Papers by Fernando Becker
Environmental Biology of Fishes, Nov 22, 2021
Oecologia Australis, Jun 16, 2021
Resumo: O conhecimento sobre paisagens fluviais e sua relação com peixes de riacho expandiu-se mu... more Resumo: O conhecimento sobre paisagens fluviais e sua relação com peixes de riacho expandiu-se muito desde os anos 1990. Entre as diversas condições determinantes deste progresso, quatro podem ser destacadas: (a) a disponibilidade de tecnologias e dados geoespaciais; (b) a contextualização da área de estudo em relação a compartimentos geográficos de ampla escala geográfica (biomas, grandes bacias hidrográficas, ecorregiões); (c) a definição das unidades espaciais de análise (e.g. bacias, riachos, segmentos de riacho) e sua caracterização por atributos (e.g., área, comprimento, declividade, intermitente/perene), e (d) o uso dessas informações para classificações das unidades espaciais de estudo. Neste trabalho, apresentamos um panorama introdutório de cada um desses aspectos, com ênfase em estudos no Brasil e, ao final, apresentamos sugestões para desenvolvimento futuro. Estas incluem: a consolidação de bases de dados regionais e nacionais que potencializem a análise de paisagens fluviais; o treinamento de estudantes e profissionais em sistemas de informação geográfica e bancos de dados espaciais; o desenvolvimento de sistemas de classificação em diferentes extensões e refinamentos espaciais e a pesquisa sobre atributos das paisagens fluviais, incluindo conectividade e dinâmica temporal.
Journal of Biogeography, Dec 15, 2020
Aim: Fish community composition is shaped by current and historical factors. In recently formed e... more Aim: Fish community composition is shaped by current and historical factors. In recently formed ecosystems, however, as the Quaternary coastal lagoons of South America, the influence of historical factors has less frequently been investigated. The low rate of endemism in these lagoons suggests a limited role for speciation while their dynamic formation history suggests local extinction and dispersal limitation could have affected present species composition. We aimed to assess the influence of past and current factors on the beta diversity of those communities and explore the main processes involved. Location: Atlantic coast of South America. Taxon: Fishes (173 species). Methods: We built a dataset of species occurrence in 129 lagoons across eight freshwater ecoregions of the world (FEOWs) located between latitudes 0° and 36°, and calculated beta diversity (β jac) and its turnover (β jtu) and nestedness (β jne) components. We used a partial Mantel test and multiple regressions on distance matrices to evaluate the importance of past and current factors, and of geographical distance in determining beta diversity. Past variables were those representing the historical freshwater habitat during the last glacial maximum (LGM), and contemporary variables were those related to current habitat. Results: We found high values of β jac within the FEOWs, with β jtu prevailing over β jne. Both past (palaeodrainage) and current (drainage area, salinity and lagoon area) factors affected species dissimilarity (β jac = 46%) and its components (β jtu = 44% and β jne = 20%), although explanation was, in part, shared with geographical distance. Individually, the influence of past factors was prevalent in beta diversity and its components. Main conclusions: The large influence of the past factors on beta diversity suggests that major changes in the availability of freshwater habitats and connectivity since the Pleistocene must have affected the colonization, extinction and recolonization processes of fishes along the eastern coast of South America. We suggest that the
Neotropical Ichthyology, 2019
We investigated whether the movement and distribution of the migratory fish, Salminus brasiliensi... more We investigated whether the movement and distribution of the migratory fish, Salminus brasiliensis, were affected by a small reservoir. We also examined how movement and distribution were related to water temperature, flow, and rainfall. In December 2011 and January 2012, 24 individuals were captured downstream from the dam, tagged with radio transmitters and released in the reservoir (5.46 km² total area). After being released in the reservoir, 18 of the 24 tagged fish travelled upstream, taking an average of 16.6 days to leave the reservoir, with daily movements varying from < 5 km/day to > 24 km/day. However, only seven tagged specimens (29.16%) returned to the lower reservoir section, while the rest remained in the intermediate and upper reservoir sections. Longitudinal distributions and movements were positively related to both upstream flow into the reservoir and water temperature. We found evidence that S. brasiliensis can recognize the longitudinal gradient and is able to continue its upstream migration. On the other hand, the reservoir negatively affected downstream movements, possibly because disorientation prevented movement to the lower reservoir section. Based on these results, we suggest that the impact of small reservoirs on migratory fish species should be objectively addressed in environmental impact assessments and management programs.
Hydrobiologia, May 30, 2020
Metacommunity structure depends on environmental and spatial factors. Stream fishes are constrain... more Metacommunity structure depends on environmental and spatial factors. Stream fishes are constrained to disperse within dendritic networks and waterfalls and other barriers add resistance to species dispersal. We evaluated the importance of environmental and spatial effects on fish metacommunity composition, adopting different models of spatial distance: overland, watercourse, resistance (physical barriers), cost distance (watercourse resistance), and asymmetrical dispersal (considering flow direction). Fishes were sampled in 31 riffle sites of a small subtropical basin of southern Brazil (* 250 km 2 effective study area). Using redundancy analysis (RDA) and variance partitioning, we found the best model was the one including flow direction weighted by watercourse distance plus environmental variables (overall adj-R 2 = 0.42). However, the explanation of fish composition was greatly improved by weighting spatial distance by stream channel sinuosity or height of barriers. Reach slope and width were the two significant environmental variables. Our study supports that dispersal, in addition to environmental factors, affects stream fish metacommunity even in a watershed of small spatial extent. Detecting spatial effects in a small watershed depends on considering realistic watershed features that affect fish dispersal in Handling editor: David J. Hoeinghaus.
Marine and Freshwater Research, 2017
Neotropical Ichthyology, 2018
Fish reproduction in floodplain rivers is often linked to flow regime and with the inundation of ... more Fish reproduction in floodplain rivers is often linked to flow regime and with the inundation of floodplain habitats. However, in confined rivers, where floodplains are absent, the relation between reproduction and flow can in comparison be expected to be distinct. In this study, we describe the reproductive life-history of Hemiancistrus fuliginosus and Hypostomus isbrueckeri in a confined river and discuss its differences relative to floodplain loricariids and also the implications for effects of dam construction and flow regulation. We found the reproductive peak of both species occurred during lowering waters, just after maximum river flow, in contrast to floodplain species that tend to spawn during rising waters. The studied species presented attributes of equilibrium life-history strategy, which are related to predictable river flow variation. Because both species spawned during low river flow, which is historically predictable in summer, we suggest that their reproduction may be severely disrupted, depending on how flow regime is affected by dam operation. These results have implications for assessing and mitigating the impacts of river damming on fish populations in confined rivers, and we point to ecologically driven flow management and conservation of free-flowing rivers as mitigation and conservation alternatives.
Neotropical Ichthyology, 2016
Photo-identification allows individual recognition of animal species based on natural marks, bein... more Photo-identification allows individual recognition of animal species based on natural marks, being an alternative to other more stressful artificial tagging/marking techniques. An increasing number of studies with different animal groups has shown that photo-identification can successfully be used in several situations, but its feasibility to study freshwater fishes is yet to be explored. We demonstrate the potential use of photo-identification for intraspecific recognition of individuals in the streamdwelling loricariid Rineloricaria aequalicuspis. We tested photo-identification in laboratory and field conditions based on the interindividual variability in abdominal bony plates. Our test yielded high correct matches in both laboratory (100%) and field conditions (> 97%), comparable to other reliable techniques and to studies that successfully used photo-identification in other animals. In field conditions, the number of correct matches did not differ statistically between computer-assisted and nakedeye identification. However, the average time expended to conclude computer-assisted photo evaluations was about half of the time expended to conclude naked-eye evaluations. This result may be exacerbated when using database with large number of images. Our results indicate that photo-identification can be a feasible alternative technique to study freshwater fish species, allowing for a wider use of mark-recapture in ecological and behavioral studies. A foto-identificação permite o reconhecimento individual de espécies de animais baseando-se em marcas naturais, sendo uma alternativa a outras técnicas de marcação artificial mais estressantes comumente usadas. O número crescente de estudos que usam foto-identificação em diferentes grupos animais mostra que esta técnica pode ser utilizada com sucesso, mas a viabilidade em estudos com peixes de água doce ainda não foi avaliada. Nós demonstramos o uso potencial da foto-identificação para o reconhecimento individual de peixes com indivíduos do loricarídeo Rineloricaria aequalicuspis. Nós testamos fotoidentificação em condições de laboratório e de campo com base na variabilidade inter-individual das placas ósseas abdominais. O teste resultou em elevada porcentagem de acerto nas comparações, tanto para a condição de laboratório (100%) quanto para a de campo (> 97%), o que é comparável com outras técnicas confiáveis e com outros estudos que empregaram fotoidentificação com sucesso. No teste de campo, o número de acertos não diferiu estatisticamente entre auxílio de computador e olho nu. Entretanto, o tempo médio despendido para concluir as avaliações com o auxílio de computador foi cerca da metade do tempo despendido para as avaliações a olho nu. Esse resultado pode ser exacerbado em avaliações com um grande número de imagens. Nossos resultados indicam que a foto-identificação pode ser uma técnica alternativa viável para estudar peixes de água doce e possibilita um uso mais amplo da marcação e recaptura para estudos ecológicos e comportamentais.
Hydrobiologia, Jul 20, 2014
Hydrobiologia, Mar 29, 2022
Environmental Biology of Fishes, Apr 21, 2023
Environmental Biology of Fishes, Aug 6, 2016
Channel slope is an important variable in lotic systems because it mediates flow. However, stream... more Channel slope is an important variable in lotic systems because it mediates flow. However, stream slope can be measured at various spatial scales and the relation with fish assemblage characteristics may be scale dependent. In this study we investigated the influence of stream slope measured at different spatial scales on fish species richness. We tested three hypotheses: 1) the relation between slope and species richness will be dependent on the spatial scale at which slope is measured; 2) species richness will be inversely related to mean stream slope; 3) species richness will be positively related to stream slope variability. We sampled riffle fish assemblages in 21 streams in southern Brazil. For each stream we measured slope at five different scales and calculated mean slope and slope variation. The influence of slope on local species richness was tested by simple regression analysis using rarefied richness as response variable. We found that the relation between slope and species richness was scale-dependent, because only slope at the whole stream channel was significantly related to species richness. We also observed that steeper streams tended to have less slope variability and lower species richness. These results suggest that processes occurring at the whole stream scale are determinant for local fish species richness. More importantly, they reinforce the need to measure slope at different scales when investigating fish-habitat relations in streams, because the influence of slope may not be detected if assessed at only one scale. We suggest that assessing mean slope and slope variability at different scales should be considered in sampling design of research and conservation aimed at stream fishes.
Neotropical Ichthyology, 2021
Body size influences the effect of individuals and assemblages on ecosystem functioning and defin... more Body size influences the effect of individuals and assemblages on ecosystem functioning and defines how they respond to ecosystem changes. We evaluated how body size structure of fish assemblages and functional groups respond to human modifications at catchment, riparian and local scales in 40 streams of the Pampa grasslands, southern Brazil. To describe body size structure, we calculated the mean, coefficient of variation, skewness, and kurtosis, using individual biomass data for the entire fish assemblages and separately by functional group. The results suggested that body size response depends on body size metrics, functional group, and the spatial scale of land use. From 11 functional groups, only five showed a clear response to land use. In general, most functional groups had a higher concentration of small sizes (left-skewed) in response to increased land use measured at distinct spatial scales (local, riparian, and catchment), and a greater concentration of sizes in a narrow and central distribution (higher kurtosis). However, the responses were complex and varied between the functional groups. We conclude that considering ecomorphological and trophic features separately by functional group and assessing multiple body size metrics contributed greatly to detecting the influence of land use on fish body size.
Journal of Vegetation Science, Aug 12, 2017
Question: Analysing taxonomic, phylogenetic and functional species distribution across a metacomm... more Question: Analysing taxonomic, phylogenetic and functional species distribution across a metacommunity allows understanding of how landscape dynamics may influence forest expansion over grassland. In this context, climbing plants are particularly interesting vegetation components, since they actively prospect the best sunlight position, altering forest structure. We investigated if forest structure differentiation along a patch size/isolation gradient would determine the distribution of phylogenetic clades, dispersal and/or establishment-related traits in climbing plant assemblages. We hypothesized that taxonomic, phylogenetic and functional species diversities would show a nested pattern along the gradient of increasing vegetation complexity. Furthermore, less mobile diaspores, as well as climbing mechanisms independent of support limitations, and deeper phylogenetic clades characterized by shade-tolerant species would be associated with more developed and less isolated patches. Location: Subtropical grassland surrounded by Araucaria forest, southern Brazil. Method: We recorded the composition and abundance of climbing plant species along a gradient of forest patches increasing in size and isolation from the surrounding continuous forest. We performed an analysis of principal coordinates of phylogenetic structure (PCPS) to investigate the distribution of phylogenetic clades across sites, tested its relationship with patch area and isolation using linear models, and for the correlation to species dispersal traits and climbing mechanisms. We employed the treeNODF (Nestedness based on Overlap and Decreasing Fill) method to estimate if there was a phylogenetic, compositional and/or functional nested pattern of the metacommunity structure during forest expansion over grassland. Results: We found that species composition distribution was explained by patch size and isolation, but not by phylogeny. Dispersal traits were more structured along the gradient compared to climbing mechanisms. We also found a nested pattern of combined species and phylogenetic/functional diversities, where smaller patches are subsets of larger patches and of continuous forest sites. Conclusion: Patch area, isolation and dispersal traits play significant roles in the distribution of climbing plants during the process of forest advance over grassland, independently of phylogenetic relatedness among species. The nested pattern indicated that continuous forest and larger patches provide all the diaspores that colonize the smaller patches in this process, making them important targets for conservation.
Environmental Monitoring and Assessment, Apr 18, 2019
Despite the importance of assessing beta diversity to understand the effects of human modificatio... more Despite the importance of assessing beta diversity to understand the effects of human modifications on biological communities, there are almost no studies that properly addressed how beta diversity varies along anthropogenic gradients. We developed an algorithm to calculate beta diversity among a set of sites included in a moving window along any given environmental gradient. This allowed us to
Ecology
The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's mo... more 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 se...
Frontiers of Biogeography
Journal of Fish Biology
We report the occurrence of an invasive alien species, palometa Serrasalmus maculatus, in the Pat... more We report the occurrence of an invasive alien species, palometa Serrasalmus maculatus, in the Patos Lagoon drainage. Primary occurrence data were based on three specimens captured and preserved as vouchers in scientific collections. Additionally, we searched for secondary records from unpublished scientific sources, public agencies reports and media news to find additional reports. We discussed the possible pathways of invasion, suggesting as the vector of introduction transpositions from the Uruguay River basin. Ecological implications for ichthyofauna, environmental impacts and risk of other events of invasion in the adjoining basins are discussed.
Revista Biociências, Sep 11, 2015
O bugio que habita a mata e a mente dos moradores de Itapuã-Uma análise de percepção ambiental no... more O bugio que habita a mata e a mente dos moradores de Itapuã-Uma análise de percepção ambiental no entorno do Parque Estadual de Itapuã, Viamão, RS The howler monkey that inhabits the forest and the mind of Itapuã residents-An analysis of environmental perception in the surroundings of the Itapuã State Park, Viamão, RS
SSRN Electronic Journal, 2022
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Papers by Fernando Becker