Freshwater fish scale database.

Scales of the ray finned fishes can be used for multiple purposes. Beside others by their specific structure and elemental composition they are usable for age determination and food-web researches. Additionally, just their presence, absence, shape, location, or numbers could provide a reliable taxonomic information. The fish scales show remarkable size variation also, which characteristics provide reliable information about the environmental needs of freshwater fish. But till now this information was not interpretable and comparable in the absence of a sufficiently large and detailed database. In this study we provide a database which can facilitate the further complex comparative studies. Our dataset consists of 2954 scale photos characterising 193 freshwater fish species. All photos have a uniquely identification code showing exactly which species the scale belongs to. In addition to the photos, our database includes a table showing the exact taxonomic classification of the studied species, the average body profile-index, and the relative scale size, as well as the ecological (flow and feeding habitat preferences) and life strategic characteristics (feeding and breeding guild memberships) of each species. The sampled species have diverse origin, covering five biogeographical regions. An average of five adults from each species were selected for sampling. Three-to-four scales were collected from the anterior part of the body between the dorsal fin and the lateral line. The removed scales were cleaned and prepared to microscope slides, and after this process they were photographed or scanned. Our database can be used for both research and educational purposes. A large number of scale photos assigned of species can be an opportunity to create an automatic species identification system. Moreover, the subjectivity in morphometric measurements can be eliminated by analysing the database with artificial intelligence.

Fishes from affluents of Rio Branco, Municipality of Caracaraí, Roraima State, northern Brazil / Peixes de afluentes do Rio Branco, Município de Caracaraí, Estado de Roraima, norte do Brasil

Abstract The Amazon has the richest freshwater ichthyofauna of the planet, with tens of new species being described annually. Although studies on Amazonian fish in the literature are increasingly common recently, there are still significant gaps concerning primary data on the ichthyofauna. One such gap is the state of Roraima and its main drainage, Rio Branco. There is a single book published in 2007 on fishes of Rio Branco, and although it presents a rather complete list of over 580 species known until then, the information is now a little outdated and many species found in some of its affluents are not listed in the book. Due to the scarcity of published data on the fish diversity of Roraima and taking into account that ichthyofaunal surveys are important tools towards freshwater conservation, we carried out an inventory of the ichthyofauna in the region of Caracaraí (RR) in 18 sampling sites including seven affluents of both left and right margins of Rio Branco. We recorded a total of 64 species of 41 genera and 18 families of five orders that occur in the Neotropical region, representing more than 11% of the species previously registered in the book for the entire Rio Branco basin. Twelve species were added to the list presented in the book, with four representing first records for the basin, one of them a new record for Brazil. Two of the 64 species are putative new taxa in need of further taxonomic studies. The order with the highest diversity was Characiformes (40 species), with highlights for the family Characidae (24 of these species), followed by Cichliformes (11 species) and Siluriformes (9 species). The richest collecting sites had 23 species, and the least rich site had only two species. Hyphessobrycon bentosi and Nannostomus marginatus occurred in more than 60% of the sites. There has been a significant difference in the exclusive ichthyofauna from affluents of both margins of Rio Branco, with the number of exclusive species in left margin tributaries approximately five times higher. Results presented herein complement data from the literature regarding the still poorly known ichthyofauna from Roraima.

Resumo A Amazônia possui a mais rica ictiofauna de água doce do planeta, com dezenas de novas espécies sendo descrita anualmente. Apesar de estudos sobre os peixes amazônicos serem cada vez mais comuns na literatura, ainda existem lacunas importantes com relação aos dados primários da ictiofauna. Uma dessas lacunas é o estado de Roraima e sua principal bacia hidrográfica, o Rio Branco. Até hoje, há apenas um livro publicado em 2007 sobre os peixes do Rio Branco, e apesar de apresentar uma lista bastante completa com pouco mais de 580 espécies conhecidas até então, atualmente as informações estão um pouco desatualizadas e diversas espécies de peixes encontradas em alguns de seus afluentes não constam do livro. Devido a escassez de dados publicados sobre a diversidade de peixes de Roraima e levando em consideração que levantamentos de ictiofauna são ferramentas importantes para mensurar o potencial de conservação dos corpos d'água, nós fizemos um levantamento da ictiofauna da região de Caracaraí (RR) em 18 pontos incluindo sete afluentes das margens esquerda e direita do Rio Branco. Foram registradas ao todo 64 espécies de 41 gêneros e 18 famílias de peixes de cinco ordens que ocorrem na região Neotropical, representando pouco mais de 11% das espécies registradas no livro para toda a bacia do Rio Branco. Doze espécies foram adicionadas à lista apresentada no livro, sendo quatro registradas pela primeira vez neste estudo, uma delas registrada pela primeira vez no Brasil. Duas das 64 espécies representam possíveis espécies ainda não descritas, necessitando de estudos taxonômicos mais aprofundados. A ordem com maior diversidade foi Characiformes (40 espécies), com destaque para a família Characidae (24 destas espécies), seguida de Cichliformes (11 espécies) e Siluriformes (9 espécies). Os pontos com maior riqueza apresentaram 23 espécies e o com menor riqueza apresentou apenas duas espécies. Hyphessobrycon bentosi e Nannostomus marginatus ocorreram em mais de 60% dos pontos. Houve diferença significativa na ictiofauna exclusiva entre os afluentes das duas margens do Rio Branco, com o número de espécies exclusivas da margem esquerda sendo aproximadamente cinco vezes maior. Os resultados apresentados aqui complementam os dados presentes na literatura a respeito da ainda pouco estudada ictiofauna de Roraima.

Factors affecting the transferability of bioindicators based on stream fish assemblages.

The development of multimetric indices (MMIs) to measure the biotic condition of aquatic habitats is based on metrics derived from biological assemblages. Considering fish assemblages, the inconsistencies in metrics responses outside of the places where they were developed limit MMI transferability and applicability to other locations, requiring local calibration. The factors behind the low transferability of these MMIs are still poorly understood. We investigated how environmental dissimilarity and spatial distance influence the transferability of metrics generated from local stream fish assemblages to other regions. We also tested whether functional and taxonomic metrics respond differently to the spatial distance. We used data from 239 fish assemblages from streams distributed across a Brazilian, the upper Parana basin and characterized each site according to the level of anthropogenic disturbance at the landscape scale using an Anthropogenic Pressure Index (API). We divided the upper Parana basin into sub-basins and used two of them to create template response models of the metrics in relation to the API. We used these response models to predict the responses outside the template sub-basins. Our response variable representing a metric of transferability was the absolute difference between metric's predicted and observed value for each site (prediction error). We thus modeled the prediction error in relation to the predictor variables that were i) the environmental dissimilarity between each site with the average of the sites from template sub-basins (climatic, topographic and soil type variables) and ii) the spatial distance (overland and watercourse distance) between each site and the center of the template sub-basin. We found that errors in metric predictions were associated with both environmental dissimilarity and spatial distance. Furthermore, functional and taxonomic metrics responded equally to spatial distance. These results indicate the need for local calibration of metrics when developing MMIs, especially if the protocols already available come from distant and environmentally dissimilar places.

Stream fish metacommunity organisation across a Neotropical ecoregion: The role of environment, anthropogenic impact and dispersal-based processes.

Understanding how assemblages are structured in space and the factors promoting their distributions is one of the main goals in Ecology, however, studies regarding the distribution of organisms at larger scales remain biased towards terrestrial groups. We attempt to understand if the structure of stream fish metacommunities across a Neotropical ecoregion (Upper Paraná-drainage area of 820,000 km2) are affected by environmental variables, describing natural environmental gradient, anthropogenic impacts and spatial predictors. For this, we obtained 586 sampling points of fish assemblages in the ecoregion and data on environmental and spatial predictors that potentially affect fish assemblages. We calculated the local beta diversity (Local Contribution to Beta Diversity, LCBD) and alpha diversity from the species list, to be used as response variables in the partial regression models, while the anthropogenic impacts, environmental gradient and spatial factors were used as predictors. We found a high total beta diversity for the ecoregion (0.41) where the greatest values for each site sampled were located at the edges of the ecoregion, while richer communities were found more centrally. All sets of predictors explained the LCBD and alpha diversity, but the most important was dispersal variables, followed by the natural environmental gradient and anthropogenic impact. However, we found an increase in the models' prediction power through the shared effect. Results suggest that environmental filters (i.e. environmental variables such as climate, hydrology and anthropogenic impact) and dispersal limitation together shape fish assemblages of the Upper Paraná ecoregion, showing the importance of using multiple sets of predictors to understand the processes structuring biodiversity distribution.

Taxonomic and non-taxonomic responses of benthic macroinvertebrates to metal toxicity in tropical reservoirs. The case of Cantareira Complex, São Paulo, Brazil.

Benthic macroinvertebrates are organisms that are recognized as water quality bio-indicators. A wide variety of indices and metrics have been shown to respond to a variety of anthropogenic impacts, usually under a general condition of environmental impairment. The absence of a clear distinction in the relations between specific pollutants and biotic variables is very common and can lead to biased interpretation of biomonitoring. The aims of this research were to test taxonomic and non-taxonomic responses to specific environmental conditions instead to general conditions. For this purpose, we estimated the theoretical toxicity by comparing toxicity values published by EPA with metal concentrations in water and sediments. Then we tested the responses of biological variables to toxicity and other environmental conditions using the linear mixed effects models approach. We generated 32 models considering 24 different biological metrics and indices that were grouped in five levels. Taxonomic and abundance metrics were best predictor than functional or tolerance-based indexes. The strongest model was that which considered subfamily taxonomic resolution responding to Al_w and Cr_s.

Physical habitat as predictor of fish trophic structure in Brazilian Atlantic rainforest streams

Trophic structure of fish assemblages is one of the most sensitive indicators of changes in streams environments. Since it is crucial to understand the response of trophic groups to habitat alteration, our study aimed to address this research gap by assessing the influence of substrate composition, meso-habitat variability, and bank stability, on the richness, biomass, and number of individuals of carnivores, invertivores, omnivores, and herbivorous-detritivores. Using an electrofishing device, we sampled 13 Atlantic rainforest streams reaches in a degradation gradient, located in the upper Paranapanema river basin. Sample points were ranked using a physical habitat index. More pristine streams had high availability of twigs, trunks, rocks and boulders in the substrate, great meso-habitat variability, and the presence of roots, trunks, and rocks in the margins. Canonical correlations between habitat characteristics and trophic groups explained more than 90% of data variability. Richness and number of individuals of invertivores increased in more preserved stream reaches, while richness of carnivores and number of individuals of omnivores decreased. These results demonstrate that trophic structure varies according to level of degradation, and that invertivore richness represents the best indicator of fish trophic structure responses to physical habitat alterations in streams.(AU)

A estrutura trófica da assembleia de peixes é um dos indicadores mais sensíveis a alterações ambientais em riachos. Considerando a relevância de entender a resposta de grupos tróficos à alteração ambiental, este estudo buscou preencher esta lacuna científica avaliando a influência da composição do substrato, variabilidade de meso-hábitats e estabilidade das margens sobre riqueza, biomassa e número de indivíduos de peixes carnívoros, invertívoros, onívoros e herbívoros-detritívoros. Amostramos com pesca elétrica 13 trechos de riachos de Mata Atlântica com estado de conservação variável, localizados na parte superior da bacia do alto rio Paranapanema. Os pontos amostrais foram ranqueados pelo índice de hábitat fisico. Riachos mais presevados apresentaram mais galhos, troncos, matacões e blocos no substrato, maior variabilidade de meso-hábitats e maior quantidade de raízes, troncos e rochas nas margens. As correlações canônicas explicaram mais de 90% da variabilidade dos dados. A riqueza e o número de indivíduos de invertívoros aumentaram em riachos mais preservados, enquanto que a riqueza de carnívoros e o número de indivíduos onívoros diminuíram. Estes resultados demonstram que a estrutura trófica varia em resposta ao nível de preservação, e que a riqueza de invertívoros é o melhor indicador de respostas da estrutura trófica às alterações do hábitat em riachos.(AU)

Ichthyofauna from serranias costeiras of the Ribeira de Iguape River basin, Southeast Brazil / Ictiofauna das serranias costeiras da bacia do rio Ribeira de Iguape, sudeste do Brasil

Abstract: The Ribeira de Iguape River basin has about 100 fish species. This study aimed to characterize the fish community from "serranias costeiras" of the Ribeira de Iguape River basin. Samplings were conducted with electrofishing during the dry season in the years 2018-2019. The sampling effort consisted of 30 streams stretches. As a result, 50 species were captured, distributed in 37 genera, 11 families, and six orders. The species richness estimate (SChao1) was 57 species, and the coverage estimate for the entire data set was C = 0.998. Harttia kronei and Chasmocranus lopezae are endemic species and can be used as bioindicators of streams in this river basin. We captured approximately nine species by stream stretch. Beta diversity was found to be more critical for gamma diversity than alpha diversity. This finding highlights the streams environmental heterogeneity importance for maintaining regional fish diversity. We captured eight individuals of the threatened species Spintherobolus papilliferus and this indicates an expansion in the geographic distribution of this species.

Resumo: A bacia hidrográfica do rio Ribeira de Iguape possui cerca de 100 espécies de peixes. O objetivo deste estudo foi caracterizar a comunidade de peixes de riachos das serranias costeiras da bacia do rio Ribeira de Iguape. O levantamento das espécies foi realizado com uso de pesca elétrica durante a estação seca de 2018-2019. As coletas ocorreram em 30 trechos de riachos. Foram capturadas 50 espécies distribuídas em 37 gêneros, 11 famílias e seis ordens. A estimativa de riqueza de espécies (SChao1) foi de 57 espécies e a estimativa de cobertura para todo o conjunto de dados foi de C = 0,998. Harttia kronei e Chasmocranus lopezae são espécies endêmicas e podem ser usadas como bioindicadores para os riachos nesta bacia hidrográfica. Capturamos aproximadamente nove espécies por trecho de riacho. A diversidade beta foi considerada mais importante para a diversidade gama do que a diversidade alfa. Esse resultado destaca a importância da heterogeneidade ambiental dos riachos para manter a diversidade regional de peixes. Capturamos seis indivíduos de uma espécie ameaçada Spintherobolus papilliferus e, dessa forma, ocorreu uma expansão da distribuição geográfica desta espécie.

A multiple hypothesis approach to explain species richness patterns in neotropical stream-dweller fish communities.

Several hypotheses are used to explain species richness patterns. Some of them (e.g. species-area, species-energy, environment-energy, water-energy, terrestrial primary productivity, environmental spatial heterogeneity, and climatic heterogeneity) are known to explain species richness patterns of terrestrial organisms, especially when they are combined. For aquatic organisms, however, it is unclear if these hypotheses can be useful to explain for these purposes. Therefore, we used a selection model approach to assess the predictive capacity of such hypotheses, and to determine which of them (combined or not) would be the most appropriate to explain the fish species distribution in small Brazilian streams. We perform the Akaike's information criteria for models selections and the eigenvector analysis to control the special autocorrelation. The spatial structure was equal to 0.453, Moran's I, and require 11 spatial filters. All models were significant and had adjustments ranging from 0.370 to 0.416 with strong spatial component (ranging from 0.226 to 0.369) and low adjustments for environmental data (ranging from 0.001 to 0.119) We obtained two groups of hypothesis are able to explain the richness pattern (1) water-energy, temporal productivity-heterogeneity (AIC = 4498.800) and (2) water-energy, temporal productivity-heterogeneity and area (AIC = 4500.400). We conclude that the fish richness patterns in small Brazilian streams are better explained by a combination of Water-Energy + Productivity + Temporal Heterogeneity hypotheses and not by just one.

Headwater stream fish fauna from the Upper Paranapanema River basin / Ictiofauna de riachos das cabeceiras da bacia hidrográfica do Alto Paranapanema

Abstract The Paraná River basin has about 600 fish species. In the Upper Paraná, 310 fish species were recorded, with 52 species were registered in the streams and headwaters of the Paranapanema River. The aim of this study was to characterize the stream fish communities in the Upper Paranapanema River basin. Samplings were conducted with electrofishing during the dry season in the year of 2014. The collection effort consisted of 30 streams stretches. As a result, 41 species of stream fish were recorded in the Upper Paranapanema River basin, distributed in 26 genera, 11 families and 7 orders. Thirty-nine percent of the species can be considered rare, 41% intermediate and 20% common. We captured approximately eight species by stream stretch and the estimated richness (Schao2) was 40 ± 6 species. Around 40% of the individuals had less than 50 mm in length.

Resumo A bacia hidrográfica do Rio Paraná possui cerca de 600 espécies de peixes. No Alto Rio Paraná, 310 espécies de peixes foram registradas com 52 espécies registradas em riachos do Rio Paranapanema. O objetivo deste estudo foi caracterizar a comunidade de peixes de riachos da bacia do Alto Rio Paranapanema. O levantamento das espécies foi realizado com uso de pesca elétrica durante a estação seca de 2014. As coletas ocorreram em 30 trechos de riachos. Foram capturas 41 espécies distribuídas em 26 gêneros, 11 famílias e 7 ordens. Trinta e nove por cento das espécies podem ser consideradas raras, 41% intermediárias e 20% comuns. Foram capturadas cerca de 8 espécies por trecho de riacho e a riqueza estimada (Schao2) foi 40 ± 6 espécies. Cerca de 40% dos indivíduos possuem comprimento menor que 50 mm.

Trophic organization and fish assemblage structure as disturbance indicators in headwater streams of lower Sorocaba River basin, São Paulo, Brazil

Studies that investigate the relationship patterns between environmental structure complexity and fish fauna provide crucial information to stream restoration efforts. In order to test the hypothesis that streams with more complex environmental structure sustain more diverse and functionally more complex fish communities we sampled fish fauna from Sorocaba River headwater stream reaches (SE - Brazil). Reaches represented two distinct treatments: (1) a simplified reach, characterized by unstable fine substrate, clay, deeper channel and higher water velocity and (2) structurally complex reaches, characterized by coarse substrate, with gravel, pebble, rock, stems and branches and leaves inside the channel, producing a diverse pattern of microhabitat, associated with sequences of pools, runs, and riffles. Both trophic structure and taxonomic composition varied significantly between treatments. Invertivorous trophic group exclusively occurred in structurally complex reaches, which also presented greater diversity and species richness. We suggest enhancing in-stream environmental structure that suffered simplification processes due to human impacts in order to reestablish fish communities and ecossistemic functioning. .

Estudos que buscam investigar os padrões de relação entre a complexidade da estrutura ambiental e a fauna de peixes fornecem informações cruciais para os esforços de restauração de riachos. Para testar a hipótese de que riachos com estrutura ambiental mais complexa sustentam comunidades ícticas mais diversas do ponto de vista taxonômico e funcional, a ictiofauna de trechos de riachos de cabeceira do rio Sorocaba (SE - Brasil) foi amostrada, representando dois tratamentos distintos: (1) um trecho de riacho simplificado, caracterizado por substrato fino e inconsolidado, composto por areia e silte, curso d'água mais profundo, com maior velocidade e poucos elementos diversificadores da estrutura de habitat e (2) trechos de riacho estruturalmente complexos, com substrato de fundo composto por elementos irregulares como cascalho, rochas, seixos, troncos, galhos e restos de madeira, produzindo um padrão diverso de microhabitats, associados à sequências de poços, corredeiras e trechos rápidos. Tanto a estrutura trófica quanto a composição taxonômica foram distintas em relação aos dois tipos de riachos. O grupo trófico dos invertívoros ocorreu somente nos trechos estruturalmente mais complexos, que apresentaram também maior diversidade e riqueza de espécies. Sugere-se incrementar a estrutura ambiental de riachos que sofreram simplificação ambiental, devido à ação humana, a fim de promover a reestruturação da comunidade íctica e o funcionamento ecossistêmico.

Compartilhamento de recursos por duas espécies de peixes nectobentônicas de riachos na bacia do rio Cachoeira (BA) / Resource sharing by two nectobenthic freshwater fish species of streams in the Cachoeira river basin (BA)

O presente estudo teve como objetivo buscar particularidades e aspectos em comum relacionados com as condições ambientais de ocorrência e recursos alimentares utilizados por Trichomycterus bahianus e Characidium aff. zebra, duas espécies típicas de riachos coletadas durante o período chuvoso na bacia do rio Cachoeira, sudeste da Bahia, uma região da Mata Atlântica, utilizando-se um equipamento de pesca elétrica em oito trechos de riachos de cabeceira. Foi verificada a correlação entre os dados ambientais e a abundância das espécies, através de uma análise de componentes principais. Para os itens alimentares verificou-se a amplitude da dieta, a sobreposição de nicho e a existência de diferenças na exploração dos recursos alimentares. Além disso, testou-se a existência de diferenças na composição e no grau de preferência alimentar em diferentes estágios de desenvolvimento. Foram coletados 55 exemplares de C. zebra e 124 de T. bahianus. Verificou-se que a abundância das duas espécies está relacionada com o gradiente gramínea-rocha na margem e areia-matacão no fundo. Pode-se afirmar que independente da espécie, as fêmeas foram maiores e mais pesadas que os machos (p < 0,001). A proporção sexual de C. zebra diferiu do esperado (Χ² = 4,091; gl = 1; p = 0,043). As duas espécies foram classificadas como invertívoras, consumindo principalmente formas imaturas de insetos aquáticos. Não houve diferença significativa no número de itens consumidos pelas espécies. A sobreposição alimentar foi elevada (Oj,k = 0,895), porém, as espécies apresentaram diferença significativa na exploração dos recursos alimentares (p < 0,001). Observou-se também que, apesar da alta sobreposição alimentar, as espécies exploraram praticamente os mesmos recursos, porém, com estratégias distintas. Isto foi evidenciado quando se levou em consideração os diferentes estágios de desenvolvimento, mostrando que a dieta de C. zebra é mais generalista que a de T. bahianus. Provavelmente o compartilhamento de recursos abundantes e as diferenças na ocupação de micro-hábitats e nas estratégias de vida de C. zebra e T. bahianus, permita a coexistência das duas espécies nos riachos da bacia do rio Cachoeira durante o período chuvoso.

The aim of this study was to investigate specific characteristics and common features related to the abundance and the gradient of environmental conditions and food resources used by Trichomycterus bahianus and Characidium aff. zebra. These species are two typical streams fishes collected during the rainy season using electric fishing equipment in eight sites at the headwaters of the Cachoeira river basin, in a region of Atlantic rainforest in southeast of Bahia State. We quantified the correlation between environmental data and abundance through a principal component analysis. It was obtained the diet amplitude, the niche overlap and tested the differences in exploitation of food resources. In addition, we tested the differences in composition and degree of food preference in different stages of development. We collected 55 specimens of C. zebra and 124 of T. bahianus. It was found that the abundance of the two species is related to the gradient grass-rock on the shore and sand-boulder at the bottom. We can say that regardless of species, females were larger and heavier than males (p < 0.001). The sex ratio of C. zebra differ from the expected (Χ2 = 4.091, df = 1, p = 0.043). The two species were classified as invertivorous, consuming mostly immature aquatic insects. There was no significant difference in the number of items consumed by the species, and the diet overlap was high (Oj,k = 0.895). However, the species showed different strategies to obtain food which lead to significant differences in exploitation of food resources (p < 0.001). This was evidenced when we took into account the different stages of development, showing that the diet of C. zebra is more generalist than T. bahianus. Probably, the sharing of abundant resources and differences in the occupation of microhabitats and life strategies allows the coexistence of this two species in the streams of the Cachoeira river basin during the rainy season.

Ictiofauna do Ribeirão Limoeiro, Bacia do Rio Cachoeira, BA / Ichthyofauna of the Ribeirão Limoeiro, Cachoeira River Basin, BA

Os riachos da Bacia do Leste caracterizam-se por serem pequenos, pouco complexos e com ictiofauna endêmica decorrente do isolamento geográfico. Neste contexto, foi realizado um estudo da distribuição das espécies e estrutura da comunidade de peixes do Ribeirão Limoeiro, BA ao longo de um gradiente espacial no período de um ano, utilizando-se a pesca elétrica como método de coleta. Foram coletadas 21 espécies totalizando 2264 indivíduos em quatro pontos: dois próximos da cabeceira (P1A e P1M), um no médio curso (P2) e outro próximo à sua foz (P3). Characiformes e Siluriformes foram as ordens mais representativas dentre as quatro registradas. Algumas espécies ocorreram exclusivamente na cabeceira (Astyanax sp. e Trichomycterus cf. bahianus) e outras próximo da foz (Leporinus sp. e Callichthys callichthys). Por outro lado, Characidium zebra, Parotocinclus cf. cristatus, Poecilia vivipara, Astyanax sp.1, Rhamdia sp. e Poecilia reticulata ocorreram em todos os pontos amostrados. Foi coletada uma espécie com "status" de vulnerável (Nematocharax venustus) e duas exóticas (Tilapia rendalli e Poecilia reticulata). Quanto à estrutura da comunidade, os valores dos índices de riqueza de "Margalef" e de diversidade de "Shannon" foram significativamente maiores no ponto P3, por outro lado, este ponto apresentou valores significativamente menores do índice de dominância de "Berger-Parker". O ponto com vegetação ripária preservada (P1M) apresentou menor valor médio da temperatura da água e os pontos de cabeceira (P1A e P1M) apresentaram os maiores valores médios de oxigênio dissolvido e velocidade superficial. Condutividade, largura e profundidade médias aumentaram da cabeceira para a foz. Vários resultados encontrados estão de acordo com a literatura atual que trata de ecologia de comunidades de peixes de riachos neotropicais.

The streams of the Eastern Basin are characterized by being small, somewhat complex and endemic fish fauna due to geographical isolation. In this context, a study of species distribution and community structure of stream fish Limoeiro, BA along a spatial gradient in one year, using electrofishing as the collection method. Twenty one fish species were collected totalizing 2264 specimens in four points: two points near the head (P1A and P1M), one in the middle course (P2) and another near the mouth (P3). Characiformes and Siluriformes were the orders more important among the four registered. Some species occurred exclusively at the head (Astyanax sp. and Trichomycterus cf. bahianus) and other near the mouth (Leporinus sp. and Callichthys callichthys). On the other hand, Characidium zebra, Parotocinclus cf. cristatus, Poecilia vivipara, Astyanax sp.1, Rhamdia sp. and Poecilia reticulata occurred all sampling points. Was collected one specie the "status" of vulnerable (Nematocharax venustus) and two exotics (Tilapia rendalli and Poecilia reticulata). About the community structure, the values of the index of richness of "Margalef" and of the index of diversity of "Shannon" were greater in this point P3, then this point were significantly lower value of "Berger-Parker" dominance index. The point with riparian vegetation preserved (P1M) showed a lower average water temperature and the points near the head (P1A and P1M) showed the highest values of dissolved oxygen and surface velocity. Conductivity, width and depth of the medium increased toward the mouth. Several results are in accordance with the current literature dealing with community ecology of neotropical stream fish.

Utilização de índices ecológicos em assembléias de peixes como instrumento de avaliação da degradação ambiental em programas de monitoramento / Utilization of ecological indexes on assemblages of fish as instrument of assessment of the environmental degradation in monitoring programs

Este trabalho utiliza índices ecológicos em taxocenoses de peixes (constância de ocorrência, diversidade de espécies, riqueza, equitabilidade, índice de qualidade integrado (IQ)) como instrumento de avaliação da degradação ambiental. As amostragens foram padronizadas e realizadas sazonalmente durante dois anos, com rede de arrasto do tipo picaré, em onze pontos da bacia hidrográfica do lago Guaíba. Os pontos que apresentaram maior regularidade sazonal nos índices coincidem com locais de melhor qualidade ambiental indicados por outros fatores (frequência de anomalias, DBO5, temperatura, coliformes totais, oxigênio dissolvido). O cálculo do índice de qualidade integrado (IQ), entretanto, foi extremamente influenciado pela abundância e riqueza de espécies, sendo que os locais considerados de melhor qualidade por este índice correspondem aos de pior qualidade ambiental indicados por outros fatores. A análise realizada demonstrou que à medida que a qualidade da água melhora, o Índice de Margalef diminui. Isto demonstra que mesmo havendo uma melhora na qualidade da água, não houve uma melhora da estrutura da comunidade deste local.

Several ecological indexes in taxocenoses of fish (constancy, diversity, richness, evenness, and integrated quality index - IQ) are used as indicators of environmental degradation through the analysis of standardized and seasonal fish samples taken along two years in eleven localities of the Lake Guaíba drainage. Localities that showed regular diversity indexes along two years are coincident with those with better environmental quality indicated by other factors (frequency of abnormalities in fishes, DBO5, temperature, total coliforms, dissolved oxygen). The integrated quality index, however, was mostly influenced by abundance and richness, being the localities indicated as the best quality by this index coincident with those indicated as bad quality by other factors. The accomplished analysis demonstrated that when the measure of water quality gets better, the Margalef Index decreases. This demonstrates that even having an improvement in water quality, there is no improvement of structure of the fish community of this place.

Local ecological and taxonomic knowledge of snapper fish (Teleostei: Actinopterygii) held by fishermen in Ilhéus, Bahia, Brazil

Local Ecological and Taxonomic Knowledge (LEK) of fish held by fishermen in the municipality of Ilhéus, Bahia, Brazil, known as the snapper ("vermelho") was examined from August 2005 to November 2006. Semi-structured interviews and tests were made with fishermen selected under the criteria of "specialists". The data analysis followed the union model of the different individual competences. Grouping analysis was performed on data referring to the localities of the occurrence of these fish, depth, coloration, and morphological characteristics of the species using the Pearson correlation coefficient (UPGMA). A total of 19 species were named within the snapper group, although three of them could not be scientifically identified. The Lutjanidae family presented the greatest numbers of species (n = 9). Other families mentioned were: the Serranidae (n = 3), Holocentridae (n = 2), Priacanthidae (n = 1), Mullidae (n = 1). The 1:1 correspondence between fishermen's local names and scientific species observed in this study indicates the richness of local fishermen knowledge. Analysis of the LEK related to the feeding habits of these fish and indicated that most were considered as being carnivorous, which agrees with the specialized literature consulted. In terms of their spatial distribution, two categories were detected: locality of occurrence (rivers/sea, coast, and offshore) and depth (surface, mid-depth, mid-depth/deep, deep). The fish were considered locally to be "winter fish", based on harvested yields. Most of the interviewees knew little about the reproductive aspects of these fish. The main criteria used to identify, name, and classify the species were based on color and morphological aspects. Much of the information gathered in this study agreed with the published literature, which strengthens the importance of including LEK in planning and decision-making processes.(AU)

Este estudo analisou o Conhecimento Ecológico Local (CEL) e taxonômico dos peixes conhecidos como vermelhos pelos pescadores no município de Ilhéus, Bahia, no período de agosto de 2005 a novembro de 2006. Foram realizadas entrevistas semi-estruturadas e testes projetivos com os pescadores selecionados pelo critério de "especialistas". A análise dos dados seguiu o modelo de união das diversas competências individuais. Foram realizadas análises de agrupamento para os dados referentes ao ambiente de ocorrência, profundidade, coloração e características morfológicas das espécies, utilizando o coeficiente de correlação de Pearson (UPGMA). No total foram citadas 19 espécies compondo o grupo dos vermelhos, sendo que três não foram identificados cientificamente. A família Lutjanidae foi a que apresentou um maior número de espécies (n = 9). Outras famílias encontradas foram a Serranidae (n = 3), Holocentridae (n = 2), Priacanthidae (n = 1) e Mullidae (n = 1). A correspondência de 1:1 obtida entre as espécies citadas pelos pescadores e a espécie científica encontrada neste estudo indica um refinado detalhamento na identificação e distinção. Analisando o CEL referente à alimentação destes peixes, pode-se constatar que a maioria é carnívora, o que está de acordo com a literatura especializada consultada. Para a distribuição espacial foram detectadas duas categorizações: ambientes de ocorrência (rio/mar, costeiro e alto mar) e profundidade (raso, meia-água, meia-água/fundo, fundo). Os peixes pesquisados foram considerados como peixes de inverno, afirmação baseada na produção pesqueira. A maioria dos entrevistados desconhece os fatores relacionados com os aspectos reprodutivos. Os principais critérios utilizados para identificar, nomear e classificar as espécies estão relacionados com a coloração e aspectos morfológicos. Muitas das informações citadas neste estudo estão de acordo com a literatura especializada consultada, o que fortalece a importância ...(AU)

Caracterização das assembléias de peixes de riachos de cabeceira no período chuvoso na bacia do rio Cachoeira (SE da Bahia, NE do Brasil) / Characterization of the fish assemblages in headwaters streams in the rainy season in the Cachoeira river basin (SE of the Bahia, NE of the Brazil)

Visando conhecer a riqueza de espécies e aspectos ecológicos das assembléias ícticas de riachos de cabeceira da Bacia do Rio Cachoeira, foram realizadas coletas de peixes, de variáveis estruturais do ambiente e da água de oito riachos durante o mês de dezembro de 2007. Foram capturados 1.915 indivíduos pertencentes a 19 espécies das quais, cerca da metade, composta por organismos inferiores a 50 mm, o que sugere endemismo. Espécies com "status" taxonômico indefinido podem ser novas para a ciência. A confirmação de outras podem representar expansão da distribuição geográfica. Sugere-se novos levantamentos na área. Ocorreu correlação significativa entre as ordenações realizadas com dados ambientais e com abundância das espécies levando a formação de três assembléias distintas com suposta ação extrínseca nas suas organizações por parte da estrutura física do canal e de qualidade da água. Visando gerar instrumentos para programas de conservação e monitoramento da biodiversidade foram definidas espécies raras e dominantes.

Fish assemblage samples, environmental structure and water variables were collected from eight small streams in December of 2007 from Cachoeira river basin in the state of Bahia, Brazil. The objective was to obtain a set of information of the species richness and ecological aspects of the ichthyofauna. A thousand nine hundred and fifteen individuals of 19 species were captured. About half of the species contained individuals with a total length smaller than 50 mm. These findings suggest that some species are endemic. Two species with uncertain taxonomic status can be new. Confirmation of others two can represent expansion of the geographic distribution. These results indicate that new surveys in the area are necessary. Ordination analysis results with ambient data and abundance of the species showed significant correlation. Were identified three assemblages and it is suggested that were formed with extrinsic factors. Aiming to generate instruments for conservation programs and biodiversity monitoring species rare and dominant were defined.

Biology of Isopisthus parvipinnis: an abundant sciaenid species captured bycatch during sea-bob shrimp fishery in Brazil

Trawling is the most common method of shrimp harvesting. This technique causes a negative impact on the fauna due to the high bycatch rates and to the animals that are accidentally caught and generally returned to the sea dead. The consequences of this technique and the biological aspects of the involved species are poorly studied, specially in the Brazilian northeast. The objective of this study was to show some aspects of the population biology of Isopisthus parvipinnis (Bigtooth corvina) captured as bycatch during sea-bob (Xiphopenaeus kroyeri) shrimp fishing in the region of Ilhéus, in the state of Bahia in Brazil. A total of 1290 individuals were caught in a monthly sampling at three different stations, from March, 2003 to February, 2005. The standardized Morisita index of dispersion suggests that this species has a clumped distribution in the studied area. The number of individuals showed a significant variation (p < 0.0001) between the seasons, being higher during the winter. The estimated first maturation length (L50) was about 159 mm, and 95 percent of the captured individuals were below this value. The sexual ratio found was 1.5 males for each female. Concerning to diet, 10 feeding categories were identified, and Decapoda Dendobranchiata was the most important in numeric frequency and occurrence. This fact suggests that Isopisthus parvipinnis is a carnivorous species, with a tendency toward crustacean-eating at least in the younger individuals.

A pesca de arrasto é o método mais comum de captura de camarão. Esta técnica causa impactos negativos na fauna demersal devido ao grande número de animais que são capturados acidentalmente e que geralmente são devolvidos mortos ao mar. As conseqüências desta metodologia de pesca e os aspectos biológicos das espécies envolvidas são pouco estudados, especialmente no Nordeste do Brasil. Este estudo tem como objetivo mostrar aspectos biológicos de Isopisthus parvipinnis (tortinha) capturada como fauna acompanhante da pesca do camarão sete barbas (Xiphopenaeus kroyeri) na região de Ilhéus, no estado da Bahia, Brasil. Um total de 1290 indivíduos foram capturados em coletas mensais, em três pontos de coleta distintos, de março de 2003 a fevereiro de 2005. O índice de dispersão de Morisita padronizado sugere que a espécie, na área analisada, apresenta uma distribuição agregada. O número de indivíduos variou significativamente entre as estações do ano (p < 0,0001), sendo maior durante o inverno. O comprimento estimado de primeira maturação (L50) foi de 159 mm, sendo que 95 por cento dos indivíduos capturados estavam abaixo deste valor. A razão sexual encontrada foi de 1,5 machos para cada fêmea. Quanto à dieta, foram identificadas 10 categorias alimentares, sendo que Decapoda Dendobranchiata foi a mais importante em freqüência numérica e de ocorrência. Este fato sugere que Isopisthus parvipinnis é uma espécie carnívora, com tendência a carcinofagia, ao menos nos indivíduos jovens.