Resumo Objetivo Nosso objetivo foi descrever a estrutura e os padrões espaciais da comunidade zooplanctônica em um pequeno sistema fluvial brasileiro (sub-bacia do rio Paranaíba) e avaliar o papel de um meandro na dinâmica dessa comunidade. Métodos Amostras de zooplâncton foram coletadas em pontos localizados em um meandro e no leito do rio Aporé durante os períodos chuvoso e seco. Coletamos essas amostras na superfície e fundo de duas zonas diferentes (litorânea e canal). Para cada período hidrológico, a análise de variância foi conduzida para determinar as diferenças na riqueza de espécies e abundância do zooplâncton entre os diferentes pontos (longitudinal), zonas (lateral) e profundidades (vertical). A análise de cluster foi realizada para avaliar a similaridade na composição de espécies. Além disso, uma análise de correspondência canônica foi usada para selecionar as variáveis ambientais que melhor explicaram a variação nos dados de abundância do zooplâncton. Resultados Registramos 152 espécies: 70 de rotíferos, 53 de amebas testáceas, 20 de cladóceros e 9 de copépodes. Observamos mudanças na riqueza de espécies e abundância do zooplâncton ao longo do eixo longitudinal do rio tanto no período chuvoso quanto no seco. No entanto, não detectamos nenhuma mudança lateral ou vertical nesses atributos. A análise de cluster também indicou que as maiores diferenças na composição de espécies estavam no eixo longitudinal do rio. A variabilidade longitudinal do zooplâncton foi associada principalmente a influência de um meandro a montante, bem como a mudanças na velocidade de fluxo d’água, turbidez e concentrações de sólidos suspensos à jusante. Conclusões Nossos resultados demonstraram a importância de uma heterogeneidade de características hidrológicas como fator estruturante da comunidade zooplanctônica no rio Aporé. Assim, destacamos a relevância de ações para proteger e manter as características naturais desses ambientes.

Abstract Aim Our objective was to describe the structure and spatial patterns of the zooplankton community in a small Brazilian river system (Paranaíba River sub-basin) and evaluate the role of an oxbow lake in the dynamics of this community. Methods Zooplankton samples were collected from sites located in an oxbow lake and the Aporé River bed during the rainy and dry seasons. We collected these samples from the surface and bottom levels of two different zones (littoral and channel). For each hydrological season, analysis of variance was conducted to determine the differences in species richness and abundance of zooplankton among different sites (longitudinal), zones (lateral), and depths (vertical). Cluster analysis was performed to assess the similarity in species composition. In addition, a canonical correspondence analysis was used to select the environmental variables that best explained the variation in zooplankton abundance data. Results We recorded 152 species: 70 rotifers, 53 testate amoebae, 20 cladocerans, and 9 copepods. We observed changes in the species richness and abundance of zooplankton along the longitudinal axis of the river in both the rainy and dry seasons. However, we did not detect any lateral or vertical changes in these attributes. Cluster analysis also indicated that the greatest differences in species composition were in the longitudinal axis of the river. The longitudinal variability of zooplankton was mainly associated with the influence of an upstream oxbow lake, as well as the changes in water flow velocity, turbidity, and concentrations of suspended solids downstream. Conclusions Our results demonstrate the importance of a heterogeneity of hydrological characteristics as a structuring factor of the zooplankton community in the Aporé River. Thus, we highlight the relevance of actions to protect and maintain the natural characteristics of these environments.

ABSTRACT By using informetric tools, we evaluated the contribution and impact of the open source computer-assisted sperm analysis (CASA) software on sperm studies, especially pertaining to fish. The article was cited 125 times between 2007 and 2014 in four publication types (articles, doctoral dissertations, master’s theses, and books). Among articles, the number of citations increased at rate of three citations per year and the calculated h-index was 17. Of the studies that cited Wilson-Leedy and Ingermann (2007), fish were the main group of organisms studied (61 articles); of these, 34 articles used the open source CASA, covering 23 marine or freshwater species. Studies conducted in 12 countries were published in 21 journals. Four ways of knowledge sharing were identified: by direct partnership with the system developers; by knowledge multipliers, who worked directly with the system developers; by groups that adopted the system by their own initiative; and through expansion of cooperation networks with autodidacts. In regard to specific analytical procedures, motility, curvilinear velocity, average path velocity, and straight-line velocity were the main CASA parameters used to describe sperm movements. As expected, the usage of this tool has been increasing over the years, being a reliable and versatile alternative to more costly similar platforms. However, the potential of the CASA system has not been completely explored and it is our assessment that some results produced by CASA are poorly understood or even misunderstood.

ABSTRACT Fish larvae and adults are morphologically distinct from each other and have different ecological requirements. Research on the dynamics of ichthyoplankton provides valuable information about the early stages of the life cycle of fish. This study analyzed the temporal and spatial distribution of the larval stages of three migratory species - Salminus brasiliensis (Cuvier, 1816), Prochilodus lineatus (Valenciennes, 1836) and Pseudoplatystoma corruscans (Agassiz, 1829) - to identify possible spawning areas in the last lotic remnant of the upper Paraná River, in the Brazilian territory. A total of 26 points were sampled monthly from October 2003 to November 2004. The PERMANOVA detected significant differences between the months only for S. brasiliensis (Pseudo-F = 3.88, p = 0.0021) and P. corruscans (Pseudo-F = 3.35, p = 0.004). Among the environmental variables, temperature was the most important and the Mantel test detected a significant correlation between temperature and the densities, only for P. lineatus (r = 0.09, p = 0.03). The species in our data chose for spawning tributaries that are not dammed, of which most are outside conservation areas. Therefore, recruitment, maintenance and possible actions aiming to recover the stocks of these species are dependent on the conservation of tributaries and floodplain lakes in the region, in addition to monitoring to prevent fishing during the reproductive period.

RESUMO Com base na hipótese de que a migração vertical diária (MVD) é um mecanismo que visa evitar predadores, o objetivo do presente estudo foi verificar a ocorrência de MVD em larvas de peixes planctívoras de Hypophthalmus edentatus (Spix, 1829) (Siluriformes, Pimelodidae) e Plagioscion squamosissimus (Heckel, 1840) (Perciformes, Sciaenidae), e nos grupos zooplanctônicos (rotíferos, cladóceros e copépodes) em uma lagoa tropical isolada da planície de inundação do alto rio Paraná, Brasil (região do Parque Nacional de Ilha Grande). Foi investigada a sobreposição espacial entre predadores (larvas de peixes) e presas (zooplâncton), bem como verificar quais variáveis físicas e químicas da água estariam relacionadas com a MVD das comunidades envolvidas neste estudo. Foram realizadas amostragens noturnas (20:00 e 4:00) e amostragens diurnas (8:00 e 16:00) na região limnética da lagoa durante um período de seis meses consecutivos, entre outubro de 2010 a março de 2011, que compreende o período reprodutivo das espécies de peixes analisadas. Durante o dia, as larvas permaneceram agregadas no fundo da lagoa, enquanto à noite procuraram dispersar-se na coluna de água. Principalmente para os cladóceros, a migração vertical diária foi um comportamento importante para evitar a predação das larvas de H. edentatus e P. squamosissimus, uma vez que diminuiu a sobreposição espacial entre presa e seu predador em potencial, dando suporte à hipótese de que a migração vertical é um mecanismo de defesa contra a predação. Embora correlações significativas foram observadas entre os fatores abióticos e a profundidade média ponderada dos microcrustáceos em determinados períodos do dia, o efeito da predação das larvas de peixes sobre o zooplâncton mostrou ser mais importante neste ambiente, visto que a pequena profundidade e o isolamento não permiti grandes variações dos fatores abióticos sazonalmente e entre os estratos da lagoa.

ABSTRACT Based on the hypothesis that diel vertical migration (DVM) is a mechanism of predator avoidance, the objective of the present study was to test for the occurrence of DVM in planktivorous fish larvae of Hypophthalmus edentatus (Spix, 1829) (Siluriformes, Pimelodidae) and Plagioscion squamosissimus (Heckel, 1840) (Perciformes, Sciaenidae), and zooplankton (rotifers, cladocerans and copepods) in an isolated tropical lagoon in the floodplain of the Upper Paraná River, Brazil (region of Parque Nacional de Ilha Grande). We investigated spatial overlap between predators (planktivorous fish larvae) and prey (zooplankton), and tested which physical and chemical variables of the water are related to the DVM of the studied communities. We performed nocturnal (8:00 pm and 4:00 am) and diurnal sampling (8:00 am and 4:00 pm) in the limnetic region of the lagoon for six consecutive months, from October 2010 to March 2011, which comprises the reproductive period of the fish species analyzed. During the day the larvae tried to remain aggregated in the bottom of the lagoon, whereas at night they tried to disperse in the water column. Especially for cladocerans, the diel vertical migration is an important behavior to avoid predation larvae of H. edentatus and P. squamosissimus once decreased spatial overlap between secured and its potential predators, which corroborates the hypothesis that DVM is a mechanism of predator avoidance. Although significant correlations were observed between the abiotic factors and WMD of microcrustaceans at certain times of day, the effect of predation of fish larvae on zooplankton showed more important in this environment, because the small depth and isolation not allow great variation of abiotic factors seasonally and between strata the lagoon.

Este trabalho descreve o desenvolvimento inicial de Pyrrhulina australis Eigenmann & Kennedy, 1903, o único Lebiasinidae da planície alagável do Alto Rio Paraná. Para isso, foram analisados 80 indivíduos, sendo 60 larvas e 20 juvenis, coletados entre os anos de 1992 e 2005, em vários ambientes (rios, canais e lagoas). De cada exemplar, foram obtidos dados morfométricos e merísticos e, posteriormente, o padrão de crescimento entre as variáveis morfométricas foi analisado. As larvas apresentaram grande concentração de pigmentos na região superior do intestino, da cabeça e ao redor da boca. A notocorda foi caracterizada por possuir um prolongamento que, posteriormente, diferenciou-se em um raio da nadadeira caudal. A seqüência de formação das nadadeiras foi: caudal, dorsal, anal, pélvica e peitoral. Em relação aos miômeros, observou-se que estes variaram de 23 a 32 (12-20 pré- e 10-16 pós-anal). A análise do crescimento revelou que o comprimento do focinho e o diâmetro do olho foram alométricos, enquanto a altura e o comprimento da cabeça, bem como a altura do corpo e a distância pré-peitoral apresentaram crescimento abrupto, evidenciando diferentes taxas de crescimento entre os períodos larval e juvenil. Esses resultados revelam que neste intervalo ocorre grande parte da metamorfose na espécie.

This work describes the initial development of Pyrrhulina australis Eigenmann & Kennedy, 1903, the only known Lebiasinidae of the upper Paraná River floodplain. Eighty specimens were analyzed, sixty larvae and twenty juveniles, collected between 1992 and 2005 in several areas (rivers, channels and ponds). From each specimen morphometric and meristic data were obtained and, subsequently, growth patterns were analyzed. Larvae presented greater pigment concentrations in the superior region of the intestine, head and around the mouth. Notochord is characterized by possessing a protrusion that later becomes part of the caudal fin. The fin formation sequence is: caudal, dorsal, anal, pelvic and pectoral. In relation to myomeres we observed that their numbers ranged from 23 to 32 (12-20 preanal and 10-16 postanal). Growth pattern analyses revealed that nose length and eye diameter were allometric, whereas head height and length, as well as body height and pre-pectoral distance were better represented by the piecewise model, revealing that most of the body metamorphosis occurs during the transitional breakpoint between the larval and juvenile periods.

Este trabalho teve por objetivo avaliar a abundância, os atributos da assembleia e a distribuição espacial e temporal de larvas de peixes, bem como a relação dessas variáveis com alguns fatores abióticos, em duas lagoas com diferentes graus de conexão com o rio Paraná, Parque Nacional de Ilha Grande, PR, Brasil. As amostragens foram realizadas em quatro locais, dois em cada lagoa. As coletas foram realizadas mensalmente à noite durante três períodos de desova (outubro a março) de 2001 a 2005, com o auxílio de redes de plâncton. A maior diversidade e abundância foram verificadas na lagoa Saraiva, sendo identificados 25 táxons. Na lagoa Xambrê somente foram capturadas espécies sedentárias e as mais abundantes foram Plagioscion squamosissimus e Hypophthalmus edentatus. Nessa lagoa as maiores ocorrências foram verificadas no período II. Na lagoa Saraiva as maiores capturas foram de Moenkhausia aff. intermedia, Hyphessobrycon sp. e Bryconamericus stramineus, entretanto, larvas de espécies migradoras também foram registradas. Nessa lagoa, as maiores ocorrências foram no período III. A abundância de larvas foi influenciada pela temperatura da água e pela condutividade elétrica. A elevada diversidade e abundância registradas na lagoa Saraiva podem ser atribuídas a sua conectividade com o rio Paraná, enquanto que a baixa diversidade e abundância observadas na lagoa Xambrê podem estar relacionadas ao seu isolamento. Os resultados obtidos com este estudo demonstram a importância das lagoas marginais para o desenvolvimento inicial dos peixes, tanto para espécies sedentárias como migradoras. Ambas as lagoas podem ser consideradas de extrema importância ecológica e altamente susceptíveis a impactos, onde qualquer interferência sem conhecimentos prévios pode causar danos irreversíveis.

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.

O objetivo deste trabalho foi avaliar o papel de fatores abióticos na ocorrência de larvas de peixes. As amostragens foram realizadas mensalmente em 12 estações (agrupadas em 4 áreas) nos rios Amambaí, Ivaí e Paraná e no reservatório de Itaipu, de outubro de 1994 a janeiro de 1995 (época de desova). Simultaneamente, foram obtidos dados de temperatura, pH, condutividade elétrica, oxigênio dissolvido, nível da água, velocidade da água e precipitação. Análises de Componentes Principais (PCA) e de Correspondência com Remoção do Efeito de Arco (DCA) foram aplicadas para sumarizar os dados abióticos e as densidades de larvas, respectivamente. O rio Amambaí diferiu significativamente das outras áreas em relação aos fatores abióticos. O reservatório de Itaipu diferiu significativamente das outras áreas quanto à composição de espécies, tendo o rio Ivaí também diferido do rio Paraná neste aspecto. A relação entre os eixos da PCA e DCA foi significativa, indicando que os fatores abióticos influenciam as larvas. Por exemplo, Leporinus elongatus preferiu o rio Amambaí, Hypophthalmus edentatus, Plagioscion squamosissimus e Hoplias aff. malabaricus o reservatório de Itaipu e Pimelodus maculatus, Auchenipterus osteomystax e Iheringichthys labrosus o rio Ivaí. Assim, sugerimos que cada espécie seleciona um conjunto de características abióticas em um dado ambiente utilizado como local de desova.

The purpose of this study was to evaluate the role of abiotic factors on fish larvae occurrence. Samplings were carried out monthly at 12 stations (grouped in four areas) in the Amambaí, Ivaí and Paraná rivers and in the Itaipu Reservoir (upper Paraná River basin), from October 1994 to January 1995 (spawning season). Simultaneously, we obtained water temperature, pH, electrical conductivity, dissolved oxygen, water level, water velocity, and rainfall. Principal Component Analyses (PCA) and Detrended Correspondence Analyses (DCA) were applied to summarize abiotic and larvae density data, respectively. Amambaí River differed significantly from the other areas in relation to abiotic factors. Itaipu Reservoir differed significantly from the other areas considering species composition, and the Ivaí River also differed from the Paraná River. The relationship among PCA and DCA axes were significant, indicating that abiotic factors do influence larva. For example: Leporinus elongatus prefered the Amambaí River, Hypophthalmus edentatus, Plagioscion squamosissimus, and Hoplias aff. malabaricus the Itaipu Reservoir, and Pimelodus maculatus, Auchenipterus osteomystax and Iheringichthys labrosus the Ivaí River. We suggest that species selected some abiotic factors characteristic to a given environment as spawning grounds.

Este trabalho teve por objetivo analisar a deriva do ictioplâncton em dois canais com diferentes condições de topografia e velocidade de fluxo, entre os estados do Paraná e Mato Grosso do Sul (Brasil). As amostragens foram realizadas no período de outubro de 1995 a abril de 1996, durante ciclos nictemerais. Amostras de água foram coletadas para determinação de algumas variáveis ambientais. A densidade de ovos diferiu significativamente entre os estratos, horários e meses; sendo que em ambos os canais, as maiores ocorrências de ovos foram verificadas entre janeiro e março, com maiores concentrações no fundo durante o período noturno. Com relação as larvas, as densidades diferiram entre os canais, horários e meses. As maiores ocorrências foram observas no canal direito, em ambos estratos, com maior período de captura entre janeiro e março. A superfície dos canais apresentou as maiores densidades de larvas durante o período noturno. A temperatura da água, condutividade elétrica e velocidade de fluxo foram diferentes entre os canais, entretanto, essas variáveis e a densidade de larvas não mostraram correlação, indicando que possivelmente outro fator, esteja influenciando a distribuição do ictioplâncton neste ambiente.

Analysis of drift of ichthyoplankton in two channels in the River Paraná, Brazil, were made. Sampling was undertaken from October 1995 to April 1996 during nychthemeral cycles. Water samples were collected to determine several environmental variables. Eggs densities largely differed to layers, times of day and months. In both the channels, highest occurrence of eggs was detected between January and March; greater concentrations at the bottom, during night. With regard to larvae, densities were significantly different in channels, times of days and months. Maximum occurrences were seen in the right channel, in both layers, with largest capture between January and March. Surface of the both channels presented highest density of larvae during night. Water temperature, electrical conductivity and flux velocity were different in the two channels, however, these variables and larvae density didn't showed correlations. This indicates that there was another possible factor, might be influencing the distribution of ichthyoplankton.

With the purpose of characterizing morphologicaly the larvae and juveniles of Apareiodon affinis (Steindachner, 1879) and to verify their temporal distribution monthly samples were taken at Leopoldo's Inlet, upper Paraná River. The specimens were captured with a conic-cylindrical plankton net of mesh size 0,5mm from March 1991 to February 1992. Soon after identification, the specimens were separeted according to their development (prefle-xion, flexion, posflexion and juvenile) and then the moiphometric analyses were performed. The results showed that the larvae were captured from August 1991 to February 1992, with greatest densities in November 1991. The specimens occured in every timetable, however, larvae in pretlexion and flexion were captured during day time and, posflexion and juvenile, at night. According to series of morphological development, high body proportions variation were verifyed mainly in the head lenght, eye diameter and in height body. Moreover, the individuais showed little pigmentation and myomeres number changing between 39 to 42. The majority of morphometric characteristics have negative allometry with the cxception of head lenght with regard to standart lenght that have positive allometry.