The aim of this study was to verify whether taxonomic and functional composition of stream fishes vary under three different preservation conditions of riparian zone: preserved (PRE), intermediate condition (INT), and degraded (DEG). Five stream stretches representing each condition were selected. Samples were taken from each stream in three occasions during the dry seasons from 2004 to 2007. Electro fishing (PRE and INT), sieves, dip nets, and hand seines (DEG) were used according to the characteristics of each sampled site. Overall, 46 species were registered. Differences in the taxonomic and functional species composition among groups were found, following the condition of riparian zones. The ichthyofauna recorded in the PRE was typical to pristine environments, consisting of species with specialized habits, notably benthic insectivores, intolerant, and rheophilics. In the INT group, replacement of riparian forest with shrubs and/or grasses created environmental conditions which favor the occurrence of tolerant species but also harbor a residual fauna of sensitive species. DEG streams presented mostly detritivores, tolerant, small sized fishes which occupy the surface and preferred slow water flux. Changes in the species composition were represented by the occurrence and dominance of tolerant species in detriment of the more sensitive and specialist species, following the gradient of degradation in the riparian zone. Forested streams act as unique habitats to many specialized species and it can be presumable that the degradation of riparian vegetation can generate biotic homogenization which may reduce species diversity and ecosystem services.O presente estudo verificou se a composição taxonômica e funcional de peixes de riachos varia ao longo de três condições de preservação da zona ripária: preservada (PRE), preservação intermediária (INT) e degradada (DEG). Cinco riachos de cada grupo foram selecionados e amostras foram obtidas em cada riacho em três ocasiões em períodos secos de 2004 a 2007. Pesca elétrica (PRE e INT), peneiras, puçás e redes de arrasto (DEG) foram usados de acordo com as características de cada local de coleta. No geral, 46 espécies foram registradas. Foram registradas diferenças na composição taxonômica e funcional de espécies entre os grupos, seguindo o gradiente de degradação da zona ripária. A ictiofauna encontrada em PRE foi típica de ambientes prístinos, consistindo em espécies de hábitos especializados, notavelmente bentônicas, insetívoras, intolerantes e reofílicas. No grupo INT, a substituição da floresta ripária por herbáceas ou gramíneas cria condições ambientais que favorecem a ocorrência de espécies tolerantes, mas também abriga uma fauna residual de espécies sensíveis. O grupo DEG foi representado principalmente por espécies detritívoras, tolerantes e de superfície. As modificações na composição de espécies foram representadas pela ocorrência e dominância de espécies tolerantes em detrimento da redução/eliminação daquelas mais sensíveis e especializadas, acompanhando o grad...

Most Rivulidae fishes are popularly known as annual fishes which live in ephemeral environments such as pools, that obligatorily dry out seasonally causing the death of adult individuals. They have unique biological characteristics such as small body size, early sexual maturation, continuous reproduction, an elaborated courtship behavior, and a great reproductive capacity among fishes. The rivulids are widely distributed in North, Central and South America. In this study, the diet and reproductive biology of Cynopoecilus melanotaenia was analyzed. A total of 263 specimens were collected and the analysis of 233 gastrointestinal contents revealed an invertivorous diet composed mainly of small crustaceans (Cladocera, Amphipoda, and Ostracoda) and immature insects (Chaoboridae, Culicidae, Syrphidae, but mainly Chironomidae larvae). Lepidophagy on male's diet was also registered. Fecundity was estimated by analyzing 59 pairs of mature ovaries and ranged from 2 to 157 oocytes (mean, 19 ± 26[SD]). The species has fractional spawning, a strategy to increase the chance of survival to prolonged depletions. This study is the first to investigate the reproductive biology of C. melanotaenia. The results confirmed the opportunistic character of the rivulid C. melanotaenia and provided unreported reproductive information that may aid conservation of the species.A maioria dos peixes da família Rivulidae são popularmente conhecidos como anuais por completarem todo seu ciclo biológico em pequenos corpos de água temporários que secam obrigatoriamente em determinados períodos do ano causando a morte dos indivíduos adultos. Possuem características biológicas peculiares como pequeno porte, maturação sexual precoce, reprodução contínua, um elaborado padrão de corte e uma grande capacidade reprodutiva entre os peixes. Os rivulídeos se encontram amplamente distribuídos nas Américas do Norte, Central e Sul. Este trabalho analisou a dieta e a biologia reprodutiva de Cynopoecilus melanotaenia. Foram coletados 263 exemplares e a análise de 233 conteúdos gastrointestinais revelou uma dieta invertívora composta principalmente por microcrustáceos (Cladocera, Amphipoda e Ostracoda) e insetos imaturos (Chaoboridae, Culicidae, Syrphidae, mas principalmente larvas de Chironomidae). Foi registrada a lepidofagia na dieta dos machos. A fecundidade foi estimada pela análise de 59 pares de ovários maduros e variou entre 2 a 157 ovócitos (média, 19 ± 26[DP]). A espécie apresentou desova parcelada, uma estratégia para aumentar a chance de sobrevivência a depleções prolongadas. Este trabalho apresenta a primeira investigação sobre a biologia reprodutiva de C. melanotaenia. Os resultados encontrados sugerem a estratégia reprodutiva oportunista de C. melanotaenia e fornecem novas informações biológicas que podem contribuir para pesquisas de conservação e manutenção da espécie em seu ambiente natural.

The lack of knowledge of the freshwater ichthyofauna of coastal streams in the State of São Paulo (Brazil) is a cause of concern, as these streams are inserted in the Atlantic forest, a hotspot highly threatened. The aim of the present study is to investigate the freshwater ichthyofauna composition of clear and blackwater streams in a preservation area of Brazilian Atlantic forest. Fish samples were taken using electrofishing. A total of 20 species were registered, with Astyanax ribeirae, Hollandichthys multifasciatus, and Mimagoniates microlepis (Characiformes, Characidae) as the more representative. In general, the observed pattern of occurrence and distribution of fish species varied according to habitat characteristics, due to the longitudinal gradient in clearwaters, and among clearwaters and blackwaters. In clearwater streams, the headwater stretches had lower species diversity, while the opposite occurred in the middle and lower sites. These longitudinal variations of ichthyofauna were related with habitat characteristics (depth, stream flow, and bottom type) in which they were found, since the diversity of habitats was higher in headwaters and lower in downstream reaches (middle and lower sites). The physical and chemical variables of water do not seem to have influenced the distribution of species in clearwater streams, but the clear and blackwater fish composition was influenced mainly by pH concentration. Unlike the spatial differences, significant temporal differences were not registered in fish assemblages, probably due to the absence of a pronounced dry season in the studied region.A falta de conhecimento dos peixes de água doce em riachos costeiros no estado de São Paulo é preocupante, considerando que estes riachos estão inseridos em um bioma brasileiro extremamente ameaçado, a floresta Atlântica. O objetivo deste trabalho é investigar a composição da ictiofauna de riachos de águas claras e pretas em uma área preservada da Mata Atlântica. A pesca elétrica foi utilizada para amostrar a ictiofauna. Foram coletadas 20 espécies, sendo Astyanax ribeirae, Mimagoniates microlepis e Hollandichthys multifasciatus (Characiformes, Characidae), as mais representativas. De modo geral, o padrão de ocorrência e distribuição da ictiofauna observado variou de acordo com as características dos habitats, tanto no gradiente longitudinal nos riachos de águas claras, quanto entre os riachos de águas claras e o de águas pretas. Nos riachos de águas claras, os trechos de cabeceiras apresentaram riqueza e diversidade de espécies menor, enquanto o inverso ocorreu nos pontos médios e inferiores. Estas variações longitudinais da ictiofauna provavelmente estão associadas às características dos ambientes (profundidade, correnteza e substrato) em que foram encontradas, visto que a diversidade de habitats foi maior nos trechos de cabeceiras e menor nos trechos médios e inferiores. As variáveis físicas e químicas da água parecem não ter influenciado tanto a distribuição das espécies nos riachos de águas claras, porém as diferenç...

Abstract:The high Paraná river basin includes the largest rivers from São Paulo State and a great ichthyofauna diversity with 236 species. The aim of this study was to describe the fish fauna composition from Mogi Guaçu hydroelectric dam and oxbow lakes downstream reservoir, according to species abundance temporal variations. A total of 2.341 individuals (85,8 kg biomass) belonging to 41 species were collected during August 2005 to July 2006. From this, 31 species were found in the reservoir and 24 in the oxbow lakes showing the Curimatidae (Cyphocharax modestus and Steindachnerina insculpta) and Characidae (Hyphessobrycon eques and H. bifasciatus) dominance and many rare species. The abundance and biomass cumulative curves showed the numerical dominance in reservoir and biomass in oxbow lakes, reflecting an environment more and less disturbed, respectively. Similar values of Shannon's diversity and evenness were found to reservoir and oxbow lakes. In general, the highest values were obtained to the wet season and the smaller to the dry, but this variation were not sufficient to detect significant differences between areas, neither seasons. The species identities are not considered in these indexes computation, being insensitive to ichthyofauna composition differences between the reservoir and the oxbow lakes. The interpretation of these results should be taken carefully because despite the Shannon's indexes showed no differences in fish fauna composition between areas, the similarity analyses using the Morisita-Horn index showed low similarity among them. Moreover, the ichthyofauna found in the studied area was composed by typical species from high Paraná river basin which indicates a good condition with native species only, despite the impacts commonly caused by hydroelectric dams. We suggest that the dam regulation and the sand extraction from the river bed are affecting the flood pulses and consequently the oxbow lake's ichthyofauna. Resumo: A bacia do alto Paraná apresenta os rios de maior porte do Estado de São Paulo e uma ictiofauna bastante diversa, com 236 espécies. Este estudo visou caracterizar a composição ictiofaunística do reservatório da UHE Mogi Guaçu e de um conjunto de lagoas marginais naturais a jusante da represa, de acordo com a variação temporal da abundância das espécies. Durante agosto de 2005 a julho de 2006, foram coletados 2.341 exemplares pertencentes a 41 espécies. Na represa foram registradas 31 espécies e nas lagoas marginais 24, revelando uma dominância de espécies de Curimatidae (Cyphocharax modestus e Steindachnerina insculpta) e Characidae (Hyphessobrycon eques e H. bifasciatus) e um número expressivo de espécies raras. As curvas cumulativas de abundância e biomassa indicaram que na represa as espécies foram dominantes em número e nas lagoas em biomassa, refletindo um ambiente sob ações antrópicas e outro menos perturbado, respectivamente. A represa e as lagoas marginais apresentaram valores próximos de diversidade e eqüitabilidade de Shannon. No geral, os maiores valores foram...

Contemporary and historical factors influence assemblage structure. The environmental and spatial influences acting on fish organization of rain forest coastal streams in the Atlantic rain forest of Brazil were examined. Fish (and functional traits such as morphology, diet, velocity preference, body size), environmental variables (pH, water conductivity, dissolved oxygen, temperature, stream width, flow, depth, substrate), and altitude were measured from 59 stream reaches. Asymmetric eigenvector maps were used to model the spatial structure considering direction of fish movements. Elevation played an important role-fish abundance, biomass, and richness all decrease with increasing elevation. Fish communities are influenced by both environmental and spatial factors, but downstream movements were shown to be more important in explaining the observed spatial variation than were bidirectional and upstream movements. Spatial factors, as well as environmental variables influenced by the spatial structure, explained most of the variation in fish assemblages. The strong spatial structuring is probably attributable to asymmetric dispersal limitation along the altitudinal profile: Dispersal is likely to be more limiting moving upstream than downstream. These fish assemblages reflect scale-dependent processes: At the stream-reach scale, fish respond to local environmental filters (habitat structure, water chemistry, and food supply), which are in turn influenced by a larger scale, namely the altitudinal gradient expected in steep coastal mountains. Thus, environmental drivers are not independent of spatial factors, and the effects of local factors can be confounded across the altitudinal gradient. These results may have implications for conservation, because downstream reaches are often neglected in management and conservation plans.Abstract in Portuguese is available with online material. K E Y W O R D Saltitude, asymmetric eigenvector maps, dispersal limitation, environmental filtering, fish metacommunities, fish movement, tropical streams conservation, variation partitioning

In stream environments habitat structure and limnological factors interact regulating patterns of energy and material transfer and affecting fish communities. In the coastal basins of Southeastern Brazil, limnological and structural characteristics differ between clear and blackwaters streams. The former have a diversity of substrate types, higher water velocities, and lower water conductivity, while the latter have sandy substrate, tea-colored and acidic waters, and low water velocities. In this study, we verified the relative importance of habitat structure and limnological variables in predicting patterns of variation in stream fish communities. Eight first to third order streams were sampled in the coastal plain of Itanhaém River basin. We captured 34 fish species and verified that community structure was influenced by physical habitat and limnology, being the former more important. A fraction of the variation could not be totally decomposed, and it was assigned to the joint influence of limnology and habitat structure. Some species that were restricted to blackwater streams, may have physiological and behavioral adaptations to deal with the lower pH levels. When we examined only the clearwater streams, all the explained variation in fish community composition was assigned to structural factors, which express specific preferences for different types of habitats.Em ambientes de riacho, fatores relacionados à estrutura dos habitats e limnologia interagem regulando os padrões de transferência de energia e matéria, afetando a composição da comunidade de peixes. Em bacias costeiras do sudeste do Brasil as características limnológicas e estrutura dos habitats diferem entre riachos de águas claras e pretas. Os primeiros são compostos por uma variedade de tipos de substrato, possuem velocidades de corrente mais elevadas e baixa condutividade, enquanto os últimos apresentam substrato arenoso, baixas velocidades de corrente e águas escuras e ácidas. Neste trabalho analisamos a importância relativa da estrutura dos habitats e das variáveis limnológicas como preditores dos padrões de composição em comunidades de peixes de riachos. Oito riachos de primeira a terceira ordem foram amostrados na planície costeira da bacia do rio Itanhaém. Capturamos 34 espécies e verificamos que a composição das comunidades foi influenciada por fatores estruturais e limnológicos, sendo os primeiros mais importantes. Uma fração de variação que não pode ser totalmente decomposta, devese à influência conjunta da limnologia e estrutura dos habitats. Algumas das espécies restritas aos riachos de águas pretas provavelmente apresentam adaptações fisiológicas e comportamentais para lidar com os baixos níveis de pH. Quando foram examinados somente os riachos de águas claras, toda a variação explicada na composição da comunidade de peixes foi atribuída aos fatores estruturais, devido a preferências específicas por diferentes características de hábitats.

Alterations in stream environments can alter fish food availability, but there is little research data related to the impacts of urbanization on fish diets in tropical streams. Thus, we sought to compare the diet of ten fish species in urbanized and nonurbanized streams reaches. Fish stomach contents were obtained for four urban and five non-urban stream reaches from two medium-sized cities. We verified the similarity of diet composition from urbanized/non-urbanized streams. In-stream features mainly related to the substrate highlighted a perturbation gradient: gravel, pebbles and cobbles were associated to the wider urban reaches while silt were representative in the narrow pools from non-urban streams. Fishes changed their diet in response to urban and non-urban treatments. Omnivorous fishes consumed more detritus and Chironomidae and less terrestrial adult insects in urban reaches, while invertivorous fish consumed more terrestrial adult insects and Trichoptera larvae in the non-urbanized stream reaches. Although the management of the physical structure of streams in Brazil has been basically focused on riparian reforestation, our results suggest that a restoration plan for urban streams cannot be limited to reforestation of its surroundings, but also need to consider the physical structure of the channel, especially the substrate, which contributes to promote in-stream variability.

The role of riparian forests in the functioning of aquatic ecosystems is well known, and they are recognized as an important food source for riverine fauna. This study investigates the trophic structure of coastal freshwater stream fishes from a large conservation area in an Atlantic rainforest using stomach content and food availability analyses. Four samples were collected from 19 sample sites. Fishes were caught with electrofishing. Prey were sampled with trays, Surber, traps, and electrofishing to evaluate the availability of food resources. The diets of 20 fish species were determined from the stomach contents of 1691 individuals. Terrestrial and aquatic insects and detritus were the most consumed items. Fish diet and prey availability were not seasonally dependent. A cluster analysis showed five trophic functional groups: terrestrial insectivores, aquatic insectivores, detritivores, carnivores, and omnivores. Insectivores predominated in species richness (60%), abundance (47%) and biomass (39%). Allochthonous and autochthonous items were found in similar proportions in the environment; however, allochthonous items were representative for insectivores and detritivores, whereas autochthonous items were important for primarily aquatic insectivores. The preference for certain insects by insectivorous fishes was associated with food selectivity rather than the availability of the resource and demonstrated the strong relationship between feeding behavior and food preference. The absence of seasonal variation in the diets of the fishes was possibly related to the consistent food supply. Our results confirm the role of the forest as a food provider for stream fishes, such as terrestrial insects and plant debris/ detritus (also consumed by aquatic insects, which subsequently serve as food for fish), highlighting the importance of conserving the Brazilian Atlantic rainforests.