Cuidado onde pisa: poças temporárias têm importante papel na ecologia de peixes em igarapés de terra firme na Amazônia

Disturbances, either natural or anthropogenic, are common in nature and their effects on biological communities depend on disturbance characteristics, and on organisms’ and landscapes’ attributes. In this thesis, we evaluated the importance of seasonal variation in hydrodynamic characteristics and of temporary environments for the dynamics of fish communities in Amazonian terra-firme forest streams, regionally known as igarapés. Through field studies in Adolpho Ducke Forest Reserve (Manaus, Brazil), we obtained information on temporal variation of fish abundance in stream channel and temporary ponds, as well as details of life-history traits of species and movement patterns of individual fish. In addition, we measured environmental characteristics related to the hydrology of the stream-pond systems and evaluated the responses of the fish to temporal changes in the environment. Based on abundance data and using a community approach, we show that the seasonal use of temporary ponds minimizes the temporal variability of assemblage composition through its effect on the abundance of fish species. We also show that the hydrological fluctuations regulate the distribution of species between the two habitats (temporary ponds and stream channel) and that this abundance partition is strongly associated with the use of different reproductive strategies among fish species. Finally, based on a capture-marking-recapture experiment with a common and abundant species in the stream-pond system (Pyrrhulina brevis, Lebiasinidae), we show that decisions of fish regarding the timing of entry and exit of ponds are based on a refined perception of momentary hydrological conditions, integrating environmental information accumulated over time. The combination of these results indicate that the aquatic environment seasonally available in the riparian zone of terra-firme forest streams comprises an important habitat for several species of fish, with important role in population processes and organization of communities, as well as being a possible agent in the evolution of behavioral and life history traits of fish in this ecosystem.Distúrbios naturais ou antropogênicos são comuns na natureza e seus efeitos sobre comunidades biológicas dependem das características do próprio distúrbio e de atributos dos organismos e da paisagem. Nesta tese de doutorado avaliamos a importância de variações sazonais na dinâmica hidrológica e o uso de ambientes temporários sobre a dinâmica da comunidade de peixes em riachos (igarapés) de floresta de terra firme da Amazônia. Através de estudos de campo na Reserva Florestal Adolpho Ducke (Manaus, AM), obtivemos informações sobre a variação temporal da abundância de peixes no canal de igarapés e em poças marginais temporárias, incluindo detalhes de características de história de vida das espécies e de padrões de movimentação individual dos peixes. Além disso, amostramos características ambientais relacionadas à hidrologia do sistema igarapépoças e avaliamos as respostas dos peixes às mudanças ambientais sazonais. Com base nos dados de abundância das espécies, e usando uma abordagem de comunidades, mostramos que o uso sazonal de poças temporárias minimiza a variabilidade temporal de composição da ictiofauna. Mostramos, ainda, que as flutuações hidrológicas regulam a distribuição das espécies entre os dois habitats (canal do igarapé e poças temporárias) e que esta partição de abundância está fortemente associada ao uso de estratégias reprodutivas diferenciadas entre as espécies de peixes. Por fim, com base em um experimento de marcação e recaptura individual de uma espécie muito comum e abundante no sistema igarapé-poça (Pyrrhulina brevis, Lebiasinidae), mostramos que as decisões dos peixes quanto ao momento de entrada e saída das poças estão baseadas em uma percepção refinada das condições hidrológicas momentâneas, integrando informações ambientais acumuladas ao longo do tempo. Esse conjunto de resultados indica que o ambiente aquático sazonalmente disponível na zona ripária de igarapés de terra firme compreende um importante habitat para várias espécies de peixe, tendo importante papel em processos populacionais e de organização de comunidades, além de ser um possível agente na evolução do comportamento e das histórias de vida dos peixes neste ecossistema

First record of a male of Kryptolebias Hermaphroditus Costa, 2011 (Cyprinodontiformes: Cynolebiidae)

During an ichthyological survey in September 2015 at the Ceará-Mirim River estuary, Rio Grande do Norte State, northeastern Brazil, we collected a male of Kryptolebias hermaphroditus, a cynolebiid species that had been previously described as containing exclusively self-fertilizing hermaphrodites. This is the first record of a male in this species, over 140 years after the discovery of the mangrove rivulid species from Brazil. Our discovery reinforces the need for more studies in K. hermaphroditus, as well as the potential of this species as a model for evolutionary studies due to its unique mating system. © 2016, Sociedade Brasileira de Ictiologia. All rights reserved

Spatio-temporal segregation and size distribution of fish assemblages as related to non-native species occurrence in the middle rio doce valley, MG, Brazil

The lakes in the middle rio Doce Valley (MG) are suffering impacts due to the introduction of invasive fish species, mainly piscivorous species like red piranha Pygocentrus nattereri and peacock bass Cichla kelberi. Fishes were collected in bimonthly samples conducted at ten lakes along a year. The present study showed that the composition of native fish assemblages is significantly related to the presence and type of non-native species. Fish species distribution among lakes can be explained by differences in species body size: smaller native species are less concentrated in lakes with invasive piscivores, which is in accordance with the hypothesis that they have greater susceptibility to predation by invaders. Another probable cause for this correlation is the proximity of lakes to the drainage system, which could explain both the non-native incidence and the turnover of native species composition. Furthermore, temporal variability in species composition was significantly higher in invaded lakes. This last factor may be linked to seasonal flood pulses, which carry immigrant fishes from streams in the vicinity. The metacommunity framework can bring insights for future studies in such spatially structured systems, and the approach should improve our understanding of processes underlying species composition as well as help direct conservation-focused management plans. Copyright © 2011 Sociedade Brasileira de Ictiologia

Efeito do isolamento e das variáveis ambientais na estrutura de comunidades de peixes do interflúvio madeira-purus na amazônia Brasileira

Due to the existence of terrestrial barriers to freshwater fish dispersion, it is believed that its distribution is strongly associated with historical factors related to the formation of the habitats they occupy. By the other hand, some studies reveal the influence of abiotic conditions (such as size of water bodies, pH, conductivity) on the composition of fish fauna occurring in small streams. This study aimed to investigate whether drainage basins, because catchment boundaries are potential barriers to fish dispersion, or the physical structure and physico-chemical characteristics of water have a greater influence on fish community structure in small streams. We sampled 22 streams belonging to five drainage basins in the Madeira-Purus interfluve. Fish were caught with dip nets and a small trawl, and data were simultaneously obtained on structural characteristics of the streams and physico-chemical characteristics of the water. Community composition was analyzed using Non-Metric Multidimensional Scaling (NMDS), and variables related to structural and physico-chemical characteristics were summarized by Principal Component Analysis (PCA). Two explanatory models relating faunal composition to environmental factors were constructed: the first using only continuous variables and the second including the drainage basin as a categorical variable. The Akaike Information Criterion (AIC) and AIC weight were used to select the best model. Although structural and physico-chemical variables significantly contributed to explaining faunal composition, the model including the drainage basin was clearly the better of the two models (more than 90% support in the data). The importance of drainage basins in structuring fish communities in streams may have significant consequences for conservation planning in these environments

Trends in studies of Brazilian stream fish assemblages

Studies about fish assemblages in Brazilian streams have grown in recent years, however, it remains unclear whether this increase is followed by increments in the diversity of addressed topics and theoretical frameworks adopted by researchers. We performed a systematic search for Brazilian studies on stream fish assemblages recording study region, publication year, objectives, and spatial and temporal scales adopted. The number of studies is unevenly distributed among regions. Most papers describe the general structure of local fish assemblages and their scientific objectives have not varied through time. Studies have been conducted mainly at small temporal and spatial scales, though the latter is increasing over time. We argue for the need of focusing on recently developed ecological theories and frameworks, and expanding the temporal and spatial scales of studies. These changes will improve regional and local conservation policies, and the visibility of aquatic Brazilian research in the global scientific community. © 2016 Associação Brasileira de Ciência Ecológica e Conservaçã

Variação temporal da ictiofauna em igarapés de terra-firme, reserva ducke, Manaus, Amazonas.

Temporal variability of fish assemblages between different season along one year and their relationship with environmental factors was investigated in 31 first and second order streams in terra-firme rainforest of Reserva Florestal Adolpho Ducke, in Central Amazonia. Fish were caught with hand and seine nets and stream volume and physical-chemical variables were estimated in 50m sections in each stream in each survey. The average richness and number of individuals captured per section were lower in the rainy season, contrasting with previous studies that detected no significant differences between seasons. Fish assemblage composition showed strong seasonal tendency, based mainly on seasonal variations in abundance of common species, possibly related to lateral moves of fish species to temporary ponds adjacent to streams in the rainy season. Water quality and substrate diversity showed seasonal tendencies, but these were not related to fish assemblage composition. Comparisons of assemblage composition between the years 2001 and 2006 revealed the maintenance of general assemblage structure based on common species, and large change in composition of less-abundant species. Common species were highly detectable in surveys and confer consistent spatial structure to the assemblage, which is predictable along environmental gradients and throughout the year. The assemblage structure based on abundances of common species should be the main focus of biodiversity monitoring programs on terra-firme streams, unless the focus of the study is on endemism, in which case special attention should be given to the spatial distribution of endemics species.A variação temporal da ictiofauna entre três diferentes momentos do ciclo hidrológico (final da seca de 2005, chuva de 2006 e início da seca de 2006) e suas relações com variações ambientais foram investigadas em 31 riachos de primeira e segunda ordem, regionalmente conhecidos como igarapés, em área de floresta de terra-firme da Reserva Florestal Adolpho Ducke, Amazônia Central. Peixes foram capturados usando puçás e redes de mão, e estimativas de volume e características físico-químicas da água foram obtidas em cada amostragem ao longo de trechos fixos de 50 metros de riacho. O número médio de espécies e de indivíduos capturados foi menor no período chuvoso, contrastando com estudos anteriores que não identificaram diferenças significantes em densidade de peixes entre épocas do ano em riachos de terra-firme. A composição da ictiofauna também apresentou uma tendência sazonal de mudança, na forma de variações de abundância das espécies mais comuns, possivelmente relacionadas a deslocamentos laterais para poças temporárias adjacentes no período chuvoso. A qualidade da água e a composição do substrato dos riachos também apresentaram mudanças sazonais, mas não estiveram relacionadas às variações da ictiofauna. Comparações da composição da ictiofauna registrada em 2006 com a composição identificada em 2001 revelaram uma manutenção da estrutura geral da comunidade, baseada na abundância das espécies mais comuns, e grande taxa de mudança de composição de espécies pouco abundantes. Espécies comuns apresentam uma elevada probabilidade de detecção no ambiente e conferem à comunidade uma estrutura previsível ao longo de gradientes ambientais e ao longo do ano. A estrutura da comunidade baseada na distribuição de abundâncias de espécies comuns deve ser o foco principal em programas de monitoramento quantitativos da biodiversidade de peixes em igarapés de terrafirme, exceto em casos de endemismos, quando atenção especial deve ser dada à distribuição espacial das espécies endêmicas

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost