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The conservation of fish assemblages depends on the longitudinal and lateral connectivity between riverine habitats, in particular during the breeding season and the initial development. This study investigated the composition and spatio-temporal structure in the ichthyoplankton of the hydrographic basin of the Paraguay River in western Brazil to identify the local spawning grounds and the importance of the longitudinal connectivity of economically valuable migratory species. Data were collected at 10 sites between two breeding seasons (2017/2018 and 2018/2019). Were collected 8,635 larvae, representing 55 taxa in 25 families, including the migratory species Brycon hilarii, Hemisorubim platyrhynchos, Piaractus mesopotamicus, Prochilodus lineatus, Pseudoplatystoma spp., Salminus brasiliensis, Sorubim lima, and Zungaro jahu, which are important fishery resources, with the highest larval densities being recorded between November and January. The Sepotuba, Paraguay, Jauru, and Cabaçal rivers were the areas of greatest connectance, and should thus be considered critical for the conservation of the longitudinal connectivity of this fluvial system, indicating that the migratory species spawn upriver. More efficient fisheries management mechanisms are needed, respecting the spawning period of migratory species, maintaining quality and longitudinal connectivity between habitats, and characteristics necessary for successful larval recruitment. Resumo A conservação das assembleias de peixes depende da conectividade longitudinal e lateral entre habitats ribeirinhos, em especial durante o período reprodutivo e de desenvolvimento inicial. Objetivou-se avaliar a composição e a estrutura espaço-temporal do ictioplâncton da bacia hidrografia do rio Paraguai no oeste do Brasil para identificar as áreas de desova e a importância da conectividade longitudinal para a reprodução das espécies migradoras de interesse comercial. Os dados foram coletados em 10 pontos entre dois períodos reprodutivos (2017/2018 e 2018/2019). Capturaram-se 8635 larvas, pertencentes a 25 famílias e 55 táxons, incluindo espécies migradoras de interesse comercial, Brycon hilarii, Hemisorubim platyrhynchos, Piaractus mesopotamicus, Prochilodus lineatus, Pseudoplatystoma spp., Salminus brasiliensis, Sorubim lima e Zungaro jahu, que são importantes recursos pesqueiros, com maiores densidades larvais entre novembro e janeiro. Os locais com maiores interações e conectância foram os rios Sepotuba, Paraguai, Jauru e Cabaçal e, portanto, devem ser considerados áreas críticas para a conservação da conectividade longitudinal no sistema fluvial, indicando que as espécies migradoras têm desovado a montante dos locais amostrados. São necessários mecanismos de gestão pesqueira mais eficientes, respeitando o período de desova das espécies migradoras, mantendo a qualidade e conectividade longitudinal entre habitats, características necessárias ao sucesso do recrutamento larval.

Made available in DSpace on 2021-06-25T12:22:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-10 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) This study was conducted to investigate fish eggs and larvae dispersal in a river stretch influenced by small hydropower plants in Southeast Brazil. The main hypothesis is that the downstream dispersal of free-flowing eggs and larvae is likely to occur given the small size of the studied reservoirs and that passage through the dam may occur, with the fish ladder contributing to it. Eggs and larvae were collected fortnightly, between November 2016 and February 2017, from locations upstream of two dams, including lotic, transition and lentic zones. Additional samples were collected inside the fish ladders at each dam. Downstream dispersal of eggs and larvae was influenced by a combination of rainfall/flow variation and stage of the reproductive cycle, with the peak of rainfall during the summer coinciding with higher abundances. Under these conditions, eggs and larvae drifted downstream through the reservoirs and reached the dams. Once in the dam, they could pass through the fish ladder. This passage was correlated with larval density in the reservoir immediately upstream, although at very low densities compared with the other sampling sites located upstream of the fish ladders. Univ Estadual Paulista, Inst Biociencias, Dept Zool, Programa Posgrad Ciencias Biol Zool, Botucatu, SP, Brazil Charles Sturt Univ, Inst Land Water & Soc, Albury, NSW, Australia Swiss Fed Inst Technol, Dept Civil Environm & Geomat Engn, Stocker Lab, Inst Environm Engn, Zurich, Switzerland Univ Estadual Maringa, Programa Posgrad Ecol Ambientes Aquat Continentai, Nucleo Pesquisas Limnol Ictiol & Aquicultura, Maringa, Parana, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Zool, Programa Posgrad Ciencias Biol Zool, Botucatu, SP, Brazil

Flow-dependent fish specialists require specific conditions for reproduction, so the success and reproductive intensity of these animals are determined by the flood regime. Thus, this study investigated the spatial and temporal reproductive patterns of fish, especially migratory Prochilodus species (flow-dependent specialists) in an unusual period of low flow in the Para River sub-basin, one of the main tributaries of the upper Sao Francisco River. For this, ichthyoplankton collections were carried out between November 2013 and February 2014. Data were analysed considering the spatial and temporal variations in density of eggs and larvae for the upper, middle, and lower portions of the Para River sub-basin, and correlating this to some environmental variables. The results showed that the small headwater stretch of the Para River is one relevant spawning area for migratory fish species. However, this area is isolated by the Cajuru reservoir, which makes it uncertain the recruitment of these embryos, due to interruption of natural drift between spawning/nursery areas caused for reservoirs. Larvae of newly hatched migratory species found in tributaries of the lower Para River sub-basin also indicate these species use these tributaries as spawning grounds and migratory routes. The period in which the research was conducted represented the most atypical low flow, one in the last 75 years, resulting in the low variability in the environmental parameters. Although few parameters increased briefly in this low flow period influenced by greater rainfall in December, this precipitation was possibly responsible for the final gonadal maturation and spawning of migratory species.

The Paraíba do Sul River is affected by extensive water collection for supply, organic and industrial pollution, and dams. Nonetheless, the ichthyofauna maintains biodiversity and sustains artisanal fisheries. This study analyzes the composition, abundance and distribution of fish larvae, an important approach to determine the reproductive period and spawning sites. The sampling occurred from August 2011 through February 2013 in five sites at a transect between the banks on the lower reach of the Paraíba do Sul River. A total of 5,412 larvae belonging to 20 taxa was captured. The predominant order was Characiformes. Larvae of Prochilodus spp. and Leporinus spp. were the most abundant; larvae of Brycon insignis, an endangered species, were present. Fewer larvae were collected in the second reproductive cycle during a severe drought. The absence of eggs indicates that the study area is not used for spawning, and highlights the need for studies in the main channel and in the tributaries of the Paraíba do Sul River. Fish larvae need to have access to the marginal lagoons along the lower stretch of the river, an area which is the object of disputes between fishermen and farmers. RESUMO O rio Paraíba do Sul é afetado por retirada de água para abastecimento, poluição orgânica e industrial e barramentos, mas mantém a biodiversidade de peixes e sustenta a pesca artesanal. Este estudo apresenta a composição, abundância e distribuição de larvas de peixes, abordagem importante para determinar o período de reprodução e locais de desova. A amostragem ocorreu entre agosto de 2011 e fevereiro de 2013 em cinco pontos de um transecto de 500 m entre as margens no trecho inferior do rio Paraíba do Sul. Um total de 5.412 larvas de 20 táxons foi capturado. Predominaram Characiformes, sendo que larvas de Prochilodus spp. e Leporinus spp. foram as mais abundantes. Larvas de Brycon insignis, espécie em extinção, foram registradas. Larvas foram menos abundantes no segundo ciclo reprodutivo, coincidindo com o início de uma seca severa na região. A ausência de ovos nas amostras indica que a área estudada não é utilizada para desova e aponta a necessidade de estudos no canal principal a montante e nos afluentes. Ressaltamos a necessidade de acesso das larvas às lagoas marginais no trecho inferior do rio Paraíba do Sul, área objeto de desentendimentos entre pescadores e agricultores.

Fish reproduction in natural environments tends to occur in conditions, including extreme pH values, ideal for the survival of offspring. In this context, the purpose of this study was to assess the influence of pH on both survival and early development of two fish species, Astyanax lacustris (short-distance migrating fish) and Piaractus mesopotamicus (long-distance migrating fish), with different reproductive strategies. Our experiments were divided into two tests (incubation and larviculture) at five pH levels. First was incubation through a water recirculation system using 2 L incubators followed by larviculture using a 2.5 L aquarium. pH had no influence on the hatching rate of A. lacustris eggs, but affected the yolk-sac diameter, while the newly-hatched larvae had some skeletal disorders. For P. mesopotamicus, pH influenced the hatching rate and perivitelline space, while the newly-hatched larvae had several skeletal disorders. The larviculture of A. lacustris revealed no effect on the survival rate, but the analyzed morphometric variables indicated significant differences between the treatments. An acidic pH negatively influenced the survival rate of P. mesopotamicus, and all morphometric variables also varied significantly between the treatments. We concluded that both the survival and development of A. lacustris and P. mesopotamicus revealed different responses at pH levels during incubation and larviculture tests.

Fish diversity loss is threatened by the construction of dams as they prevent the regular natural dispersal among populations. Thus, conservation of key riverine habitats for fish reproduction may be essential for the recruitment of new native species of fish. The present study aimed to identify key habitats for fish spawning and early development in the Paranapanema River basin, as well as to determine the taxonomic composition, reproductive and life-history strategy, and to report spatial distribution of eggs, larvae and juveniles. The importance of lagoons, tributaries, and sub-tributaries was evaluated in the Paranapanema River basin between October 2012 and March 2013. Eggs and larvae samples were collected at dawn and dusk with conical plankton nets (0.5 mm mesh size), whereas juveniles were captured during the day with seine and sieve (0.5 cm mesh size). A total of 547 eggs, 904 larvae and 1 228 juveniles were captured. We observed that 2 larvae and 288 juveniles of non-migratory species, parental care, and equilibrium life-history strategy, predominated in lagoons and tributaries. On the other hand, 13 larvae and 60 juveniles of short migratory distance, no parental care, and periodic life-history strategy predominated in sub-tributaries. The highest densities of eggs were recorded in tributaries and sub-tributaries (Tukey’s test, P = 0.001 and P = 0.03, respectively), and the highest densities of larvae were recorded for lagoons and tributaries (P = 0.005 and P = 0.0001, respectively). Captures of eggs and larvae were higher at night; while the highest catches per unit effort of juveniles were recorded for tributaries and sub-tributaries. Fish species that adopt different life-history strategies can use diverse types of habitats during the early stages. Lagoons, tributaries and sub-tributaries of the Paranapanema River play different roles in the reproductive success of fish fauna in a heavily modified basin. The preservation of spawning and nursery areas trapped between reservoirs is necessary for Neotropical fish species recruitment and survival. Rev. Biol. Trop. 66(2): 605-621. Epub 2018 June 01. Resumen Los riesgos de pérdida de diversidad de peces aumentan con la construcción de represas, ya que impide la dispersión de individuos entre las poblaciones. Por lo tanto, la conservación del habitat ribereño clave para la reproducción de peces puede ser esencial para el reclutamiento de nuevos individuos de especies nativas. El presente estudio tiene como objetivo identificar hábitats clave para el desove y el desarrollo temprano de peces en la cuenca del río Paranapanema, así como determinar la composición taxonómica, la estrategia reproductiva y la historia de vida, y reportar la distribución espacial de huevos, larvas y juveniles. Se evaluó la importancia de lagunas, afluentes y subafluentes en la cuenca del río Paranapanema entre octubre de 2012 y marzo de 2013. Se recogieron muestras de huevos y larvas al amanecer y al atardecer con redes de plancton cónico (tamaño de malla de 0,5 mm), mientras que los juveniles fueron capturados durante el día con redes de cerco y tamiz (tamaño de malla de 0,5 cm). Se capturaron un total de 547 huevos, 904 larvas y 1 228 juveniles. Como resultado fue observado que 2 larvas y 288 juveniles de especies no migratorias, cuidado parental y estrategia de vida de equilibrio son predominantes en lagunas y afluentes. Por otro lado, 13 larvas y 60 juveniles de espécies migratorias de corta distancia, sin cuidado parental y estrategia de vida periódica predominaron en subafluentes. Se registraron las densidades más altas de huevos para afluentes y subafluentes (Prueba de Tukey, P = 0.001 y P = 0.03, respectivamente), y se registraron las densidades más altas de larvas para las lagunas y afluentes (P = 0.005 y P = 0.0001, respectivamente). Las capturas de huevos y larvas eran más altas por la noche. Las mayores capturas por unidad de esfuerzo de juveniles se registraron para los afluentes y subafluentes. Las especies de peces que adoptan diferentes estrategias de historia de vida pueden utilizar diversos tipos de hábitats durante las primeras etapas. Lagunas, afluentes y subafluentes del río Paranapanema desempeñan diferentes papeles en el éxito reproductivo de la fauna de peces en una cuenca fuertemente modificada. La preservación de áreas de desove y cría atrapadas entre el embalse es necesaria para el reclutamiento de especies de peces neotropicales.

Fish diversity loss is threatened by the construction of dams as they prevent the regular natural dispersal among populations. Thus, conservation of key riverine habitats for fish reproduction may be essential for the recruitment of new native species of fish. The present study aimed to identify key habitats for fish spawning and early development in the Paranapanema River basin, as well as to determine the taxonomic composition, reproductive and life-history strategy, and to report spatial distribution of eggs, larvae and juveniles. The importance of lagoons, tributaries, and sub-tributaries was evaluated in the Paranapanema River basin between October 2012 and March 2013. Eggs and larvae samples were collected at dawn and dusk with conical plankton nets (0.5 mm mesh size), whereas juveniles were captured during the day with seine and sieve (0.5 cm mesh size). A total of 547 eggs, 904 larvae and 1 228 juveniles were captured. We observed that 2 larvae and 288 juveniles of non-migratory species, parental care, and equilibrium life-history strategy, predominated in lagoons and tributaries. On the other hand, 13 larvae and 60 juveniles of short migratory distance, no parental care, and periodic life-history strategy predominated in sub-tributaries. The highest densities of eggs were recorded in tributaries and sub-tributaries (Tukey’s test, P = 0.001 and P = 0.03, respectively), and the highest densities of larvae were recorded for lagoons and tributaries (P = 0.005 and P = 0.0001, respectively). Captures of eggs and larvae were higher at night; while the highest catches per unit effort of juveniles were recorded for tributaries and sub-tributaries. Fish species that adopt different life-history strategies can use diverse types of habitats during the early stages. Lagoons, tributaries and sub-tributaries of the Paranapanema River play different roles in the reproductive success of fish fauna in a heavily modified basin. The preservation of spawning and nursery areas trapped between reservoirs is necessary for Neotropical fish species recruitment and survival. Rev. Biol. Trop. 66(2): 605-621. Epub 2018 June 01.

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.

Aim: To analyze temporal distribution of larvae and juveniles and the early development and of Moenkhausia cf. gracilima. Methods Samples were taken quarterly in twenty-five sites in the upper Paraná River floodplain between August 2013 and May 2015. The samples were taken under the water surface at night using 0.5 mm mesh plankton nets. In the laboratory, samples were sorted, identified and separated into larval (preflexion, flexion and postflexion) and juvenile periods. Results A total of 248 individuals was collected, mainly in the Saraiva Lagoon, suggesting that the entire life cycle of this species occurs in this environment. The reproductive period takes place between December and April, since the postflexion larvae were found until May. However, the occurrence of juveniles between February and May indicates probable batch spawning. Among the 95 individuals used for ontogenic description, 82 were larvae and 13 juveniles. Larvae may be characterized by irregular pigmentation in the upper region of the head, mouth, and body, increasing throughout development; upper lobe of the caudal fin more pigmented than the lower lobe, only visible in postflexion larvae; terminal mouth; anal opening located anterior to the median region of the body and total number of myomers ranging from 34 to 40 (15 to 20 pre and 16 to 23 postanal), while juveniles have characteristics similar to adults. The total number of fin rays is: P. 11-16, V. 7-11, D, 9-11 and A. 21-23. Conclusions According to the distribution of developmental periods it is possible to conclude that this species reproduces in the summer, preferably in lagoons. Growth analysis indicated important alterations in larval morphology (metamorphosis) that may be associated with the ecomorphological characteristics of the species. The morphological separation of larvae of M. cf. gracilima from other larvae of small characids, especially at preflexion and flexion stages may be complicated by the overlap of traits, suggesting the use of other variables, mainly morphometric, for the separation of the species. Resumo Objetivo: Analisar a distribuição temporal de larvas e juvenis e o desenvolvimento inicial de Moenkhausia cf. gracilima. Métodos Foram amostrados trimestralmente vinte e cinco estações distribuídas na planície de inundação do alto rio Paraná entre agosto de 2013 e maio de 2015. As coletas foram na subsuperfície, no período noturno, utilizando redes de plâncton com malha 0,5 mm. Em laboratório, as amostras foram triadas, identificadas e separadas em períodos larval (pré-flexão, flexão e pós-flexão) e juvenil. Resultados Foram capturados 248 indivíduos, sendo a maioria na Lagoa Saraiva, sugerindo que todo o ciclo de vida desta espécie aconteça neste ambiente, e que o período reprodutivo ocorre entre dezembro e abril, uma vez que larvas em pós-flexão foram encontradas até maio. A ocorrência de juvenis entre fevereiro e maio indica provável desova parcelada. Entre os 95 indivíduos utilizados na descrição ontogênica, 82 eram larvas e 13 juvenis. As larvas podem ser caracterizadas pela pigmentação irregular na região superior da cabeça, na boca e no corpo, aumentando ao longo do desenvolvimento; lobo superior da nadadeira caudal mais pigmentado do que o inferior, só visível em larvas em pós-flexão; boca em posição terminal, abertura anal localizada anteriormente à região mediana do corpo e número total de miômeros variando de 34 a 40 (15 a 20 pré e 16 a 23 pós-anal), enquanto os juvenis apresentam características semelhantes ao adulto. O número de raios das nadadeiras é: P. 11-16, V. 7-11, D, 9-11 e A. 21-23. Conclusões De acordo com a distribuição dos períodos de desenvolvimento, é possível concluir que esta espécie se reproduz no verão, de preferência em lagoas. A análise do crescimento indicou alterações importantes na morfologia larval (metamorfoses) que podem estar associadas às características ecomorfológicas da espécie. A separação morfológica das larvas de M. cf. gracilima de outras larvas de caracteres pequenos, especialmente nos estágios de preflexão e flexão, pode ser complicado pela sobreposição de traços, sugerindo o uso de outras variáveis, principalmente morfométricas, para a separação das espécies.

Freshwater fish reproduce annually in environments that provide favourable conditions for spawning and larval survival and growth. Thus, the aims of this study were to use long-term larval density data to evaluate the temporal distribution of the dourado Salminus brasiliensis, its habitat use for larval development and the effects of environmental variables on reproduction. S. brasiliensis larvae were mainly recorded in October and January in the Ivinheima River, and higher densities of larvae, primarily in the preflexion and flexion stages, were captured in the river and backwater biotopes. Water level, dissolved oxygen and temperature were the primary variables affecting the density of larvae, and this species can migrate over 200km to reproduce in the Ivinheima River and its tributaries. Therefore, S. brasiliensis is reproducing annually, indicating favourable local conditions for migration and spawning, and exhibits differential use of biotopes for reproduction, including rivers and backwaters (spawning) and lagoons (refuge and growth). Therefore, considering that the dourado is a key species for conservation, ensuring its reproductive success means maintaining a balanced ecological structure.

Aim: To analyze temporal distribution of larvae and juveniles and the early development and of Moenkhausia cf. gracilima. Methods Samples were taken quarterly in twenty-five sites in the upper Paraná River floodplain between August 2013 and May 2015. The samples were taken under the water surface at night using 0.5 mm mesh plankton nets. In the laboratory, samples were sorted, identified and separated into larval (preflexion, flexion and postflexion) and juvenile periods. Results A total of 248 individuals was collected, mainly in the Saraiva Lagoon, suggesting that the entire life cycle of this species occurs in this environment. The reproductive period takes place between December and April, since the postflexion larvae were found until May. However, the occurrence of juveniles between February and May indicates probable batch spawning. Among the 95 individuals used for ontogenic description, 82 were larvae and 13 juveniles. Larvae may be characterized by irregular pigmentation in the upper region of the head, mouth, and body, increasing throughout development; upper lobe of the caudal fin more pigmented than the lower lobe, only visible in postflexion larvae; terminal mouth; anal opening located anterior to the median region of the body and total number of myomers ranging from 34 to 40 (15 to 20 pre and 16 to 23 postanal), while juveniles have characteristics similar to adults. The total number of fin rays is: P. 11-16, V. 7-11, D, 9-11 and A. 21-23. Conclusions According to the distribution of developmental periods it is possible to conclude that this species reproduces in the summer, preferably in lagoons. Growth analysis indicated important alterations in larval morphology (metamorphosis) that may be associated with the ecomorphological characteristics of the species. The morphological separation of larvae of M. cf. gracilima from other larvae of small characids, especially at preflexion and flexion stages may be complicated by the overlap of traits, suggesting the use of other variables, mainly morphometric, for the separation of the species.

Natural and induced disturbances greatly influence the temporal distribution of ichthyoplankton abundance. This study assesses and compares the temporal variability of fish larvae assemblages in controlled and free environments to determine the influence of environment variables on the main taxa in these systems. The study was conducted at the Chapecó (without dam impact) and Ligeiro (with dam impact) river mouths, which are located in the upper Uruguay River. Samples were made between October 2001 and March 2004 during three reproductive periods. The larvae assemblages were composed of small and medium-sized Characiformes and Siluriformes. The variation in the distribution of larvae was mainly temporal (>85%). When the three reproductive periods were compared, it was observed in the second period, characterized by a larger water flow and a lower temperature, that there was a reduction in abundance, a lower number of taxa, an absence of stages in post-flexion and a high dissimilarity in larvae assemblage structure. In general, the environmental variables of water flow and temperature most influenced the distribution of egg and larvae abundance. In the studied area, a smaller temporal variability was observed in the structure of larvae assemblages at the sampling sites in the Chapecó River mouth than in in the Ligeiro River mouth under the influence of dams. Os distúrbios naturais e induzidos têm notável influência na distribuição temporal da abundância do ictioplâncton. Este estudo visa avaliar e comparar a variabilidade temporal das assembleias de larvas de peixes, entre ambientes regulados e ambientes livres, bem como, determinar a influência das variáveis ambientais sobre os principais táxons presentes nestes ambientes. O trabalho foi conduzido na foz dos rios Chapecó (sem impacto de barramento) e Ligeiro (impactado por barragens), ambos localizados no alto rio Uruguai. As coletas foram realizadas entre outubro de 2001 e março de 2004 durante três períodos reprodutivos. As assembléias de larvas estiveram compostas principalmente por Characiformes e Siluriformes de pequeno e médio porte. A variação na distribuição de larvas foi principalmente temporal (>85%). Quando comparados os três períodos reprodutivos, foi observado que no segundo período, caracterizado por uma maior vazão da água e menor temperatura, houve redução na abundância, menor número de táxons, ausência de estágios em pós-flexão e elevada dissimilaridade na estrutura da assembléia de larvas. Em geral, as variáveis ambientais vazão e temperatura da água foram as que mais influenciaram a distribuição da abundância de ovos e larvas. Nos ambientes estudados, foi observado que existe uma menor variabilidade temporal na estrutura das assembléias de larvas das estações presentes na foz do rio Chapecó do que naquelas presentes na foz do rio Ligeiro, o qual esta sob influência dos barramentos.

Fish, like other animals, choose environments for reproduction that are favorable for their offspring’s initial development. For example, these environments may be chosen to provide shelter and food. This study examined the fish larvae inhabiting the Ivinheima River sub-basin. The study aimed to (i) characterize the taxonomic composition of the larval fish fauna, (ii) analyze the structure of the larval assemblage, and (iii) verify the relationship between the larval assemblages and environmental variables. The sampling areas included three environments: the Ivinheima River, the Finado Raimundo Lagoon and the Patos Lagoon. Sampling was performed between October 2002 and March 2006 during four reproductive periods (RPs). The data were analyzed with correspondence analysis (CA) and canonical correlation analysis (CCA). A total of 120 619 larvae were collected. These larvae belonged to several species characterized by different reproductive strategies. Our results showed differences between the composition of the Ivinheima River’s assemblages, where there were more larvae of migratory fish, and the lagoons, where larvae of sedentary species were predominant. In addition, differences were found among the RPs evaluated in the Ivinheima River: the first and second RPs were characterized by milder floods and by a greater abundance of migratory piscivore larvae, whereas the third and fourth RPs had more outflow and a greater abundance of larvae of detritivore and omnivore species. We conclude that the Ivinheima River plays a significant role in the maintenance of native migratory fish stocks in the upper Parana River basin and that the environment shows a segregation of the spatial and temporal composition and abundance of larvae related to running and flooding/standing water.

Studies that assess reproduction dynamics and ichthyoplankton distributions are scarce for the upper Uruguay River, especially in environments such as tributary mouths. Therefore, this study aimed to evaluate: (i) ichthyoplankton composition; (ii) spatial and temporal variation in ichthyoplankton abundance; and (iii) relationships between environmental variables and the abundance of ichthyoplankton during one annual cycle in this region. Monthly samples were collected from September 2001 to August 2002 in 48 h cycles at 6 h intervals between each sampling. Samples of eggs and larvae were collected from three of the main tributaries of the region (Ligeiro, Palomas and Chapeco rivers) and from three stretches of the Uruguay River near the confluence of these tributaries. Surface samples were collected with a 0.5 mm mesh cylindro-conical net. In general, reproductive seasonality was well-defined between October and February. It was most intense from November to January, when the photoperiod reached its highest values, flow was decreased, and the water temperature was increased. Based on egg and larval distributions, we found that spawning occurred mainly in the Ligeiro and Chapeco tributaries and in the Uruguay/Chapeco section. In contrast, fish spawning in the sites downstream of dams was more restricted. Finally, a difference was observed between the egg and larval distributions of the main river and its tributaries: the greatest reproductive activity in the tributaries occurred during periods of high flow and increased water temperature, while in the main river, more eggs and larvae were observed when the flow decreased and the water temperature increased.

Fish larvae of ‘corvinas’ (Pachyurus bonariensis and Plagioscion ternetzi) from Sinhá Mariana Lagoon, Mato Grosso State, were collected from March 2000 to March 2004, in order to determine the parasitic fauna of fishes. Larvae from the two species were parasitized by the same endoparasites: Contracaecum sp. Type 2 (larvae) (Nematoda: Anisakidae) in the mesentery and Neoechinorhynchus (Neoechinorhynchus) paraguayensis (Acanthocephala: Neoechinorhynchidae) in the stomach and the terminal portion of the intestine. Statistical analysis showed that there was a significant positive correlation between the standard length of hosts and the abundance of acanthocephalans and nematodes, and that the prevalence of nematodes presented a significant positive correlation with the standard length of the two species of hosts, indicating the presence of a cumulative process of infection. The present study constitutes the first record of nematodes and acanthocephalans parasitizing larval fish, as well as the first record of endoparasites in fish larvae in Brazil. In addition, it lists a new locality and two species of hosts for Contracaecum sp. Type 2 (larva) and N. (N.) paraguayensis.

The effects of a dam closure (Porto Primavera Dam) on reproduction of the main species that use the floodplain located below a nursery area were determined. Specifically, we examined, before and after the closure of the dam, the spatial distribution of larvae and the differences in density according to life strategy (migratory and non-migratory species). Fifteen points distributed along the channels of the Parana, Ivinheima and Paranapanema rivers were sampled, between 1997 and 2001, (October 1997 to December 1998—pre; and between January 1999 to March 2001—post closure), during the spawning period of most fish species found in the region (October to March). Samplings were always conducted at night, using a conical-cylindrical plankton net (0.5 mm mesh) with a flowmeter attached. There were significant differences in larvae densities between pre and post dam closure for several species. Also, there were significant differences between the pre and post-closure periods for densities of migratory and non-migratory species, and between sampling sites. These findings indicate decline in densities and number of taxa caught after the closure of the dam. Larvae of migratory species, formerly common in the entire study area, were registered only in points influenced by the non dammed rivers (such as the Ivinheima River), indicating that the closure of Porto Primavera caused negative impacts on fish reproduction downstream of the dam. Copyright © 2006 John Wiley & Sons, Ltd.

We sampled the Baia River (Mato Grosso do Sul State, Brazil) monthly, to survey taxonomic composition and temporal and spatial distribution of fish larvae. The ichthyoplankton was mainly composed by larvae of small and medium sized sedentary species and it was numerically dominated by six taxa: Plagioscion squamosissimus, Hypophthalmus edentatus, Hoplias aff. malabaricus, Bryconamericus stramineus, Serrasalmus spp. and Catathyridium jenynsii. These taxa present distinct temporal and spatial occurrence patterns: H. edentatus, B. stramineus and C. jenynsii are abundant between September and March in lentic areas; H. aff. malabaricus and Serrasalmus spp. were caught between October and February in lotic areas; whereas P. squamosissimus occurs in all sampled areas, with peak of capture in January. Hypophthalmus edentatus, H. aff. malabaricus, Serrasalmus spp. and B. stramineus were the taxa that most contributed to structure the assemblages temporally and spatially, and their abundances were influenced by the interaction of several environmental variables.

Univ Estadual Maringa, Dept Biol, Posgrad Ecol Ambientes Aquat Continentais, BR-87020900 Maringa, Parana, Brazil

Em reservatórios, são escassos os estudos que consideram as fases iniciais do ciclo de vida de peixes, sendo que informações sobre a ecologia de larvas de peixes são úteis para o entendimento da biologia das espécies, visto que os estágios iniciais representam um período crítico no ciclo de vida dos peixes. Neste contexto, o conhecimento a respeito das assembleias de larvas pode ser valioso para a predição e o entendimento do recrutamento, auxiliando desta maneira, no manejo do ambiente. Desta forma, o presente trabalho pretende verificar a composição da assembleia de larvas de peixes em diferentes regiões do reservatório. As coletas foram realizadas trimestralmente (março, junho, setembro e dezembro) no ano de 2002, nas regiões limnética e litorânea das zonas fluvial, transição e lacustre do reservatório de Rosana. No laboratório, o material foi triado e as larvas foram separadas e identificadas ao menor nível taxonômico possível. Os táxons que tiveram maior contribuição na região limnética foram Plagioscion squamosissimus (Perciformes), Hypophthalmus edentatus, Pimelodus maculatus (Siluriformes), Astyanax spp. e Roeboides descalvadensis (Characiformes), enquanto na região litorânea Bryconamericus stramineus e Apareiodon affinis (Characiformes). As regiões limnética e litorânea do reservatório, assim como suas respectivas zonas apresentaram diferenças na composição de espécies de larvas e a segregação das assembleias pode estar sendo influenciada pela preferência por habitats ou por questões evolutivas que envolvem as estratégias reprodutivas das espécies. There are few studies in reservoirs that consider the Early Life Stages (ELS) of fish. Information on the ecology of fish larvae are useful for understanding the biology of the species, since ELS represent a critical period in fish life cycle. In this context, knowledge about the assemblages of larvae can be valuable for the prediction and understanding of recruitment, thus assisting in the management of the environment. Therefore, this study intends to investigate the composition of the assemblage of fish larvae in different regions of Rosana reservoir. Samples were collected quarterly (March, June, September and December) in 2002, in the limnetic and littoral regions of the zones fluvial, transition and lacustrine of reservoir. In the laboratory, the material was sorted and larvae were separated and identified to lowest possible taxonomic level. The taxa that were the major contributors in the limnetic region were Plagioscion squamosissimus (Perciformes), Hypophthalmus edentatus, Pimelodus maculatus (Siluriformes), Astyanax spp. and Roeboides descalvadensis (Characiformes), whereas in the coastal region Bryconamericus stramineus and Apareiodon affinis (Characiformes) prevailed. Limnetic and littoral regions of the reservoir, as well as their respective zones showed differences in larvae species composition and segregation of assemblages can be influenced by a preference for habitats or evolutionary questions involving reproductive strategies of species.

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.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.

Researches on ichthyoplankton seems to be an important tool to identification of spawning areas and periods for freshwater fish. Ichthyoplankton was sampled monthly in the headwaters of the Cuiabá River, upper Paraguay River basin, (Mato Grosso State, Brazil), and in four of its tributaries, between November 2007 and March 2008, to evaluate the spatial and temporal distribution of fish eggs and larvae and the influence of regional and local variables on their distribution. In total, 22,067 eggs and 1,045 larvae were collected. A significant negative correlation was found between egg density and the variables of river level and flow volume. Larval density was not significantly correlated with any of the regional variables. The egg and larval densities were significantly higher at the sampling sites in the main river. The highest densities were found in environments with greater river widths, intermediate depths and lowest values of dissolved oxygen, electrical conductivity, and transparency. Anostomidae, Zungaro zungaro, Bryconamericus spp., Pimelodus spp., Pimelodidae, Auchenipteridae, and Siluriformes were the most abundant groups of larvae, and were observed at the sampling sites in the main river. The study site is an important spawning area for migratory and, non-migratory fish species, and highlight the importance of the main river to the reproductive event, by the influence of local variables transparency and river width, which in turn maybe temporally influenced by the river level. O estudo do ictioplâncton tem se mostrado uma importante ferramenta na identificação de áreas e períodos de desova para as espécies de peixes de água doce.Amostragens de ictioplâncton foram realizadas mensalmente na região de cabeceira do rio Cuiabá, bacia do alto rio Paraguai, (Mato Grosso, Brasil) e em quatro de seus tributários, entre novembro de 2007 e março de 2008, com o objetivo de avaliar a distribuição espaço-temporal de ovos e larvas de peixes. Foram amostrados 22.067 ovos e 1.045 larvas. Identificou-se correlação significativa e negativa entre a densidade de ovos, o nível fluviométrico e a vazão. A densidade de larvas não apresentou correlação significativa com nenhuma das variáveis regionais. As densidades, tanto de ovos quanto de larvas, foram significativamente maiores nos pontos no rio principal. As maiores abundâncias foram observadas em ambientes com maiores valores de largura do rio, valores intermediários de profundidade e menores valores de O2 dissolvido, condutividade e transparência. Os grupos taxonômicos de larvas mais abundantes foram Anostomidae, Zungaro zungaro, Bryconamericus spp., Pimelodus spp., Pimelodidae, Auchenipteridae e Siluriformes, com maiores abundâncias observadas nos pontos no rio principal. Os resultados mostram que o local de estudo é uma importante área de desova para as espécies de peixes migradores e não-migradores, e destacamos a importância do rio principal para o evento reprodutivo, pela influência das variáveis locais, transparência e largura do rio, que por sua vez parecem ser influenciadas temporalmente pelo nível fluviométrico.

Information on ichthyoplankton is an important tool in determining reproduction periods that - if associated to environmental variables - allows for inferences about the factors that regulate their intensity, beginning, and ending. In this context, this study aims to establish (i) ichthyoplankton composition; (ii) temporal variations in the overall density of eggs and larvae and among the most important taxa; and (iii) the influence of some abiotic and biotic variables on these organisms' abundance. Ichthyoplankton sampling was undertaken during the period between April 2005 and March 2006 at the Ivinhema River, upper Paraná River basin (MS/Brazil). Differences in the ichthyoplankton's temporal variation were evaluated using unifactorial ANOVAs. Principal Component Analysis and Pearson's correlation were used for the relationships between eggs and larvae densities and environmental variables. A total of 3,341 eggs and 2,896 larvae were captured during the period studied, and most of them were medium-sized and large species that carried out some type of reproductive migration. The highest densities of eggs and larvae occurred during the months of spring and summer, except for those of Bryconamericus stramineus, which was most abundant during the winter. The density of ichthyoplankton was most positively correlated with the water's outflow and temperature. However, Plagioscion squamosissimus was positively related to the increase in pH and in zooplanktonic organisms, while B. stramineus was inversely correlated with water outflow and temperature. The study concludes that spawning is most intense in the spring and summer, especially between November and January, and is related to the greatest values of water temperature and outflow. Nevertheless, the response and reproductive intensity in relation to the environmental variables vary according to the species.As informações sobre o ictioplâncton são ferramentas importantes para a determinação do período de reprodução que, se associado às variáveis ambientais, permitem inferências sobre os fatores que regulam sua intensidade, início e término. Nesse contexto, o presente estudo visa determinar: (i) a composição do ictioplâncton; (ii) as variações temporais na densidade de ovos, larvas e dos táxons mais importantes; e (iii) a influência de algumas variáveis abióticas e bióticas sobre a abundância destes organismos. As coletas de ictioplâncton foram realizadas no período de abril de 2005 a março de 2006, no rio Ivinhema, bacia do alto rio Paraná (MS/Brasil). Diferenças nas variações temporais do ictioplâncton foram avaliadas por ANOVAs unifatoriais. Análises de Componentes Principais e correlação de Pearson foram utilizadas para avaliar as relações entre densidade de ovos e larvas e as variáveis ambientais. Durante o período estudado, foram capturados 3.341 ovos e 2.896 larvas, sendo que a maior parte foi de espécies de médio e grande porte e que realizam algum tipo de migração reprodutiva. Ovos e larvas apresentaram suas maiores densidades nos meses de primavera e verão, exceto Bryconamericus stramineus que foi mais abundante no inverno. A densidade de ictioplâncton esteve mais correlacionada positivamente com a vazão e a temperatura da água. Contudo, Plagioscion squamosissimus apresentou relação positiva com o aumento do pH e dos organismos zooplanctônicos, enquanto B. stramineus apresentou correlação inversa com a vazão e temperatura da água. Conclui-se que as desovas são mais intensas na primavera-verão, principalmente entre novembro e janeiro, e estão relacionadas aos maiores valores de temperatura e vazão da água. Entretanto, a resposta e a intensidade reprodutiva às variáveis ambientais variam de acordo a espécie.

In ecological studies, knowledge of the main factors regulating the growth and survival of fish in early stages of development is essential for the conservation of fishery resources as well as for understanding their trophic relationships and the functioning of various aquatic ecosystems. Thus, studies that seek to understand the trophic interaction between fish larvae and their main prey, as well as their possible effects on the different components of planktonic food webs, especially in tropical environments, where such studies are still scarce, knowledge is incipient. Tested to evaluate the participation of ciliate protozoa, as a food item, in the different stages of development of larvae of Astyanax lacustris, when presented to a natural prey assembly. Thus, we tested the hypothesis that ciliate protozoa would be an important food resource for Astyanax larvae in the early stages of their development, becoming a supplementary resource in more advanced stages, where zooplankton organisms would be the main energy source. The results showed that the ciliates are an important item in the diet of Astyanax larvae, being fundamental for the survival of the larvae in early stages of development and becoming a supplementary resource in later stages when larger organisms such as adult copepods, they are the main resource used by them. The objective was to understand the direct and indirect effects of the predation of the different stages of development of Astyanax larvae on the different zooplanktonic groups, as well as on the structure of the microbial food webs. From this, we tested the hypothesis that larvae of different ages would structure the microbial communities in different ways. The results showed that the different larval ages of Astyanax caused in different configurations of the food webs, affecting strongly the abundance of the zooplankton groups and the flagellates and ciliates protozoa, but having weak effects on the heterotrophic bacterias and picocyanobacterias. Em estudos ecológicos, o conhecimento sobre os principais fatores que regulam o crescimento e a sobrevivência de peixes em estágios iniciais de desenvolvimento é essencial para a conservação de recursos pesqueiros, bem como para o entendimento de suas relações tróficas e do funcionamento de diversos ecossistemas aquáticos. Portanto, tornam-se imprescindíveis os estudos que buscam entender a interação trófica entre larvas de peixes e suas principais presas, bem como seus possíveis efeitos sobre os distintos componentes das teias alimentares planctônicas, sobretudo em ambientes tropicais, onde essas pesquisas são ainda escassas e o conhecimento é incipiente. Avaliou-se a participação de protozoários ciliados, como item alimentar, nas diferentes fases de desenvolvimento de larvas de Astyanax lacustris, quando apresentados a uma assembleia natural de presas. Testou-se a hipótese de que os protozoários ciliados seriam um importante recurso alimentar para larvas nos primeiros estágios de desenvolvimento, passando a ser um recurso suplementar em estágios mais avançados, onde os organismos zooplanctônicos, seriam a principal fonte energética. Os resultados mostraram que os ciliados constituem um importante item na dieta de larvas, sendo fundamentais para a sobrevivência das mesmas em estágio iniciais de desenvolvimento e passando a ser um recurso suplementar para larvas maiores, uma vez que os copépodes adultos, constituiram o principal recurso utilizado pelas mesmas. Buscou-se também, compreender os efeitos diretos e indiretos da predação dos diferentes estágios de desenvolvimento larval sobre os distintos grupos zooplanctônicos e sobre a estrutura das teias alimentares microbianas. Para tanto, foi testada a hipótese de que larvas de diferentes idades estruturariam as comunidades microbianas de maneiras distintas. Os resultados obtidos permitiram constatar que larvas com diferentes idades ocasionaram distintas configurações das teias alimentares, afetando fortemente a abundância dos grupos zooplanctônicos e dos protozoários flagelados e ciliados, mas com fraco efeito sobre as bactérias heterotróficas e picocianobactérias. 62 f

Reproduction of fish in a natural environment tends to occur in ideal conditions for offspring survival. Among these conditions the extreme values of pH can affect the initial stages of fish species differently. In this context, this study aimed to evaluate the influence of pH on the survival and early development of two species of fish with different reproductive strategies, Astyanax lacustris (small distance migrant) and Piaractus mesopotamicus (long distance migrator). The experiments were divided into two trials (incubation and larviculture) with five pH levels. The first test was the incubation, by means of a water recirculation system with the aid of incubators made with 2-liter pet bottles. The second test was the larviculture, where three-liter aquaria were used. The pH did not influence the hatching rate of A. lacustris eggs, but affected the diameter of the calf, while the newly hatched larvae presented some skeletal deformities. Piaractus mesopotamicus had a pH effect on hatching rate and perivitelline space, while newly hatched larvae had several skeletal deformities. In A. lacustris larviculture there were no effects on larval survival, but the variables analyzed showed significant differences between treatments. The survival rate of P. mesopotamicus was affected by acid pH and all variables analyzed also varied significantly between treatments. It is concluded that the incubation and larviculture assays of A. lacustris and P. mesopotamicus revealed a significant and differentiated influence of the pH variable on the survival and development of these species. A reprodução dos peixes em ambiente natural tende a ocorrer em condições ideais para a sobrevivência da prole. Dentre estas condições os valores extremos de pH podem afetar diferentemente os estágios iniciais das espécies de peixe. Neste contexto, este estudo teve como objetivo avaliar a influência do pH sobre a sobrevivência e o desenvolvimento inicial de duas espécies de peixes com diferentes estratégias reprodutivas, Astyanax lacustris (migrador de pequenas distâncias) e Piaractus mesopotamicus (migrador de longas distâncias). Os experimentos foram divididos em dois ensaios (incubação e larvicultura) com cinco níveis de pH. O primeiro ensaio realizado foi a incubação, por meio de um sistema de recirculação de água com auxilio de incubadoras confeccionadas com garrafas pets de 2 litros. Já o segundo ensaio executado foi a larvicultura, onde foram utilizados aquários de três litros. O pH não influenciou na taxa de eclosão dos ovos de A. lacustris, mas afetou o diâmetro do vitelo, enquanto as larvas recém-eclodidas apresentaram algumas deformidades esqueléticas. Piaractus mesopotamicus sofreu efeito do pH na taxa de eclosão e no espaço perivitelino, enquanto as larvas recém-eclodidas apresentaram várias deformidades esqueléticas. Na larvicultura de A. lacustris não foram observados efeitos sobre a taxa de sobrevivência das larvas, porém as variáveis analisadas apresentaram diferenças significativas entre os tratamentos. A taxa de sobrevivência de P. mesopotamicus foi afetada pelo pH ácido e todas as variáveis analisadas também variaram significativamente entre os tratamentos. Conclui-se que os ensaios com incubação e larvicultura de A. lacustris e P. mesopotamicus revelaram uma influência importante e diferenciada da variável pH sobre a sobrevivência e o desenvolvimento destas espécies. 37 f

The reproduction of freshwater fish occurs annually in environments that provide favorable environmental conditions for spawning and subsequent survival and growth of their larvae. The aim of this study was to evaluate the spatial and temporal distribution of larvae Salminus brasiliensis in order to understand the intra and interannual variations in their abundance and the influence of environmental variables on reproduction. Samples were collected at different biotypes (river, backwater and lagoon) of Ivinheima River floodplain of the upper Paraná River, Brazil. At the same time, were obtained temperature, dissolved oxygen, pH, electrical conductivity, river level and rainfall. The larvae of S. brasiliensis were captured mainly in the months of October and January, the biotope river and backwater and no significant difference in relation to its vertical and nycterohemeral. It is estimated that this species can migrate over 200 km to reproduce in the river Ivinheima and its tributaries as the river Guiraí. The temperature, the river level, pH and dissolved oxygen were the main variables that influence the larvae density. The importance of maintaining this last damming free lotic and is essential for the maintenance of natural stocks, especially of S. brasiliensis, because mechanisms such as intensity of flooding and delay flooding are factors that act directly on the reproductive success of the species and depend on these natural conditions. Salminus brasiliensis is a key species to propose management and conservation measures for all fish population, once guaranteed the reproductive success of this species, other migratory and sedentary species will also benefit. A reprodução de peixes de água doce ocorre anualmente em ambientes que proporcionam condições ambientais favoráveis para a desova e, posterior sobrevivência e crescimento de suas larvas. O objetivo deste estudo foi avaliar a distribuição espacial e temporal de larvas de Salminus brasiliensis, a fim de compreender as variações intra e interanual de sua abundância e a influências de variáveis ambientais sobre a reprodução. As coletas foram realizadas em diferentes biótopos (rio, remanso e lagoa) do rio Ivinheima, planície alagável do alto rio Paraná, Brasil. Concomitantemente, foram obtidas a temperatura, o oxigênio dissolvido, o pH, a condutividade elétrica, o nível fluviométrico e a precipitação. As larvas de S. brasiliensis foram capturadas principalmente nos meses de outubro e janeiro, nos biótopos rio e remanso e não apresentaram diferença significativa em relação a sua distribuição vertical e nictemeral. Estima-se que esta espécie possa migrar acima de 200 km para se reproduzir no rio Ivinheima e em seus tributários como o rio Guiraí. A temperatura, o nível fluviométrico, o pH e o oxigênio dissolvido foram as principais variáveis que influenciaram na densidade de larvas. A importância da manutenção deste último trecho lótico livre de represamento é essencial para a manutenção dos estoques naturais, sobretudo de S. brasiliensis, pois os mecanismos como intensidade de inundação e atraso de cheias são fatores que agem diretamente no sucesso reprodutivo da espécie e dependem destas condições naturais. Salminus brasiliensis é uma espécie-chave para propor medidas de manejo e conservação para toda fauna ictiológica, uma vez que garantido o sucesso reprodutivo desta espécie, as demais espécies migradoras e sedentárias também serão beneficiadas. 36 f

Among the different species of fish, the life cycle is synchronized to avoid or exploit flows with magnitudes variables. For example, the natural frequency of high or low flow trigger the different stages of the life cycle, such as spawning, incubation of eggs, the initial development and the lateral migration in the flood plain. However, the timing of each of these characteristics with the attributes of floods, strategies presented depends on the species, being complex events and their interdependence has not yet fully understood. In this study it was found over five reproductive periods, the effect of flow regime and its components on the dynamics of ichthyoplankton in this Ivinheima river and two ponds connected to this system. The variation in the abundance of fish eggs and larvae over a reproductive period and was verified that there were changes in the composition of the assemblage and its relationship with environmental variables were assessed. For the five reproductive periods, the attributes of the flood pulse were calculated by PULSO software and soon after were summarized by a PCA. Possible differences in the density of eggs and larvae between reproductive periods, and in only one period were tested with Permutational Multivariate Analysis of Variance. For the similarity of patterns in the assembly of larvae were used Non-metric Multidimensional Scaling. To test the relationship of the biota of the attributes with the hydrological variability and environmental variables were used Spearman correlations. Higher densities of eggs were recorded in Ivinheima river in flood periods. The density of larvae was similar in the environments, and the Finado Raimundo lagoon had greater abundance in the river there was a predominance of migratory species, as in the lagoons was the domain of sedentary species. The assemblage of larvae presented is structured in the months in which they were checked the flood pulses, migratory species organized in the early months and in the later months predominant species with different reproductive strategies. It can also be noted that dry and intermediate years have importance for the reproduction of species, mainly sedentary. In the reproductive period, higher densities of larvae occur in the months of highest precipitation, tests showed significant differences between the months and revealed that migratory species were related to the months of highest precipitation. The densities of eggs and larvae, as well as some migratory species were positively correlated with rainfall, while the temperature was negatively correlated with the migratory. We conclude that the most extensive floods favored fish reproduction, ascertained by the greatest abundance of eggs and larvae in these periods, as well as to favor migratory species and also caused the increase of wealth in some habitats. For the reproductive phase is concluded that the seasonality of reproduction of the species (especially migratory) presents synchrony with the rainy periods. On the other hand in the months with low rainfall occurs playing some species with large reproductive plasticity. Entre as diferentes espécies de peixes, o ciclo de vida está sincronizado para evitar ou explorar os fluxos com magnitudes variáveis. Assim, as flutuações sazonais no nível do rio desencadeiam as diferentes etapas do ciclo de vida das espécies, como a desova, a incubação de ovos, o desenvolvimento inicial e a migração lateral na planície de inundação. Porém, o sincronismo de cada uma destas etapas com os atributos das cheias depende das estratégias apresentadas pelas espécies, sendo eventos complexos sua interdependência ainda não totalmente compreendida. Ao longo de cinco períodos reprodutivos observou-se o efeito do regime de cheias e de seus componentes sobre a dinâmica do ictioplâncton presente no rio Ivinheima e em duas lagoas conectadas a este sistema. Foi avaliada a variação na abundância de ovos e larvas de peixes ao longo de um período reprodutivo, bem como verificado se ocorreram modificações na composição da assembléia e sua relação com as variáveis ambientais. Para os cinco períodos reprodutivos, os atributos do pulso de inundação foram calculados pelo software PULSO e, logo após, foram sumarizados por uma PCA. As possíveis diferenças na densidade de ovos e larvas entre os períodos reprodutivos, e em apenas um período, foram testadas através de análises permutacionais. Para os padrões de similaridade na assembleia de larvas foram usados escalonamentos multidimensionais não métricos. Para testar as relações dos atributos da biota com a variabilidade hidrológica e, com as variáveis ambientais, foram usadas correlações de Spearman. Maiores densidades de ovos foram registradas no rio Ivinheima, nos períodos de cheias. A densidade de larvas foi semelhante nos ambientes, sendo que a lagoa do finado Raimundo teve maior abundância. No rio Ivinheima houve o predomínio de espécies migradoras, enquanto nas lagoas houve o domínio de espécies sedentárias. A assembleia de larvas apresentou estruturação temporal durante os pulsos de inundação, sendo que as espécies migradoras se organizaram nos primeiros meses e as demais nos meses mais tardios. Observou-se, também, que anos secos e intermediários foram importantes para a reprodução de espécies, principalmente sedentárias. No periodo reprodutivo, maiores densidades de larvas ocorreram nos meses de maior precipitação, com diferenças significativas entre os meses. As densidades de ovos e de larvas, bem como de algumas espécies migradoras estiveram correlacionadas positivamente com a precipitação, enquanto que a temperatura se relacionou de forma negativa com os migradores. As cheias mais extensas favoreceram a reprodução dos peixes, com destaque para as espécies migradoras, ao passo que e a sazonalidade da reprodução destas espécies apresenta sincronia com as épocas mais chuvosas. Ainda que nos meses com baixa precipitação ocorre a reprodução de algumas espécies, as quais apresentam grande plasticidade reprodutiva. 70 f

The fish larvae are organisms that exhibit spatial and temporal variations in floodplain environments. In order to evaluate how the diversity of fish larvae are structured in different temporal (months and hours) and spatial (biotopes) scales in the sub-basin of the Ivinheima river (MS), upper Paraná River floodplain, monthly samples of fish larvae were carried out in two reproductive periods. Samplings were conducted in seven stations, which were grouped according to the biotope that they belong (lagoon, river and remanso) and at four different hours of the day. The samples were always collected using a cylindrical-conical plankton net (mesh aperture of 500-μm) and equipped with a mechanical flowmeter. The individuals were sorted and identified. The variation of α diversity was evaluated using a nested ANOVA, and the variation of β diversity was assessed using a dispersion multivariate analysis based on distance (PERMDISP). The additive partitioning was used to verify the relative contribution of each scale to γ diversity. The reproductive period of 2010/2011 (PR1) had the highest intensity in flood and this favored a greater γ diversity of fish larvae due to the increase of β diversity. The α and β diversity also varied among different biotopes, where species with different reproductive strategies occupied different biotopes. Among the hours, there was only variation of α diversity, which was higher at night. The components β1 (variation between months) and β3 (variation between biotopes), significantly explain the γ diversity in both reproductive periods, indicating that the floods with higher intensity may favor the reproduction and thus a greater diversity of fish larvae. Both temporal and spatial scales are important in maintaining the biodiversity of a system. In this sense, it is suggested that conservation efforts should consider not only the space but also prioritize the temporal hydrological dynamics that occurs in rivers, especially in places affected by dams which control the operation of these systems. Eggs and larvae in different stages of development need different environments to complete their life cycle. Thus, the maintenance of heterogeneous areas, that is, with different characteristics, promotes diversity as a whole, because they allow different species to reproduce in this area. A diversidade de larvas de peixes em ambientes de planícies de inundação apresenta variações espaciais e temporais. Com o objetivo de avaliar como a diversidade de larvas peixes está estruturada em diferentes escalas temporais (meses e horários) e espacial (biótopos) na sub-bacia do rio Ivinheima (MS), planície de inundação do alto rio Paraná, foram realizadas coletas mensais em dois períodos reprodutivos. As coletas foram realizadas em sete estações as quais foram agrupadas de acordo com o biótopo a qual pertencem (lagoa, remanso e rio) e em quatro horários diferentes durante um período de 24 horas. Em todas as coletas foram utilizadas redes de plâncton cônicocilíndricas (malha de 500-μm), equipadas com fluxômetro mecânico. Os indivíduos foram triados e identificados. A variação da diversidade α foi avaliada com ANOVA aninhada, e a variação da diversidade β, com análise multivariada de dispersão baseado em distância (PERMDISP). O particionamento aditivo da diversidade foi utilizado para verificar a contribuição relativa de cada escala para diversidade γ. O período reprodutivo de 2010/2011 (PR1) apresentou maior intensidade e duração da cheia o que favoreceu uma maior diversidade γ das larvas de peixes em função do aumento da diversidade β. As diversidades α e β também variaram entre os diferentes biótopos, onde espécies com diferentes estratégias reprodutivas ocuparam diferentes biótopos. Já entre os horários só houve variação da diversidade α que foi maior no período noturno. Os componentes β1 (variação entre meses) e β3 (variação entre biótopos) explicaram significativamente a diversidade γ nos dois períodos reprodutivos, indicando que as cheias mais intensas podem favorecer a reprodução e uma maior diversidade de larvas de peixes. Tanto a escala temporal quanto a espacial são importantes na manutenção da biodiversidade de um sistema. Nesse sentido, sugere-se que os esforços de conservação devem considerar não somente o espaço, mas também priorizar a dinâmica hidrológica temporal que ocorre nos rios, principalmente em locais afetados por barragens que controlam o funcionamento desses sistemas. Ovos e larvas em diferentes estágios de desenvolvimento precisam de diferentes ambientes para completarem o seu ciclo de vida. Assim, a manutenção de áreas heterogêneas, ou seja, com diferentes características, favorecem a diversidade como um todo, pois permitem que diferentes espécies conseguiam se reproduzir nesta área. 29 f

This work aimed to study the ontogeny and feeding selectivity of larval and juvenile fishes of different trophic guilds (Catathyridium jenynsii, Pyrrhulina australis and Hoplosternum littorale). For the analysis of ontogeny were considered individuals sampled in the main river channel Ivinhema, in Patos and Finado Raimundo lagoons, Mato Grosso do Sul, and selectivity were considered only samples taken in the lagoons. Samples were taken between the months October to March the years 2005 to 2009. Simultaneously to the ichthyoplankton samples were collected zooplankton. After collection the samples were screened and larvae and juveniles identified, measured for length standard, head length, upper jaw, and grouped into stages of development. Zooplankton was identified and quantified. Changes in the development of digestive tract have been described in relation to the position of the mouth and the morphology of the tube. The diet analysis was performed using the methods Occurrence and Numerical of Frequency. It was also analyzed feeding strategy, the amplitude changes of diet and intra and interespecific diet by Discriminant Analysis. To test the relationship between the size of the mouth and head length between species, we used Analysis of Covariance (ANCOVA) and each species, we applied the Linear Regression test. The differences in diet and these variations in the size of intra and interspecific mouth was assessed using the Multi-response Permutation Procedure. The existence of items that serve as diet of indicators among species was assessed by Indicator Species of Analysis and to assess the choice of prey on zooplankton community values were obtained selectivity. C. jenynsii was zooplanktivore during larval and juvenile fish in insectivore, P. australis ranged from insects and zooplankton during the larval and juvenile was insectivorous, while H. littorale was zooplanktivore during the early development. Only C. jenynsii presented food strategy specialist, while the others were intraspecific differences in diet. During the larval development of C. jenynsii niche amplitude remained the same and decreased in juveniles. For the other species increased values of niche breadth. To C. jenynsii increasing the size of the items consumed relates to increase the mouth during development, for P. australis and H. littorale was no variation of the sizes of the items taken. The composition of the diet varied intra and interespecific. The indicators of dietary items found in C. jenynsii were Cladocera and Calanoida and H. littorale were Alona sp., Chydoridae, Chydorus nitidulus, Daphnia gessneri, Diaphanosoma birgei and Calanoid, for P. australis was not registered any indicator species. Items Rotifera were abundant in the middle, followed by Cladocera and Copepoda. The C. jenynsii and P. australis larvae selected while the juveniles mainly Cladocera, Copepoda. For H. littorale was selection of Moina minuta and Plationus sp. in the stages of flexion and post-flexion. Thus we can conclude that the position of the mouth and digestive tract morphology and diet influence eating habits and this is yet acquired in the larval stages. Zooplankton has the largest contribution to the diet of fish larvae, however, other food items may be used. The species differ in intra and interspecific relation to diet. The choice of food is influenced by the size of the mouth, while the abundance of food influence individually the species and stage of development. Some items serve as indicators of the diet of the species, where morphological differences of the mouth determine the variation of types and sizes of prey. Individuals can select the food or enjoy the abundance in the middle. For this also depends on the swimming ability and visual acuity, which influences the capture and ingestion of food. Este trabalho teve como objetivo estudar a ontogenia e a seletividade alimentar de larvas e juvenis de peixes de diferentes guildas tróficas (Catathyridium jenynsii, Pyrrhulina australis e Hoplosternum littorale). Para a análise da ontogenia foram considerados os indivíduos amostrados no canal principal do rio Ivinhema, na lagoa dos Patos e na lagoa do Finado Raimundo, MS e para a seletividade foram consideradas somente as amostras realizadas nas lagoas. As amostragens foram realizadas entre os meses de outubro a março dos anos de 2005 a 2009. Concomitantemente às amostragens de ictioplâncton foram colhidas amostras de zooplâncton. Após as coletas as amostras foram triadas e as larvas e juvenis identificados, medidos quanto ao seu comprimento padrão, comprimento da cabeça, maxila superior e os indivíduos agrupados em estágios de desenvolvimento. O zooplâncton foi identificado e quantificado. As mudanças no desenvolvimento do trato digestório foram descritas em relação à posição da boca e a morfologia do tubo digestório. A análise da dieta foi realizada utilizando os métodos de Frequência de Ocorrência e Numérica. Analisou-se também a estratégia alimentar, a amplitude da dieta e as alterações inter e intraespecifica da dieta através da Análise Discriminante. Para testar a relação entre o tamanho da boca e comprimento da cabeça entre as espécies utilizou-se a Análise de Covariância (ANCOVA) e para cada espécie, aplicou-se o teste de Regressão Linear. As diferenças na dieta e as variações destas em relação ao tamanho da boca intra e interespecífica foi avaliada através do Procedimento de Permutação Multi-resposta. A existência de itens que funcionam como indicadores da dieta entre as espécies foi avaliada através da Análise de Espécies Indicadoras e para avaliar a escolha da presa na comunidade zooplanctônica foram obtidos os valores de seletividade. No período larval Catathyridium jenynsii foi zooplanctívora e insetívoras nos juvenis, P. australis oscilou entre insetos e zooplâncton no período larval e foi insetívora nos juvenis, enquanto H. littorale foi zooplanctívora durante todo o desenvolvimento inicial. Somente C. jenynsii apresentou estratégia alimentar especialista, sendo que as demais tiveram diferenças intraespecíficas da dieta. Durante o desenvolvimento larval de C. jenynsii a amplitude de nicho manteve-se a mesma e nos juvenis diminuiu. Para as demais espécies houve aumento dos valores de amplitude de nicho. Para C. jenynsii o aumento do tamanho dos itens consumidos relaciona-se ao aumento da boca durante o desenvolvimento, enquanto para P. australis e H. littorale houve variação dos tamanhos dos itens ingeridos. A composição da dieta variou inter e intraespecificamente. Os itens indicadores da dieta encontrados em C. jenynsii foram Cladocera e Calanoida e para H. littorale foram Alona sp., Chydoridae, Chydorus nitidulus, Daphnia gessneri, Diaphanosoma birgei e Calanoida, enquanto para P. australis não foi registrada nenhuma espécie indicadora. Os itens abundantes no meio foram Rotifera, seguido de Cladocera e Copepoda. As larvas de C. jenynsii e P. australis selecionaram principalmente Cladocera enquanto os juvenis, Copepoda. Para H. littorale houve seleção de Moina minuta e Plationus sp nos estágios de flexão e pós-flexão. Assim pode-se concluir que a posição da boca e a morfologia do tubo digestório influenciam a dieta e o hábito alimentar sendo este adquirido ainda nos estágios larvais. O zooplâncton tem a maior contribuição na dieta das larvas de peixes, no entanto, outros itens alimentares podem ser utilizados. As espécies se diferenciam intra e interespecificamente em relação à dieta. A seleção do alimento é influenciada pelo tamanho da boca, enquanto que a abundância do alimento influencia, individualmente, as espécies e estágios de desenvolvimento. Alguns itens funcionam como indicadores da dieta das espécies, onde as diferenças morfológicas da boca determinam a variação dos tipos e dos tamanhos de presas. Os indivíduos podem selecionar o alimento ou aproveitar a abundância no meio. Para isto depende também da capacidade de natação e acuidade visual, o que influencia na captura e ingestão do alimento. 62 f

Made available in DSpace on 2017-07-10T18:13:23Z (GMT). No. of bitstreams: 1 Tatiane Mary Gogola.pdf: 469917 bytes, checksum: 708503e683dc73e48a69548553b10094 (MD5) Previous issue date: 2010-07-23 Itaipu Binacional The study of initial stages of the lifecycle of the fish is important for understanding the success of species in the environment and determine areas and spawning periods. This study analyzed the composition and structure of the assembly of fish larvae in a region of the last lotic stretch of the Paraná River at Ilha Grande National Park, searching for differences in spatial and temporal patterns of abundance, richness, diversity of larvae and indicator taxa and to examine the possible influence of some abiotic factors on the catch. Samples were taken monthly at night and six consecutive breeding seasons (October-March) between 2001 and 2008 (periods I, II, III, IV, V and VI) in three different environments (river, lake and tributaries). To this end, we used networks of conical-cylindrical plankton mesh 0.5 mm, equipped with a flowmeter to obtain the volume of filtered water. Simultaneously to the data were obtained at water temperature, dissolved oxygen, electrical conductivity and pH. Besides these, were also obtained data on the river level and rainfall. Was determined, besides the abundance of larvae, the number of species (richness), the diversity index of Shannon and the specific indicator taxa for each environment and periods analyzed using the indicator value (IndVal). To determine whether there were significant differences between the biotic, was applied to analysis of variance of main effects (ANOVA, one-way) and Tukey's test, modified for number of elements between different groups (Unequal) to determine which levels differed. To assess the relationship of environmental variables and abundances was applied to multiple regression analysis. The assemblage of fish larvae of the National Park of Ilha Grande was composed for the most part by bodies covered by the order Characiformes. Periods I and IV were the highest density of larvae, while the latter showed the highest richness and diversity of species. The indicator species of the periods were mostly sedentary, but Rhinelepis aspera and Salminus brasiliensis, captured in the (V and I, respectively) higher river level and rainfall. Between environments, pond was significantly different from tributaries and the catches were quite high, with high wealth and low diversity. Among indicator species of this environment, we find migratory and non migratory species. The House of larvae was related to water temperature, pH, dissolved oxygen, river level and rainfall. It was then possible to observe the existence of spatial and temporal differences in assemblage structure and composition of larvae in the region of the Ilha Grande National Park, mainly related to the characteristics of the study sites and environmental factors. It was observed further that lentic provided favorable characteristics for development of both sedentary species as migratory, while the tributaries are apparently being used as a migratory route and spawning areas due to capture of newly hatched larvae, demonstrating the importance of adopting measures to protect these types of environment, not only in the region of Ilha Grande National Park, but throughout the remainder of the lotic stretch of the floodplain of the Paraná River. O estudo das fases inicias do ciclo de vida dos peixes é importante para entendimento do sucesso das espécies no ambiente e determinar áreas e períodos de desova. Este estudo analisou a composição e a estrutura da assembleia de larvas de peixes em uma região do último trecho lótico do rio Paraná, no Parque Nacional de Ilha Grande, buscando a existência de diferenças espaciais e temporais nos padrões de abundância, riqueza, diversidade de larvas e táxons indicadores, bem como analisar possíveis influências de alguns fatores abióticos sobre as capturas. As amostragens foram noturnas e realizadas mensalmente em seis períodos reprodutivos (outubro a março) entre 2001 e 2008 (períodos I, II, III, IV, V e VI) em três ambientes distintos (rio, tributários e lagoa). Para tanto, foram utilizadas redes de plâncton cônico-cilíndricas de malha 0,5 mm, equipadas com fluxômetro para a obtenção do volume de água filtrada. Concomitantemente às amostragens, foram obtidos dados de temperatura da água, oxigênio dissolvido, condutividade elétrica e pH. Além destes, também foram obtidos dados referentes ao nível fluviométrico e pluviosidade. Foram determinadas, além das abundâncias de larvas, o número de espécies (riqueza), o índice de diversidade de Shannon e determinado os táxons indicadores para cada ambiente e períodos analisados através do valor indicador (IndVal). Para determinar se houve diferenças significativas entre os fatores bióticos, foi aplicada a análise de variância de efeitos principais (ANOVA; one-way) e o teste de Tukey, modificado para número de elementos distintos entre grupos (Unequal) para determinar qual nível diferiu. Para avaliar a relação das variáveis ambientais e as abundâncias foi aplicada a análise de regressão múltipla. A assembleia de larvas de peixes do Parque Nacional de Ilha Grande foi composta em sua maior parcela por organismos enquadrados na ordem Characiformes. Os períodos I e IV foram os de maior densidade de larvas, sendo que o último apresentou a maior riqueza e diversidade de espécies. As espécies indicadoras dos períodos foram na maioria sedentárias, com exceção de Rhinelepis aspera e Salminus brasiliensis, capturadas nos períodos (V e I, respectivamente) de maior nível fluviométrico e pluviosidade. Entre os ambientes, lagoa foi significativamente diferente de tributários e as capturas foram bastante elevadas, com alta riqueza e baixa diversidade. Dentre as espécies indicadoras deste ambiente, encontramos espécies migradoras e não migradoras. A assembleia de larvas esteve relacionada com a temperatura da água, pH, oxigênio dissolvido, nível fluviométrico e pluviosidade. Com isso foi possível observar a existência de diferenças espaciais e temporais na composição e estrutura da assembléia de larvas na região do Parque Nacional de Ilha Grande, principalmente relacionadas às características dos ambientes amostrados e aos fatores ambientais. Foi possível observar ainda que os ambientes lênticos proporcionaram características favoráveis ao desenvolvimento tanto de espécies sedentárias como de migradoras, enquanto que os tributários aparentemente estão sendo utilizados como rota migratória e áreas de desova devido a captura de larvas recém eclodidas, demonstrando a importância da adoção de medidas visando a proteção destes tipos de ambiente, não só na região do Parque Nacional de Ilha Grande, mas em todo o remanescente do trecho lótico da planície de inundação do alto rio Paraná.