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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Diversidade de Hydropsychidae Curtis e Leptoceridae Leach (Insecta, Trichoptera) em riachos do Parque Estadual Intervales, Serra de Paranapiacaba, Estado de São Paulo / Diversity of Hydropsychidae Curtis e Leptoceridae Leach (Insecta, Trichoptera) in streams of Parque Estadual Intervales, Serra de Paranapiacaba, Estado de São Paulo.

Rafael Alberto Moretto 13 February 2012 (has links)
A presente dissertação de mestrado resume-se a um estudo da diversidade de Leptoceridae e Hydropsychidae (Insecta, Trichoptera) do Parque Estadual Intervales, Estado de São Paulo, objetivando diminuir as lacunas distribucionais das espécies e facilitar o acesso de tais informações a outros pesquisadores, fornecendo subsídios taxonômicos para futuros trabalhos ecológicos ou de cunho conservacionista, aumentando assim, o conhecimento sobre as famílias Leptoceridae e Hydropsychidae e, consequentemente, sobre a ordem Trichoptera. A coleta foi realizada em dez riachos entre os meses de julho e agosto de 2010. O material coletado foi triado, preparado e identificado até o nível taxonômico de espécie. Análises quantitativas e testes estatísticos foram realizados para a determinação da riqueza e a abundância das duas famílias, além de, a partir das informações bióticas e abióticas nos diferentes riachos e das localidades de coleta, tentar inferir quais fatores ambientais são determinantes na distribuição faunística de tricópteros entre os diferentes riachos. Foi criada também uma checklist para as espécies de Leptoceridae e Hydropsychidae que ocorrem no Parque Estadual Intervales. Com a análise do material coletado, foi possível o reconhecimento de novas espécies e novos registros de espécies para o Estado de São Paulo. As novas espécies foram descritas ou encaminhadas para tricopterólogos especialistas, aumentando assim o conhecimento taxonômico do grupo em questão e contribuindo diretamente para a diminuição entre a diferença no número de espécies descritas na literatura e as estimativas do número de espécies existentes. / This dissertation summarizes a study of the diversity of Leptoceridae and Hydropsychidae (Insecta, Trichoptera) in Parque Estadual Intervales streams, State of São Paulo, aiming to reduce the distributional gaps of species and facilitate the access of such information to other researchers, providing subsidies for future taxonomic or ecological studies and for nature conservation, and increasing the knowledge about the families Leptoceridae and Hydropsychidae and, consequently, of the order Trichoptera. Data were obtained between July and August 2010, when ten streams were sampled. The collected material was sorted, prepared and identified to the taxonomic level of species. Quantitative analysis and statistical tests were performed to determine the richness and abundance of the two families. Biotic and abiotic information from different streams and sampling localities were also analysed, trying to infer which environmental factors are determinant in the distribution of the fauna of caddisflies. A checklist of the species of Leptoceridae and Hydropsychidae from Parque Estadual Intervales is also presented. The analysis of the collected material showed the presence of new species; these were described or sent to experts, thus increasing the taxonomic knowledge of the Trichoptera and contributing to decrease the difference between the number of described species and estimates of the number of existing species.
22

Ciclo de vida, produtividade secundária, distribuição, alimentação e crescimento de Massartella brieni (Lestage) (Ephemeroptera: Leptophlebiidae) em riachos do Parque Estadual Intervales, Estado de São Paulo / Life cycle, secondary production, distribution, feeding habits and growth of Massartela brieni from streams of the Parque Estadual Intervales, State of São Paulo

Gabriel de Paula Paciencia 29 July 2008 (has links)
O presente trabalho teve como objetivo geral estudar o ciclo de vida, a produtividade secundária, a distribuição, a alimentação e o crescimento de Massartela brieni em riachos do Parque Estadual Intervales, Estado de São Paulo. O material analisado foi coletado em seis pontos de coleta, um no córrego Roda d´Água, um no córrego Mirante, um no córrego Bocaina, dois no córrego Água Comprida e um no córrego Lajeado. Em todos os pontos, substrato rochoso foi coletado com um amostrador de Surber com 0,250 mm de malha, em cada amostragem foram feitas 10 subamostras aleatórias perfazendo o total de 1m2. No Córrego Bocaina, folhiço em corredeira e em remanso também foram amostrados com rede D (10 pacotes de folhiço com 0,01 m2 cada). As coletas foram feitas entre Setembro/1999 e Setembro/2001. A análise dos histogramas referentes ao número de indivíduos em diferentes classes de tamanho foi inconclusiva quanto ao voltinismo da espécie estudada. A produtividade secundária anual de Massartella brieni foi 4802,79 mg.m-2ano-1 para um CPI de 120 dias, 3842,24 mg.m-2ano-1 para um CPI de 150 dias e 3201,86 mg.m-2ano-1 para um CPI de 180 dias. Os resultados indicam que M. brieni ocorreu preferencialmente em locais com menor velocidade de água associados com acúmulo de folhiço. Não houve uma relação linear negativa entre a vazão, a precipitação (mês anterior) e a densidade de M. brieni no córrego Mirante. No entanto, foi possível observar que meses com maior vazão ou precipitação (mês anterior) nunca apresentaram altas densidades. Na maior parte dos meses, os períodos com baixas densidades também foram os que apresentaram menor biomassa, exceto para os meses de Março a Maio de 2000 (meses que ocorreram indivíduos de maior porte). Durante o crescimento a maior parte das estruturas da cabeça tiveram alometria negativa, enquanto que as do abdômen e a maior parte das do tórax tiveram alometria positiva. A mudança de forma da maxila (Deformação Relativa I) teve uma leve relação significativa com o crescimento de M. brieni. / The present work had as general aim to study the life cycle, secondary production, distribution, feeding habits and growth of Massartela brieni from streams of the Parque Estadual Intervales, State of São Paulo. The analyzed material was collected in six collection stations, one in Roda d´Água stream, one in Mirante stream, one in Bocaina stream, two in Água Comprida stream and one in Lajeado stream. In all stations, rocky substratum was collected with Surber sampler with 0,250 mm of mesh, in each sampling 10 sampling units were taken randomily, totalling 1m2. In the Bocaina stream, litter in riffles and in pools were also sampled with D net (10 litter patches with 0,01 m2 each). The collections were carried out between September/1999 and September/2001. The analysis of size frequency histograms representing the number of individuals in different classes of size was inconclusive in relation to voltinism of the studied species. The annual secondary production of Massartella brieni was 4802,79 mg.m-2yr-1 for a CPI of 120 days, 3842,24 mg.m-2yr-1 for a CPI of 150 days and 3201,86 mg.m-2yr-1 for a CPI of 180 days. The results indicate that M. brieni occurred preferentialy in sites with lesser water speed and with litter accumulations. There was not a negative linear relation between the discharge and the precipitation (previous month) with density of M. brieni in Mirante stream. However, it was possible to observe that months with higher discharge or precipitation (previous month) did not present high densities. For the most part of the months, the periods with low densities had lesser biomass, except for the months from March to May of 2000 (months in which individuals of larger size occurred). During the growth, the most of the structures of the head had negative allometry, whereas of the abdomen and most measurements of the thorax had positive allometry. The change of shape of the maxillae (Relative Warps I) had a slight significant relationship with the growth of M. brieni.
23

Protistas Ciliados (Protista, Ciliophora) encontrados no Córrego São Pedro (Bacia do Rio Paraibuna), município de Juiz de Fora, Minas Gerais: taxonomia, morfologia, biomonitoramento e relações epibióticas

Dias, Roberto Júnio Pedroso 26 February 2007 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-05-10T11:33:41Z No. of bitstreams: 1 robertojuniopedrosodias.pdf: 16324224 bytes, checksum: d89ac49f5783a9ad6211a6e7c47c0824 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T15:03:54Z (GMT) No. of bitstreams: 1 robertojuniopedrosodias.pdf: 16324224 bytes, checksum: d89ac49f5783a9ad6211a6e7c47c0824 (MD5) / Made available in DSpace on 2017-05-17T15:03:54Z (GMT). No. of bitstreams: 1 robertojuniopedrosodias.pdf: 16324224 bytes, checksum: d89ac49f5783a9ad6211a6e7c47c0824 (MD5) Previous issue date: 2007-02-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No presente trabalho, foram estudados os aspectos da taxonomia e morfologia dos protistas ciliados encontrados no córrego São Pedro (Juiz de Fora, MG), bem como o potencial destes microorganismos como indicadores da qualidade da água e ainda os aspectos ecológicos das relações epibióticas entre os ciliados e alguns macroinvertabrados bentônicos. A presente dissertação está dividida em sete capítulos. No capítulo 1, foi realizado o inventário dos ciliados encontrados em cinco estações amostrais do córrego, durante um ano de estudo, e foi observada a sucessão destes protistas em laboratório. Foram identificadas 42 espécies de ciliados e caracterizou-se morfologicamente Apoamphisiella sp. nov. (Spirotrichea, Amphisiellidae). No capítulo 2, foi descrito um doublet do tipo imagem espelhada em Gastrostyla setifera (Spirotrichea, Oxytrichidae), obtida de amostras de água e sedimento de uma estação amostral do córrego São Pedro. O capítulo 3 registra a presença de Neobursaridium gigas (Oligohymenophorea, Neobursaridiidae) no córrego e apresenta uma revisão dos aspectos morfológicos, ecológicos e da distribuição geográfica deste ciliado. No capítulo 4, verificou-se a influência da poluição orgânica sobre a composição e a distribuição da taxocenose de protistas ciliados ao longo do córrego, com o objetivo de avaliar a qualidade da água deste sistema lótico. Durante o estudo de um ano, em cinco estações amostrais ao longo do córrego, foram encontradas 39 espécies de protistas ciliados, das quais 32 estão incluídas no sistema sapróbio e são consideradas bioindicadoras. A composição e a distribuição da taxocenose de protistas ciliados variaram espacial e temporalmente. O índice sapróbio e o índice de valência sapróbia foram utilizados para avaliar a qualidade da água das cinco estações amostrais e demonstraram o alto grau de poluição das estações 4 e 5. Os dados obtidos confirmam que, em águas correntes, a poluição orgânica parece ser um fator determinante, capaz de influenciar a composição, a distribuição e a estrutura trófica da taxocenose de protozoários ciliados. Os capítulos seguintes versam sobre as associações epibióticas dos protistas ciliados com moluscos, oligoquetas e larvas de insetos. No capítulo 5, foram registradas sete espécies de ciliados sobre as conchas de Pomacea figulina, sendo seis pertencentes à subclasse Peritrichia: Carchesium polypinum, Vorticella microstoma, Vorticella campanula, Epistylis plicatilis, Epistylis sp., Opercullaria sp. e uma pertencente à subclasse Suctoria: Hypophrya fasciculata. Os resultados são discutidos em termos das vantagens e desvantagens desta relação para os protistas ciliados e dos aspectos ecológicos envolvidos nesta associação. No capítulo 6, foram investigados o sítio de localização e o padrão de distribuição espacial e temporal de protistas ciliados peritríquios do gênero Rhabdostyla colonizando oligoquetas límnicos tubificídeos da espécie Limnodrilus hoffmeisteri (Oligochaeta, Tubificidae) nas cinco estações amostrais do córrego, ao longo de 11 meses de coleta. O padrão de ocorrência dos epibiontes sobre os oligoquetas apresentou heterogeneidade espacial e temporal. Os resultados são discutidos em termos das possíveis causas da localização dos ciliados preferencialmente na região posterior dos oligoquetas e dos fatores relacionados ao padrão de distribuição espacial e temporal heterogêneo. E finalmente, o capítulo 7 relata a ocorrência de Rhabdostyla chironomi (Ciliophora, Peritrichia) sobre larvas de Chironomus decorus (Diptera, Chironomidae) no córrego e reporta, ainda, os fatores envolvidos na localização dos ciliados sobre os túbulos abdominais dos hospedeiros e a possível utilização desta relação como indicadora da qualidade da água. / In the present study, both taxonomy and morphology aspects of the ciliate protists found in São Pedro stream (Juiz de Fora-MG), as well as their potential as water quality indicators were studied together with the ecological aspects of the epibiotic relation between the ciliate and some benthic macroinvertebrates. The present dissertation is divided into seven chapters. In chapter 1, the survey of ciliate protists was obtained from samples of water and sediment from the stream, during a hole year, and the succession of these protists was observed in laboratory. Forty-two ciliate species were identified and Apoamphisiella sp. n. (Spirotrichea, Amphisiellidae) was morfologically characterized. In chapter 2, mirror-image doublet was described in Gastrostyla setifera (Spirotrichea, Oxytrichidae), obtained from samples of water and sediment at the São Pedro stream. The Chapter 3 registers the presence of Neobursaridium gigas Balech, 1941 (Oligohymenophorea, Neobursaridiidae) in the stream and presents a revision of the morphological aspects of this ciliate, as well as its ecological and geographical distribution. In chapter 4, the influence of the organic pollution on both the composition and the distribution of the taxocenose of ciliate protists along the stream had the aim of evaluating the water quality of this lotic system. During the one year study, 39 ciliate protist species were found, 32 of which were included in the saprobic system and their potencial as indicators are considered. The composition and the distribution of the taxocenose of ciliate protist varied both spatial and seasonally. The saprobic index and the valency methods were used to evaluate the water quality at the five stations and they demonstrated the high degree of pollution on stations 4 and 5. Our results confirm that the organic load in watercourses may be a dominating factor capable of influencing the composition, distribution and trophic structure of the taxocenose of ciliate protist. The following chapters consider the epibiotic ciliate protist associations to mollusks, oligochates and insect larvae. In chapter 5, seven ciliate species were registered on the shells of Pomacea figulina, six of which belonging to the subclass Peritrichia: Carchesium polypinum, Vorticella microstoma, Vorticella campanula, Epistylis plicatilis, Epistylis sp., Opercullaria sp. and one belonging to the subclass Suctoria: Hypophrya fasciculata. Results are discussed in terms of the advantages and disadvantages of this relationship from the ciliate protist point of view, together with the ecological aspects involved in this association. In chapter 6, location ranch and both spatial and temporal distribution patterns of Rhabdostyla peritrichids were found colonizing limnic oligochaetes Tubificidae of the species Limnodrilus hoffmeisteri in the five amostral stations, during 11 months of collection. The occurrence pattern of the epibionts on the oligochaetes was spatial and seasonally heterogeneous. Results are discussed in terms of the possible causes for the site preference of the ciliates in the posterior region of the oligochaetes and factors related to the heterogeneous pattern of space and temporal distribution. Finally, chapter 7 registers the occurrence of Rhabdostyla chironomi (Ciliophora, Peritrichia) on Chironomus decorus larvae (Diptera, Chironomidae) in the stream and still it moderates the factors involved in the location of the ciliates on the ventral tubules of its hosts and the possible usage of this relationship as indicative of the water quality.
24

Cenário ambiental da Bacia Hidrográfica do Arroio Grande a partir das diatomáceas epíliticas e fatores abióticos / Environmental setting of arroio grande hydrographical basin from epilithic diatoms and abiotic factors

Silva, Juliana Ferreira da 26 February 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Activities carried on around aquatic systems are reflected in the water quality of these environments as well as in their biotic communities. Epilithic diatomsare known effective bioindicators.This study aimed to assess the environmental situation of the Arroio Grande Hydrographical Basin, RS, Brazil, situated in agricultural land and away from urban occupation. Monthly samplings of water and epilithic diatoms were carried out from October 2012 to March 2013 in thirteen sampling points. Permanent slides for the analysis of diatom communities were mounted andat least 600 valves per slide were counted to estimate the relative abundance. Taxa were identified to species level. Dissolved oxygen, conductivity, turbidity and water temperature were measured on site while pH, biochemical oxygen demand, alkalinity, hardness, nitrate, nitrite, phosphate and pesticides were analysed in the laboratory. 110 taxa belonging to 22 families and 39 genera were identified.The most representative families were Sellaphoraceae (20) followed by Naviculaceae (15) and Cymbellaceae (12). The sampling sites with higher species richness were the points on the west side of the basin. The richest genera were GomphonemaEhrenberg, Sellaphora Mereschkowskyand Navicula Bory. Diatom relative abundance and abiotic variables results were analysed by multivariate ordination and Anosim. The greatest variation was found among sampling months and a spatial gradient has not been identified.Althought water quality in the area was found to be good, the diatom community has responded to the various agricultural activities carried out along the sampling period. / As atividades exercidas no entorno de ambientes aquáticos são refletidas na qualidade da água desses ambientes assim como nas comunidades que os habitam. As diatomáceas epiliticas desempenham satisfatoriamente esse papel bioindicador. Diante disso, o presente trabalho teve como objetivo avaliar a situação ambiental da Bacia Hidrográfica do Arroio Grande, RS, Brasil, uma bacia de área predominentemente agrícola. Amostragens mensais de água e diatomáceas epilíticas foram realizadas de outubro de 2012 a março de 2013 em treze pontos amostrais. Foram confeccionadas lâminas permanentes para a análise das comunidades de diatomáceas, com contagem de no mínimo 600 valvas por lâmina para estimativa da abundância relativa e identificação das espécies presentes. Oxigênio dissolvido, condutividade elétrica, turbidez e temperatura da água foram medidos no local enquanto o pH, demanda química de oxigênio, alcalinidade, dureza, nitrato, nitrito, fosfato e agroquímicos em laboratório. Foram identificados 110 táxons pertencentes a 22 famílias e 39 gêneros e 77 táxons abundantes.As famílias mais representativas foram Sellaphoraceae (20) seguida porNaviculaceae (15) e Cymbellaceae (12). Os pontos amostrais com maior riqueza específica foram os pontos situados do lado oeste da bacia. Os gêneros mais ricos em espécies foram Gomphonema Ehrenberg, Sellaphora Mereschkowskye Navicula Bory.As análises de ordenamento e a ANOSIM revelaram uma estruturação ambiental principalmente por mês de coleta, sendo que um gradiente espacial não foi identificado. A situação ambiental da Bacia Hidrográfica do Arroio Grande a partir dos fatores abióticos e bióticos não se mostrou degradada pelas atividades exercidas ao seu entorno, porém mesmo em curto prazo pode-se observar uma resposta das comunidades as atividades exercidas.
25

An Assessment of Environmental Dna as a Tool to Detect Fish Species in Headwater Streams

Jane, Stephen F 01 January 2014 (has links) (PDF)
Recent years have seen an explosion of interest in the use of freely available DNA present in aquatic systems, otherwise known as environmental DNA (eDNA), as a tool for monitoring aquatic organisms. However, much remains unknown about the behavior of eDNA over a range of environmental conditions. This is particularly true in high gradient headwater streams, which have received less attention than other types of water bodies. In the summer of 2011, a headwater stream system with well established species distributions was sampled using eDNA techniques. Though species were detected where known to be present, detections also occurred where traditional techniques failed to detect species. This suggests that a cautious approach to positive eDNA detections is advisable. In 2012 a second study was conducted to better understand the dynamics of eDNA concentration in lotic systems. Caged brook trout (Salvelinus fontinalis) were introduced into two otherwise fishless headwater streams, and eDNA samples were collected at evenly spaced intervals downstream of the cage. This was repeated 19 times from mid-summer through autumn, over flows ranging from approximately 1 to 96 l/sec. Quantitative PCR was used to relate DNA copy number to distance from source for each of these 19 sampling events. In all cases, DNA was detectable at 239.5 m from the cage. Increasing flows generally decreased eDNA copy number near the cage but had relatively little effect at downstream sites. Additionally, the presence of leaf biomass during the fall period had the potential to completely erase otherwise high DNA levels.
26

Changes in Benthic Algal Community Structure Following an Unpredictable Stream-Wide Desiccation Event

Bambakidis, Theodore 28 July 2009 (has links)
No description available.
27

The Lotic-Lentic Gradient in Reservoirs and Estuaries

Ruhl, Nathan A. 11 September 2012 (has links)
No description available.
28

Environmental and Digital Data Analysis of the National Wetlands Inventory (NWI) Landscape Position Classification System

Sandy, Alexis Emily 27 July 2006 (has links)
The National Wetlands Inventory (NWI) is the definitive source for wetland resources in the United States. The NWI production unit in Hadley, MA has begun to upgrade their digital map database, integrating descriptors for assessment of wetland functions. Updating is conducted manually and some automation is needed to increase production and efficiency. This study assigned landscape position descriptor codes to NWI wetland polygons and correlated polygon environmental properties with public domain terrain, soils, hydrology, and vegetation data within the Coastal Plain of Virginia. Environmental properties were applied to a non-metric multidimensional scaling technique to identify similarities within individual landscape positions based on wetland plant indicators, primary and secondary hydrology indicators, and field indicators of hydric soils. Individual NWI landscape position classes were linked to field-validated environmental properties. Measures provided by this analysis indicated that wetland plant occurrence and wetland plant status obtained a stress value of 0.136 (Kruskal's stress measure = poor), which is a poor indicator when determining correlation among wetland environmental properties. This is due principally to the highly-variable plant distribution and wetland plant status found among the field-validated sites. Primary and secondary hydrology indicators obtained a stress rating of 0.097 (Kruskal's stress measure = good) for correlation. The hydrology indicators measured in this analysis had a high level of correlation with all NWI landscape position classes due the common occurrence of at least one primary hydrology indicator in all field validated wetlands. The secondary indicators had an increased accuracy in landscape position discrimination over the primary indicators because they were less ubiquitous. Hydric soil characteristics listed in the 1987 Manual and NTCHS field indicators of hydric soils proved to be a relatively poor indicator, based on Kruskal's stress measure of 0.117, for contrasting landscape position classes because the same values occurred across all classes. The six NWI field–validated landscape position classes used in this study were then further applied in a public domain digital data analysis. Mean pixel attribute values extracted from the 180 field-validated wetlands were analyzed using cluster analysis. The percent hydric soil component displayed the greatest variance when compared to elevation and slope curvature, streamflow and waterbody, Cowardin classification, and wetland vegetation type. Limitations of the soil survey data included: variable date of acquisition, small scale compared to wetland size, and variable quality. Flow had limitations related to its linear attributes, therefore is often found insignificant when evaluating pixel values that are mean of selected pixels across of wetland landscape position polygons. NLCD data limitations included poor quality resolution (large pixel size) and variable classification of cover types. The three sources of information that would improve wetland mapping and modeling the subtle changes in elevation and slope curvature that characterize wetland landscapes are: recent high resolution leaf-off aerial photography, high-quality soil survey data, and high-resolution elevation data. Due to the data limitations and the choice of variables used in this study, development of models and rules that clearly separate the six different landscape positions was not possible, and thus automation of coding could not be attempted. / Master of Science
29

POPULATION GENETIC STRUCTURE OF <em>NECTURUS MACULOSUS</em> IN CENTRAL AND EASTERN KENTUCKY

Murphy, Mason Owen 01 January 2016 (has links)
Population structure is influenced by extrinsic factors, such as landscape architecture and dispersal barriers. Lotic network architecture is known to constrain ecological, demographic and evolutionary processes, including population genetic structure. I assessed the population structure of a widespread aquatic salamander, Necturus maculosus, across three river basins in central and eastern Kentucky. I examined the role of network architecture, anthropogenic barriers, and spatial scale on patterns of population structure. I also provided a review of N. maculosus capture methods and offer an improved trap design. I identified significant structuring between the combined Licking/Kinniconick basin and the Kentucky River basin, with further structure within each basin. I found evidence for both hierarchically organized populations structure (e.g. Stream Hierarchy Model), as well as population structure unaffected by network hierarchy (e.g. Death Valley Model). These results highlight the importance of scale when examining population structure. Whereas one model may suffice to explain population structure at a local scale, a second model may be necessary to accurately describe the population structure across larger spatial scales. These results suggest that local factors affect population structure uniquely across a species’ range, and support a multi-model approach for assessing population structure.
30

Stream channelization effects on fish abundance and species composition

Johansson, Ulf January 2013 (has links)
Streams are important habitats, providing shelter and feeding opportunities for a wide range of organisms. The species depending on running waters includes a wide array of fish species, using these waters for their whole or parts of their lifecycle. Streams are also the subject of different anthropogenic impact, e.g. hydropower development. Hydropower development usually means lost connectivity, altered flow regimes and channelization. Channelization is one of the major factors causing stream habitat loss and degradation and thereby a threat to biodiversity of running waters. In the present study, the ecological impact of channelization on the fish fauna along a gradient of channelization severeness was examined. Besides channelization, stream velocity and depth were taken in to account. The study was carried out in two adjacent nemoboreal streams, Gavleån and Testeboån. The study was conducted between the 6th of June and the 10th of October 2012 at 15 sites. Sites were selected using historical maps and field observations and graded 0-3 depending on the degree of channelization. Fish community were sampled with, Nordic multi-mesh Stream Survey Net (NSSN). In all, 1.465 fish were captured, representing 15 species and seven families. The sites differed in species richness, abundance and proportion of individuals. Based on the results from rarefaction curves and ANOVA, channelization was found to be the main factor affecting the fish biota, both in abundance as well as species richness and composition. In general the rheophilic species declined along the gradient of increasing channelization severeness, while limnophilic species increased

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