A análise de isótopos estáveis (AIE) vem sendo empregada em diversas linhas de pesquisa da ecologia e em diferentes grupos zoológicos. Esta ferramenta tem se mostrado muito eficiente, especialmente em análises de ecologia trófica. O princípio básico da AIE consiste na ideia de que a proporção dos isótopos estáveis de um elemento em um tecido animal pode estar relacionada com a de sua dieta, e é descrita por um fator de discriminação (FD). O FD é um dos parâmetros mais importantes na AIE. Estimativas precisas do FD são de extrema importância porque são utilizadas em modelos de mistura e para determinar o nível trófico de espécies. Neste contexto, este trabalho objetivou quantificar, cienciometricamente, a produção científica que investigou as fontes de variabilidade do fator de discriminação, enfocando os peixes. Além disso, buscou-se sintetizar e discutir os resultados obtidos até o momento sobre este tema, como também sobre os métodos de obtenção do FD. Utilizou-se a base de dados ISI Web of Science para a busca de artigos. Constatou-se que a maior parte das pesquisas foi realizada nos Estados Unidos, Reino Unido e Alemanha. O músculo foi o tecido mais utilizado. Recentemente, escamas e partes das nadadeiras têm sido utilizadas por representarem amostras não letais. Além do δ 13 C e δ 15 N, tem sido utilizado o δD (deutério) como um traçador de teias alimentares. Evidenciou-se que o tipo de dieta, o grupo trófico, e as taxas metabólicas e de crescimento são importantes fontes de variação do FD. A análise de isótopos estáveis de compostos específicos, como por exemplo, de aminoácidos, oferece uma oportunidade de reduzir a variação relacionada ao conteúdo proteico. Acredita-se que há grande necessidade de investigar (i) o FD em ambiente tropical, (ii) o efeito da temperatura no FD, (iii) a variação dos valores de FD nos diferentes grupos tróficos. Recomenda-se também maior ênfase no uso de amostras não letais. Palavras-chave: isótopos estáveis; músculo; compostos específicos; cienciometria. ABSTRACT DISCRIMINATION FACTOR IN THE TROPHIC ECOLOGY OF FISHES: A REVIEW ABOUT SOURCES OF VARIATION AND METHODS TO OBTAIN IT. The stable isotope analysis (SIA) has been employed in several areas in Ecology and with different taxonomic groups. This tool has been very important in trophic ecology studies. The basic principle of the SIA is that the proportion of the stable isotopes of an element in an animal tissue could be related with its diet, and it is described by the discrimination factor (DF). The DF is one of the most important parameters in stable isotope analysis. Accurate estimates of the DF are extremely important because they are used in mixture models and to determine the species trophic level. The goals of this study were to quantify, by a scientometric analysis, the research that investigates the sources of variability of the discrimination factor, focusing in fishes. The results obtained were discussed and synthesized, as well the methods employed to estimate the DF. A survey in the ISI Web of Science was perform...

Ecological models are useful for evaluating fishery management scenarios, as they allow researchers to investigate alternative fishing effort, as well as varying environmental and trophic interaction scenarios. Through an ecosystem modeling approach (Ecopath with Ecosim), we addressed the possible impacts of small-scale fisheries on the structure and functioning of a tropical ecosystem (Itaipu Reservoir, Brazil). We found that fishing effects and predator-prey interactions were the main drivers explaining catch trends in the Itaipu Reservoir fisheries. The mean trophic level of catch did not change throughout the analyzed time period and no losses in secondary production from exploitation (L index) were observed, indicating that Itaipu fisheries are sustainable regarding ecosystem effects. The negative impacts of introduced species on native species seem to be greater than the fishing impacts. Fishing simulations from the ecosystem Maximum Sustainable Yield (MSY) reduced the biomass of some important species in the local fishery. Regarding management advice, our results indicate that fishing efforts should not be increased for curimba (Prochilodus lineatus), pintado (Pseudoplatystoma corruscans),

GIS and spatial data science (SDS) tools have been recently approaching each other by establishing bridge technologies between them. R as one of the most prominent programming languages used in SDS projects has been granted access to GIS infrastructure, while R scripts can be integrated and executed in GIS functions. Unfortunately, the treatment of spatial fuzziness has so far not been considered in SDS projects and bridge technologies due to a lack of software packages that can handle fuzzy spatial objects. This paper introduces an R package named fsr as an implementation of the fuzzy spatial data types, operations, and predicates of the Spatial Plateau Algebra that is based on the abstract Fuzzy Spatial Algebra. This R package solves the problem of constructing fuzzy spatial objects as spatial plateau objects from real datasets and describes how to conduct exploratory spatial data analysis by issuing geometric operations and topological predicates on fuzzy spatial objects. Further, fsr provides the possibility of designing fuzzy spatial inference models to discover new findings from fuzzy spatial objects. It optimizes the inference process by deploying the particle swarm optimization to obtain the point locations with the maximum or minimum inferred values that answer a specific user request.

This study investigated the isotopic niches of two fish species, one exotic and one native. It was hypothesized that these species would show little or no isotopic niche overlap. This hypothesis was tested with the isotopic niche concept and the trophic Layman's metrics. A considerable isotopic niche overlap was observed between the species, mainly for the exotic that showed the greater percentage of overlapping, indicating an interspecific competition for food resources. Layman's metrics also showed this species probably exploits a more specific array of food resources when compared with the native species. The native species probably has the ability to exploit a wider array of resources, highlighted by the higher values given for the Layman's metrics. The juveniles and adults of native species showed minor overlapping between the isotopic niches. This indicates that they have probably adopted different foraging strategies, minimizing intraspecific competition. Evidences that the exotic species explores a narrower range of resources and that the native species has a greater isotopic niche and possibly suffer less intraspecific competition, indicates that the native species can tolerate the presence of the exotic species and promote survival and maintenance of its population even under possible competition effects imposed by the exotic species.

A�������. The relationship between people and the environment is critical for the development of projects and actions towards the sustainable use of nature resources. This study investigated the relationship between a number of socio-demographic variables and environmental awareness in two cities of southern Brazil (Maringá and Sarandí). We found that levels of education and income were positively associated with environmental awareness. Individuals with higher level of education were 3.2 times more likely to have good environmental awareness than individuals with a lower level. Our results contribute to understand social-ecological interactions of urban citizens from this region and to develop management actions to involve urban residents into environmental conservation actions.