land cover alterations impact stream fish communities. Unlike other commonly used regional frameworks, the rationale and methods used to develop LDPRs properly accounts for the causal relationship between physiography and land cover. Therefore, I recommend the use of LDPRs as a tool for stratifying watersheds based on physiography in future investigations so that the processes by which human land use results in stream degradation can be understood. / Master of Science

Les écosystèmes procurent de nombreux services essentiels aux sociétés humaines à travers les effets positifs de la biodiversité des communautés d'espèces. Par conséquent, identifier le rôle des organismes vivants et les facteurs influençant la diversité de leurs fonctions (ou diversité fonctionnelle), est indispensable pour prédire efficacement l'évolution des écosystèmes soumis aux pressions locales et globales.Cette thèse s'articule donc autour de deux axes: (i) établir un cadre méthodologique pour décrire la structure fonctionnelle locale et régionale des communautés, et (ii) améliorer la connaissance de l'impact des poissons sur la dégradation de la matière organique.Dans un premier temps, nous avons consolidé les outils méthodologiques permettant (i) d'améliorer la fiabilité des dendrogrammes fonctionnels, (ii) l'étude comparative des principaux indices de diversité fonctionnelle à l'échelle locale, et (iii) le développement d'une nouvelle décomposition de la diversité fonctionnelle en composantes locale (α), régionale (γ) et turnover (β). Appliqué aux communautés ichthyologiques échantillonnés le long d'un gradient de salinité, dans le système lagunaire de Patos-Mirim (Brésil), ce socle méthodologique nous a permis de révéler une structure fonctionnelle stable le long du gradient, en dépit d'une forte variabilité en composition d'espèces, ces communautés étant structurées majoritairement par un filtre environnemental agissant sur les capacités de locomotion des poissons.Dans un second temps, nous avons étudié l'impact des communautés ichthyologiques sur le cycle des nutriments. Plus précisément, nous avons estimé le potentiel de dégradation de la matière organique de plusieurs espèces de poissons, en étudiant la diversité fonctionnelle et génétique de leur flore bactérienne intestinale. Nous avons montré que les communautés ichthyologiques pouvaient influencer le recyclage des nutriments de façon non négligeable en raison d'un important potentiel de dégradation commun à la plupart des espèces étudiées, ce potentiel étant peu affecté par la diversité génétique ou les facteurs environnementaux. / Ecosystems provide many services essential to Human societies through the positive effects of biodiversity exhibited by species communities. Therefore, identifying the role of living organisms and the factors influencing the diversity of their functions (i.e. functional diversity) is fundamental to accurately predict the evolution of ecosystems undergoing local and global pressures.This thesis is organized around two axes: (i) establishing a methodological framework to describe the functional structure of local and regional communities, and (ii) improving our knowledge of the impact of fish on the degradation of organic matter.First, we have consolidated the methodological tools through (i) the improvement of functional dendrograms reliability, (ii) the comparative study of the main indices estimating local functional diversity, and (iii) the development of a new decomposition of functional diversity into local (α) and regional (γ) components, and functional turnover (β). Applied to fish assemblages sampled along a salinity gradient in Patos-Mirim lagoons complex (Brazil), this methodological framework allowed us to reveal a steady functional structure, despite a high variability in species composition, these communities being primarily structured by environmental filtering acting on fish locomotion abilities.   In a second step, we studied the impact of fish communities on nutrient cycling. More specifically, we estimated degradation of organic matter potential of several fish species by studying the genetic and functional diversity of their intestinal bacterial flora. We showed that the fish community could significantly influence nutrient cycling through an important degradation potential, common to most species studied, which is weakly affected by genetic diversity or environmental factors.

Made available in DSpace on 2016-04-28T14:56:18Z (GMT). No. of bitstreams: 1 2006-Eduardo Oliveira Estilino.pdf: 1971115 bytes, checksum: d74b7f8933183575eb6582e98673509a (MD5) Previous issue date: 2006-05-05 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Species-environment relationships are important to assess the biological patterns, mainly those related to spatial distribution, since species undergo seletive pressure along their evolutive history, which determine the success in colonizing habitats. In fluvial ecosystems the geomorphology can acts as a constraint for fish species distribution, by determining kinds and levels of habitats structuring to which species are associated. This work aims to address the relationship between fluvial geomorphology and fish assemblages from Paraiba do Sul watershed, in an attempt to explaining the underlying spatial assemblages distribution patterns. Additionally, we assess the use of two river classification systems, developed for temperate regions, to this case study. Thirty-seven sites along the watershed were sampled during the dry season (May-October) between 2003 and 2005. The rivers were classified in three size categories: small (1?. to 3?. Order), medium (4?. to 6?. order) , and larger (> 6?. order), based in fluvial hierarchical classification scale. Fishes and geomorphological variables were sampled in a stretch of approximately 20 times the width for small and medium rivers, and in approximately 1 km for large rivers. Four fish assemblages were detected by cluster analysis and non-metric multidimensional scales MDS; one dominated by Tricomycterus immaculatum and Neoplecostomus microps, corresponding to small and medium rivers from hillslopes, straigths, with high slopes and channel showing bedrock, step-pool, and cascade. The second, dominated by Rhamdia quelen, Astyanax parahybae and Harttia loricariformis and the third, by Phalloceros caudimaculatus and Geophagus brasiliensis, corresponding to meandering rivers, with low and moderated slopes, channels showing pool-riffles, non-entrenchment, with channels associated to floodpains areas. The fourth assemblages is dominated by A. bimaculatus and Oligosarcus hepsetus, which are widely distributed along all watershed; in the lower reaches Loricariichthys spixii occurs in high frequency as well as eurihalines marine species, corresponding to low and medium sinuosity rivers with low slopes, channels showing pool-riffle, dune-ripple and braided, large cross-section, flooplains well developed and bed formed by gravel and sand. Slope, entrenchetment and width-depth ratio were the main constraints controlling the habitat. Our results match the main predictions of the Process Domain Concept (PDC) which postulate that fish assemblages vary in response to local habitat characteristics and the richness is directly associtated to cross-section area, contrasting with the prediction of the River Continuum Concept which postulate that assemblages vary previsible along the longitudinal gradient. / As rela??es esp?cie-ambiente s?o fundamentais para a compreens?o dos padr?es biol?gicos, principalmente aqueles relacionados ? distribui??o espacial, uma vez que as esp?cies sofrem press?es seletivas ao longo da hist?ria evolutiva que determinam seu sucesso na coloniza??o dos habitats. Em ecossistemas fluviais a geomorfologia pode atuar como uma condicionante da distribui??o das assembl?ias de peixes, por determinar os tipos e os n?veis de estrutura??o de habitat aos quais as esp?cies est?o associadas. Esse trabalho teve como objetivo analisar as rela??es entre a geomorfologia fluvial e as assembl?ias de peixes da bacia do rio Para?ba do Sul, na tentativa de explicar os padr?es de distribui??o. Foram amostrados 37 s?tios ao longo da bacia, no per?odo seco (maio-outubro) entre 2003 e 2005. Os rios foram estratificados em tr?s categorias de tamanho: pequeno (1?. a 3?. Ordem), m?dio (4?. a 6?. ordem) , e grande (> 6?. ordem), baseado na hierarquia fluvial. Os peixes e as vari?veis geomorfol?gicas foram amostrados num trecho cerca de 20 vezes a largura nos rios pequenos e m?dios, e num trecho de aproximadamente 1 km nos grandes rios. Quatro assembl?ias de peixes foram detectadas pelas an?lises de agrupamento e escalonamento multidimensional n?o m?trico MDS, uma dominada por Tricomycterus immaculatum, Neoplecostomus microps, e Harttia loricariformis, correspondendo a rios pequenos e m?dios das escarpas dos planaltos, retil?neos, com elevados gradientes de inclina??o do leito (slope), canais tipo bedrock, step-pool, e cascade. A segunda e a terceira assembl?ias s?o dominadas tanto por Astyanax scabripinnis e, Astyanax intermedium, quanto por esp?cies de ampla distribui??o como Rhamdia quelem, Geophagus brasiliensis, Oligosarcus hepsetus, correspondendo a rios sinuosos, com baixos a moderados gradientes, canais do tipo pool-riffles, n?o entalhados, com forma??o de plan?cies de inunda??o. A quarta assembl?ia ? dominada por A. bimaculatus, A. paraybae, G. brasiliensis, O. hepsetus, Pimelodus maculatus, Hypostomus affinis, Hoplosternum littorale, as quais s?o amplamente distribu?das ao longo da bacia, por?m, nas por??es inferiores da bacia as assembl?ias tamb?m apresenta Loricariichthys spixii e esp?cies marinhas eurialinas, correspondendo a rios com m?dia a baixa sinuosidade, baixos a moderados gradientes, canais tipo me?ndrico (pool-riffle), dunas e ondula??es (dune-ripple) e Anastomosado (braided), grande ?rea da se??o transversal, plan?cies de inunda??o bem desenvolvidas e leito formado basicamente por areia e cascalho. O gradiente e as raz?es de Entalhamento e Largura-Profundidade mostraram-se fatores dominantes controlando o habitat. Nossos resultados corroboram as principais predi??es do Conceito dos Dom?nios de Processos (PDC) que postula que as assembl?ias de peixes variam em fun??o das caracter?sticas de h?bitat locais e que a riqueza ? diretamente proporcional ? ?rea da se??o transversal, contrastando com as predi??es do Conceito do Rio Cont?nuo (RCC) que postula que as assembl?ias variam previsivelmente ao longo de um gradiente longitudinal.

Submitted by Leticia Schettini (leticia@ufrrj.br) on 2016-09-19T13:26:00Z No. of bitstreams: 1 2009 - Leonardo Mitrano Neves.pdf: 932793 bytes, checksum: 1e42ee61916afbed6020d0c2430fa7a4 (MD5) / Made available in DSpace on 2016-09-19T13:26:00Z (GMT). No. of bitstreams: 1 2009 - Leonardo Mitrano Neves.pdf: 932793 bytes, checksum: 1e42ee61916afbed6020d0c2430fa7a4 (MD5) Previous issue date: 2009-03-05 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPQ / The estuarine systems influence fish assemblages, throughout their longitudinal gradients and remarkable salinity changes. Such assemblages adapt to different habitat constraints and change in spatial and temporal scales. The aim of this study was to assess the ichthyofauna composition and structure in three zones of the Mambucaba estuary (CZ ? coastal zone; MZ ? mixture zone and RZ ? river zone) and their relationship with environmental variables and habitat characteristics. Systematic fish collections (2 months in each seasons) were performed between October 2007 and August 2008, by using otter trawl at two sites in CZ (C1 e C2), beach seine at three sites in MZ (M1, M2, M3) and mesh trays at two sites in RZ (R1 e R2). At each fish sampling occasion, both surface and depth environmental variables of temperature, salinity, conductivity, turbidity and dissolved oxygen were taken and depth was measured. A total of 14,320 individuals, in 111 species (RZ ? 18; MZ ? 50, and CZ - 66) were collected. Distinct fish assemblages were found for each zone, as indicated by low number of common species (14 - MZ and CZ; 8 - MZ and RZ; and 2 - CZ and RZ), and only one abundant species (> 1% of the total number of fish within the zone) being common in more than one zone (Eucinostomus argenteus in CZ and MZ). Such pattern can be related to high salinity variation in MZ and narrow (20 m) channel width connecting the estuary with the sea, which can limit fish movement (into/out of the estuary). In CZ, the three more abundant species were Paralonchurus brasiliensis, Ctenosciaena gracillicirrhus, Anchoa lyolepis, Larimus breviceps and Stellifer brasiliensis, with large contribution of fish from the Scieanidae family in this zone (18 species). Spatial changes inf fish species were not consistent in CZ, probably due to lack of spatio-temporal estuarine plume influence on depth environmental variables (ANOVA, p>0.05). Depth was the main factor to influence spatial changes for Diapterus rhombeus (negative association) more abundant in C1 (average depth = 10 m; ANOVA, p<0.05) and Micropogonias furnieri, P. brasiliensis and Pellona harroweri (positive association) more abundant in C2 (average depth = 17 m; ANOVA, p<0.00). Diapterus rhombeus and Etropus crossotus occured mainly in Spring and Summer, and Eucinosomus gula in Spring. The most abundant species in CZ, typical of high salinty influence, is a indication that this zone have characteristics to inner continental shelf. In MZ, most abundant species (Eugerres brasilianus, Eucinostomus melanopterus, Trinectes paulistanus, Gobionellus shufeldti, G. oceanicus, Geophagus brasiliensis, Centropomus parallelus and Citharichthys arenaceus) have higher number and weight of individuals in M1 (ANOVA, p<0.01), an adjacent lagoon connected to the main channel. In spite of the significant negative correlation between this species and salinity (r-Spearman>0.32, p<0.01), the more sheltered areas in M1 seem to be more important to determine this pattern than salinity itself. The site M1 also have more number of individuals and species (ANOVA, p<0.01), and larger number of fish of smaller size (CT median = 58mm) compared to M2 and M3, located in the main channel (median = 106mm) according to Median and Kruskall-Wallis tests (p<0.01; 2 = 1167.5), indicating the importance of this area for species recruitment. Low average similarity (SIMPER) for sites M2 (38.7%) and M3 (17.8%) indicate larger variability of assemblage in these sites, probably due to lesser habitat structure e higher dynamism. In RZ, the fish assemblage have few species (5) with abundance higher than 1% of the total number of fishes, being dominated by Dormitator maculatus, Astyanax sp and ix Microphis brachyurus lineatus, species typical of upper estuaries and lower river reaches. Spatial variation was detected for D. maculatus only, more abundant at R2, a site with abundant riparian vegetation, mainly grass. Dormitator maculatus was more abundant in Summer and Autumn, M. brachyurus lineatus, in Spring, Autumn and Winter and Astyanax sp was absent in Spring only. Patterns in fish assemblage structure were at large scale, primarily species-specific responses to dominant environmental gradient, while at small scale, results of association with the habitat. / Os sistemas estuarinos influenciam as assembl?ias de peixes, ao longo de seus gradientes longitudinais e das marcadas varia??es da salinidade. Estas assembl?ias se adaptam ?s diferentes condicionantes do habitat e variam em escalas espaciais e temporais. O objetivo do presente estudo foi avaliar a composi??o e estrutura da ictiofauna em tr?s zonas do estu?rio do rio Mambucaba (ZC ? zona costeira; ZM ? zona de mistura e ZR ? zona de rio) e suas rela??es com as vari?veis ambientais e caracter?sticas do habitat destas zonas. Coletas sistem?ticas de peixes (2 meses por esta??o do ano) foram realizadas entre outubro de 2007 e agosto de 2008, com arrastos de fundo em dois locais da ZC (C1 e C2), arrasto de praia em 3 locais da ZM (M1, M2, M3) e peneira em 2 locais da ZR (R1 e R2). Em cada amostragem de peixes, foram tomadas, para a superf?cie e fundo, as vari?veis ambientais de temperatura, salinidade, condutividade, turbidez e oxig?nio dissolvido, bem como medida a profundidade. Um total de 14320 indiv?duos, constitu?dos por 111 esp?cies (ZR ? 18; ZM ? 50 e ZC - 66) foram coletados. Assembl?ias de peixes distintas foram identificadas para cada zona, indicadas pelo baixo n?mero de esp?cies comuns (14 - ZM e ZC; 8 - ZM e ZR; e 2 - ZC e ZR), e com apenas uma esp?cie abundante (> 1% do numero total de peixes na zona) comum em mais de uma zona (Eucinostomus argenteus na ZC e ZM). Tal padr?o pode estar relacionado ? maior variabilidade da salinidade existente na ZM e a estreita (20 m) largura do canal de conex?o com o mar, fatores que podem ser limitantes aos movimentos (entrada/sa?da) de peixes. Na ZC, as tr?s esp?cies mais abundantes foram Paralonchurus brasiliensis, Ctenosciaena gracillicirrhus, Anchoa lyolepis, Larimus breviceps e Stellifer brasiliensis, com a maior participa??o de peixes da fam?lia Sciaenidae nesta zona (18 esp?cies). As varia??es espaciais das esp?cies foram pouco consistentes na ZC, provavelmente relacionado a influencia da pluma estuarina n?o ter provocado mudan?as espa?o-temporais nas vari?veis ambientais de fundo (ANOVA, p>0,05). A profundidade foi o principal fator respons?vel pela separa??o espacial encontrada para Diapterus rhombeus (associa??es negativas) mais abundante em C1 (profundidade m?dia = 10 m; ANOVA, p<0,05) e Micropogonias furnieri, P. brasiliensis e Pellona harroweri (associa??es positivas) mais abundantes em C2 (profundidade m?dia = 17 m; ANOVA, p<0,00). Diapterus rhombeus e Etropus crossotus ocorreram principalmente na primavera e ver?o, e Eucinosomus gula na primavera. As esp?cies mais abundantes da ZC, t?picas de ?guas com maior influencia salina, ? um indicativo de que esta zona tem caracter?sticas mais associadas ? plataforma continental interna. Na ZM, a maioria das esp?cies mais abundantes (Eugerres brasilianus, Eucinostomus melanopterus, Trinectes paulistanus, Gobionellus shufeldti, G. oceanicus, Geophagus brasiliensis, Centropomus parallelus e Citharichthys arenaceus) apresentou maior n?mero e peso de indiv?duos em M1 (ANOVA, p<0,01), uma lagoa adjacente conectada ao canal principal. Apesar das correla??es negativas significativas observadas entre estas esp?cies e a salinidade (r-Spearman>0.32, p<0,01), as ?reas mais abrigadas em M1 parecem ser mais determinantes neste padr?o do que a salinidade em si. O local M1 tamb?m apresentou o maior n?mero de indiv?duos e de esp?cies (ANOVA, p<0,01), com maior n?mero de peixes de menor tamanho (CT mediana = 58mm) do que dos locais M2 e M3, situados no canal principal (mediana = 106mm) de acordo com o Teste das Medianas e Teste de Kruskallvii Wallis (p<0,01; 2 = 1167,5), indicando a import?ncia desta ?rea para o recrutamento das esp?cies. A baixa similaridade m?dia (SIMPER) para os locais M2 (38,7%) e M3 (17,8%) indicam uma maior variabilidade na assembl?ia destes locais, possivelmente devido a menor estrutura??o do habitat e maior dinamismo. Na ZR, a assembl?ia de peixes apresentou poucas esp?cies (5) com abund?ncia maior que 1% do n?mero total de peixes, sendo dominada por Dormitator maculatus, Astyanax sp e Microphis brachyurus lineatus, esp?cies t?picas de ?reas lim?trofes entre a zona superior do estu?rio e a zona baixa de rio. Varia??es espaciais foram detectadas apenas para D. maculatus, mais abundantes em R2, um local com abundante vegeta??o marginal composta principalmente por gram?neas. D. maculatus foi mais abundante no ver?o e outono, M. brachyurus lineatus, na primavera, outono e inverno e Astyanax sp foi ausente somente na primavera. Os padr?es na estrutura da assembl?ia de peixes s?o, em maior escala, primariamente resultado das respostas individuais das esp?cies ao gradiente ambiental dominante, enquanto em menor escala, resultado das associa??es com o habitat.

Ecosystem-level changes have taken place in the Mediterranean Sea over the last decades due to both anthropogenic interferences and natural perturbations. Compared to the western Mediterranean Sea, influences of these factors especially on flora and fauna characteristics are much more dramatic and intense in the eastern part, particularly in the northeastern Levant Sea where the study area is located. In this study, life history traits of some core species (both native and immigrant) occupying the continental shelf of the northeastern Levant Sea were studied in this changing ecosystem to improve limited ecological understanding of the demersal fish assemblages of the northeastern Levant Sea. For this purpose, the annual patterns in allocation and utilization of energy in demersal fish species, temporal and bathymetrical trends in fish distribution with respect to biological requirements of the species and strategies adapted by the species in growth, reproduction and energy storage were investigated by examining growth parameters, biological indices and abundance and biomass variations. Influences of environmental variables on spatiotemporal distribution and biological characteristic of Mullus barbatus were also explored by generalized additive models. Biological data were collected at monthly intervals between May 2007 and May 2010 by trawl sampling while sample collection of environmental variables (temperature and salinity) was performed from December 2008 to May 2010. Results of this study reveal that the components of the demersal fish assemblage in the region fulfill their biological activities within a short period of time when the highest productivity is reached in the area. Moreover, results indicate that within this short period of time, some native components of the demersal fish assemblages studied (Mullus barbatus and Pagellus erythrinus) exhibit strategies such as fast growth, early maturation, short reproduction season, secondary spawners to cope with the environmental peculiarities. On the other hand, the successful exotic colonizers develop strategies as well but these successful immigrants also use time (Lagocephalus suezensis) and space (depth) (Upeneus pori) slot that the native species avoid. In some of the species examined (Mullus barbatus and Lagocephalus suezensis), growth is fast, sexual maturity is early, reproduction period is short, and reproduction potential is high. With the peculiar environmental condition, these life history traits are attributed to the &ldquo / r-strategy&rdquo / of the species. In this study, generalized additive models of Mullus barbatus explain 81.5 % variations in Gonadosomatic Index (GSI), 55.2 % in Hepatosomatic Index (HSI) and 43.9 % in Condition Factor (K). The time component in the GAM model captures the same cyclic pattern observed in GSI of Mullus barbatus. Besides, The GAM results suggest that the highest GSI values associated with the bottom water temperature are between 18 &ndash / 19 &deg / C while the partial effect of bottom salinity is at 38.7 psu. A positive effect of depth on GSI of the species starts after 60 meters depth and increasing trend continues until 125 meters depth and then decreases. The HSI results are almost identical to GSI outputs indicating that the effects of the parameters concerned act in a similar manner. The results of the GAM models failed to explain influence of environmental parameters on vertical and seasonal distribution of adult Mullus barbatus. However 83.5 % variances were explained in distribution of juveniles. The salinity and temperature have the highest impact on the distribution of juveniles among the parameters evaluated. The results indicate that the occurrence of Atlantic Water in the area has a positive influence on M. barbatus, particularly on the recruits through either by its low salinity or by another factor associated with this water mass. The vertical distribution range are set by the high temperatures (&gt / 27 &deg / C) at the shallow depths during summer and the low temperatures on the shelf break zone (&lt / 16 &deg / C). A comparison of vertical abundance distribution of Mullus barbatus and the vertical temperature variations indicate that the species may tolerate up to 27 &deg / C and then individuals move to the deeper depths so that to the cooler waters when the temperature exceeds their tolerance limit. As well as the life history traits adopted by the species, there are some other factors providing advantages to the species. The fisheries regulations, particularly the time limits applied in the area are in favor of the species especially of pre-recruits. In the study area the pre-recruitment phase and summer YOY aggregations in shallow waters of most species studied in this thesis take place during a time when the fishing season is closed.

The hills of Yazoo Basin have a long history of land use modification and subsequent erosion and flood control issues. In response, federal actions were taken to address these issues beginning after the Mississippi River flood of 1927. Four major flood control reservoirs were built in 1932-1957, and instream low-drop grade control structures (GCS) were installed beginning in the 1980s. The objective of my dissertation was to ascertain the long-term effects of these efforts on stream fish assemblages and channel morphology. To assess whether the reservoirs affected upstream fish assemblages as barriers to recolonization by fluvial fishes or as source population for invasion by lentic generalist fishes (Chapter 1), I used stream data collected 43-61 years after the rivers were impounded to test for differences in fish assemblages between sites upstream and downstream of the reservoirs. Analysis of catch per effort and diversity metrics displayed little influence of the reservoirs, but trait-based analysis revealed marginal increases in planktivores, herbivores, detritivores, and generalists in upstream assemblages. After determining that potential effects of reservoirs would not confound further analysis, I assessed the effects of GCS on channel morphology (Chapter 2) and fish assemblages (Chapter 3) 30 years post-installation. To assess GCS effects on channel morphology, stream cross-sections were used to calculate Bank Height Ratio, Width/Depth Ratio, and Entrenchment Ratio, while point estimates made along the transects were used to calculate the average sediment size distribution. Analyses revealed that the GCS were successful in checking channel incision moving headward in the streams: sites upstream of the GCS were less incised and had greater accumulations of fine substrates compared to downstream sites and sites on streams lacking erosion control structures. The GCS could potentially affect fish assemblages through habitat modification or by selectively filtering the assemblages as a barrier to upstream migration. Analysis of beta diversity revealed that diversity was driven by species replacement rather than nestedness, which indicates GCS were not acting as filters on the assemblages. Analysis of catch per effort data confirmed differences in assemblage structure that echoed the instream habitat differences revealed in Chapter 2.

No description available.