Ecologia e Meio Ambiente Índices bióticos mono e multimétricos de avaliação da qualidade da água ... more Ecologia e Meio Ambiente Índices bióticos mono e multimétricos de avaliação da qualidade da água em riachos de Mata Atlântica Mono and multimetric biotic indices for the evaluation of water quality in Atlantic Forest streams Os protocolos de avaliação de hábitats e os índices bióticos utilizados no biomonitoramento de rios no Brasil fornecem boas informações sobre a qualidade da água e indicações sobre as modificações do ecossistema aquático. No entanto, a interpretação de seus resultados têm limitações. Estudos anteriores apontaram limitações destes índices para aferir a qualidade de riachos de baixa ordem, já que os índices medem somente impactos orgânicos. A degradação ambiental desses riachos está relacionada principalmente a impactos causados pela alteração da paisagem, tais como erosão, assoreamento, retificação do canal, perda de mata ciliar, e redução do fluxo da água. Os riachos da Serra do Japi estão sujeitos a alguns desses impactos provocados por atividades rurais. Porta...
Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although ... more Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although studies that evaluate the influence of these temporal differences on the entire web are very scarce. Under the hypothesis that trophic interactions and the food web structure are under seasonal influences, two forested streams (named S1 and S2) were sampled during the wet and dry periods. The samplings were conducted in August 2007 and April 2008 and included algae, macrophytes, plankton. macroinvertebrates, and fish. All ...
The study of the diet of fish is an important tool to assess different levels of environmental de... more The study of the diet of fish is an important tool to assess different levels of environmental degradation, since the availability of food in the environment is a key factor for the fish occurrence. The removal of riparian vegetation usually degrades environmental quality, as this vegetation has an important role in providing energy to the ecosystem. This study investigates the effects of the removal of riparian vegetation on the fish assemblage trophic network. The study was carried out in two stretches of a southeastern Brazilian stream, one in a forest fragment and another in a pasture, during the wet and dry seasons of 2014. We analyzed the items consumed by each fish species using the frequency of occurrence and area of each item, which were combined to calculate the alimentary index, which was used to determine the food niche overlap of the fish and the specialization index of the trophic network. Aquatic Hexapoda, vegetal debris and organic matter dominated the trophic network of the two stretches. We detected higher values of food niche overlap in the forested stretch and more complex trophic networks in the pasture stretch. We found few seasonal variations in the items consumed and calculated indices in both stretches studied. The presence of grass on the banks in the pasture stretch and the importation of food resources from the upstream area may have provided a higher diversity of resources and consequently showed a more complex trophic network when compared to the forested stretch.
Colonization routes of benthic macroinvertebrates in a stream in southeast Brazil. The colonizati... more Colonization routes of benthic macroinvertebrates in a stream in southeast Brazil. The colonization of the benthic substrate by macroinvertebrates of a tropical stream was investigated through four routes: downstream movement, upstream movement, movement from the subsurface and colonization by aerial source. Traps were built and installed to quantify separately each route. Samples were removed after 1, 3, 7, and 21 days of colonization. The community showed two main characteristics: the dominance of two groups (Chironomidae and Baetidae) and a progressive increase in richness and density in a temporal scale. Although this dominance occurred at all routes, they differed in relation to the total richness, total density, community composition, and over time. The density of the main groups sampled differed significantly among routes only at the 21st colonization day. When considered the percentage density by each route (only at 21 colonization day) for the ten most common taxonomic groups, three patterns can be pointed out. (1) Seven taxa used the four routes (Chironomidae, Trichoptera, Baetidae, Leptophlebiidae, Copepoda, Leptohyphidae and Elmidae), (2) one taxa used three routes (Annelida), and (3) two taxa used only two routes (Simuliidae and Glossosomatidae). In this study, the four colonization routes were important for replacement of denuded areas. Groups of benthic macroinvertebrates, which used preferential routes, determined the differences in community structure between different colonization routes.
A comparative analysis was conducted of the colonization by benthic macroinvertebrates of rocky a... more A comparative analysis was conducted of the colonization by benthic macroinvertebrates of rocky and leaf pack substrates, both natural and artificial. This colonization was evaluated by season, with the objective of ascertaining the infl uence of rainfall on the rate of colonization. The total density of macroinvertebrates after 21 days of colonization was signifi cantly greater in the dry than in the wet season. When the substrate types were compared, artifi cial leaf pack substrate presented the smallest density for both seasons. In the wet season, Chironomidae, Leptohyphidae, Hydropsychidae, Elmidae, immature stages of Trichoptera, and Hydroptilidae showed a more representative density. In the dry season, Chironomidae, Baetidae and Oligochaeta were the most abundant taxa. The artifi cial rocky substrate used in this experiment was the most appropriate, due to its resemblance with natural substrate conditions in terms of the maintenance of the structural integrity of the substrate throughout the experimental period. Successional and seasonal eff ects were of great relevance, playing an important role in the colonization process.
Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotri... more Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotrigonids species in the Upper Paraná River and some aspects about their biology. Biota Neotrop. Jan/Apr 2007 vol. 7, no. 1 http://www.biotaneotropica.org.br/v7n1/pt/abstract?short-communication+bn00707012007 ISSN 1676-0603.
No presente trabalho, a contribuição da utilização de dados da dieta da ictiofauna para caracteri... more No presente trabalho, a contribuição da utilização de dados da dieta da ictiofauna para caracterização da comunidade bentônica foi evidenciada na análise dos grandes grupos, com perfeita correspondência em escalas espacial e temporal do predomínio de Hexapoda. Na análise em nível das ordens de Hexapoda, uma perfeita correspondência ocorreu em função do predomínio de Diptera. Porém, o elevado porcentual de Coleoptera no ambiente e de Trichoptera na dieta pode estar relacionado com a capacidade de forrageamento dos peixes e hábito de vida dos hexápodes. Uma maior mobilidade dos coleópteros (aqui representados principalmente por Elmidae-Heterelmis) poderia dificultar sua captura pelos peixes, enquanto o hábito agarrador e construtor de teia coletora dos tricópteros (principalmente Hydropsychidae-Smicridea) facilitaria sua captura pelos mesmos. Assim, consideramos apropriado o uso da dieta dos peixes para levantamento da fauna bentônica destes riachos, permitindo uma visão dos grupos ex...
O objetivo deste trabalho foi montar redes ecológicas baseadas em dados da estrutura trófica da i... more O objetivo deste trabalho foi montar redes ecológicas baseadas em dados da estrutura trófica da ictiofauna e verificar se a estrutura destas redes poderia ser relacionada com o fator espacial (diferenças nas características do habitat, como dimensão, tipo de entorno, substrato) e temporal (duas estações e dois anos de coleta). Na análise das redes ecológicas dos três ambientes estudados foi possível relacionar sua estrutura com variações espaciais e temporais na estrutura dos habitats. Assim, a ecologia de redes, complementar à ecologia de comunidades, parece constituir um campo promissor para a compreensão do funcionamento das comunidades, podendo também vir a ajudar na elaboração de programas de conservação.
ABSTRACT Through a manipulative experiment, the colonization of leaf litter by invertebrates was ... more ABSTRACT Through a manipulative experiment, the colonization of leaf litter by invertebrates was investigated in two sections of a tropical stream (spatial scale) that differed in function of the canopy cover, one with the presence (closed area) and another without riparian vegetation (open area), during one month of the dry and one of the wet season (temporal scale). The work aimed to verify differences related to four variables: season, canopy cover, leaf type and leaf condition. Litter bags containing arboreal and herbaceous leaves (leaf type variable), non-conditioned and preconditioned (leaf condition variable) were placed at the bottom of the stream in each area (canopy cover variable) and season (dry and wet), and removed after 13-day colonization. The analysis of the remaining litter dry mass per leaf bag emphasizes differences related mainly to seasonality, canopy cover and leaf type, although leaf condition was also important when combined with those three factors. Comparing the abundance of invertebrates per treatment, there was a tendency of high predominance of Chironomidae during the dry season and greater taxa diversity and evenness during the wet season, when the water flow increase could alter the availability of microhabitats for local fauna. Even though canopy cover alone was not a significant source of variation in the abundance of invertebrates, the results showed a tendency of a combined effect of canopy cover with seasonality and leaf condition.
Brazilian journal of biology = Revista brasleira de biologia, 2014
Preservation of terrestrial fauna and flora has been the main reason for the settlement of most p... more Preservation of terrestrial fauna and flora has been the main reason for the settlement of most protected areas in the past 30 years, but although those areas may include water bodies, this does not necessarily mean that the biodiversity of freshwater environments are also protected. In the present study, the fauna inventory of eight streams (1st, 2nd, 4th and 5th orders) of three microbasins of Japi Mountain, a Biosphere Reserve of Atlantic Forest recognised by UNESCO since 1994, located in São Paulo state, southeast of Brazil, was conducted. The hypothesis of this study is that the conservation of this area is important for the maintenance of the aquatic biodiversity of this biome, and so, this world hotspot deserves priority conservation actions. From 2005 to 2007, benthic macroinvertebrates, fishes and, eventually, anuran amphibians were sampled in these streams. The results showed that Japi Mountain contributes to the conservation of 138 taxonomic units of the aquatic biota and...
The life history of freshwater stingrays (Potamotrygonidae) under natural conditions has been poo... more The life history of freshwater stingrays (Potamotrygonidae) under natural conditions has been poorly documented. In this study, we investigated the period of activity and the habitat use of two species of the genus Potamotrygon in the upper Paraná River basin, Southeastern Brazil. Potamotrygon falkneri and P. motoro are similar to each other as far as the analyzed behavior is concerned. Individuals of both species segregate according to their size, and in function of the depth and period of the day. Younger individuals inhabit mostly sandy beaches and places that are no deeper than four meters throughout the whole day. Bigger stingrays realize bathymetric migrations, alternating their position between places deeper than eight meters during the day, and shallow areas at night. Individuals of intermediate size inhabit transition environments that have greater habitat diversity. Both species presented mostly nocturnal habits, especially regarding their feeding behavior. The behavioral patterns observed seem to go through ontogenetic variations and probably change throughout the year, between dry and wet seasons.
In studies on the partitioning of resources, one issue which has been largely neglected is the ch... more In studies on the partitioning of resources, one issue which has been largely neglected is the change in feeding habits based on the availability of food in the environment, an aspect which is dealt with here with regard to the ichthyofauna of a tropical stream. Feeding preference was analyzed for eight species of fish which consumed high percentages of aquatic insects, based on a collection of fish and invertebrates during both the dry season (June 2006) and the wet season (December 2006) and in two different stretches of the stream, one of which shaded by gallery forest ("closed area") and the other just bordered by herbaceous vegetation ("open area"). Based on a quantitative analysis of the composition of the benthic fauna and the diet of the ichthyofauna, the electivity index was calculated in order to assess potential alterations in the feeding preferences in line with seasonal and spatial modifications to the structure of the habitat and the supply of food. The analysis of the abundance of aquatic insects in the environment showed a predominance of Ephemeroptera in all situations analyzed (areas and seasons), with this insect group being the food item preferred by the majority of fish. However, space-time variations were observed in prey selection by the ichthyofauna. The analysis of supply, consumption and preference demonstrated somewhat varied situations for the majority of species, with both high and low selectivity for items consumed in low and high percentages, with the preferred item varying both spatially and seasonally. The sole exception to this was Phalloceros harpagos, choosing Diptera-Chironomidae in all the situations analyzed.
Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although ... more Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although studies that evaluate the influence of these temporal differences on the entire web are very scarce. Under the hypothesis that trophic interactions and the food web structure are under seasonal influences, two forested streams (named S1 and S2) were sampled during the wet and dry periods. The samplings were conducted in August 2007 and April 2008 and included algae, macrophytes, plankton, macroinvertebrates, and fish. All heterotrophic taxa sampled were submitted to diet analysis. The similarity among samples was estimated by a cluster analysis using quantitative data of environmental variables, community attributes, and food web properties. A total of 2,250 individuals of 139 trophic species were identified. The food webs were mainly detritus-based, which resulted in a great proportion of trophic species at the first trophic level and high omnivory in all samples. All fish species were top species because they had no predators. The S1 stream, predominantly composed of a sandy substrate, presented lower abundance than the predominantly rocky S2 stream in both dry and wet periods, although the richness was similar. The cluster analysis demonstrated that environmental attributes were more similar between seasons, community attributes were more similar between streams, and food web parameters were very similar (94% similarity) both between streams and seasons. Therefore, we concluded that although environmental attributes varied temporally and community attributes varied spatially, the trophic relationships and overall food web structure of these preserved streams remain the same.
Trophic organization and food web structure of southeastern Brazilian streams: a review. The pres... more Trophic organization and food web structure of southeastern Brazilian streams: a review. The present study reviews some trophic patterns of southeastern Brazilian streams. The food resources availability, the relationship between production and importation, the establishment of feeding guilds, and the patterns of trophic structure of fish and macroinvertebrate communities, with a particular emphasis on food webs, are discussed. In the four food webs used as examples, the following aspects were emphasized: (1) the importance of allochthonous material input to the aquatic system, (2) the importance of detritus and algae as a link between the detritus and the grazing chain, (3) the spatial and temporal variation in the trophic structure, and (4) the high degree of omnivory. Key-words: trophic structure, stream, macroinvertebrates, fish, food web.
Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotri... more Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotrigonids species in the Upper Paraná River and some aspects about their biology. Biota Neotrop. Jan/Apr 2007 vol. 7, no. 1 http://www.biotaneotropica.org.br/v7n1/pt/abstract?short-communication+bn00707012007 ISSN 1676-0603.
Os protocolos de avaliação de hábitats e os índices bióticos utilizados no biomonitoramento de ri... more Os protocolos de avaliação de hábitats e os índices bióticos utilizados no biomonitoramento de rios no Brasil fornecem boas informações sobre a qualidade da água e indicações sobre as modificações do ecossistema aquático. No entanto, a interpretação de seus resultados têm limitações. Estudos anteriores apontaram limitações destes índices para aferir a qualidade de riachos de baixa ordem, já que os índices medem somente impactos orgânicos. A degradação ambiental desses riachos está relacionada principalmente a impactos causados pela alteração da paisagem, tais como erosão, assoreamento, retificação do canal, perda de mata ciliar, e redução do fluxo da água. Os riachos da Serra do Japi estão sujeitos a alguns desses impactos provocados por atividades rurais. Portanto, neste estudo foi avaliado se a redução das características naturais de alguns desses ambientes diminuiria a qualidade da água. A pontuação obtida pela aplicação do Protocolo de Diversidade de Hábitat salientou a ação de impactos difusos da atividade agrorrural sobre a qualidade do hábitat. Porém, os índices bióticos aplicados -Biological Monitoring Working Party Score System, Average Score Per Taxon e Índice da Comunidade Bentônica para Rios -, não foram afetados pelos usos do entorno dos riachos, já que apontaram alta qualidade da água de todos os ambientes analisados. Uma adequação dos atributos e da classificação a partir das pontuações é sugerida para uma melhor definição de políticas de conservação da área.
Ecologia e Meio Ambiente Índices bióticos mono e multimétricos de avaliação da qualidade da água ... more Ecologia e Meio Ambiente Índices bióticos mono e multimétricos de avaliação da qualidade da água em riachos de Mata Atlântica Mono and multimetric biotic indices for the evaluation of water quality in Atlantic Forest streams Os protocolos de avaliação de hábitats e os índices bióticos utilizados no biomonitoramento de rios no Brasil fornecem boas informações sobre a qualidade da água e indicações sobre as modificações do ecossistema aquático. No entanto, a interpretação de seus resultados têm limitações. Estudos anteriores apontaram limitações destes índices para aferir a qualidade de riachos de baixa ordem, já que os índices medem somente impactos orgânicos. A degradação ambiental desses riachos está relacionada principalmente a impactos causados pela alteração da paisagem, tais como erosão, assoreamento, retificação do canal, perda de mata ciliar, e redução do fluxo da água. Os riachos da Serra do Japi estão sujeitos a alguns desses impactos provocados por atividades rurais. Porta...
Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although ... more Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although studies that evaluate the influence of these temporal differences on the entire web are very scarce. Under the hypothesis that trophic interactions and the food web structure are under seasonal influences, two forested streams (named S1 and S2) were sampled during the wet and dry periods. The samplings were conducted in August 2007 and April 2008 and included algae, macrophytes, plankton. macroinvertebrates, and fish. All ...
The study of the diet of fish is an important tool to assess different levels of environmental de... more The study of the diet of fish is an important tool to assess different levels of environmental degradation, since the availability of food in the environment is a key factor for the fish occurrence. The removal of riparian vegetation usually degrades environmental quality, as this vegetation has an important role in providing energy to the ecosystem. This study investigates the effects of the removal of riparian vegetation on the fish assemblage trophic network. The study was carried out in two stretches of a southeastern Brazilian stream, one in a forest fragment and another in a pasture, during the wet and dry seasons of 2014. We analyzed the items consumed by each fish species using the frequency of occurrence and area of each item, which were combined to calculate the alimentary index, which was used to determine the food niche overlap of the fish and the specialization index of the trophic network. Aquatic Hexapoda, vegetal debris and organic matter dominated the trophic network of the two stretches. We detected higher values of food niche overlap in the forested stretch and more complex trophic networks in the pasture stretch. We found few seasonal variations in the items consumed and calculated indices in both stretches studied. The presence of grass on the banks in the pasture stretch and the importation of food resources from the upstream area may have provided a higher diversity of resources and consequently showed a more complex trophic network when compared to the forested stretch.
Colonization routes of benthic macroinvertebrates in a stream in southeast Brazil. The colonizati... more Colonization routes of benthic macroinvertebrates in a stream in southeast Brazil. The colonization of the benthic substrate by macroinvertebrates of a tropical stream was investigated through four routes: downstream movement, upstream movement, movement from the subsurface and colonization by aerial source. Traps were built and installed to quantify separately each route. Samples were removed after 1, 3, 7, and 21 days of colonization. The community showed two main characteristics: the dominance of two groups (Chironomidae and Baetidae) and a progressive increase in richness and density in a temporal scale. Although this dominance occurred at all routes, they differed in relation to the total richness, total density, community composition, and over time. The density of the main groups sampled differed significantly among routes only at the 21st colonization day. When considered the percentage density by each route (only at 21 colonization day) for the ten most common taxonomic groups, three patterns can be pointed out. (1) Seven taxa used the four routes (Chironomidae, Trichoptera, Baetidae, Leptophlebiidae, Copepoda, Leptohyphidae and Elmidae), (2) one taxa used three routes (Annelida), and (3) two taxa used only two routes (Simuliidae and Glossosomatidae). In this study, the four colonization routes were important for replacement of denuded areas. Groups of benthic macroinvertebrates, which used preferential routes, determined the differences in community structure between different colonization routes.
A comparative analysis was conducted of the colonization by benthic macroinvertebrates of rocky a... more A comparative analysis was conducted of the colonization by benthic macroinvertebrates of rocky and leaf pack substrates, both natural and artificial. This colonization was evaluated by season, with the objective of ascertaining the infl uence of rainfall on the rate of colonization. The total density of macroinvertebrates after 21 days of colonization was signifi cantly greater in the dry than in the wet season. When the substrate types were compared, artifi cial leaf pack substrate presented the smallest density for both seasons. In the wet season, Chironomidae, Leptohyphidae, Hydropsychidae, Elmidae, immature stages of Trichoptera, and Hydroptilidae showed a more representative density. In the dry season, Chironomidae, Baetidae and Oligochaeta were the most abundant taxa. The artifi cial rocky substrate used in this experiment was the most appropriate, due to its resemblance with natural substrate conditions in terms of the maintenance of the structural integrity of the substrate throughout the experimental period. Successional and seasonal eff ects were of great relevance, playing an important role in the colonization process.
Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotri... more Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotrigonids species in the Upper Paraná River and some aspects about their biology. Biota Neotrop. Jan/Apr 2007 vol. 7, no. 1 http://www.biotaneotropica.org.br/v7n1/pt/abstract?short-communication+bn00707012007 ISSN 1676-0603.
No presente trabalho, a contribuição da utilização de dados da dieta da ictiofauna para caracteri... more No presente trabalho, a contribuição da utilização de dados da dieta da ictiofauna para caracterização da comunidade bentônica foi evidenciada na análise dos grandes grupos, com perfeita correspondência em escalas espacial e temporal do predomínio de Hexapoda. Na análise em nível das ordens de Hexapoda, uma perfeita correspondência ocorreu em função do predomínio de Diptera. Porém, o elevado porcentual de Coleoptera no ambiente e de Trichoptera na dieta pode estar relacionado com a capacidade de forrageamento dos peixes e hábito de vida dos hexápodes. Uma maior mobilidade dos coleópteros (aqui representados principalmente por Elmidae-Heterelmis) poderia dificultar sua captura pelos peixes, enquanto o hábito agarrador e construtor de teia coletora dos tricópteros (principalmente Hydropsychidae-Smicridea) facilitaria sua captura pelos mesmos. Assim, consideramos apropriado o uso da dieta dos peixes para levantamento da fauna bentônica destes riachos, permitindo uma visão dos grupos ex...
O objetivo deste trabalho foi montar redes ecológicas baseadas em dados da estrutura trófica da i... more O objetivo deste trabalho foi montar redes ecológicas baseadas em dados da estrutura trófica da ictiofauna e verificar se a estrutura destas redes poderia ser relacionada com o fator espacial (diferenças nas características do habitat, como dimensão, tipo de entorno, substrato) e temporal (duas estações e dois anos de coleta). Na análise das redes ecológicas dos três ambientes estudados foi possível relacionar sua estrutura com variações espaciais e temporais na estrutura dos habitats. Assim, a ecologia de redes, complementar à ecologia de comunidades, parece constituir um campo promissor para a compreensão do funcionamento das comunidades, podendo também vir a ajudar na elaboração de programas de conservação.
ABSTRACT Through a manipulative experiment, the colonization of leaf litter by invertebrates was ... more ABSTRACT Through a manipulative experiment, the colonization of leaf litter by invertebrates was investigated in two sections of a tropical stream (spatial scale) that differed in function of the canopy cover, one with the presence (closed area) and another without riparian vegetation (open area), during one month of the dry and one of the wet season (temporal scale). The work aimed to verify differences related to four variables: season, canopy cover, leaf type and leaf condition. Litter bags containing arboreal and herbaceous leaves (leaf type variable), non-conditioned and preconditioned (leaf condition variable) were placed at the bottom of the stream in each area (canopy cover variable) and season (dry and wet), and removed after 13-day colonization. The analysis of the remaining litter dry mass per leaf bag emphasizes differences related mainly to seasonality, canopy cover and leaf type, although leaf condition was also important when combined with those three factors. Comparing the abundance of invertebrates per treatment, there was a tendency of high predominance of Chironomidae during the dry season and greater taxa diversity and evenness during the wet season, when the water flow increase could alter the availability of microhabitats for local fauna. Even though canopy cover alone was not a significant source of variation in the abundance of invertebrates, the results showed a tendency of a combined effect of canopy cover with seasonality and leaf condition.
Brazilian journal of biology = Revista brasleira de biologia, 2014
Preservation of terrestrial fauna and flora has been the main reason for the settlement of most p... more Preservation of terrestrial fauna and flora has been the main reason for the settlement of most protected areas in the past 30 years, but although those areas may include water bodies, this does not necessarily mean that the biodiversity of freshwater environments are also protected. In the present study, the fauna inventory of eight streams (1st, 2nd, 4th and 5th orders) of three microbasins of Japi Mountain, a Biosphere Reserve of Atlantic Forest recognised by UNESCO since 1994, located in São Paulo state, southeast of Brazil, was conducted. The hypothesis of this study is that the conservation of this area is important for the maintenance of the aquatic biodiversity of this biome, and so, this world hotspot deserves priority conservation actions. From 2005 to 2007, benthic macroinvertebrates, fishes and, eventually, anuran amphibians were sampled in these streams. The results showed that Japi Mountain contributes to the conservation of 138 taxonomic units of the aquatic biota and...
The life history of freshwater stingrays (Potamotrygonidae) under natural conditions has been poo... more The life history of freshwater stingrays (Potamotrygonidae) under natural conditions has been poorly documented. In this study, we investigated the period of activity and the habitat use of two species of the genus Potamotrygon in the upper Paraná River basin, Southeastern Brazil. Potamotrygon falkneri and P. motoro are similar to each other as far as the analyzed behavior is concerned. Individuals of both species segregate according to their size, and in function of the depth and period of the day. Younger individuals inhabit mostly sandy beaches and places that are no deeper than four meters throughout the whole day. Bigger stingrays realize bathymetric migrations, alternating their position between places deeper than eight meters during the day, and shallow areas at night. Individuals of intermediate size inhabit transition environments that have greater habitat diversity. Both species presented mostly nocturnal habits, especially regarding their feeding behavior. The behavioral patterns observed seem to go through ontogenetic variations and probably change throughout the year, between dry and wet seasons.
In studies on the partitioning of resources, one issue which has been largely neglected is the ch... more In studies on the partitioning of resources, one issue which has been largely neglected is the change in feeding habits based on the availability of food in the environment, an aspect which is dealt with here with regard to the ichthyofauna of a tropical stream. Feeding preference was analyzed for eight species of fish which consumed high percentages of aquatic insects, based on a collection of fish and invertebrates during both the dry season (June 2006) and the wet season (December 2006) and in two different stretches of the stream, one of which shaded by gallery forest ("closed area") and the other just bordered by herbaceous vegetation ("open area"). Based on a quantitative analysis of the composition of the benthic fauna and the diet of the ichthyofauna, the electivity index was calculated in order to assess potential alterations in the feeding preferences in line with seasonal and spatial modifications to the structure of the habitat and the supply of food. The analysis of the abundance of aquatic insects in the environment showed a predominance of Ephemeroptera in all situations analyzed (areas and seasons), with this insect group being the food item preferred by the majority of fish. However, space-time variations were observed in prey selection by the ichthyofauna. The analysis of supply, consumption and preference demonstrated somewhat varied situations for the majority of species, with both high and low selectivity for items consumed in low and high percentages, with the preferred item varying both spatially and seasonally. The sole exception to this was Phalloceros harpagos, choosing Diptera-Chironomidae in all the situations analyzed.
Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although ... more Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although studies that evaluate the influence of these temporal differences on the entire web are very scarce. Under the hypothesis that trophic interactions and the food web structure are under seasonal influences, two forested streams (named S1 and S2) were sampled during the wet and dry periods. The samplings were conducted in August 2007 and April 2008 and included algae, macrophytes, plankton, macroinvertebrates, and fish. All heterotrophic taxa sampled were submitted to diet analysis. The similarity among samples was estimated by a cluster analysis using quantitative data of environmental variables, community attributes, and food web properties. A total of 2,250 individuals of 139 trophic species were identified. The food webs were mainly detritus-based, which resulted in a great proportion of trophic species at the first trophic level and high omnivory in all samples. All fish species were top species because they had no predators. The S1 stream, predominantly composed of a sandy substrate, presented lower abundance than the predominantly rocky S2 stream in both dry and wet periods, although the richness was similar. The cluster analysis demonstrated that environmental attributes were more similar between seasons, community attributes were more similar between streams, and food web parameters were very similar (94% similarity) both between streams and seasons. Therefore, we concluded that although environmental attributes varied temporally and community attributes varied spatially, the trophic relationships and overall food web structure of these preserved streams remain the same.
Trophic organization and food web structure of southeastern Brazilian streams: a review. The pres... more Trophic organization and food web structure of southeastern Brazilian streams: a review. The present study reviews some trophic patterns of southeastern Brazilian streams. The food resources availability, the relationship between production and importation, the establishment of feeding guilds, and the patterns of trophic structure of fish and macroinvertebrate communities, with a particular emphasis on food webs, are discussed. In the four food webs used as examples, the following aspects were emphasized: (1) the importance of allochthonous material input to the aquatic system, (2) the importance of detritus and algae as a link between the detritus and the grazing chain, (3) the spatial and temporal variation in the trophic structure, and (4) the high degree of omnivory. Key-words: trophic structure, stream, macroinvertebrates, fish, food web.
Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotri... more Garrone Neto, D., Haddad Jr., V., Vilela, M.J.A. & Uieda, V.S. Occurrence record of two potamotrigonids species in the Upper Paraná River and some aspects about their biology. Biota Neotrop. Jan/Apr 2007 vol. 7, no. 1 http://www.biotaneotropica.org.br/v7n1/pt/abstract?short-communication+bn00707012007 ISSN 1676-0603.
Os protocolos de avaliação de hábitats e os índices bióticos utilizados no biomonitoramento de ri... more Os protocolos de avaliação de hábitats e os índices bióticos utilizados no biomonitoramento de rios no Brasil fornecem boas informações sobre a qualidade da água e indicações sobre as modificações do ecossistema aquático. No entanto, a interpretação de seus resultados têm limitações. Estudos anteriores apontaram limitações destes índices para aferir a qualidade de riachos de baixa ordem, já que os índices medem somente impactos orgânicos. A degradação ambiental desses riachos está relacionada principalmente a impactos causados pela alteração da paisagem, tais como erosão, assoreamento, retificação do canal, perda de mata ciliar, e redução do fluxo da água. Os riachos da Serra do Japi estão sujeitos a alguns desses impactos provocados por atividades rurais. Portanto, neste estudo foi avaliado se a redução das características naturais de alguns desses ambientes diminuiria a qualidade da água. A pontuação obtida pela aplicação do Protocolo de Diversidade de Hábitat salientou a ação de impactos difusos da atividade agrorrural sobre a qualidade do hábitat. Porém, os índices bióticos aplicados -Biological Monitoring Working Party Score System, Average Score Per Taxon e Índice da Comunidade Bentônica para Rios -, não foram afetados pelos usos do entorno dos riachos, já que apontaram alta qualidade da água de todos os ambientes analisados. Uma adequação dos atributos e da classificação a partir das pontuações é sugerida para uma melhor definição de políticas de conservação da área.
RESUMO Em ecossistemas lóticos é comum a formação de diferentes mesohabitats intercalados ao long... more RESUMO Em ecossistemas lóticos é comum a formação de diferentes mesohabitats intercalados ao longo do rio, como poções, corredeiras e rápidos, frequentemente acompanhados de alterações na estrutura da fauna bentônica associada. No trabalho analisamos a fauna de invertebrados bentônicos em rápidos e corredeiras de um trecho de serra do Rio Capivara (Bacia do Médio Rio Tietê). A análise das características ambientais e a coleta da fauna foram realizadas em três corredeiras e três rápidos, em um mês da estação chuvosa (cinco réplicas de cada). Os mesohabitats se diferenciaram quanto ao maior porcentual de blocos nos rápidos e maiores valores de profundidade, correnteza e porcentual de matacões nas corredeiras. Do total de 57 Unidades Taxonômicas Operacionais (UTO's) amostradas, 75% foram comuns aos dois mesohabitats (Similaridade de Morisita = 0,86). Quando analisado o porcentual de abundância, a similaridade espacial se manteve e dois grupos se sobressaíram em abundância: Hexapoda (>80%, sendo a maioria Ephemeroptera, Diptera e Trichoptera) e Annelida (10%). As análises exploratórias (cluster e NMDS) também apontaram para uma elevada similaridade espacial, porém os resultados da Análise de Similaridade (ANOSIM) indicaram uma diferença significativa entre os mesohabitats (p<0,1%), seja analisando o total de UTO's ou retirando as UTO's raras. Cinco grupos tiveram uma maior contribuição para a média de dissimilaridade entre os mesohabitats: Simulium e Baetodes mais abundantes nas corredeiras, Traveryphes, Hagenulopsis e Macrelmis nos rápidos. Assim, os resultados da ANOSIM salientaram a importância do refinamento na identificação para a interpretação mais precisa acerca da relação entre a fauna e a estrutura do habitat. ABSTRACT The formation of different mesohabitats, such as pools, riffles and runs, is common along the courses of stream ecosystems, and these are frequently accompanied by changes in the
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