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The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

The Brazilian strategy to overcome the spread of COVID-19 has been particularly criticized due to the lack of a national coordinating effort and an appropriate testing program. Here, a successful approach to control the spread of COVID-19 transmission is described by the engagement of public (university and governance) and private sectors (hospitals and oil companies) in Macaé, state of Rio de Janeiro, Brazil, a city known as the National Oil Capital. In 2020 between the 17th and 38th epidemiological week, over two percent of the 206,728 citizens were subjected to symptom analysis and RT-qPCR testing by the Federal University of Rio de Janeiro, with positive individuals being notified up to 48 h after swab collection. Geocodification and spatial cluster analysis were used to limit COVID-19 spreading in Macaé. Within the first semester after the outbreak of COVID-19 in Brazil, Macaé recorded 1.8% of fatalities associated with COVID-19 up to the 38th epidemiological week, which was at least five times lower than the state capital (10.6%). Overall, considering the successful experience of this joint effort of private and public engagement in Macaé, our data suggest that the development of a similar strategy countrywise could have contributed to a better control of the COVID-19 spread in Brazil. Quarantine decree by the local administration, comprehensive molecular testing coupled to scientific analysis of COVID-19 spreading, prevented the catastrophic consequences of the pandemic as seen in other populous cities within the state of Rio de Janeiro and elsewhere in Brazil.

With the aim of assessing whether hydrological alterations differently affect non-native and native fish species in coastal systems, we investigated fish assemblages along the fluvio-estuarine ecotone of the Neotropical Sao Joao River, Brazil. During a year, samplings with standardized efforts and limnological parameter records were carried out bimonthly at 15 sampling points in the last 50 km of the Sao Joao River, representing natural (meandering riverine and estuarine) and modified (reservoir, channelized and drained floodplain) stretches. We recorded 48 marine and 51 freshwater fish species, with 12 non-native species among the latter. Several native species were exclusively found within natural stretches, whereas non-native species presented significantly higher biomass catches in modified stretches. Only three species occurred in the entire study area, all of which were non-native species. Non-native species were associated with low dissolved oxygen and pH levels below the dam, whereas native freshwater species responded negatively to water transparency, and marine species responded positively to water conductivity at the hydrologically unaltered points. The hydrological alterations disrupted the fluvio-estuarine ecotone of the lower Sao Joao River, which plays the role of a dispersion source for non-native species and where invasive species are favored.

Peacock basses (Cichla spp.) are native to the Amazon basin but introduced to different parts of the world. Almost thirty years ago, Cichla kelberi was introduced in an impoundment of the Sao Joao River, a coastal system in southeastern Brazil. Recently, this cichlid invaded the estuarine section of the basin. This study aims to analyze spatial and temporal variations in catch of C. kelberi and fish assemblage structure along the estuarine stretch of this river and how abiotic variables affect their distribution. Sampling was performed in four segments downstream of the dam. Principal component analysis revealed that abiotic variables displayed temporal and spatial variation, in part due to the salinity gradient, that were more pronounced in the dry season. Cichla kelberi occurred in all segments, but mainly in shallow and vegetated habitats of the middle course and barely in the most downstream. Eighty-one fish species were recorded, nine of which were non-native, representing 33.4% of total catch. A redundancy analysis indicated that the fish assemblages showed marked spatial variation, mostly related to the salinity gradient. The lowermost segment of the river was dominated by marine species, the only locality where non-native species summed less than 40% of the catches. In the upstream segments, higher oxygen levels and lower temperatures influenced the occurrence of most species. Higher salinity of the estuary seems to limit the spread of C. kelberi, but the invader may reach adjacent basins in years of exceptional floods. The eurihalinity and piscivory of C. kelberi partly explain its invasive success.

Ethnoichthyology has been used to understand how humans perceive environmental changes, including species introductions. In Rio de Janeiro State, southeastern Brazil, fishers introduced juveniles of peacock bass Cichla kelberi in the Juturnaiba Reservoir in the 1990’s. In the last years, this fish started to be caught in the Sao Joao River, downstream of the dam. This study aimed to identify whether fishers recognize the potential impact of the peacock bass over the native species, to understand the economic valuation they made to the services provided by this species, and if they include management of the non-native peacock bass in their practices. Semi-structured interviews with artisanal and sport fishers were employed between September and October 2016. A total of twenty-five interviews were carried out, 12 with artisanal and 13 with sport fishers. In general, fishers expressed knowledge about biological and behavioral aspects of the peacock bass, but opinions diverged on its impact over the native ichthyofauna. Differently from the artisanal, most sport fishers do not relate the decline in the population of other native species to the occurrence of the peacock bass. Instead, they mention other anthropogenic impacts in the Sao Joao River basin. The later advocate the practice of fish and release for the peacock bass, in order to maintain their population in the study area. The ethnoichthyological knowledge gathered from fishers provide novel information related to the native ichthyofauna, peacock bass introduction and other anthropogenic impacts, and might constitute a powerful tool to the development of sustainable strategies.

Made available in DSpace on 2019-10-06T15:36:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-02-28 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis Understanding whether and how different habitat features affect patterns of life-history variation is an intriguing aim in evolutionary ecology. We tested how a suite of biotic and abiotic factors simultaneously affect life-history patterns in six populations of the livebearing fish Poecilia vivipara inhabiting coastal lagoons in southeastern Brazil, varying greatly in salinity and fish communities. We sampled potential competitors (cyprinodontiform fishes) and piscivores, and we measured nine limnological variables in the wet and dry seasons during 2 years. We found that size at maturity and offspring size were strongly and negatively influenced by the abundance of piscivores, and that reproductive allocation was strongly and positively influenced by variations in resource abundance and temperature among seasons. Effects of salinity on size at maturity, female reproductive investment and offspring size were indirect, via piscivore abundance, highlighting the potential for indirect effects that can be detected only by analysing multiple habitat features simultaneously. This suggests caution in interpreting associations between life histories and salinity in wild populations. Observed patterns generally matched theoretical predictions and prior empirical work, but some predictions were not met. Our results suggest that life histories result from a partly predictable complex combination of direct and indirect effects of habitat features, which can sometimes act antagonistically. Universidade Estadual Paulista (UNESP) Instituto de Biociências, Av. 24-A, 1515 Universidade Federal Do Rio de Janeiro Instituto de Biodiversidade e Sustentabilidade Department of Biological Sciences W.M. Keck Center for Behavioral Biology North Carolina State University Universidade Federal Do Rio de Janeiro Instituto de Biologia Universidade Estadual Paulista (UNESP) Instituto de Biociências, Av. 24-A, 1515

Background Brazilian strategy to overcome the spread of COVID-19 has been particularly criticized due to the lack of a national coordinating effort and an appropriate testing program. Here, a successful approach to control the spread of COVID-19 transmission is described by the engagement of public (university and governance) and private sectors (hospitals and oil companies) in Macaé, state of Rio de Janeiro, Brazil, a city known as the National Oil Capital. Methods Until the 38th epidemiological week, over two percent of the 206,728 citizens were subjected to symptom analysis and massive RT-qPCR testing by the Federal University of Rio de Janeiro, with positive individuals being notified up to 48 hours after swab collection. Geocodification and spatial cluster analysis were used to limit COVID-19 spreading in Macaé. Findings: Within the first semester after the outbreak of COVID-19 in Brazil, Macaé recorded 1.8% of fatality associated to COVID-19 up to the 38th epidemiological week, which was at least five times lower than the state capital (10.92%). Overall, considering the successful experience of this joint effort of private and public engagement in Macaé, our data suggest that the development of a similar strategy country wise would have saved over 50,000 lives. Interpretation: Quarantine decree by the local government, molecular massive testing coupled to scientific analysis of COVID-19 spreading prevented the catastrophic consequences of the pandemic as seen in other populous cities within the state of Rio de Janeiro and elsewhere in Brazil.

Camara, E.M.; Caramaschi, E.P.; Di Dario, F., and Petry, A.C., 2018. Short-term changes in two tropical coastal lagoons: Effects of sandbar openings on fish assemblages. Sandbar openings (SBOs) are among the largest possible disturbances in coastal lagoons. This study investigated the mechanisms of the responses of fish assemblages to short-term environmental changes resulting from several SBOs during 1 year in two coastal lagoons in southeastern Brazil. Lagoons were sampled monthly in sites closer to, and more distant from, the sandbars. A principal component analysis summarized limnological differences between periods of contact and isolation from the sea, and site- and lagoon-based variation partitioning and independent redundancy analyses (RDAs) quantified the unique and shared effects of limnology, space, and period on species and groups of species (marine, estuarine, and freshwater). Limnological differences between periods were associated with a higher marine influence during SBOs and an i...

Neotropical freshwater ecosystems are experiencing a great expansion in the number of invasive species, which is especially alarming since this region harbours 30% of the world’s fish biodiversity with high levels of endemism. We aimed to evaluate the main predictors of peacock basses (Cichla spp.) abundance outside their native range, which are the Amazon and Tocantins-Araguaia river basins. We used multivariate ordination techniques and multimodel inference to analyse peacock basses abundance in twelve reservoirs of the Paraiba do Sul river basin, southeastern Brazil. Interestingly, reservoirs at higher (southernmost) latitudes, located in more populated areas, had higher water temperature and lower turbidity, due to increased water residence time, and these three variables were also positively correlated with abundance of this warm-water invasive fish. Habitat structure was less important in explaining peacock basses abundance, which was not significantly related to biotic factors (fish species richness and time since peacock basses introduction). We hypothesize that the observed effects of reservoir management on limnological features and peacock bass abundance, particularly water residence time (as a mediator of temperature and turbidity), may apply to other Neotropical basins and could influence the impact of this invader.

This study aimed to characterize species composition and abundance of fish assemblages of low-order streams of the Machado River Basin and to identify the main environmental factors associated to fish assemblages along the elevational gradient. Fishes were collected by seine and dip nets, along an 80-m stretch of 71 streams. In each site, we recorded physical, chemical, and land–water ecotone variables. We collected 22,702 specimens of 91 species. Species richness and abundance varied negatively with elevation. Ordination and similarity analyses detected that streams located in higher and middle elevation ranges differed in species composition from those in the lower elevation range. Almost one-third of the recorded species were selected as indicator species. Species of the families Trichomycteridae, Cichlidae, Gymnotidae, and Characidae were closely associated with the land–water ecotone and structural characteristics of lower elevation range, whereas several other Characidae species were more abundant in middle elevation range, where aquatic vegetation cover and conductivity values were higher. By assuming that composition and relative abundance of fish respond to environmental changes, hydrological characteristics may be viewed as environmental filters for stream assemblages by ultimately selecting the pool of species able to reach for specific elevation ranges and meet their biological requirements.

Understanding whether and how ambient ecological conditions affect the distribution of personality types within and among populations lies at the heart of research on animal personality. Several studies have focussed on only one agent of divergent selection (or driver of plastic changes in behavior), considering either predation risk or a single abiotic ecological factor. Here, we investigated how an array of abiotic and biotic environmental factors simultaneously shape population differences in boldness, activity in an open-field test, and sociability/shoaling in the livebearing fish Poecilia vivipara from six ecologically different lagoons in southeastern Brazil. We evaluated the relative contributions of variation in predation risk, water transparency/visibility, salinity (ranging from oligo- to hypersaline), and dissolved oxygen. We also investigated the role played by environmental factors for the emergence, strength, and direction of behavioral correlations. Water transparency explained most of the behavioral variation, whereby fish from lagoons with low water transparency were significantly shyer, less active, and shoaled less than fish living under clear water conditions. When we tested additional wild-caught fish from the same lagoons after acclimating them to homogeneous laboratory conditions, population differences were largely absent, pointing toward behavioral plasticity as a mechanism underlying the observed behavioral differences. Furthermore, we found correlations between personality traits (behavioral syndromes) to vary substantially in strength and direction among populations, with no obvious associations with ecological factors (including predation risk). Altogether, our results suggest that various habitat parameters simultaneously shape the distribution of personality types, with abiotic factors playing a vital (as yet underestimated) role. Furthermore, while predation is often thought to lead to the emergence of behavioral syndromes, our data do not support this assumption.

Invasive Cichla populations in the Sao Joao River basin were genetically analysed and compared with Cichla populations from other neotropical hydrographic basins. Polymorphic sequences within the mitochondrial DNA D-loop region confirmed the introduction of different populations to the regions under analysis. Cichla kelberi was introduced to the Juturnaiba reservoir and a downstream area of the Sao Joao River, with Cichla monoculus restricted to downstream river areas. Results from this study will be useful for monitoring invasive Cichla populations in the coastal basin since it elucidated the taxonomic units in the reservoir and an areas downstream.

The first record of pughead deformity in a Neotropical freshwater fish not raised in captivity is provided, based on an adult male of Cichla kelberi introduced into an estuary of Rio de Janeiro State, south-eastern Brazil. A general biological characterization of the specimen is provided and aspects of its aberrant anatomy are described. Environmental and biological factors that may cause pughead deformity in fishes are discussed.

The aim of this study was to evaluate the anesthetic efficacy and determine the lowest effective concentration in the guppy, Poecilia vivipara. Fishes were exposed to benzocaine, tricaine methanesulfonate and eugenol at three different concentrations. After induction, they were transferred to an aquarium free of anesthetic for evaluating their recovery time. At the lowest concentration of the three anesthetics (50 mg L−1), fish did not reach complete induction. Time to accomplish a light sedation stage was significantly negative-related with concentration using tricaine (145 ± 13.4 s with 50 mg L−1 to 4.7 ± 0.7 s with 200 mg L−1) and benzocaine (152.8 ± 13 s with 50 mg L−1 to 4.0 ± 0.9 s with 200 mg L−1). For eugenol, significant differences were found between the lowest concentration, 50 mg L−1 (241 ± 57.6 s) with 100 mg L−1 (13.3 ± 3.9 s) and 200 mg L−1 (9.5 ± 2.6 s). Recovery times were significantly longer (P

Demographic changes during the late Pleistocene-Holocene left signatures in the DNA of contemporary populations. These signatures reveal demographic phenomena like the increase or decrease in effective population size. In this paper we searched for signatures of demographic change in the DNA of the Neotropical freshwater fish Poecilia vivipara . Also, we investigated whether demographic changes are correlated with palaeoclimatic events of the late Pleistocene-Holocene, in particular, if changes in effective population size are correlated with expansion and contraction of available habitats, induced by global ice-volume changes and sea-level fluctuations. We used Bayesian Skyline Plot (BSP) analysis with sequences from the mitochondrial gene cytochrome b to estimate the ancestral demography of the Neotropical freshwater fish P. vivipara . To test the assumptions of neutrality and absence of population structure we used Tajima’s D and Spatial Analysis of Molecular Variance (SAMOVA), respectively. Effective population size of P. vivipara remained stable until 75,000 years ago, increased by 10-fold reaching a maximum at approximately 25,000 years ago, then suddenly declined at the Pleistocene- Holocene boundary. Variation in effective population size in P. vivipara correlates with expansion and contraction of habitats induced by sea-level fluctuations, caused by the advance and retreat of ice sheets during the Last Glacial Maximum (LGM)., Facultad de Ciencias Naturales y Museo

The relationships between fish composition, connectivity and morphometry of 103 lagoons in nine freshwater ecoregions (FEOW) between 2·83° S and 37·64° S were evaluated in order to detect possible congruence between the gradient of species richness and similarities of assemblage composition. Most lagoons included in the study were

The present study provides the length‐weight relationship (LWR) for eight species from the estuarine stretch of the Macae River, Rio de Janeiro State, Brazil. Data were obtained quarterly between June 2011 and March 2012. These LWRs are the first records for six species and present new maximum values of total length for three ones.

The removal of native forest affects stream characteristics, processes, and organisms at the local scale. We compared the structure of fish assemblages between microbasins impacted by deforestation and those in pristine condition in the Amazonian Machado River basin, Brazil. Fish were collected with seine and dip nets along an 80-m stretch of 28 streams. At each site, we recorded physical, chemical, and land-water ecotone variables. We collected 6,586 specimens of 109 species, being 39 and 18 of them exclusively of forested and deforested streams, respectively. Non-significant differences were found for abundance and species richness between forested and deforested streams. A total of four main trophic groups were identified. Carnivores were more abundant in forested streams, whereas herbivores, omnivores and detritivores species were the most abundant in deforested streams. The deforested streams showed higher abundance and richness of algae and periphyton consumers, while forested streams presented higher abundance and richness of invertebrate consumers. Forested streams presented longer foodchains, higher occurrence and abundance of species that have more specialized habits and are intolerant to degraded environments, whereas generalist and tolerant species predominated in deforested streams. We conclude that species composition in Amazonian streams predictably responds to the degree of forest cover.

Communities can be structured over time by deterministic, stochastic, or both mechanisms. This study evaluated whether the fish assemblages of the Upper Parana River floodplain were spatio-temporally structured and examined the mechanisms driving these organizational patterns. The floodplain ichthyofauna was sampled quarterly with seines and gillnets. The structure of the assemblage was assessed using the C-Score co-occurrence index and null models. The influence of both the environment (physical and chemical variables and hydrometric levels) and time on the species’ organization patterns was assessed via principal component analysis, multiple and simple regressions, and analyses of variance. Assemblages with larger species showed patterns of species segregation at both spatial and temporal scales, while those composed of smaller species often exhibited random patterns. The physical and chemical variables did not predict co-occurrence among species. For assemblages of large species, the patterns of co-occurrence tended to be random when the river level increased but only during high-water months. Therefore, the life history traits of the species, such as body size, may predict the structure of the assemblages in floodplains, but this effect depends on variations in the hydrometric level.

El Programa de Postgrado en Ciencias del Ambiente y Conservacion (PPG-CiAC), creado en 2011, es el primer PPG de la Universidad Federal de Rio de Janeiro (UFRJ) fuera de la capital del estado. En los ultimos cinco anos, fueron defendidas mas de 50 tesis de maestria en el programa, que por lo general tuvieron como objeto de estudio los ecosistemas y la sociedad del norte del estado de Rio de Janeiro, una region que ha experimentado importantes cambios socioeconomicos en las ultimas decadas. En conjunto, la produccion del PPG-CiAC contribuye al aumento del conocimiento cientifico multi e interdisciplinario regional, basado en la integracion de las ciencias naturales y sociales. En este articulo se presenta un resumen de las principales contribuciones del PPG-CiAC centrado en la promocion del desarrollo sustentable de la region.

The first checklist of fishes of the estuary of the Macaé River (Rio de Janeiro State, Brazil) and its adjacent freshwater section is presented. A total of 24,157 specimens belonging to 110 species in 44 families and 21 orders of the Teleostei were collected based on quarterly samplings, between June 2011 and March 2012. The Sciaenidae was the most representative family in species number, whereas the Ariidae, Pristigasteridae, and the invasive Clariidae predominated numerically and/or in terms of biomass. One hundred fifty-seven species of the Teleostei are now recorded in the Macaé River, including 68 species previously reported from its upper and middle portions. More than 100 of them permanently or temporarily inhabit the lower 16 km of the river, suggesting that the estuary is relevant to the maintenance of the fish diversity of the region in spite of several human activities that have significantly altered its natural features.

A list of fishes is reported from right bank tributaries of the lower Kouilou River, left bank tributaries of the Noumbi River, and a series of independent coastal catchments near Madingo-Kayes in the Kouilou Province of the Republic of Congo. Thirty-two sites were sampled in a variety of aquatic habitats in the wet and dry seasons of 2012. Fifty-five fish species distributed in 29 families were collected, three of which represent putatively undescribed species. The most diverse families in the study region were the Cichlidae and the Mormyridae. This paper provides a comparison and update to earlier species lists reported for the general area and offers a baseline that may be used as a point of departure for future ichthyological assessments.

Understanding whether and how ambient ecological conditions affect the distribution of personality types within and among populations lies at the heart of research on animal personality. Several studies have focussed on only one agent of divergent selection (or driver of plastic changes in behavior), considering either predation risk or a single abiotic ecological factor. Here, we investigated how an array of abiotic and biotic environmental factors simultaneously shape population differences in boldness, activity in an open‐field test, and sociability/shoaling in the livebearing fish Poecilia vivipara from six ecologically different lagoons in southeastern Brazil. We evaluated the relative contributions of variation in predation risk, water transparency/visibility, salinity (ranging from oligo‐ to hypersaline), and dissolved oxygen. We also investigated the role played by environmental factors for the emergence, strength, and direction of behavioral correlations. Water transparency explained most of the behavioral variation, whereby fish from lagoons with low water transparency were significantly shyer, less active, and shoaled less than fish living under clear water conditions. When we tested additional wild‐caught fish from the same lagoons after acclimating them to homogeneous laboratory conditions, population differences were largely absent, pointing toward behavioral plasticity as a mechanism underlying the observed behavioral differences. Furthermore, we found correlations between personality traits (behavioral syndromes) to vary substantially in strength and direction among populations, with no obvious associations with ecological factors (including predation risk). Altogether, our results suggest that various habitat parameters simultaneously shape the distribution of personality types, with abiotic factors playing a vital (as yet underestimated) role. Furthermore, while predation is often thought to lead to the emergence of behavioral syndromes, our data do not support this assumption.

AIM: We evaluated zooplankton resting egg banks and active communities in five coastal lagoons and in five temporary pools, aiming to compare the active and the dormant communities in such environments. As they differ in hydroperiod, we expected that pools present richer resting egg banks in comparison to those found in lagoons. METHODS: Zooplankton community was sampled twice in 2006 (lagoons) and in 2010 (pools) and resting egg banks were sampled once in December 2007 (lagoons) and in May 2010 (pools). Resting eggs were isolated from the sediment by applying the sugar flotation method. RESULTS: In opposition to our expectation, species richness in the resting egg banks of pools did not differ from those of lagoons. Additionally, no difference was found between the active and the dormant zooplankton communities in each water body for both temporary and permanent environments. However, similarity between active and dormant communities was greater in permanent environments than it was in temporary environments. CONCLUSIONS: It seems that the diapause strategy observed in certain tropical zooplankton populations cannot be predicted based on the awareness of the environment type (permanent or temporary), since hatching cues may be species-specific.

The hydrological regime represents the driver of ecological function and biodiversity in tropical river floodplains. This study aimed to document the species composition and evaluate the effect of the flood pulse on the fish community of Amapa Lake, an oxbow lake temporarily connected to the Acre River. Between October 2008 and September 2009, fish were sampled monthly with gill nets, and seven physical–chemical variables were recorded at three sampling stations along the lake. The fish community structure and physical–chemical variables were compared among the hydrological phases of pre-flooding, minor and major flood and post-flooding, and the degree of association between the limnological characteristics and species composition was explored with a canonical correspondence analysis. A total of 2131 specimens belonging to 53 species were captured. The numerical abundance and biomass of fish and water temperature were higher in the pre and post-flooding phases. Samples of the pre-flooding phase comprised more than 40% of the overall numerical abundance (115 ind. 1000 m 2 24 h −1 ± 16 se) and biomass (9949 g 1000 m 2 24 h −1 ± 1.816 se) due to the greater dominance of few species, mainly small (the Siluriformes Hypoptopoma gulare ) to medium sized (the Characiformes Triportheus curtus ) during low waters. With the onset of the minor flood, conductivity decreased and depth increased in the lake, whereas total phosphorous and pH reduced significantly at major flood. The composition and abundance of fish community changed more among hydrological phases than species richness and 26% of this annual variability in the biotic component was shaped exclusively by the physical–chemical variables. As fish community and physical-chemistry of the Amapa Lake undergo to the hydrological cycle of the Acre River, these results reinforce the general pattern of predictable seasonal alterations in the functioning of tropical floodplains. Based on the general decrease in dominance during the long flood pulse and the occurrence of piscivorous migrators among the five most abundant species, we conclude that the seasonal variation in the hydrometric level of the Acre River plays an important role in maintaining the high fish diversity observed in the Amapa Lake all year round.

The influence of the water-soluble fraction of petroleum (WSF) on prey consumption and growth of juvenile trahira Hoplias aff. malabaricus was investigated. Juveniles were submitted to either WSF or Control treatment over 28 days, and jewel tetra Hyphessobrycon eques adults were offered daily as prey for each predator. Total prey consumption ranged from 16 to 86 individuals. Despite the initially lower prey consumption under WSF exposure, there were no significant differences in overall feeding rates between the two treatments. Water-soluble fraction of petroleum had a negative effect on the growth in length of H. aff. malabaricus juveniles. Although unaffected, prey consumption suggested a relative resistance in H. aff. malabaricus to WSF exposition and the lower growth of individuals exposed to WSF than the Control possibly reflects metabolic costs. The implications of the main findings for the individual and the food chain are discussed, including behavioral aspects and the role played by this predator in shallow aquatic systems. Resumo A influência da fração solúvel de petróleo (FSP) no consumo de presas e crescimento de juvenis da traíra Hoplias aff. malabaricus foi investigada. Os juvenis foram submetidos aos tratamentos FSP e Controle durante 28 dias, e adultos de matogrosso Hyphessobrycon eques foram oferecidos diariamente como presa para cada predador. O total de presas consumidas variou de 16 a 86 indivíduos. Apesar do menor consumo inicial de presas sob exposição de FSP, não houve diferenças significativas nas taxas de consumo entre os dois tratamentos. A FSP teve um efeito negativo no crescimento em tamanho de juvenis de H. aff. malabaricus. Embora a ausência de efeito no consumo de presas sugira uma relativa resistência de H. aff. malabaricus à exposição à FSP, o menor crescimento em tamanho dos indivíduos expostos ao poluente reflete possivelmente custos metabólicos. As implicações dos principais resultados nos níveis do organismo e da cadeia alimentar são discutidos, incluindo aspectos comportamentais e o papel desempenhado por este predador em ecossistemas aquáticos rasos.

Essa revisao buscou detectar as tendencias no uso do fator de condicao a partir de estudos com diferentes grupos animais e apresentar os principais indices e suas utilizacoes para peixes, avaliando seu potencial de aplicacao em questoes que envolvam o efeito de alteracoes ambientais sobre as populacoes. Foi realizado um levantamento bibliografico envolvendo todos os artigos cientificos publicados entre 1950 e 2009, que utilizaram algum tipo de fator de condicao. Os dados obtidos foram avaliados em duas etapas. Na primeira, mais geral, foi detectado um crescimento significativo no numero de publicacoes, com a ocorrencia de 2666 artigos, em 567 periodicos. A maioria dos estudos envolveu o grupo peixes, seguida de moluscos, crustaceos, aves, mamiferos, anfibios e repteis. Esta era uma tendencia esperada, pois a ferramenta foi desenvolvida inicialmente para o primeiro grupo. Na segunda etapa, restrita a peixes, verificou-se que o fator de condicao mais utilizado foi o de Fulton (K=M.L -3 ), seguido pelos fatores de condicao alometrico (K = W.L - b ) e relativo (Kr = W.W' -1 ). De modo geral, os artigos analisados respeitaram as limitacoes intrinsecas a cada tipo de indice no que diz respeito a aplicabilidade em populacoes de especies com diferentes intensidades de alometria entre os sexos e amplitudes de classes de tamanho. A importância da utilizacao desses indices como ferramentas praticas e acessiveis na avaliacao de questoes populacionais em diferentes escalas ecologicas se traduz na grande variedade de temas e formas de abordagem dos artigos. Estes fatores justificam a busca de aprimoramento matematico dos indices, bem como padronizacao dos tipos de fator de condicao utilizados em estudos com as mesmas especies, facilitando comparacoes e, consequentemente, acoes de manejo e conservacao destas.

We assessed the influence of hydrological connectivity in structuring fish communities through seasonal samplings of environmental variables and fishes in a coastal lagoon and associated pools in the Restinga de Jurubatiba National Park, Brazil. Community structure attributes such as species richness, numerical density and biomass, Shannon-Wiener diversity index and evenness were compared between periods of the lowest and highest hydrological connectivity, while the environmental gradient and fish zonation were explored through ordination techniques. The greater hydrological connectivity established in the rainy season promoted the homogenisation of most environmental variables and fish species, which differed markedly from the arrangement observed in the dry season. Despite variation in fish species composition, community attributes showed non-significant differences between the dry and rainy seasons. The patterns of composition and numerical density in pools were strongly influenced by local factors, especially salinity, dissolved oxygen, total phosphorous concentration and water colour in the dry season, in addition to total nitrogen concentration and depth in the rainy season. Comparable to the role played by flood pulses in river-floodplain systems, the hydrological connectivity in these tropical coastal waterbodies seems to strongly influence fish community structure, and, therefore to determine regional biodiversity.

The physicochemical variables and the ichthyofauna associated with aquatic macrophyte beds in two stretches of the baia Caicara were evaluated seasonally between September 2005 and May 2007. Low depth, high water transparency, and relatively well-oxygenated waters characterized both stretches during the low water season, whereas the flooding of the upper Paraguay River correlated with drastic alterations in these variables: depth registered a fivefold increase, and turbid and anoxic waters predominated during the high water season. During the falling and low water seasons, species richness, fish abundance, biomass, and diversity were significantly higher than during periods of rising and high waters. The presence of large-sized migratory species, however, was strictly associated with the high water season. The results suggest strong relationships between the abiotic and biotic components of the system and indicate an overall high degree of dependence of the system on the hydrological seasonality of the upper Paraguay River.

The Paraná River is the second longest river in South America and the tenth largest river in the world in water discharge. The upper stretches are characterized by high human occupation and intense anthropogenic activities, and few areas are still in pristine conditions. Despite this, fish diversity is remarkably high in the upper Paraná River basin, and the existence of different habitats greatly influences fish biodiversity. Although most species are sedentary, migratory species are considered the most important, since they have historically sustained commercial and recreational fisheries. Recently, stocks of migratory species have diminished in many rivers due to overfishing and habitat modifications caused by dams. Impoundments have a long history in the basin and constitute the main source of impacts for both sedentary and migratory fish species. Government agencies have implemented management actions to mitigate the effects of damming on fish populations, which included fish stocking (using native and non-native species), the construction of transposition mechanisms and fishery control. However, their efficacy for conservation has been severely questioned and, in many instances, these actions have produced negative outcomes to biodiversity. The lack of studies and monitoring programs contributed to the uncritical adoption of some dubious management actions. Inevitably, management plans directed to conserve fish biodiversity in the basin need urgent revision.