Homogeneização da ictiofauna : cientometria, hierarquização da hipótese e dinâmica do processo em reservatórios neotropicais

Orientador : Prof. Dr. João Ricardo Simões VituleCoorientador : Prof. Dr. Éder André GubianiTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Zoologia. Defesa: Curitiba, 15/03/2017Inclui referências : f. 125-143Resumo: A homogeneização biótica é definida como o aumento da similaridade taxonômica, funcional ou genética, entre duas ou mais biotas ao longo do tempo. Este processo tem sido detectado em diferentes ecossistemas e diversos grupos de organismos, em especial para peixes de água doce. Entretanto, sua dinâmica permanece pouco esclarecida, principalmente quanto às escalas espaciais e temporais utilizadas e os mecanismos determinantes: introdução de espécies não-nativas, extinção de espécies nativas e modificações ambientais. Nesse sentido, dada à importância desse processo, faz-se necessária a síntese dos dados quantitativos de diferentes estudos, com o objetivo de encontrar generalizações, identificar as lacunas e direcionar estudos futuros. Sendo assim, foi utilizada a abordagem cienciométrica e o método de hierarquização-de-hipóteses, através do qual o processo de homogeneização biótica foi dividido em sub-hipóteses mais específicas. As regiões zoogeográficas Neártica e Paleártica apresentaram o maior número de artigos publicados relacionados ao processo de homogeneização biótica em peixes de água doce. Houve um maior número de artigos publicados avaliando o processo de homogeneização em rios, lagos e reservatórios, enfatizando que especial atenção deve ser destinada à riachos. A maioria das sub-hipóteses apresentaram observações suportando a homogeneização biótica. Quanto às formas de homogeneização, a maior parte das observações foi para a homogeneização taxonômica, sendo esta suportada em amplas escalas espaciais e temporais. Além disso, ficou evidente a escassez de estudos avaliando a dinâmica do processo em escalas temporais e espaciais mais refinadas. Adicionalmente, buscando avaliar a dinâmica do processo em reservatórios Neotropicais, a quantificação da homogeneização biótica em diferentes escalas temporais e espaciais mostrou que, na escala interbacias ocorreu homogeneização biótica devido, principalmente, à introdução e estabelecimento das mesmas espécies não-nativas na maioira dos reservatórios (i.e. espécies com alta pressão de propágulos como tilápias). Enquanto em escala intrabacias foi detectada diferenciação biótica, devido ao estabelecimento de diferentes espécies não-nativas em cada reservatório e a extirpação de espécies nativas. Por fim, devido a falta de estudos quantificando a dinâmica da homogeneização funcional na região Neotropical, a qual possui a maior diversidade funcional para peixes de água doce, buscou-se um melhor detalhamento e distinção dos principais aspectos desse processo em reservatórios. Para tal, a dinâmica das mudanças na composição de espécies e atributos funcionais foi avaliada, considerando diferentes escalas temporais e espaciais. Na escala inter-ecoregiões, devido à introdução de espécies não-nativas com traços funcionais similares, e a perda de espécies nativas exibindo tanto traços similares como distintos, foi detectado o aumento da similaridade taxonômica (homogeneização taxonômica), enquanto ocorreu a diferenciação functional no primeiro período e, no último período a homogeneização funcional. Para a escala intra-ecoregião, para a maioria das ecoregiões avaliadas, foi detectada diferenciação taxonômica e functional, devido a introdução de diferentes espécies não-nativas, possuindo traços funcionais distintos. No entanto, nesta escala, para a ecoregião do Iguaçu, foi detectada diferenciação taxonômica enquanto houve homogeneização funcional, devido à extirpação de espécies nativas com traços funcionais distintos e, à introdução de diferentes espécies não-nativas funcionalmente redundantes. Palavras-chave: diversidade beta; invasões biológicas; diferenciação biótica; ictiofauna; homogeneização funcional.Abstract: Biotic homogenization is defined as the increase in the taxonomic, functional or genetic similarity, between two or more biotas over time. This process has been detected in different ecosystems and several taxonomic groups, especially for freshwater fish. However, its dynamics remain unclear, mainly regarding the spatial and temporal scales used and the determining mechanisms: introduction of non-native species, extinction of native species and environmental modifications. In this sense, given the importance of this process, it is necessary to synthesize quantitative data from different studies, with the aim of find generalizations, identify gaps and conduct future studies. Thus, was used the scientometric approach and the hypothesis-hierarchical method, through which the biotic homogenization process was divided into more specific sub-hypotheses. The zoogeographic regions Nearctic and Palearctic presented the largest number of published articles related to the process of biotic homogenization in freshwater fish. There was a greater number of published articles evaluating the homogenization process in rivers, lakes and reservoirs, emphasizing that special attention should be directed to streams. Most of the sub-hypotheses presented observations supporting the biotic homogenization. Related to the forms of homogenization, most of the observations were to the taxonomic homogenization, which was supported in wide spatial and temporal scales. In addition, it was evident the scarcity of studies evaluating the dynamics of the process in more refined temporal and spatial scales. Additionally, in order to evaluate the dynamics of the process in Neotropical reservoirs, the quantification of biotic homogenization at different temporal and spatial scales showed that biotic homogenization occurred at the interbasin scale, mainly due to the introduction and establishment of the same non-native species in most reservoirs (i.e. species with high propagule pressure such as tilapia). Whereas at intrabasin scale the biotic differentiation was detected due to the establishment of different non-native species in each reservoir and the extirpation of native species. Finally, due to the lack of studies quantifying the dynamics of the functional homogenization in the Neotropical region, which possess the greatest functional diversity for freshwater fish, it was sought a better detailing and distinction of the main aspects of this process in reservoirs. For this, the dynamics of the changes in the species composition and functional attributes was evaluated, considering different temporal and spatial scales. In the inter-ecoregions scale, due to the introduction of non-native species with similar functional traits, and the loss of native species exhibiting each similar and distinct traits, the increase in the taxonomic similarity (taxonomic homogenization) was detected, whereas the functional differentiation occurred in the first period and, in the last period the functional homogenization. To the intra-ecoregion scale, for most ecoregions evaluated, the taxonomic and functional differentiation may be detected, due to introduction of different non-native species, with different functional traits. However, at this scale, to the Iguaçu ecoregion, taxonomic differentiation was detected while functional homogenization occurred, due to the extirpation of native species with distinct functional traits and, the introduction of different non-native species, which were functionally redundant. Keywords: beta diversity; biological invasions; biotic differentiation; ichthyofauna; functional homogenizatio

Protected areas: A focus on Brazilian freshwater biodiversity

Brazil has a variety of aquatic ecosystems and rich freshwater biodiversity, but these components have been constantly damaged by the expansion of unsustainable activities. An array of different conservation strategies is needed, especially the creation of protected areas (PAs, hereafter). However, Brazil's PAs are biased towards terrestrial ecosystems and we argue that current PAs have limited efficacy in the protection of freshwater biodiversity. New PAs should better consider aquatic environments, covering entire basins, rivers and other freshwater habitats. We recommend ways to implement these PAs and provide guidance to avoid social impacts. Freshwater systems in Brazil provide essential goods and services but these ecosystems are being rapidly degraded and will be lost if not adequately protected. © 2018 The Authors. Diversity and Distributions Published by John Wiley & Sons Lt

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

Biology, ecology and biogeography of the South American silver croaker, an important Neotropical fish species in South America

The South American silver croaker is a popular fish that has recently received substantial attention from scientists, mainly due to its importance as source of animal protein and as a key fisheries species. However, little is known about the conditions that explain its historical and current spatial distribution, both in its native habitat and where it is a successful invasive species. The aim of the present study was to explore the ecological information available for this species, to then critically examine ecological theories related to the conditions underpinning its success. To this end, an exhaustive literature search was conducted with the immediate aim of investigating whether the success of South American silver croaker was driven by species-climate or species–human interactions. The non-native populations were found to occupy climate niche spaces different from those observed in their native ranges. In addition, it was clear that humans played a role in facilitating the large-scale dispersion of silver croaker, and assisted as agents of impact driving the observed current and, probably, the future spatial distribution, which we can predict from our data and from the pattern of propagule pressure. Overall, the current biogeography of this species illustrates how the construction of dams, along with the introduction and stocking of non-native species, overfishing and other human activities can alter fish populations and assemblages. Such processes can reduce native species, increase the abundance and distribution of invasive species, as well as cause changes in life-history traits and genetic variability, all with long-term socioeconomic consequences. © 2018, Springer International Publishing AG, part of Springer Nature

Water diversion in Brazil threatens biodiversity

Construction of water diversions is a common response to the increasing demands for freshwater, often resulting in benefits to communities but with the risk of multiple environmental, economic, and social impacts. Water-diversion projects can favor massive introductions and accelerate biotic homogenization. This study provides empirical evidence on the consequences of a proposed law intended to divert water from two large and historically isolated river basins in Brazil: Tocantins to São Francisco. Compositional similarity (CS) and β-diversity were quantified encompassing aquatic organisms: mollusks, zooplankton, crustaceans, insects, fishes, amphibians, reptiles, mammals, and plants. For CS we (i) considered only native species, and (ii) simulated the introduction of non-natives and assumed the extinction of threatened species due to this water-diversion project. We highlight the environmental risks of such large-scale projects, which are expected to cause impacts on biodiversity linked to bioinvasion and homogenization, and we recommend alternatives in order to solve water-demand conflicts. © 2019, Royal Swedish Academy of Sciences

Fish larvae assemblages in two floodplain lakes with different degrees of connection to the Paraná River, Brazil

The objective of this study was to assess the abundance, attributes of assemblages, and spatial and temporal distributions of fish larvae and their relationships with some abiotic variables in two floodplain lakes with different degrees of connection to the Paraná River in Ilha Grande National Park, PR, Brazil. Four sampling sites were chosen, two in each floodplain lake. Night samples were taken with plankton nets during three spawning seasons (monthly, from October to March) from 2001 to 2005. The highest diversity and abundance were recorded at Saraiva Lake, with 25 taxa being identified. In Xambrê Lake, only sedentary species were captured, and the most abundant species were Plagioscion squamosissimus and Hypophthalmus edentatus. The greatest abundance of larvae was found in the second spawning season. In the Saraiva Lake, the most abundant species were Moenkhausia aff. intermedia, Hyphessobrycon sp., and Bryconamericus stramineus, but larvae of known migratory species were also documented. In this lake, the greatest abundance of larvae was found in the third spawning. Larvae abundance was influenced by water temperature and conductivity. The high diversity and abundance recorded in Saraiva Lake may be a result of its connectivity with the Paraná River, and the low diversity and abundance observed at Xambrê Lake are likely due to its isolation from the river. This work shows the importance of these lagoons for fish development, for both sedentary and migratory species. Both lagoons may be considered to have extreme ecological importance and they are also extremely susceptible to impacts, so any careless disturbance may cause irreversible damage

Neotropical freshwater fisheries : 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