Francisco Gerson Araújo

Federal Rural University of Rio de Janeiro | UFRRJ · Department of Animal Biology

The strategies that allow invasive alien species to perpetuate themselves in the long term are still poorly understood in invasion science. Considering top predators, a key issue is how they overcome the prey decline which they have caused during the invasion process. We investigate factors related to the persistence, impacts and long‐term success...

Dams modify river physical and chemical attributes. This disruption hampers fish migration, leading to the introduction of non‐native species and losses of specialised native species. Small hydropower plants (SHPs) have been suggested for replacing large dams to minimise reservoir size and preserve natural flow regimes. We evaluated the influences...

We investigate the effects of spatial changes in environmental conditions and anthropogenic influences on larval fish communities in two tropical estuaries with varying levels of human impact. Our findings revealed a distinct structure of larval fish assemblages between the two estuaries located in northeastern Brazil, and we observed that eutrophi...

Functional characteristics of species are of great importance for understanding their roles in ecosystems and can be used to detect long‐term chances in the environment. We evaluated temporal changes (1983–1985 and 2017–2019) in taxonomic and functional indices of the fish fauna in shallow areas of a tropical bay heavily impacted by anthropogenic a...

Damming of large rivers has promoted well‐documented ecosystem changes that constitute critical threats to freshwater fish biodiversity. However, it is unclear how trait–environment relationships drive community assembly in older (>50 years) tropical river‐reservoir systems. We assessed physical features filtering functional traits (RLQ and fourth‐...

Environmental influences on species’ functional traits are important ecological issues to assess biodiversity. Relationships among fish abundance, their functional traits, and environmental conditions across different levels of anthropogenic impacts in a tropical Brazilian river were evaluated. We combined RLQ and fourth-corner methods, utilizing l...

A Coleção Ictiológica do Laboratório de Ecologia de Peixes da Universidade Federal Rural do Rio de Janeiro reúne cerca de 2600 lotes tombados com 380 espécies de peixes, compreendendo as Classes Chondrichthyes, Actinopterygii e Sarcopterygii. A coleção reune espécimes coletados entre 1954 e 2020, e destaca-se por sua representatividade dos mais div...

As human-induced environmental changes reduce niche opportunities from global to local scales, permanent shifts in species traits alter ecosystem processes. Disentangling multiscale mechanisms driving temporal changes in coastal fish biodiversity is thus critical to conservation aims. From seasonal to multiyear periods, we investigated how local en...

Leptopanchax opalescens is a critically endangered small annual fish. Reproductive traits of this species were studied to improve our understanding of the strategies that facilitate the occupation of temporary wetlands. We compiled egg diameter and maximum total length data from 136 neotropical killifishes (Rivulidae) to establish comparisons betwe...

Leptopanchax opalescens is a critically endangered small annual fish. Reproductive traits of this species were studied to improve our understanding of the strategies that facilitate the occupation of temporary wetlands. We compiled egg diameter and maximum total length data from 136 neotropical killifishes (Rivulidae) to establish comparisons betwe...

The alternation of light and darkness drives species’ activities, and identifying diel rhythms is critical for understanding the ecology and representing the biodiversity of a range of communities. This study aimed to investigate diel changes in rocky reef fish assemblage composition and structure and to identify the most underestimated nocturnal s...

Industrial wastewater and agricultural practices are among the main activities discharging organic pollutants, such as Polychlorinated biphenyl (PCB) congeners and organochlorine insecticides (e.g. DDT - dichloro diphenyl trichloroethane), to the environment. In this study, we used the native Cichlidae fish species Geophagus brasiliensis as a senti...

Estuarine shallow waters have many habitats favouring the colonization and establishment of different fish species. Our study investigated the variability in the composition of these communities by examining beta diversity and evaluated the relationship between fish beta diversity and environmental heterogeneity, which can be dependent on the level...

A new approach for visual fish survey in reservoirs using underwater drones (remotely operated vehicle- ROV) is presented. The ROV was applied to identify abiotic gradients and to compare fish assemblages on the steep slopes in a tropical reservoir. The tested hypothesis is that fish are concentrated in the littoral zone due to the better physicoch...

The dynamics of fish assemblages in reservoirs depend on factors such as the morphometry of the catchment, habitat structure, and the uses of the reservoir. In the Paraíba do Sul (PSR) basin in southeastern Brazil, there are several types of reservoirs, some on the main channel, some are cascade reservoirs originated from a diversion of the waters...

Multiscale processes through dynamic boundaries drive the local contributions (LCBD; uniqueness in species composition and abundance) and species contributions (SCBD; individual species abundance variation) to fish beta diversity in coastal seascapes. We partitioned LCBD into LCBDRepl (replacement) and LCBDAbDiff (abundance difference), and used mo...

O Parque Natural Municipal Bosque da Barra é uma Unidade de Conservação de Proteção Integral criada em 2003 e uma das mais visitadas do Município do Rio de Janeiro. Estudos prévios indicam que a lagoa da UC é artificial e o parque abrange ambientes de brejos, originais da restinga da Mata Atlântica. Suas águas são provenientes da chuva e do complex...

Resource partitioning is essential for coexistence of phylogenetically related species in altered environments, where changes in biotopes can limit resources and change ecological strategies. We investigated resource partitioning between two congeneric catfishes (Hypostomus affinis and H. luetkeni) in three niche dimensions (trophic, spatial, and t...

Introdução Fusarium é um gênero fúngico saprofítico que acomete comumente animais e plantas. Dentre os animais susceptíveis à infecção por esse microorganismo, estão os peixes, objeto de estudo do presente trabalho. A contaminação de peixes por Fusarium pode causar lesões na superfície da pele que evoluem para úlceras, muitas vezes fatais (FERNANDO...

Shallow coastal habitats are ruled by fluctuating environmental conditions, which lead to shifts in fish communities. Functional groups of habitat use and trophic strategy were used to address the responses of fish composition and diversity, since comparisons of rich tropical systems are often complex through species-based approaches. We hypothesiz...

Guia de espécies de peixes do Reservatório de Lajes, do qual fui, não um dos autores, mas sim o revisor taxonômico.

Increases in temperatures over the last century, more intensively after the eighties, were recorded in several databases for the south‐eastern Brazil. These increases are likely to change fish communities in aquatic systems by decreasing abundances, biomass and sizes of some species more sensitive to climate change. Reservoirs may be particularly s...

Understanding the effects of environmental drivers on fish distribution is of primary importance for designing effective conservation measures to protect endangered species. In this study, we investigated which habitat and spatial predictors enhance the abundance and biomass of the parrotfish Sparisoma frondosum in tropical rocky reefs from a South...

The introduction of non-native predator fish is thought to have important negative effects on native prey populations. Opsanus beta is a non-native toadfish that was originally described in the Gulf of Mexico, between the west coast of Florida and Belize. In the present study, we describe, for the first time, the occurrence of O. beta in Sepetiba B...

Disentangling multilevel sources of variation is critical for understanding of diversity patterns in high-variability environments. We investigated the scale sensitivity of short-term environmental effects on the temporal beta diversity of fishes in 3 tropical coastal lagoons in Southeastern Brazil. Environmental effects were investigated at 3 hier...

Leptopanchax opalescens (Myers, 1942) is a small seasonal killifish endemic to coastal drainages in the state of Rio de Janeiro, Brazil. Leptopanchax opalescens was recaptured in temporary open vegetation pools (22°42.35'S, 43°41.59'W) in the hydrographic basin of the Guandu River, state of Rio de Janeiro, Brazil, after eight years without records....

The reproductive strategy of the non‐native predator cichlid Cichla kelberi was determined to explain its success after more than 60 years of being introduced into an isolated reservoir in southeastern Brazil. This was one of the first‐known translocations of the genus Cichla out of its natural range. Macro‐ and microscopy characteristics of the go...

Fish and benthic invertebrates are important groups that inhabit shallow coastal areas. Many studies use these two groups separately to answer questions related to environmental relationships, but few assess the correlation between these two groups. This study aimed to assess correlation between richness and composition of fish and benthic inverteb...

The native fishes of the Neotropical region have been heavily impacted by the construction of reservoirs that block the rivers in different degrees. Small Hydroelectric Power Plants (SHPP) have been an alternative way to take advantage of small electricity production potential, with low cost. However, there is no basis in the belief that SHPP have...

We investigated the effects of local- and landscape-scale environmental variables and spatial structure at three hierarchical levels (i.e. type of system, individual systems, and zones within each system) on the fish species composition and abundance in bays and coastal lagoons in southeastern Brazil. The effects were assessed at the assemblage lev...

Classifying species into groups based on taxonomic relationship and functions are objective approaches to evaluate environmental and anthropogenic influences on coastal fishes. We evaluated temporal (1993–1995 and 2012–2015) changes in the taxonomic and functional indices in three zones of a tropical bay heavily impacted over the recent decades. We...

Fragmentation and interconnection of water bodies cause severe changes in the natural flow regime of continental water systems. However, assessments of these impacts on the freshwater fish distribution are still scarce. We investigated whether an artificial flow regime generated by discharges from an aqueduct would promote a longitudinal environmen...

Coastal ecosystems can vary considerably in their habitat characteristics and environmental conditions, resulting in divergent fish community structures. However, comparisons among coastal systems, such as oceanic beaches, bays and coastal lagoons, have not been thoroughly evaluated. We test the hypothesis that coastal systems that differ in wave e...

The gonadal development of the characin Astyanax aff. bimaculatus from Funil Reservoir, an impoundment in the middle reaches of the Paraiba do Sul River in southeastern Brazil was analysed through histological, histochemical and histometric techniques, and the spawning season was determined. Unbalanced sex ratio was found, with females outnumbering...

The process of energy acquisition and allocation to the gonadal development involves the use of reserves obtained from the food intake and/or stored in different parts of the body. Some fish species acquire and store energy prior the spawning season (capital breeders). For others species, the energy acquisition through by feeding activity continues...

Resource use diversity occurs when a population is composed of ecologically heterogeneous individuals who use only a subset of the population’s resource availability. The aim of this study was to examine the diet of juveniles, sub-adults and adults of Prionotus punctatus (40 to 190 mm Total Length - TL) to assess the importance of factors driving i...

Coastal lagoons are naturally stressed systems and experience changes in environmental conditions because freshwater inputs change environmental variables, mainly the salinity. We hypothesized that fish assemblages would change in structure and richness in three tropical lagoons that had different salinity ranges (a hyperhaline lagoon, 36–54; a euh...

Movements of coastal fish species between estuarine systems (rearing grounds) and adjacent platforms (spawning grounds) are complex and can be influenced by multiple biotic and abiotic factors associated with the life cycle of each species. Understanding fish movement patterns between these habitats is crucial for sustainable management of these re...

Phenotypic differentiation among fish populations may be used for management of distinct stocks and helps in conserving biodiversity. We compared morphometric and meristic characters of the anchovy Anchoa januaria from shallow semi-closed bays between the south-eastern (Tropical, 23°S) and southern (Subtropical, 25°S) Brazilian coast. We hypothesiz...

The relationship between taxonomic and functional diversity indices has been used to better describe and understand the structure of biological communities. Functional diversity is expected to have an asymptotic relationship with species richness because at some point, the addition of new species will increase some of the already established functi...

The temperature in the South Atlantic underwent an increase from 1948 to 2016, and the Brazilian coast is very likely suffering from climate change. We examined temporal shifts in the abundance of the fish fauna that inhabit shallow waters and aimed to associate these shifts with climate effects. We selected candidate species according to changes i...

. Phoretic relationships often bring large advantages to epibionts. By attaching themselves to mobile hosts, epibionts are able to: expand their ranges without spending energy, reduce their risk of being predated, and increase their probability of finding food. We assessed the phoretic relationship between the siluriform fish Ancistrusmultispinis (...

The nearshore fish assemblage structures and their seasonal changes were compared between two habitats (estuarine and surf zones) in three climatic regions (Tropical, 7°S; Transition, 23°S; and Warm Temperate, 32°S) encompassing ∼3200 km in the Brazilian coast. Regional patterns of species richness and taxonomic distinctiveness of the fish communit...

The Paraíba do Sul River (PSR) drainage basin in Southeastern Brazil covers one of the most industrialized and densely populated regions of the country. The impact of chemical contamination on the PSR basin seems to be more pronounced in its middle reach where a number of potentially polluting plants are located. In this study, we used hepatic EROD...

Biomarkers are measurements within an organism that respond to environmental effects and are used as tools in bioassessment programs since they reflect physiological changes induced by exposure to pollutants. The hepatosomatic index (HSI) and the condition factor (CF) in three fish species Geophagus brasiliensis, Hypostomus affinis and Hypostomus a...

Otoliths are part of the auditory system of teleostean fishes, and are species-specific structures that may have intraspecific variation depending on the environmental conditions at a regional scale. The main aim of this study was to assess changes in otolith shape of Micropogonias furnieri along its geographical distribution range between the trop...

Several species of marine fish use different coastal systems especially during their early development. However, these habitats are jeopardized by anthropogenic influences threatening the success of fish populations, and urgent measures are needed to priorize areas to protect their sustainability. We applied taxonomic (Δ+) and functional (X+) disti...

Studies on age and growth of fish populations have direct application in fisheries and contribute for policies of conservation. Our aim was update information on the Micropogonias furnieri growth parameters based on sagittae otoliths annulis readings, and we expected that the studied population from Southeast Brazil can reach more longevity than th...

The conservation and management of site-attached assemblages of coastal reefs are particularly challenging because of the tremendous environmental variation that exists at small spatial scales. In this sense, understanding the primary sources of variation in spatial patterns of the biota is fundamental for designing effective conservation policies....

River discharge plume on a rocky reef. Reef located 3.3 km from the stating gradient point. Photographs were taken at 01-28-2012 (before rain) and 02-28-2012; after 76 mm rain. (DOCX)

Physical, topographical and benthic predictors per site. Mean ±SE of topographical and selected benthic cover predictors (%). Exposure to wave activity: S–sheltered sites; E–exposed sites. (DOCX)

List of species by family with trophic group classification. Mean abundance (individuals per 40 m2±SE), percent of total observed (%) and frequency of occurrence (FO) of fish species observed in the three site-groups (close, intermediate and far). Groups were defined according to the relationship between fish assemblage structure and environmental...

Summary of regression analyses between predictors and fish assemblage parameters. Predictor variables that influenced significantly descriptors of fish assemblage according to simple regression. r, Pearson correlation coefficient. Levels of significance: ***earP<0.001, ** = P<0.01, * = P<0.05. (DOCX)

Length–weight relationships parameters used to estimate the fish biomass. (DOCX)

Most discriminating species for fish assemblage structure. Scores for species that best discriminated the first two dbRDA axes and respective trophic and site groups. (DOCX)

Selected species among exposure and site-groups. PERMANOVA results testing the effect of groups (defined according to distribution of the sites along the dbRDA axis), wave exposure and sampling period on the abundances of selected species. df = degrees of freedom, MS = mean sum of squares, F = pseudo-F, *** = P<0.001, ** = P<0.01, * = P<0.05. (DOCX...

We compared fish community structure in Guaratiba Mangrove, SE Brazil, among three seasons of the hydrological cycle [(i) spring, increasing temperature and rainfall, decreasing salinity; (ii) summer/early fall, high temperature and rainfall, intermediate salinity; (iii) late fall/winter, low temperature and rainfall, high salinity] and between the...

We assessed inter-annual changes in fish assemblages of a tropical bay which experienced a heavily industrialized process in the last decades. A highly significant difference in community structure among the bay zones, and a decrease in fish richness and abundance over time were found. Changes in fish richness and abundance between the two first (1...

We developed a multimetric index for assessing ecological conditions in rocky reefs areas to evaluate thermal and urban influences on fish community. Eight metrics were selected to assess thermal influence: (1) total number of species; (2) number of water column species; (3) number of transient species; (4) density of individuals with low resilienc...

We examined the benthic fauna in four areas along a mangrove tidal channel in south-eastern Brazil, between October 2008 and August 2009. The tested hypothesis is that the most abundant groups avoid competition as they occupy different types of substrata and that the longitudinal distance from the sea also affects the occurrence of benthic fauna al...

Cynoscion leiarchus (Cuvier, 1830) is a coastal fish species that is widely distributed along the Western Atlantic coast, from Belize to Southern Brazil. In Brazil, C. leiarchus It is an important resource for commercial and artisanal fisheries. Our objective was to describe the oogenesis and spermatogenesis stages of the species and to estimate ba...

The physical habitat simulation sub-routine of the Instream Flow Incremental Methodology (IFIM) uses hydraulic modeling and suitability indices of target fish species to predict how differences in-stream flows affect the microhabitat occupation by fish species. This habitat modelling approach was adopted to assess the ecological effects of running...

Closely connected reservoirs were hypothesized to have more similar fish compositions than do spatially isolated reservoirs, and that environmental variables play an important role in shaping assemblage structure on a local scale. Fish assemblages and environmental variables were sampled in seven reservoirs constructed to generate hydroelectricity,...

Enzymatic activities for digestion of proteins and carbohydrates were compared among three organs of the digestive system of Pimelodus maculatus in two reservoirs with different trophic conditions during the winter of 2006. The aim was to test the hypothesis that enzymatic activity for the digestion of proteins and carbohydrates differed among orga...

RESUMO A corvina Micropogonias furnieri é um dos recursos pesqueiros mais importantes das pescarias artesanais costeiras do Sudeste do Brasil. Entretanto, a legislação pesqueira é incipiente no que diz respeito à regulamentação da pesca desta espécie. Objetivou-se investigar se as táticas reprodutivas da população de corvinas de Ubatuba-SP são cons...

Endocrine cells secrete hormones through the mucosa of the gastrointestinal tract (GIT) and act on the overall regulation of digestive processes such as nutrient absorption, gut motility and intestinal blood flow. This study aimed to determine regional distribution and frequency of endocrine cells secretory of serotonin (5-HT), somatostatin (SST) a...

El método de simulación del hábitat físico, integrado en el marco de la metodología IFIM (Instream Flow Incremental Methodology) y en otros marcos metodológicos hoy día, utiliza variables hidráulicas e índices de idoneidad del hábitat (a escala de microhábitat) para predecir los cambios potenciales del hábitat al cambiar el caudal circulante. Este...

Length-weight relationships were determined for 15 fish species from the tributary Atlantic rain forest steams that drain into Sepetiba Bay, southeastern Brazil. This is the first record of length-weight relationships for 12 of these species and new maximum lengths for four species. These results will be useful for management and conservation of th...

Streams are under environmental pressures acting at different scales that influence the ecological organisation of their fish assemblages. However, the relative influence of the different scale-related variables on assemblage composition and function is poorly understood. We evaluated the importance of local- and catchment-scale environmental varia...

Eleven ecomorphological attributes and diet of seventeen juvenile fish species were examined to test the hypothesis that morphological patterns determine resource uses in estuarine habitats. Species were separated according to the apparatus to food capture and habitat use (benthic or pelagic) in three different groups: (1) a group with depressed fi...

Feeding guilds and spatial, seasonal and ontogenetic changes in the diets of 24 fish species in a tropical bay in Southeastern Brazil were examined. The hypotheses tested were that groups of species form specific trophic guilds and that the feeding partitioning differs along the niche dimensions. Five trophic guilds (Polychaeta, Copepoda, Teleostei...

Understanding the distribution patterns of reef fish and the relationships between those patterns and habitat and anthropogenic factors is important for the development of conservation policies by environmental managers. Fish assemblage structure was studied over 22 rocky shores with different physical complexity and benthic cover in Ilha Grande Ba...

We investigated the reproductive strategy developed by the armored catfish Hypostomus auroguttatus Kner 1854 in a tropical river of Southeastern Brazil. A total of 173 females (157–370 mm TL) and 165 males (140–357 mm TL) were analyzed. Sex ratio (1 female: 1.05 male) was well balanced. Six stages of oogenesis and five of spermatogenesis were descr...

Micropogonias furnieriis one of the most important fishery resources in Southeastern Brazil. However, the Brazilian law for exploitation of this resource is incipient. Ourmain aim was to assess whether reproductive tactics developed by Ubatubapopulationsare consistent with the available information and to evaluate their suitability to support measu...

The Gram-negative intestinal microbiota of Hypostomus auroguttatus and Pimelodus maculatus, a detritivorous and an omnivorous fish species, respectively, were compared between fishes from the reservoir and the stretch of the river below the dam of the Funil hydroelectric plant, Rio de Janeiro, Brazil. Four selective culture media were used under ae...

The Brazil coast suffers influence of the tropical Brazil Current that moves southward between latitudes 20-30oS and is very likely to be suffering climate change. We examined temporal and distributional shifts in the fish fauna and tried to associate to climate and non-climate effects. Primary historical and updated information mixed with synthesi...

Histological analysis of the gonadal development of Leporinus copelandii Steindachner, 1875, a rheophilic Characiformes species in the Paraiba do Sul River, South-eastern Brazil, was described. We expect that this species adapt gonadal development to succeed in this river basin that has its longitudinal profile blocked by several impoundments. Fish...

Habitat structure and physico-chemical variables determine distribution of fish species at local scale. We aimed to determine influences of physico-chemical variables and habitat descriptors on fish assemblage structure in a regulated river in Rio de Janeiro State, Southeastern Brazil. The tested hypotheses are that assemblages are determined by th...

We examined the benthic macroinfauna at three strata during two seasons (winter and summer) on two sandy beaches (dissipative and reflective) in south-eastern Brazil. The hypothesis raised is that effects of morphodynamics and zonation determine the structure of macroinfauna, with dissipative beaches having comparatively higher species richness and...

The diet of three cooccurring abundant fish species (Eucinostomus argenteus, Diapterus rhombeus and Micropogonias furnieri) and its ontogenetic changes in a mudflat area of a tropical bay in southeastern Brazil were described. The working hypothesis is that these three species shift the use of the available resources throughout their growth. Early...

Fish assemblages in an insular (preserved) and a continental (disturbed) sandy beach were compared to assess any changes that could be attributed to anthropogenic influences and/or the proximity of the fish spawning grounds. We expected that the closer geographical position to the spawning grounds and the small amount of anthropogenic disturbance o...

Length–weight relationships of 23 fish species from the Guaratiba mangrove area in southeastern Brazil were estimated. The value of the parameter b ranged from 2.63 to 3.39 (median = 2.97). This study presents the first estimation of LWR for two species (Ctenogobius stomatus and Ctenogobius boleosoma). New maximum length records were obtained for t...

The present work reports the length–weight relationships (LWR) for 20 fish species from the Guandu River basin, Southeastern, Brazil, a lotic system that supplies most of the water for Rio de Janeiro Municipality and nearby cities. Length–weight relationships for nine of these species were unknown to Fishbase, and new maximum lengths are given for...

The aim of this study was to assess the ecomorphological patterns and diet of four Characiformes fish species in a poorly physically structured tropical reservoir. We tested the hypothesis that body shape and diet are associated, because environmental pressure acts on the phenotype, selecting traits according to the available resources. Ten ecomorp...

Título PT: Concentração de metais pesados e incidência de eritrócitos micronucleados e atividade de EROD hepática em duas espécies de peixes comestíveis na bacia do Rio Paraíba do Sul, Brasil A bacia do rio Paraíba do Sul (PSR) atravessa uma das regiões mais povoadas e industrializadas do Brasil, recebendo efluentes de indústrias metalúrgicas, de...

The analysis and understanding of fish growth are important for the knowledge of their population dynamics. In this context growth parameters were calculated for Eucinostomus argenteus (carapicu), one of the most abundant species in Sepetiba Bay (RJ), Brazil. Growth parameters were estimated based on length frequency distribution data according to...

We determined in this study the habitat preferences of seven native fish species in a regulated river in Southeastern Brazil. We tested the hypothesis that fishes differ in habitat preference and that they use stretches of the river differing in hydraulic characteristics and substrate type. We surveyed fishes in four 1-km long river stretches encom...