NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics.

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.

Biological Invasions in Neotropical Regions: Continental Ichthyofauna and Risk Assessment Protocols.

The objectives of this study were to compare four risk assessment protocols for non-native species in neotropical regions and to assess the potential application of these tools for the management of invasive species and conservation of the ichthyofauna in Brazil. The protocols Fish Invasiveness Screening Kit (FISK), Aquatic Species Invasiveness Screening Kit (AS-ISK), European Non-Native Species in Aquaculture Risk Assessment Scheme (ENSARS) and Fish Invasiveness Screening Test (FIST) were applied for the species Oreochromis niloticus, Coptodon rendalli, Poecilia reticulata and Apteronotus aff. albifrons, whose sources of introduction are aquaculture and fishkeeping. The species were classified as low, medium or high risk of invasion. The scores of the species O. niloticus, C. rendalli and P. reticulata classified them as high risk of invasion in all protocols, whereas A. aff. albifrons had medium risk in the protocols FISK and AS-ISK and low risk in the FIST. Although the results were similar for species whose impacts are widely described, less studied species may have their classification compromised by the lack of evidences in the literature. Despite the difficulties for practical application, the use of these tools may be encouraged, considering the potential threats of other invasive species emerging in Brazil. The comparison between the methods showed that the use of AS-ISK, combined with ENSARS in cases of introductions by aquaculture, provides important answers about ecological impacts on natural environments and about the stages of the aquaculture production chain that should be better inspected.

Functional responses of stream fish communities to rural and urban land uses

We tested the effects of ruralization and urbanization on the functional diversity indices and the composition of functional traits of Neotropical stream fish communities. The study was carried out in 24 streams of the Pirapó, Piquiri, Paraná III and Iguassu river basins. Land use in the watershed was categorized as percentages of native vegetation, rural occupation and urban occupation. Statistical tests revealed negative bivariate correlations between functional dispersion and the proportion of native vegetation in the watershed. The results indicate that a higher percentage of rural or urban occupation is associated with increased functional dispersion. In the analyzes of trait composition, significant alterations were observed in response to urbanization while only the increase in herbivory responded to ruralization. As the area of native vegetation is reduced by urbanization, the trait composition changes, with reduced proportions of species with intolerance to hypoxia, migratory reproductive behavior, external fertilization, and subterminal mouth, and increased proportions of species with parental care, detritivory, internal fertilization, and an upper mouth. Therefore, fish species that have these specific characteristics are more likely to disappear from streams as urbanization progresses. In summary, urbanization was related to a greater change in the composition of functional traits than ruralization.(AU)

Nós testamos os efeitos da ruralização e da urbanização sobre os índices de diversidade funcional e da composição de traços funcionais em assembleias de peixes de riachos Neotropicais. Amostras foram feitas em 24 riachos distribuídos nas bacias dos rios Pirapó, Piquiri, Paraná III e Iguaçu. O uso do solo foi categorizado por meio das porcentagens de vegetação, ocupação rural e urbana. Testes estatísticos revelaram correlações negativas bivariadas entre a dispersão funcional e a proporção de vegetação. Os resultados indicaram que maior percentual de ocupação rural ou urbana está associado ao aumento da dispersão funcional. Nas análises de composição de traços foram observadas alterações significativas em resposta à urbanização, enquanto apenas o aumento de herbívoros respondeu à ruralização. À medida que a área de vegetação é reduzida, a composição de traços muda, com redução nas proporções de espécies com intolerância à hipóxia, comportamento reprodutivo migratório, fertilização externa e boca subterminal, e aumento da proporção daquelas com cuidado parental, detritivoria, fertilização interna e boca superior. Portanto, espécies que apresentam essas características têm maior probabilidade de desaparecer dos riachos à medida que a urbanização avança. Em resumo, a urbanização foi relacionada a maior alteração na composição de traços funcionais do que a ruralização.(AU)

Unified Multimetric Index for the Evaluation of the Biological Condition of Streams in Southern Brazil Based on Fish and Macroinvertebrate Assemblages.

We developed MMI models that combine responses of fish and benthic macroinvertebrates for the evaluation of the biotic integrity of streams. The MMI was developed using a dataset covering stream sampling sites in the South of Brazil. Reference streams were identified based on the physical and chemical conditions and riparian vegetation. Thirty-four metrics were calculated and evaluated for their range, redundancy, and responsiveness to the environmental perturbation. We applied a robust approach to select the most sensitive metrics and MMI models based on the complexity and ability of the index in distinguishing impacted and reference sites. The four best MMI models selected are composed of different combinations of the eight metrics: % fish herbivorous, fish evenness, fish abundance, % macroinvertebrate shredder; % macroinvertebrate predator; % macroinvertebrate tolerant, % macroinvertebrate swimmer, and % macroinvertebrate burrower. All of the MMI models selected presented good performance in distinguishing reference streams from those impacted by different forms of land use. This study is one of the few attempts to use more than one biological assemblage in a single-multimetric index. Accordingly, we believe that the unified MMI we developed could be a useful tool to assist in the conservation and management of water resources in Neotropical regions, specially, in the implementation of ecological integrity tools more cost-effectively.

Comparison of fish and macroinvertebrates as bioindicators of Neotropical streams.

The biomonitoring of aquatic ecosystems in developing countries faces several limitations, especially related to gathering resources. The present study aimed at comparing the responses of fish and benthic macroinvertebrates to environmental change, to identify which group best indicates the differences between reference and impacted streams in southern Brazil. We determined reference and impacted sites based on physical and chemical variables of the water. For the analysis and comparison of biological responses, we calculated 22 metrics and submitted them to a discriminant analysis. We selected from this analysis only six metrics, which showed that the two studied assemblages respond differently to environmental change. A larger number of metrics were selected for macroinvertebrates than for fish in the separate analysis. The metrics selected for macroinvertebrates in the pooled analysis (i.e., fish and macroinvertebrates together) were different from those selected in the separate analysis for macroinvertebrates alone. However, the metrics selected for fish in the pooled analysis were the same selected in the separate analysis for fish alone. The macroinvertebrate assemblage was more effective for distinguishing reference from impacted sites. We suggest the use of macroinvertebrates as bioindicators of Neotropical streams, especially in situations in which time and money are short.

Effects of abiotic variables on the distribution of fish assemblages in streams with different anthropogenic activities in southern Brazil

Studies on fish assemblages in streams point out, that understanding the relationship between species and their environment is crucial for conservation. The present study aimed at evaluating the effects of changes in abiotic variables on the composition and structure of fish assemblages in Neotropical urban streams from southern Brazil with different levels of urbanization. The composition and structure of fish assemblages showed significant differences along the urbanization gradient observed in the streams. Tolerant and non-native species were found in more urbanized sites. A matrix correlation revealed a relationship between abiotic variables and the spatial pattern of structure and composition of fish assemblages. Abiotic variables, such as total phosphorus, dissolved oxygen, and conductivity, determined the distribution of fish assemblages. Streams without urban influence exhibited intrinsically low species richness, suggesting that they are highly susceptible to species loss and diversity reduction. Thus, changes in water quality or hydrological conditions induced by urbanization may intensify these impacts.

Estudos sobre as assembleias de peixes em riachos têm enfatizado que a compreensão da relação entre as espécies e seu ambiente é crucial para a conservação das espécies. O objetivo deste estudo foi avaliar os efeitos de alterações nas variáveis abióticas sobre a composição e estrutura das assembleias de peixes em riachos urbanos com diferentes percentuais de urbanização no Brasil. A composição e estrutura das assembleias de peixes mostraram diferenças significativas ao longo do gradiente de urbanização dos riachos. Espécies tolerantes e não-nativas foram encontradas em locais mais urbanizados. A análise de correlação de matrizes indicou uma relação entre as variáveis abióticas e do arranjo espacial da estrutura e composição nas assembleias de peixes. Variáveis abióticas, tais como fósforo total, oxigênio dissolvido e condutividade, determinaram a distribuição das assembleias de peixes. Riachos sem influência urbana exibem naturalmente baixa riqueza específica, sugerindo ser suscetíveis à perda de espécies e redução da diversidade. Assim, mudanças induzidas pela urbanização na qualidade da água ou no regime hidrológico podem exacerbar esses impactos.

Morphological patterns of fish and their relationships with reservoirs hydrodynamics

Neste estudo, são analisados as restrições na ocupação de peixes em reservatórios com diferentes tempos de retenção da água e estágios de colonização de acordo com características morfológicas das espécies. Busca-se padrões morfológicos mais adaptados na ocupação dos reservatórios considerando diferentes habitats e estratégias alimentares. Os dados morfológicos foram obtidos em 10 indivíduos das espécies mais abundantes em seis reservatórios do estado do Paraná. Os atributos ecomorfológicos que melhor segregaram as espécies foram determinados através de uma Análise Discriminante, sendo estes posteriormente utilizados em uma Análise de Componentes Principais (PCA). Diferenças entre os reservatórios na ocupação do espaço ecomorfológico foram testados através de Análise de Variância (modelo nulo). Os seis reservatórios diferiram na ocupação do espaço ecomorfológico com os dois primeiros eixos da PCA explicando 66,3% variabilidade total dos dados. Conclui-se então que alterações na dinâmica da água também afetam os padrões de distribuição das espécies de peixes em reservatórios.