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Impactos de pequenas obras de regularização nas comunidades de invertebrados e peixes da bacia hidrográfica do Rio Tua (Bacia do Douro, Portugal)

Sarmento, Sara Isabel Fernandes
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
26.5%
São conhecidos os impactos negativos da construção de grandes barragens no funcionamento de ecossistemas lóticos. No entanto, permanece por esclarecer a influência de pequenas obras de regularização em ecossistemas aquáticos de montanha, nomeadamente em vários rios do Nordeste Transmontano onde estão já implantados alguns Aproveitamentos Hidroelétricos, perspetivando-se, num curto prazo de tempo, a construção de mais alguns empreendimentos. O objetivo do presente trabalho consistiu na avaliação dos impactos dos Aproveitamentos Hidroelétricos das Trutas, Nunes, Torga e Rebordelo na qualidade ecológica dos cursos de água da bacia hidrográfica do rio Tua. Realça-se que os troços de cabeceira destes ecossistemas lóticos estão inseridos no Parque Natural de Montesinho, onde existem habitats singulares e espécies com elevado valor em termos de conservação. Na avaliação dos impactos ecológicos recorreu-se a um conjunto de metodologias que permitiram caracterizar: 1) a componente abiótica, caso da qualidade físico-química da água e da condição dos habitats aquático e ribeirinho e 2) a componente biótica, baseada na amostragem das comunidades de macroinvertebrados e de peixes, que seguiram os protocolos emanados pela Diretiva Quadro da Água. Deste modo...

Light-related photosynthetic characteristics of lotic macroalgae

Necchi, O.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica Formato: 139-155
ENG
Relevância na Pesquisa
46.66%
Photosynthetic characteristics in response to irradiance were analysed in 42 populations of 33 macroalgal species by two distinct techniques (chlorophyll fluorescence and oxygen evolution). Photosynthesis-irradiance (PI) curves based on the two techniques indicated adaptations to low irradiance reflected by low saturation values, high to moderate values of photosynthetic efficiency (alpha) and photoinhibition (beta), for Bacillariophyta and Rhodophyta, which suggests they are typically shade-adapted algae. In contrast, most species of Chlorophyta were reported as sun adapted algae, characterized by high values of I-k and low of alpha, and lack of or low photoinhibition. Cyanophyta and Xanthophyta were intermediate groups in terms of light adaptations. Photoinhibition was observed in variable degrees in all algal groups, under field and laboratory conditions, which confirms that it is not artificially induced by experimental conditions, but is rather a common and natural phenomenon of the lotic macroalgae. Low values of compensation irradiance (I-c) were found, which indicate that these algae can keep an autotrophic metabolism even under very low irradiances. High ratios (>2) of photosynthesis/respiration were found in most algae, which indicates a considerable net gain. These two physiological characteristics suggest that macroalgae may be important primary producers in lotic ecosystems. Saturation parameters (I-k and I-s) occurred in a relatively narrow range of irradiances (100-400 mumol photons m(-2) s(-1))...

Photosynthetic responses to temperature in tropical lotic macroalgae

Necchi Jr., Orlando
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 140-148
ENG
Relevância na Pesquisa
46.66%
A comparative analysis of the photosynthetic responses to temperature (10-30°C) was carried out under short-term laboratory conditions by chlorophyll fluorescence and oxygen (O2) evolution. Ten lotic macroalgal species from southeastern Brazil (20°11-20°48′S, 49°18-49°41′W) were tested, including Bacillariophyta, Chlorophyta, Cyanophyta, Rhodophyta and Xanthophyta. Temperature had significant effects on electron transport rate (ETR) only for three species (Terpsinoe musica, Bacillariophyta; Cladophora glomerata, Chlorophyta; and C. coeruleus, Rhodophyta), with highest values at 25-30°C, whereas the remaining species had no significant responses. It also had similar effects on non-photochemical quenching and ETR. Differences in net photosynthesis/dark respiration ratios at distinct temperatures were found, with an increasing trend of respiration with higher temperatures. This implies in a decreasing balance between net primary production and temperature, representing more critical conditions toward higher temperatures for most species. In contrast, high net photosynthesis and photosynthesis/dark respiration ratios at high and wide ranges of temperature were found in three species of green algae, suggesting that these algae can be important primary producers in lotic ecosystems...

Sponge spicules indicate Holocene environmental changes on the Nabileque River floodplain, southern Pantanal, Brazil

Kuerten, Sidney; Parolin, Mauro; Assine, Mario L.; McGlue, Michael M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 171-183
ENG
Relevância na Pesquisa
26.66%
Sponge spicules are siliceous microfossils that are especially useful for analysis of sandy fluvio-lacustrine sediments. Sponge spicules in a long sediment core (~550 cm below surface), consisting of fine sand, sandy silt, and organic-rich mud, recovered from the floodplain of the Nabileque River, southern Pantanal, Brazil (S20°16′38. 3″/W57°33′00. 0″), form the basis of a novel paleoenvironmental interpretation for this region. Optically stimulated luminescence dates constrain the timing of deposition to the middle-late Holocene and all spicules identified are typical of the Brazilian cerrado biome. The base of the section is dominated by Oncosclera navicella Carter 1881, Metaniaspinata Carter 1881, and Corvospongilla seckti Bonetto and Ezcurra de Drago 1966, which indicate a lotic to semi-lotic environment strongly influenced by an actively meandering river channel at ~6. 7-5. 7 ka BP. The appearance of Heterorotula fistula Volkmer-Ribeiro and Motta 1995, Dosilia pydanieli Volkmer-Ribeiro 1992 and Radiospongilla amazonensis Volkmer-Ribeiro and Maciel 1983 at ~340 cm downcore suggests a reduction in flowing water and a more stable lentic environment, consistent with deposition in an oxbow lake. This oxbow lake environment existed during an interval of regional aridity between ~4. 5 and 3. 9 ka BP. Spicules...

Monogeneans (Dactylogyridae) parasitizing gills of Salminus hilarii from a Neotropical reservoir, Brazil

Brandao, Heleno; Yamada, Fabio Hideki; Toledo, Gislayne de Melo; Carvalho, Edmir Daniel; Silva, Reinaldo Jose da
Fonte: Brazilian Coll Veterinary Parasitology Publicador: Brazilian Coll Veterinary Parasitology
Tipo: Artigo de Revista Científica Formato: 579-587
ENG
Relevância na Pesquisa
26.85%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Processo FAPESP: 11/22603-3; With the aim of creating an inventory of the metazoan gill parasites of Salminus hilarii in the Taquari River, state of Sao Paulo, Brazil, five species of monogeneans (Anacanthorus contortus, A. bicuspidatus, Annulotrematoides parisellei, Jainus iocensis and Tereancistrum arcuatus) are reported the first time for this host. A total of 28 fish were sampled quarterly between April 2011 and January 2012, with 10 hosts in a lentic ecosystem and 18 in a lotic ecosystem. Quantitative ecological descriptors (prevalence, intensity of infestation and abundance) were calculated for the purpose to comparing the two ecosystems sampled (lentic and lotic ecosystems). However, no quantitative difference between the lentic and lotic ecosystems was observed. The present study has made available a checklist for species of the genus Anacanthorus and their hosts and geographical distribution in the Neotropical region up to the present time.

Richness, abundance, and seasonality of macroalgal communities at different spatial scales in streams of the central-southern state region of Parana State

Krupek, Rogerio Antonio; Zanini Branco, Ciro Cesar
Fonte: Fundacao Zoobotanica Rio Grande Sul, Museu Ciencias Naturais Publicador: Fundacao Zoobotanica Rio Grande Sul, Museu Ciencias Naturais
Tipo: Artigo de Revista Científica Formato: 5-15
POR
Relevância na Pesquisa
36.58%
The structure and seasonality of benthic macroalgal communities of lotic ecosystems was evaluated at different spatial scales of observation in streams of the central-southern region of Parana State. Samples were collected monthly from January to December 2007. We found 16 taxa (38% Cyanobacteria, 31% Chlorophyta, 19% Rhodophyta and 12% Heterokontophyta) without a confirmed seasonality pattern. The floristic composition varied at all spatial scales corroborated by low values of diversity index. The most significant differences were obtained for the drainage basin and shading scales, especially regarding the availability of light energy. Richness and abundance of species had seasonal patterns influenced by variables current velocity (mesohabitat) and irradiance (shading) respectively. Both variables have been widely described as determining factors on the community structure of lotic macroalgae.

Avaliação experimental do efeito do controle top-down e bottom-up sobre a cadeia de detritos em ambiente aquático

Navarro, Fernanda Keley Silva Pereira
Fonte: Universidade de Brasília Publicador: Universidade de Brasília
Tipo: Tese
POR
Relevância na Pesquisa
26.62%
Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-graduação em Ecologia, 2014.; Em ecossistemas lóticos, principalmente nas regiões de cabeceira, onde o metabolismo heterotrófico é dominante (P

The effects of wildfire on lotic macroinvertebrate communities in Portugal; Os efeitos dos fogos florestais nas comunidades de macroinvertebrados lóticos em Portugal

Machado, Ana Luísa Felgueiras de Brito
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
46.76%
The effects of wildfires in Mediterranean lotic communities are still poorly documented. Despite some progress in recent years, the published data refer mainly to studies conducted in North America, with little information on European rivers. Given the importance of regional geographic context, both on the effects of fire and on the resilience of the communities, the gap in the biogeographical knowledge represent a limitation to the implementation of appropriate management measures. This thesis consists in a systematic study of the effects of fire on the macroinvertebrate communities of streams of North and Central Portugal. A chronosequence survey was conducted in order to analyze long-term effects of wildfires (1-18 years) and provide chronological information on the ecological recovery of macroinvertebrate communities. The results indicated that the macroinvertebrate communities recover in abundance and taxa richness and in terms of community structure about two years after the fire impact. A short-term survey was also carried out, where the initial response of macroinvertebrates to fire disturbance was documented, in streams recently affected by wildfires. The parameters analyzed were compared with reference sites without fire impact for the last 20 years. In all sampling periods...

Natural variability of lotic Mediterranean ecosystems or wildfire perturbations: who will win?

Pinto, Paulo; Ferreira, Maria Teresa; Caraça, Rute; Pedro, Ana; Novais, Maria Helena; Morais, Manuela; Robinsons, C. T.
Fonte: TEMPRIV2012 International Conference on Temporay Rivers Publicador: TEMPRIV2012 International Conference on Temporay Rivers
Tipo: Aula
ENG
Relevância na Pesquisa
46.85%
This study evaluates the impacts of wildfires in lotic Mediterranean ecosystems. It was carried out at Monchique ridge after big wildfires occurred during 2002 and 2003. Deferential impacts were evaluated comparing historical results obtained before the wildfires (1999 and 2001), with the post fire ones (2006 and 2007). Physical and chemical parameters of the water, habitat morphology, diatoms, macrophytes, macroinvertebrates and fishes were evaluated at 10 collecting places, before and after wildfires. High recovering rates were observed to the vegetation, but it is still possible to found fire impacts over macrophytes and river morphology. Wildfires, contributed to canopy decrease and, consequently to the growth of plants that usually are controlled by shadow. As a result, vegetation biodiversity tend to increase. River banks tend also to be invaded by terrestrial plants. Higher post fires recover rates were observed to the more aquatic communities (diatoms, macroinvertebrates and fishes). For those communities, comparing spring situations before and after the fires no substantial differences were observed. Sometimes differences between consecutive years are even higher. So it can be concluded that magnitude of wildfire impacts is less than the natural inter-annual variability of Mediterranean rivers. Long-term effects of forest fires...

Leaf litter decomposition in western iberian forested wetlands: lentic versus lotic response

Sampaio, Ana; Rodriguez-Gonzalez, Patricia; Varandas, Simone; Cortes, Rui Manuel; Ferreira, Maria Teresa
Fonte: Asociacion Iberica de Limnologia Publicador: Asociacion Iberica de Limnologia
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
Relevância na Pesquisa
36.72%
Leaf litter breakdown is frequently used to measure both structural and functional integrity in aquatic ecosystems. Forested wetlands are interface systems that received little attention, especially in the Iberian Peninsula. The present study compares the decomposition of alder and willow in two biotopes (lentic and lotic) located in two different sites (Caxarias and Alpiarc¸a). Litterbags were used to compare decomposition among the different treatments. Throughout decay, dry weight loss, nitrogen and phosphorus content, microbial community physiological profiles, microbial and macro-invertebrate colonization were measured at days 2, 4, 8, 16, 32 and 64. Decomposition rates ranged from intermediate to rapid for alder (0.006 day−1 to 0.0338 day−1) and slow to rapid for willow (0.0024 day−1 to 0.0272 day−1), depending on site and biotopes type. The combined effects biotope × time was significant for heterotrophs (P < 0.05), molds (P < 0.05) and yeasts (P < 0.001). The analysis of average well colour development (AWCD), richness (R) and Shannon-Wiener index (H ) based on the oxidation of carbon and nitrogen sources by the microbial community, showed differences between the two biotopes, lotic and lentic, and sites. These differences were also shown by the principal component analysis (PCA). Moreover...

Biodiversity assessment of benthic macroinvertebrates in altitudinal lotic ecosystems of Serra do Cipó (MG, Brazil)

GALDEAN,N.; CALLISTO,M.; BARBOSA,F. A. R.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2001 EN
Relevância na Pesquisa
36.62%
Five lotic systems of Serra do Cipó, south-east Brazil, were investigated in order to assess the existing diversity of benthic macroinvertebrates, habitats-microhabitats, and the available trophic resources. For each river it was analysed the communities of benthic macroinvertebrates and the composition of some taxonomic groups (Plecoptera, Ephemeroptera, Trichoptera and Diptera Chironomidae): the community with Bivalvia Sphaeriidae, Oligochaeta and Ephemeroptera Baetidae (being supposed a closed relation Bivalvia-Oligochaeta based on the process of bioturbation and enrichment of sediment in organic matter) in Tanque River; the macrofauna associated to aquatic macrophytes from rivers Peixe and Preto do Itambé reflecting the reaction of the ecosystems versus the quantities of nutrients which originate from the farmlands; the lithoreophilic communities of Cipó River; the community depending on deposits of leaves and filamentous algae in Congonhas Stream; the very rich community of the moss clumps in the Indaiá Stream. A proposal for biological zonation of Cipó River and some comments about the importance of the analysed benthic macroinvertebrates in the biological production of the aquatic communities were done.

Biological monitoring of lotic ecosystems: the role of diatoms

Bere,T.; Tundisi,JG.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2010 EN
Relevância na Pesquisa
46.66%
Increasing anthropogenic influence on lotic environments as a result of civilisation has captured public interest because of the consequent problems associated with deterioration of water quality. Various biological monitoring methods that provide a direct measure of ecological integrity by using the response of biota to environmental changes have been developed to monitor the ecological status of lotic environments. Diatoms have been used extensively in this regard and this review attempts to summarise the basic concepts associated with biological monitoring using benthic diatoms. Where possible, examples from work carried out in Brazil are used.

Monogeneans (Dactylogyridae) parasitizing gills of Salminus hilarii from a Neotropical reservoir, Brazil

Brandao,Heleno; Yamada,Fabio Hideki; Toledo,Gislayne de Melo; Carvalho,Edmir Daniel; Silva,Reinaldo Jose da
Fonte: Colégio Brasileiro de Parasitologia Veterinária Publicador: Colégio Brasileiro de Parasitologia Veterinária
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
26.85%
With the aim of creating an inventory of the metazoan gill parasites of Salminus hilarii in the Taquari River, state of São Paulo, Brazil, five species of monogeneans (Anacanthorus contortus, A. bicuspidatus, Annulotrematoides parisellei, Jainus iocensis and Tereancistrum arcuatus) are reported the first time for this host. A total of 28 fish were sampled quarterly between April 2011 and January 2012, with 10 hosts in a lentic ecosystem and 18 in a lotic ecosystem. Quantitative ecological descriptors (prevalence, intensity of infestation and abundance) were calculated for the purpose to comparing the two ecosystems sampled (lentic and lotic ecosystems). However, no quantitative difference between the lentic and lotic ecosystems was observed. The present study has made available a checklist for species of the genus Anacanthorus and their hosts and geographical distribution in the Neotropical region up to the present time.

Diversity of phytoplankton community in different urban aquatic ecosystems in metropolitan João Pessoa, state of Paraíba, Brazil

Costa,Davi Freire da; Dantas,Ênio Wocyli
Fonte: Associação Brasileira de Limnologia Publicador: Associação Brasileira de Limnologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
26.54%
AIM: The aim of the present study was to identify which environmental factors affect the seasonal phytoplankton structure in different types of tropical aquatic ecosystems. Phytoplankton sampling was performed bi-monthly from August 2009 to June 2110 at three sites in the Solon de Lucena Lake, Jaguaribe River and Águas Minerais reservoir. METHODS: The environmental variables were water temperature, transparency, depth, degree of infestation of aquatic macrophytes, air temperature, wind speed, solar radiation and precipitation. The phytoplankton community was studied in terms of richness, density, diversity and evenness. The data were treated with analysis of variance and canonical correspondence analysis. RESULTS: Spatial variations in the data only occurred between ecosystems (p < 0.05). The reservoir and river exhibited typical phytoplankton of lotic environments, with a greater richness of Bacillariophyta (52.8% and 47.8%, respectively). The lake exhibited the typical richness lentic environments, with the greatest contribution from Chlorophyta (52.8%). This ecosystem was characterized by an absence of macrophytes, a low degree of water transparency (0.3 ± 0 m) and high algal density (89,903 ± 38,542 ind. mL-1), with a dominance of Aphanocapsa nubilum. In the river environment...

Tolerance of benthic macroinvertebrates to organic enrichment in highland streams of northeastern Rio Grande do Sul, Brazil

Mazzoni,Aline Correa; Lanzer,Rosane; Schafer,Alois
Fonte: Associação Brasileira de Limnologia Publicador: Associação Brasileira de Limnologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
Relevância na Pesquisa
46.62%
AIM: the aim of this study was to determine the ecological valence of benthic macroinvertebrates at different pollution levels in highland rivers and streams of Rio Grande do Sul; METHODS: the dataset proceeds from samplings performed between 2002-2011 in 35 lotic ecosystems. The Chemical Index was used to determine pollution levels. Indices of richness and Shannon diversity were applied to characterize the structure of benthic communities. The descriptors used to determine taxa's ecological valence were selected according to Coefficient of Variation and regression analyses. Groups of tolerance were identified using Interquartile range and cluster analysis; RESULTS: Conductivity and Chemical Index were the descriptors best related with diversity of benthic macroinvertebrate community. These metrics were used to determine the tolerance range of 38 taxa. Interquartile range and cluster analysis revealed three groups of taxa, according to their occurrence in different levels of pollution: taxa with narrow amplitudes, present at sites with very low or very high load of organic enrichment; taxa with moderate amplitude, found until moderately polluted sites; and taxa with occurrence in widespread environmental conditions. The results...

Groundwater-dependent ecosystems and the dangers of groundwater overdraft: A review and an Australian perspective

Nevill, J.; Hancock, P.; Murray, B.; Ponder, W.; Humphreys, W.; Phillips, M.; Groom, P.
Fonte: Surrey Beatty & Sons Publicador: Surrey Beatty & Sons
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
36.54%
In many parts of the world, access to groundwater is needed for domestic, agricultural and industrial uses, and global groundwater exploitation continues to increase. The significance of groundwater in maintaining the health of rivers, streams, wetlands and associated vegetation is often underestimated or ignored, resulting in a lack of scrutiny of groundwater policy and management. It is essential that management of groundwater resources considers the needs of natural ecosystems, including subterranean. We review the limited Australian literature on the ecological impacts of groundwater overdraft and place Australian information within an international context, focusing on lentic, lotic, stygobitic and hyporheic communities as well as riparian and phreatophytic vegetation, and some coastal marine ecosystems. Groundwater overdraft, defined as abstracting groundwater at a rate which prejudices ecosystem or anthropocentric values, can substantially impact natural communities which depend, exclusively or seasonally, on groundwater. Overdraft damage is often underestimated, is sometimes irreversible, and may occur over time scales at variance to those used by water management agencies in modelling, planning and regulation. Given the dangers of groundwater overdraft...

Efeitos da resolução taxonômica de invertebrados bentônicos no diagnóstico da qualidade de ecossistemas lóticos; Effects of taxonomic resolution of benthic invertebrates in the assessment of lotic ecosystem's quality

Mazzini, Flávia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/09/2007 PT
Relevância na Pesquisa
36.62%
Nas últimas décadas, tem-se observado uma expressiva queda da qualidade ambiental e perda de biodiversidade nos ecossistemas aquáticos em função de múltiplos impactos advindos de atividades antrópicas. Dessa forma, considerando-se que a estrutura das comunidades pode ser alterada por tais perturbações, diversos métodos têm sido propostos para avaliações da qualidade nesses ecossistemas, destacando-se, entre eles, o uso dos macroinvertebrados bentônicos. Alguns estudos empregando estes indicadores defendem a sua identificação ao nível genérico por fornecer maior número de informações, resultar em classificações ambientais mais confiáveis e apresentar melhor capacidade de distinção entre os pontos, quando comparado aos níveis de resolução mais abrangentes. Entretanto, na maioria dos trabalhos a identificação desse grupo restringe-se ao nível de família, principalmente em função da economia nos recursos despendidos durante a identificação o que não se justifica caso este nível não retenha informações suficientes para que os objetivos sejam alcançados. Neste trabalho, esse conflito foi avaliado através da comparação de avaliações biológicas decorrentes da aplicação de índices estruturais baseados na identificação de Chironomidae...

Patterns of spatial distribution in macroalgal communities from tropical lotic ecosystems

Borges,Fábio R.; Necchi Júnior,Orlando
Fonte: Sociedade Botânica de São Paulo Publicador: Sociedade Botânica de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2006 EN
Relevância na Pesquisa
36.44%
Three sampling sites were analysed in each of the following tropical regions: 1) northwestern São Paulo State, representing a disturbed region; 2) Bonito, Mato Grosso do Sul State, representing a hard water region; and 3) Ubatuba, northern costal region of São Paulo State, a well preserved tropical rainforest region. The hard water region had the highest mean values for macroalgal species richness (6.3) and diversity index (H' = 0.62). Northwest and rainforest regions had the highest percent cover values (22.5% and 17.0%, respectively). All sites in the northwest region had one or two dominant species (percent cover significantly higher than the remaining species), characterizing the niche pre-emption distribution pattern. The same pattern was found in two sites of the Atlantic rainforest. The hard water region had dominance of one species in two out of the three sites, but differently from the northwest region, niche overlap values were lower, evidencing a patch distribution. Competition for space was one of the main factors to explain spatial distribution. Overall, sites characterized by niche pre-emption had lower species richness, higher values for niche width and overlap, dominance index and percent cover of dominant species. In contrast...

Spatial-temporal patterns of functional feeding groups in mountain streams of Córdoba, Argentina

Príncipe,Romina E; Gualdoni,Cristina M; Oberto,Ana M; Raffaini,Graciela B; Corigliano,María C
Fonte: Ecología austral Publicador: Ecología austral
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
36.44%
Trophic structure of benthic communities is influenced by the availability of food resources which indeed may be conditioned by stream size, shading and substrate. This study aims to analyze the distribution of macroinvertebrate Functional Feeding Groups in different habitats of mountain streams (Córdoba, Argentina) and to assess the environmental variables conditioning this distribution at the habitat level. Four streams were sampled in two hydrological periods (high and low discharge) and three benthic samples were taken in riffles and runs of coarse and fine substrate. Gathering collectors were dominant in most of the habitats, streams and periods except in riffles during the low water period in which filtering collectors dominated. At the habitat level, current velocity, substrate, abundance of macroalgae and twigs and leaves were the most important variables explaining functional feeding group distribution. Functional feeding group abundances varied in relation to the stream, the hydrological period and the habitat. The dominance of collectors demonstrates the importance of the role of this functional group and that fine detritus is the main food resource in these lotic ecosystems. The phenology and life history of the species...

Water temperature and riverine ecosystems: An overview of knowledge and approaches for assessing biotic responses, with special reference to South Africa

Dallas,Helen
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2008 EN
Relevância na Pesquisa
46.62%
Available information pertaining to water temperature in riverine ecosystems is examined and consolidated into an overview that describes the spatial and temporal variation in water temperature, the importance of water temperature in lotic ecosystems, the measurement and modelling of water temperature, anthropogenic factors that modify water temperature, the effects of temperature changes on the physical and chemical characteristics of water; and on aquatic organisms and ecosystems. Methods for assessing the effects of temperature changes on aquatic organisms are discussed and current water temperature guidelines for the protection of aquatic ecosystems are outlined. This paper highlights the complexity of water temperature in the aquatic environment and the importance of understanding the spatio-temporal variability in water temperature and the variable responses of aquatic organisms to thermal stress. Anthropogenic modifiers of the thermal regime, which include heated discharges, flow modifications, riparian vegetation removal and global climate change; present ongoing threats to aquatic ecosystems. Whilst Northern Hemisphere information on water temperature is plentiful, this overview has identified the huge gap that exists in temperature-related data in South Africa. Without baseline data on water temperature and the thermal requirements of aquatic organisms...