Temporal variation in composition, abundance and biomass of the fish fauna after impact on subtropical transitional water

Transitional waters are characterized by large variations in salinity, temperature, turbidity, among other factors, such as tidal cycle, wind action and rainfall, that are constantly changing over time. The distribution of biota in these environments is regulated by these natural variations and also by human activities, such as pollution, overexploitation of resources, acceleration of urbanization, suppression of habitats and changes in hydrological dynamics. The objective of this study was to analyze the temporal dynamics of the fish fauna of the Saco dos Limões Cove, state of Santa Catarina, Brazil, after the construction of a highway. Fish community was evaluated over five years by annual and monthly variation in species richness, abundance and biomass. A total of 17,993 individuals were collected, distributed in 33 families, 59 genera and 79 species. The evaluated years were similar to each other in species composition. Community descriptors varied over time but did not show seasonal trends. In all years, abundance was higher than biomass, indicating both the disturbance and the ecosystem function as a nursery in the studied area. This was corroborated by the large number of juveniles of dominant species (Genidens genidens, Eucinostomus gula and Eucinostomus argenteus).(AU)

Protection of spawning habitat for potamodromous fish, an urgent need for the hydropower planning in the Andes

Because dams block migratory routes of potamodromous fish to their spawning areas, and energy generation changes natural flow seasonality, it is necessary to identify spawning areas and their conditions. This information will help in management decisions in the Magdalena River basin regarding the future hydropower development. We identified which characteristics of the tributaries to the Magdalena River are important for determining potamodromous fish spawning grounds, and we estimated the percentage of future loss of spawning areas because of dam development. Ichthyoplankton density is directly related to the floodplain area, and inversely related with channel slope. Low channel slopes offer adult fish a longer distance for their upstream migration and a longer time for embryo development during their drift downstream from the spawning areas to nursery habitats (floodplain lakes). These features could increase the migration distance of the adults, the time for initial embryo development, and, because of its relationship with nursery habitats access, the offspring survival. The potential loss of the actual spawning grounds in the river network was estimated to be nearly 70% because of new dams. Our findings will help to reduce conflicts between hydropower and ecological interests.(AU)

La construcción de hidroeléctricas puede afectar la reproducción de los peces migratorios potamódromos, ya sea porque las represas bloquean las rutas migratorias a sus áreas de desove, o porque la generación de energía cambia la estacionalidad del flujo natural. Esto hace necesario generar información sobre las áreas de desove y sus características, que permitan tomar decisiones de manejo, teniendo en cuenta el desarrollo hidroeléctrico propuesto a futuro en la cuenca del río Magdalena. Identificamos qué características de algunos afluentes del río Magdalena son importantes para los desoves y estimamos el porcentaje de pérdida futura de áreas de desoves debido al desarrollo hidroeléctrico. La densidad del ictioplancton se relacionó directamente con el área de la llanura aluvial e inversamente con la pendiente del canal. Estas características aumentan la distancia de migración de los adultos maduros, el tiempo para el desarrollo inicial del embrión y la supervivencia de la descendencia debido a la proximidad y/o conectividad con los hábitats de cría. La pérdida potencial de las zonas de desove en la red fluvial se estimó en casi el 70% debido a las nuevas presas. Nuestros hallazgos ayudarán a tomar decisiones sostenibles para reducir los conflictos entre intereses de desarrollo hidroeléctrico y ecológicos.(AU)

Protection of spawning habitat for potamodromous fish, an urgent need for the hydropower planning in the Andes

Because dams block migratory routes of potamodromous fish to their spawning areas, and energy generation changes natural flow seasonality, it is necessary to identify spawning areas and their conditions. This information will help in management decisions in the Magdalena River basin regarding the future hydropower development. We identified which characteristics of the tributaries to the Magdalena River are important for determining potamodromous fish spawning grounds, and we estimated the percentage of future loss of spawning areas because of dam development. Ichthyoplankton density is directly related to the floodplain area, and inversely related with channel slope. Low channel slopes offer adult fish a longer distance for their upstream migration and a longer time for embryo development during their drift downstream from the spawning areas to nursery habitats (floodplain lakes). These features could increase the migration distance of the adults, the time for initial embryo development, and, because of its relationship with nursery habitats access, the offspring survival. The potential loss of the actual spawning grounds in the river network was estimated to be nearly 70% because of new dams. Our findings will help to reduce conflicts between hydropower and ecological interests.(AU)

La construcción de hidroeléctricas puede afectar la reproducción de los peces migratorios potamódromos, ya sea porque las represas bloquean las rutas migratorias a sus áreas de desove, o porque la generación de energía cambia la estacionalidad del flujo natural. Esto hace necesario generar información sobre las áreas de desove y sus características, que permitan tomar decisiones de manejo, teniendo en cuenta el desarrollo hidroeléctrico propuesto a futuro en la cuenca del río Magdalena. Identificamos qué características de algunos afluentes del río Magdalena son importantes para los desoves y estimamos el porcentaje de pérdida futura de áreas de desoves debido al desarrollo hidroeléctrico. La densidad del ictioplancton se relacionó directamente con el área de la llanura aluvial e inversamente con la pendiente del canal. Estas características aumentan la distancia de migración de los adultos maduros, el tiempo para el desarrollo inicial del embrión y la supervivencia de la descendencia debido a la proximidad y/o conectividad con los hábitats de cría. La pérdida potencial de las zonas de desove en la red fluvial se estimó en casi el 70% debido a las nuevas presas. Nuestros hallazgos ayudarán a tomar decisiones sostenibles para reducir los conflictos entre intereses de desarrollo hidroeléctrico y ecológicos.(AU)

Larvae of migratory Characiformes species in an archipelago in the Lower Amazon River

In the Amazon basin, most of the migratory Characiformes species represent an important fishing resource for local people. However, the lack of information about the main areas and periods of reproduction and the importance of certain environments for the maintenance of species may jeopardize the renewal of fish stocks. Thus, the aim was to examine the spatial and seasonal variation in the density of larvae of migratory Characiformes species in an archipelago in the Lower Amazon River and to assess the importance of this environment for the biological recruitment of the studied species. The capture of larvae was carried out in places close to restinga swamps, steep ruts,and inlet areas with a plankton net (300 μm) in monthly sampling from January to December 2013. An analysis of variance was used to verify differences in larval density between seasons and sampling months. A total of 30,997 larvae were captured and showed no significant differences in their distributions between habitats. However, a variationbetween the phases of the hydrological cycle was evident, in which the highest larval concentrations were observed during the flooding (17.72 larvae.10m-3) and the drought (1.33 larvae.10m-3). The study area has a great capacity to assist in the maintenance and renewal of regional fish stocks, as it is an important retention and nursery site for larvae of Characiformes that drift along the main channel of the Amazon River.

Larvae of migratory Characiformes species in an archipelago in the Lower Amazon River

In the Amazon basin, most of the migratory Characiformes species represent an important fishing resource for local people. However, the lack of information about the main areas and periods of reproduction and the importance of certain environments for the maintenance of species may jeopardize the renewal of fish stocks. Thus, the aim was to examine the spatial and seasonal variation in the density of larvae of migratory Characiformes species in an archipelago in the Lower Amazon River and to assess the importance of this environment for the biological recruitment of the studied species. The capture of larvae was carried out in places close to restinga swamps, steep ruts,and inlet areas with a plankton net (300 μm) in monthly sampling from January to December 2013. An analysis of variance was used to verify differences in larval density between seasons and sampling months. A total of 30,997 larvae were captured and showed no significant differences in their distributions between habitats. However, a variationbetween the phases of the hydrological cycle was evident, in which the highest larval concentrations were observed during the flooding (17.72 larvae.10m-3) and the drought (1.33 larvae.10m-3). The study area has a great capacity to assist in the maintenance and renewal of regional fish stocks, as it is an important retention and nursery site for larvae of Characiformes that drift along the main channel of the Amazon River.(AU)

Spawning and recruitment areas of migratory fish in the Uruguay river: applying for rivers connectivity conservation in South America / Áreas de desova e recrutamento de peixes migradores no rio Uruguai: aplicação para conservação da conectividade de rios na América do Sul

Identifying spawning and recruitment areas of Neotropical migratory fish is an important conservation issue, because it allows to define connectivity between habitats used during the initial life cycle of these species. In this sense, the objective of this study was to delimit spawning and recruitment areas of three migratory fish (Megaleporinus obtusidens, Salminus brasiliensis and Prochilodus lineatus) along of an altitude gradient of the Uruguay River. Samplings of ichthyoplankton and juveniles were applied with five different fishing devices in four river stretches, one in reservoir and three in a free section, for two consecutive years (2015-2016 and 2016-2017), during the reproductive period of the species. Larvae and juveniles were not collected in the reservoir and, in the free section, larvae in the early stages of development were found only at an intermediate stretch, and the most larvae at more advanced stages (~80%) and juveniles (~95%) were recorded in the lower sampling stretch. Based on the larval stage and abundance of juveniles, spawning-recruitment connectivity sections were presumed for these migratory species. After, these sections were associated to the location of future hydroelectric dams in the study area, with possible negative implications for the conservation of these populations in the Uruguay River.

Identificar áreas de desova e recrutamento de peixes migradores neotropicais é um item importante de conservação, pois permite definir conectividade entre habitats utilizados durante o ciclo de vida inicial destas espécies. Neste sentido, o objetivo deste estudo foi delimitar áreas de desova e recrutamento de três peixes migradores (Megaleporinus obtusidens, Salminus brasiliensis e Prochilodus lineatus) ao longo de um gradiente de altitude do rio Uruguai. Amostragens de ictioplâncton e de juvenis foram aplicadas com cinco diferentes apetrechos de pesca em quatro trechos de rio, um em reservatório e três em uma seção livre, por dois anos consecutivos (2015-2016 e 2016-2017), durante o período reprodutivo das espécies. Larvas e juvenis não foram coletados no reservatório e, na seção livre, larvas em estágios iniciais de desenvolvimento foram encontradas somente em um trecho intermediário, e a maioria das larvas em estágios mais avançados (~80%) e juvenis (~95%) foram registrados no trecho de amostragem mais baixo. Baseando-se no estágio larval e abundância de juvenis, foram presumidas seções de conectividade desova-recrutamento para estas espécies migradoras. Posteriormente, estas seções foram associadas à localização de futuros barramentos hidrelétricos na área de estudo, com possíveis implicações negativas para a conservação destas populações no rio Uruguai.

Spawning and recruitment areas of migratory fish in the Uruguay river: applying for rivers connectivity conservation in South America / Áreas de desova e recrutamento de peixes migradores no rio Uruguai: aplicação para conservação da conectividade de rios na América do Sul

Identifying spawning and recruitment areas of Neotropical migratory fish is an important conservation issue, because it allows to define connectivity between habitats used during the initial life cycle of these species. In this sense, the objective of this study was to delimit spawning and recruitment areas of three migratory fish (Megaleporinus obtusidens, Salminus brasiliensis and Prochilodus lineatus) along of an altitude gradient of the Uruguay River. Samplings of ichthyoplankton and juveniles were applied with five different fishing devices in four river stretches, one in reservoir and three in a free section, for two consecutive years (2015-2016 and 2016-2017), during the reproductive period of the species. Larvae and juveniles were not collected in the reservoir and, in the free section, larvae in the early stages of development were found only at an intermediate stretch, and the most larvae at more advanced stages (~80%) and juveniles (~95%) were recorded in the lower sampling stretch. Based on the larval stage and abundance of juveniles, spawning-recruitment connectivity sections were presumed for these migratory species. After, these sections were associated to the location of future hydroelectric dams in the study area, with possible negative implications for the conservation of these populations in the Uruguay River.(AU)

Identificar áreas de desova e recrutamento de peixes migradores neotropicais é um item importante de conservação, pois permite definir conectividade entre habitats utilizados durante o ciclo de vida inicial destas espécies. Neste sentido, o objetivo deste estudo foi delimitar áreas de desova e recrutamento de três peixes migradores (Megaleporinus obtusidens, Salminus brasiliensis e Prochilodus lineatus) ao longo de um gradiente de altitude do rio Uruguai. Amostragens de ictioplâncton e de juvenis foram aplicadas com cinco diferentes apetrechos de pesca em quatro trechos de rio, um em reservatório e três em uma seção livre, por dois anos consecutivos (2015-2016 e 2016-2017), durante o período reprodutivo das espécies. Larvas e juvenis não foram coletados no reservatório e, na seção livre, larvas em estágios iniciais de desenvolvimento foram encontradas somente em um trecho intermediário, e a maioria das larvas em estágios mais avançados (~80%) e juvenis (~95%) foram registrados no trecho de amostragem mais baixo. Baseando-se no estágio larval e abundância de juvenis, foram presumidas seções de conectividade desova-recrutamento para estas espécies migradoras. Posteriormente, estas seções foram associadas à localização de futuros barramentos hidrelétricos na área de estudo, com possíveis implicações negativas para a conservação destas populações no rio Uruguai.(AU)

Composition and abundance of decapod crustaceans in mixed seagrass meadows in the Paraguaná Peninsula, Venezuela

RESUMEN Thalassia testudinum y Halodule wrigthii son las hierbas marinas dominantes en el Caribe, siendo comunes en costas someras, tanto en monocultivos como en cultivos mixtos. Entre la macrofauna asociada a estas comunidades, los crustáceos son considerados esenciales para el funcionamiento del ecosistema. Sin embargo, el conocimiento sobre la comunidad de crustáceos decápodos asociada a praderas mixtas de T. testudinum y H. wrigthii es escaso, en particular fuera de zonas protegidas. En este trabajo presentamos ocho nuevas especies de decápodos para la Península de Paraguaná (estado Falcón, Venezuela) asociados a praderas mixtas de hierbas marinas: Achelous tumidulus Stimpson, 1871, Alpheus floridanus Kingsley, 1878, Chorinus heros (Herbst, 1790), Clibanarius antillensis (Stimpson, 1859), Clibanarius sclopetarius (Herbst, 1796), Latreutes parvulus (Stimpson, 1866), Panopeus occidentalis Saussure, 1857, y Processa fimbriata Manning & Chace, 1971. Estos registros representan extensiones de hábitat y completan brechas en la distribución geográfica de las especies a lo largo de la costa septentrional de Sudamérica. Diferencias estadísticas en la abundancia y composición de las especies de decápodos fueron posiblemente causadas por la acción conjunta de cobertura y heterogeneidad de las praderas. Las especies más influyentes en la comunidad son típicas para el Caribe; no obstante, la abundancia de Penaeus schmitti Burkenroad, 1936 juveniles fue notable, puesto que raramente han sido encontrados en estos hábitats. Este hallazgo resalta el rol de áreas no protegidas como hábitats de cría para especies de importancia comercial. Nuestros resultados muestran que las praderas de hierbas marinas en la Península de Paraguaná reflejan un buen estado en comparación con otras zonas del Caribe, y representan un hábitat importante para el mantenimiento de las poblaciones de crustáceos.

ABSTRACT Thalassia testudinum and Halodule wrigthii are the dominant seagrasses in the Caribbean, being common across shallow shorelines, either as monospecific or as intermixed meadows. Among the macrofauna associated with these beds, crustaceans are considered essential for the whole ecosystem functioning. However, knowledge about the associated community of decapod crustaceans in assemblages of T. testudinum and H. wrigthii is still scarce, particularly outside of protected areas. Here we report eight new decapod species for the Paraguaná Peninsula (Falcón State, Venezuela) in association with intermixed seagrass beds: Achelous tumidulus Stimpson, 1871, Alpheus aff. floridanus Kingsley, 1878, Chorinus heros (Herbst, 1790), Clibanarius antillensis (Stimpson, 1859), Clibanarius sclopetarius (Herbst, 1796), Latreutes parvulus (Stimpson, 1866), Panopeus occidentalis Saussure, 1857, and Processa fimbriata Manning & Chace, 1971. These records represent habitat extensions and fill gaps in the geographical distribution of the species along the northern coast of South America. Furthermore, we found that statistical differences in decapod species abundance and composition are likely to be caused by the joint action of coverage and heterogeneity of the beds. Our results indicate that typical Caribbean species were the most influential in the community; nevertheless, the abundance of juvenile Penaeus schmitti Burkenroad, 1936 was notable, since they have rarely been found in these habitats. This finding highlights the role of non-protected areas as nursery habitats for economically important species. Our results show that seagrass meadows in the Paraguaná Peninsula reflect overall good health when compared to other Caribbean zones, representing an important habitat for the maintenance of crustacean populations.

Nutritional supplementation required by native Cerrado species development, in nursery / Exigência de suplementação nutricional no desenvolvimento de espécies nativas do Cerrado, em viveiro

The ecological restoration of Cerrado ecosystems involves challenges pertinent to the fertilization of the substrate for seedlings in nursery, which are often produced by a single type of substrate. However, habitat heterogeneity suggests that the species may have different nutritional requirements. The objective was to assess the effect of substrate fertilization and nutritional supplementation by leaf in developing seedlings of Kielmeyera coriacea Mart. & Zucc. Eugenia dysenterica (Mart.) and DC Handroanthus impetiginosus (Mart. ex DC.) Mattos. The experiment was implemented in a 3x3 factorial completely randomized design (three types of substrates x three levels of foliar fertilization), with ten replicates. The treatments were tested by analysis of variance. For K. coriacea and H. impetiginosus, it is recommended to use a substrate composed of Soil + Manure (2:1), for E. dysenterica, it is recommended to use the complete substrate. Foliar fertilization is not recommended for all species. Regarding the soil analysis, organic matter, phosphorus and calcium were determinants in the formation of fertility groups for each of the major components of the Principal Component Analysis.

A restauração ecológica dos ecossistemas do Cerrado envolve desafios pertinentes à fertilização do substrato para mudas em viveiro, sendo muitas vezes produzidas por um único tipo de substrado. A heterogeneidade de habitats, porém, indica que as espécies podem ter exigências nutricionais distintas. Objetivou-se, portanto, avaliar o efeito da fertilização do substrato e da suplementação nutricional via folha no desenvolvimento de mudas de Kielmeyera coriacea Mart. & Zucc., de Eugenia dysenterica (Mart.) DC e de Handroanthus impetiginosus (Mart. ex DC.) Mattos. O experimento foi implantado com a utilização de delineamento inteiramente casualizado, em esquema fatorial 3 x 3 (três tipos de substratos x três níveis de adubação foliar), com dez repetições. Os tratamentos foram submetidos a análise de variância. Para as espécies K. coriacea e H. impetiginosus recomenda-se utilizar substrato composto por Solo + Manure (2:1); já para a E. dysenterica, recomenda-se utilizar o substrato Completo, não se recomendando realizar a adubação foliar para todas as espécies. Em relação à análise do solo, a matéria orgânica, o fósforo e o cálcio foram determinantes na formação dos grupos de fertilidade para cada um dos principais componentes da Análise de Componentes Principais.

Nutritional supplementation required by native Cerrado species development, in nursery / Exigência de suplementação nutricional no desenvolvimento de espécies nativas do Cerrado, em viveiro

The ecological restoration of Cerrado ecosystems involves challenges pertinent to the fertilization of the substrate for seedlings in nursery, which are often produced by a single type of substrate. However, habitat heterogeneity suggests that the species may have different nutritional requirements. The objective was to assess the effect of substrate fertilization and nutritional supplementation by leaf in developing seedlings of Kielmeyera coriacea Mart. & Zucc. Eugenia dysenterica (Mart.) and DC Handroanthus impetiginosus (Mart. ex DC.) Mattos. The experiment was implemented in a 3x3 factorial completely randomized design (three types of substrates x three levels of foliar fertilization), with ten replicates. The treatments were tested by analysis of variance. For K. coriacea and H. impetiginosus, it is recommended to use a substrate composed of Soil + Manure (2:1), for E. dysenterica, it is recommended to use the complete substrate. Foliar fertilization is not recommended for all species. Regarding the soil analysis, organic matter, phosphorus and calcium were determinants in the formation of fertility groups for each of the major components of the Principal Component Analysis.(AU)

A restauração ecológica dos ecossistemas do Cerrado envolve desafios pertinentes à fertilização do substrato para mudas em viveiro, sendo muitas vezes produzidas por um único tipo de substrado. A heterogeneidade de habitats, porém, indica que as espécies podem ter exigências nutricionais distintas. Objetivou-se, portanto, avaliar o efeito da fertilização do substrato e da suplementação nutricional via folha no desenvolvimento de mudas de Kielmeyera coriacea Mart. & Zucc., de Eugenia dysenterica (Mart.) DC e de Handroanthus impetiginosus (Mart. ex DC.) Mattos. O experimento foi implantado com a utilização de delineamento inteiramente casualizado, em esquema fatorial 3 x 3 (três tipos de substratos x três níveis de adubação foliar), com dez repetições. Os tratamentos foram submetidos a análise de variância. Para as espécies K. coriacea e H. impetiginosus recomenda-se utilizar substrato composto por Solo + Manure (2:1); já para a E. dysenterica, recomenda-se utilizar o substrato Completo, não se recomendando realizar a adubação foliar para todas as espécies. Em relação à análise do solo, a matéria orgânica, o fósforo e o cálcio foram determinantes na formação dos grupos de fertilidade para cada um dos principais componentes da Análise de Componentes Principais.(AU)

Composition and abundance of decapod crustaceans in mixed seagrass meadows in the Paraguaná Peninsula, Venezuela / Composición y abundancia de crustáceos decápodos en praderas mixtas de hierbas marinas en la península de Paraguaná, Venezuela

Thalassia testudinum y Halodule wrigthii son las hierbas marinas dominantes en el Caribe, siendo comunes en costas someras, tanto en monocultivos como en cultivos mixtos. Entre la macrofauna asociada a estas comunidades, los crustáceos son considerados esenciales para el funcionamiento del ecosistema. Sin embargo, el conocimiento sobre la comunidad de crustáceos decápodos asociada a praderas mixtas de T. testudinum y H. wrigthii es escaso, en particular fuera de zonas protegidas. En este trabajo presentamos ocho nuevas especies de decápodos para la Península de Paraguaná (estado Falcón, Venezuela) asociados a praderas mixtas de hierbas marinas: Achelous tumidulus Stimpson, 1871, Alpheus floridanus Kingsley, 1878, Chorinus heros (Herbst, 1790), Clibanarius antillensis (Stimpson, 1859), Clibanarius sclopetarius (Herbst, 1796), Latreutes parvulus (Stimpson, 1866), Panopeus occidentalis Saussure, 1857, y Processa fimbriata Manning & Chace, 1971. Estos registros representan extensiones de hábitat y completan brechas en la distribución geográfica de las especies a lo largo de la costa septentrional de Sudamérica. Diferencias estadísticas en la abundancia y composición de las especies de decápodos fueron posiblemente causadas por la acción conjunta de cobertura y heterogeneidad de las praderas. Las especies más influyentes en la comunidad son típicas para el Caribe; no obstante, la abundancia de Penaeus schmitti Burkenroad, 1936 juveniles fue notable, puesto que raramente han sido encontrados en estos hábitats. Este hallazgo resalta el rol de áreas no protegidas como hábitats de cría para especies de importancia comercial. Nuestros resultados muestran que las praderas de hierbas marinas en la Península de Paraguaná reflejan un buen estado en comparación con otras zonas del Caribe, y representan un hábitat importante para el mantenimiento de las poblaciones de crustáceos.(AU)

Thalassia testudinum and Halodule wrigthii are the dominant seagrasses in the Caribbean, being common across shallow shorelines, either as monospecific or as intermixed meadows. Among the macrofauna associated with these beds, crustaceans are considered essential for the whole ecosystem functioning. However, knowledge about the associated community of decapod crustaceans in assemblages of T. testudinum and H. wrigthii is still scarce, particularly outside of protected areas. Here we report eight new decapod species for the Paraguaná Peninsula (Falcón State, Venezuela) in association with intermixed seagrass beds: Achelous tumidulus Stimpson, 1871, Alpheus aff. floridanus Kingsley, 1878, Chorinus heros (Herbst, 1790), Clibanarius antillensis (Stimpson, 1859), Clibanarius sclopetarius (Herbst, 1796), Latreutes parvulus (Stimpson, 1866), Panopeus occidentalis Saussure, 1857, and Processa fimbriata Manning & Chace, 1971. These records represent habitat extensions and fill gaps in the geographical distribution of the species along the northern coast of South America. Furthermore, we found that statistical differences in decapod species abundance and composition are likely to be caused by the joint action of coverage and heterogeneity of the beds. Our results indicate that typical Caribbean species were the most influential in the community; nevertheless, the abundance of juvenile Penaeus schmitti Burkenroad, 1936 was notable, since they have rarely been found in these habitats. This finding highlights the role of non-protected areas as nursery habitats for economically important species. Our results show that seagrass meadows in the Paraguaná Peninsula reflect overall good health when compared to other Caribbean zones, representing an important habitat for the maintenance of crustacean populations.(AU)

Composition and abundance of decapod crustaceans in mixed seagrass meadows in the Paraguaná Peninsula, Venezuela / Composición y abundancia de crustáceos decápodos en praderas mixtas de hierbas marinas en la península de Paraguaná, Venezuela

Thalassia testudinum y Halodule wrigthii son las hierbas marinas dominantes en el Caribe, siendo comunes en costas someras, tanto en monocultivos como en cultivos mixtos. Entre la macrofauna asociada a estas comunidades, los crustáceos son considerados esenciales para el funcionamiento del ecosistema. Sin embargo, el conocimiento sobre la comunidad de crustáceos decápodos asociada a praderas mixtas de T. testudinum y H. wrigthii es escaso, en particular fuera de zonas protegidas. En este trabajo presentamos ocho nuevas especies de decápodos para la Península de Paraguaná (estado Falcón, Venezuela) asociados a praderas mixtas de hierbas marinas: Achelous tumidulus Stimpson, 1871, Alpheus floridanus Kingsley, 1878, Chorinus heros (Herbst, 1790), Clibanarius antillensis (Stimpson, 1859), Clibanarius sclopetarius (Herbst, 1796), Latreutes parvulus (Stimpson, 1866), Panopeus occidentalis Saussure, 1857, y Processa fimbriata Manning & Chace, 1971. Estos registros representan extensiones de hábitat y completan brechas en la distribución geográfica de las especies a lo largo de la costa septentrional de Sudamérica. Diferencias estadísticas en la abundancia y composición de las especies de decápodos fueron posiblemente causadas por la acción conjunta de cobertura y heterogeneidad de las praderas. Las especies más influyentes en la comunidad son típicas para el Caribe; no obstante, la abundancia de Penaeus schmitti Burkenroad, 1936 juveniles fue notable, puesto que raramente han sido encontrados en estos hábitats. Este hallazgo resalta el rol de áreas no protegidas como hábitats de cría para especies de importancia comercial. Nuestros resultados muestran que las praderas de hierbas marinas en la Península de Paraguaná reflejan un buen estado en comparación con otras zonas del Caribe, y representan un hábitat importante para el mantenimiento de las poblaciones de crustáceos.

Thalassia testudinum and Halodule wrigthii are the dominant seagrasses in the Caribbean, being common across shallow shorelines, either as monospecific or as intermixed meadows. Among the macrofauna associated with these beds, crustaceans are considered essential for the whole ecosystem functioning. However, knowledge about the associated community of decapod crustaceans in assemblages of T. testudinum and H. wrigthii is still scarce, particularly outside of protected areas. Here we report eight new decapod species for the Paraguaná Peninsula (Falcón State, Venezuela) in association with intermixed seagrass beds: Achelous tumidulus Stimpson, 1871, Alpheus aff. floridanus Kingsley, 1878, Chorinus heros (Herbst, 1790), Clibanarius antillensis (Stimpson, 1859), Clibanarius sclopetarius (Herbst, 1796), Latreutes parvulus (Stimpson, 1866), Panopeus occidentalis Saussure, 1857, and Processa fimbriata Manning & Chace, 1971. These records represent habitat extensions and fill gaps in the geographical distribution of the species along the northern coast of South America. Furthermore, we found that statistical differences in decapod species abundance and composition are likely to be caused by the joint action of coverage and heterogeneity of the beds. Our results indicate that typical Caribbean species were the most influential in the community; nevertheless, the abundance of juvenile Penaeus schmitti Burkenroad, 1936 was notable, since they have rarely been found in these habitats. This finding highlights the role of non-protected areas as nursery habitats for economically important species. Our results show that seagrass meadows in the Paraguaná Peninsula reflect overall good health when compared to other Caribbean zones, representing an important habitat for the maintenance of crustacean populations.

Reproduction, feeding and migration patterns of Prochilodus nigricans (Characiformes: Prochilodontidae) in northeastern Ecuador

The black prochilodus, Prochilodus nigricans, is an important food fish distributed throughout aquatic habitats of the Ecuadorian Amazon. We sampled gonad weight, body condition, and feeding of this species to address the question of whether changes in these biological parameters are related to hydrological variation and migration patterns. High frequency of empty stomachs and poor body condition corresponded to migration periods. Gonad condition analysis revealed a single, discrete spawning period in April (end of rising water season). We synthesized our own and published observations on migration patterns of black prochilodus and presumptive factors that influence those movements. Mature individuals make lateral migrations from peripheral flooded habitats to large white water rivers to spawn. Eggs and larvae drift downstream to nurseries at least into Peru and perhaps into Brazil; there do not appear to be nursery habitats in Ecuador. After 6-18 months, they migrate upstream, recruiting to parental stocks. Long-distance migrations of black prochilodus and similar fishes in Neotropical rivers disobey political boundaries. Conservation and management of such migratory fishes, thus, requires international co-operation and integrated conservation efforts.(AU)

El bocachico, Prochilodus nigricans, es una fuente importante de proteínas, distribuido en hábitats acuáticos de las tierras bajas de la Amazonía ecuatoriana. Se muestreo el peso de las gónadas, la condición corporal, y alimentación de esta especie para determinar la relación de estos parámetros biológicos con la variación hidrológica y patrones migratorios. Una frecuencia alta de estómagos vacíos y la pobre condición corporal corresponde a períodos de migración. El análisis del estado de las gónadas reveló un corto periodo de desove en abril (fin de la temporada de aumento del río). Hemos sintetizado nuestras observaciones propias y publicadas sobre migraciones del bocachico, así como los factores que presumiblemente influyen en estos movimientos. Los peces adultos migran lateralmente desde hábitats periféricos inundados hasta ríos de aguas blancas para desovar. Los huevos y larvas flotan aguas abajo hasta llegar a sitios de crianza en Perú y posiblemente en Brasil; no parece haber hábitats de crianza en Ecuador. Después de 6-18 meses, los bocachicos migran aguas arriba, reclutando a las poblaciones parentales. Las migraciones a larga distancia del bocachico y peces similares en ríos Neotropicales desobedecen las fronteras políticas. Una gestión apropiada de este recurso requiere de cooperación internacional y esfuerzos integrados de conservación.(AU)

Reproduction, feeding and migration patterns of Prochilodus nigricans (Characiformes: Prochilodontidae) in northeastern Ecuador

The black prochilodus, Prochilodus nigricans, is an important food fish distributed throughout aquatic habitats of the Ecuadorian Amazon. We sampled gonad weight, body condition, and feeding of this species to address the question of whether changes in these biological parameters are related to hydrological variation and migration patterns. High frequency of empty stomachs and poor body condition corresponded to migration periods. Gonad condition analysis revealed a single, discrete spawning period in April (end of rising water season). We synthesized our own and published observations on migration patterns of black prochilodus and presumptive factors that influence those movements. Mature individuals make lateral migrations from peripheral flooded habitats to large white water rivers to spawn. Eggs and larvae drift downstream to nurseries at least into Peru and perhaps into Brazil; there do not appear to be nursery habitats in Ecuador. After 6-18 months, they migrate upstream, recruiting to parental stocks. Long-distance migrations of black prochilodus and similar fishes in Neotropical rivers disobey political boundaries. Conservation and management of such migratory fishes, thus, requires international co-operation and integrated conservation efforts.(AU)

El bocachico, Prochilodus nigricans, es una fuente importante de proteínas, distribuido en hábitats acuáticos de las tierras bajas de la Amazonía ecuatoriana. Se muestreo el peso de las gónadas, la condición corporal, y alimentación de esta especie para determinar la relación de estos parámetros biológicos con la variación hidrológica y patrones migratorios. Una frecuencia alta de estómagos vacíos y la pobre condición corporal corresponde a períodos de migración. El análisis del estado de las gónadas reveló un corto periodo de desove en abril (fin de la temporada de aumento del río). Hemos sintetizado nuestras observaciones propias y publicadas sobre migraciones del bocachico, así como los factores que presumiblemente influyen en estos movimientos. Los peces adultos migran lateralmente desde hábitats periféricos inundados hasta ríos de aguas blancas para desovar. Los huevos y larvas flotan aguas abajo hasta llegar a sitios de crianza en Perú y posiblemente en Brasil; no parece haber hábitats de crianza en Ecuador. Después de 6-18 meses, los bocachicos migran aguas arriba, reclutando a las poblaciones parentales. Las migraciones a larga distancia del bocachico y peces similares en ríos Neotropicales desobedecen las fronteras políticas. Una gestión apropiada de este recurso requiere de cooperación internacional y esfuerzos integrados de conservación.(AU)

Bioecology and movements of bull sharks, Carcharhinus leucas, caught in a long-term longline survey off northeastern Brazil

A robust understanding of habitat usage by coastal shark species, and how it overlaps with human presence in densely-populated regions is needed to inform the development of efficient conservation strategies for these important top predators. An intensive longline survey conducted in nearshore waters off northeastern Brazil from 2004 through 2014 caught a total of 18 bull sharks (Carcharhinus leucas) (male-female ratio = 0.63:1), which can be dangerous to humans. Although most sharks were sexually mature, there was no evidence that this region could be used as a parturition or nursery area. Prey items identified in the guts of the sharks comprised teleosts, mollusks and elasmobranchs. Additionally, one satellite-tagged bull shark covered a great distance (> 3,000 km) in 75 days at liberty, making most use of shallow waters (< 20 m depth) and presumably also entering an estuarine area. Although bull sharks are not an important fishery resource in this region, such a reduced abundance coupled with its affinity for coastal and inshore habitats highlights the potential vulnerability of C. leucas to deleterious anthropic interferences off northeastern Brazil.(AU)

Um melhor entendimento sobre a utilização de hábitat das espécies de tubarões costeiros, e como ela se sobrepõe à presença humana em regiões altamente populosas, se faz necessário a fim de subsidiar o desenvolvimento de eficientes medidas de conservação para esses importantes predadores de topo. Um estudo intensivo utilizando espinhel, conduzido em águas costeiras do nordeste do Brasil entre os anos de 2004 e 2014, capturou um total de 18 tubarões cabeça-chata (Carcharhinus leucas) (proporção macho-fêmea = 0,63:1), os quais podem ser perigosos para humanos. Apesar da maioria dos tubarões estarem sexualmente maduros, não houve evidências de que essa região esteja sendo utilizada como uma área de parto ou berçário. Entre os itens alimentares identificados foram encontrados teleósteos, moluscos e elasmobrânquios. Além disso, um tubarão cabeça-chata marcado com um transmissor satélite percorreu uma grande distância (> 3.000 km) em 75 dias em liberdade, fazendo o uso de águas superficiais (< 20 m profundidade) e presumivelmente entrando em uma área estuarina. Apesar de os tubarões cabeça-chata não corresponderem a um recurso pesqueiro importante nessa região, tal reduzida abundância juntamente com a sua afinidade por hábitats costeiros reforçam a potencial vulnerabilidade de C. leucas às interferências antrópicas deletérias ao longo da costa nordeste do Brasil.(AU)

Bioecology and movements of bull sharks, Carcharhinus leucas, caught in a long-term longline survey off northeastern Brazil

A robust understanding of habitat usage by coastal shark species, and how it overlaps with human presence in densely-populated regions is needed to inform the development of efficient conservation strategies for these important top predators. An intensive longline survey conducted in nearshore waters off northeastern Brazil from 2004 through 2014 caught a total of 18 bull sharks (Carcharhinus leucas) (male-female ratio = 0.63:1), which can be dangerous to humans. Although most sharks were sexually mature, there was no evidence that this region could be used as a parturition or nursery area. Prey items identified in the guts of the sharks comprised teleosts, mollusks and elasmobranchs. Additionally, one satellite-tagged bull shark covered a great distance (> 3,000 km) in 75 days at liberty, making most use of shallow waters (< 20 m depth) and presumably also entering an estuarine area. Although bull sharks are not an important fishery resource in this region, such a reduced abundance coupled with its affinity for coastal and inshore habitats highlights the potential vulnerability of C. leucas to deleterious anthropic interferences off northeastern Brazil.(AU)

Um melhor entendimento sobre a utilização de hábitat das espécies de tubarões costeiros, e como ela se sobrepõe à presença humana em regiões altamente populosas, se faz necessário a fim de subsidiar o desenvolvimento de eficientes medidas de conservação para esses importantes predadores de topo. Um estudo intensivo utilizando espinhel, conduzido em águas costeiras do nordeste do Brasil entre os anos de 2004 e 2014, capturou um total de 18 tubarões cabeça-chata (Carcharhinus leucas) (proporção macho-fêmea = 0,63:1), os quais podem ser perigosos para humanos. Apesar da maioria dos tubarões estarem sexualmente maduros, não houve evidências de que essa região esteja sendo utilizada como uma área de parto ou berçário. Entre os itens alimentares identificados foram encontrados teleósteos, moluscos e elasmobrânquios. Além disso, um tubarão cabeça-chata marcado com um transmissor satélite percorreu uma grande distância (> 3.000 km) em 75 dias em liberdade, fazendo o uso de águas superficiais (< 20 m profundidade) e presumivelmente entrando em uma área estuarina. Apesar de os tubarões cabeça-chata não corresponderem a um recurso pesqueiro importante nessa região, tal reduzida abundância juntamente com a sua afinidade por hábitats costeiros reforçam a potencial vulnerabilidade de C. leucas às interferências antrópicas deletérias ao longo da costa nordeste do Brasil.(AU)

Temporal dynamics of a fish community in the lower portion of a tidal creek, Pando sub-estuarine system, Uruguay / Dinâmica temporal de uma comunidade de peixes na parte baixa de um arroio costeiro, sistema subestuarino Pando, Uruguai

Estuaries are highly dynamic ecosystems subjected to variability of their fish communities over different time scales. The nearshore fish community of the lower Pando estuary, a temperate sub-system of the Río de la Plata estuary, was sampled from May 2002 to June 2003. A total of 2,165 fishes, represented by 16 species were caught by seine netting. Captures were dominated by juveniles (>90%), as well as by the sciaenid Micropogonias furnieri (Desmarest, 1823) (82.8%). The fish community showed high seasonal variability, with the greatest diversity and biomass in summer and spring and the highest species richness during summer. Lowest values of all community parameters occurred in winter and autumn, seasons that presented the highest similarity in fish composition. Number of species was correlated with water temperature and salinity. The ichthyofaunal composition showed significant diel differences in summer and spring. Diel changes were observed in the density of M. furnieri and Odontesthes argentinensis (Valenciennes, 1835), occurring mainly during the day, and of Mugil liza Valenciennes, 1836, Parapimelodus valenciennis (Lütken, 1874) and Brevoortia aurea (Spix & Agassiz, 1829), caught mostly during the night. Temporal variability was attributed to environmental fluctuations, life cycle of species as well as to feeding patterns and small-scale displacements. Presented findings in the Pando sub-estuary denote similar juvenile use and seasonal patterns to those found in estuaries. Further studies in the nursery function and juvenile dynamics over the year are recommended in order to better understand the ecological role of sub-estuaries.(AU)

Os estuários são ecossistemas dinâmicos que apresentam variabilidade nas suas comunidades de peixes em diferentes escalas de tempo. A comunidade de peixes costeiros do baixo estuário do Pando, um subsistema temperado do estuário do Río de la Plata, foi amostrada entre maio de 2002 e junho de 2003. Um total de 2.165 peixes, representados por 16 espécies, foi documentado com a pesca de arrasto. As capturas foram dominadas pelos jovens (>90%), assim como pelo sciaenídeo Micropogonias furnieri (Desmarest, 1823) (82,8%). A comunidade de peixes apresentou uma grande mudança sazonal, com a máxima diversidade e biomassa no verão e primavera, e a máxima riqueza de espécies durante o verão. Os menores valores de todos os parâmetros comunitários ocorreram no inverno e outono, estações com a maior similaridade na composição da ictiofauna. O número de espécies foi correlacionado com a temperatura de água e salinidade. A composição da ictiofauna apresentou mudanças significativas diárias no verão e primavera. Verificou-se uma variabilidade diária na densidade da M. furnieri e Odontesthes argentinensis (Valenciennes, 1835), ocorrendo principalmente durante o dia, e de Mugil liza Valenciennes, 1836, Parapimelodus valenciennis (Lütken, 1874) e Brevoortia aurea (Spix & Agassiz, 1829), observadas principalmente durante à noite. A variabilidade temporal foi atribuída a interação com o ambiente, ciclo de vida das espécies assim como a atividade alimentar e movimentos de pequena escala. Resultados no subestuário Pando denotam um uso de juvenis e padrões sazonais semelhante aos dos estuários. Mais pesquisas no papel das áreas de berçário e dinâmicas juvenis ao longo do ano são recomendadas para compreender melhor o papel ecológico dos subestuários.(AU)

Temporal dynamics of a fish community in the lower portion of a tidal creek, Pando sub-estuarine system, Uruguay / Dinâmica temporal de uma comunidade de peixes na parte baixa de um arroio costeiro, sistema subestuarino Pando, Uruguai

Estuaries are highly dynamic ecosystems subjected to variability of their fish communities over different time scales. The nearshore fish community of the lower Pando estuary, a temperate sub-system of the Río de la Plata estuary, was sampled from May 2002 to June 2003. A total of 2,165 fishes, represented by 16 species were caught by seine netting. Captures were dominated by juveniles (>90%), as well as by the sciaenid Micropogonias furnieri (Desmarest, 1823) (82.8%). The fish community showed high seasonal variability, with the greatest diversity and biomass in summer and spring and the highest species richness during summer. Lowest values of all community parameters occurred in winter and autumn, seasons that presented the highest similarity in fish composition. Number of species was correlated with water temperature and salinity. The ichthyofaunal composition showed significant diel differences in summer and spring. Diel changes were observed in the density of M. furnieri and Odontesthes argentinensis (Valenciennes, 1835), occurring mainly during the day, and of Mugil liza Valenciennes, 1836, Parapimelodus valenciennis (Lütken, 1874) and Brevoortia aurea (Spix & Agassiz, 1829), caught mostly during the night. Temporal variability was attributed to environmental fluctuations, life cycle of species as well as to feeding patterns and small-scale displacements. Presented findings in the Pando sub-estuary denote similar juvenile use and seasonal patterns to those found in estuaries. Further studies in the nursery function and juvenile dynamics over the year are recommended in order to better understand the ecological role of sub-estuaries.

Os estuários são ecossistemas dinâmicos que apresentam variabilidade nas suas comunidades de peixes em diferentes escalas de tempo. A comunidade de peixes costeiros do baixo estuário do Pando, um subsistema temperado do estuário do Río de la Plata, foi amostrada entre maio de 2002 e junho de 2003. Um total de 2.165 peixes, representados por 16 espécies, foi documentado com a pesca de arrasto. As capturas foram dominadas pelos jovens (>90%), assim como pelo sciaenídeo Micropogonias furnieri (Desmarest, 1823) (82,8%). A comunidade de peixes apresentou uma grande mudança sazonal, com a máxima diversidade e biomassa no verão e primavera, e a máxima riqueza de espécies durante o verão. Os menores valores de todos os parâmetros comunitários ocorreram no inverno e outono, estações com a maior similaridade na composição da ictiofauna. O número de espécies foi correlacionado com a temperatura de água e salinidade. A composição da ictiofauna apresentou mudanças significativas diárias no verão e primavera. Verificou-se uma variabilidade diária na densidade da M. furnieri e Odontesthes argentinensis (Valenciennes, 1835), ocorrendo principalmente durante o dia, e de Mugil liza Valenciennes, 1836, Parapimelodus valenciennis (Lütken, 1874) e Brevoortia aurea (Spix & Agassiz, 1829), observadas principalmente durante à noite. A variabilidade temporal foi atribuída a interação com o ambiente, ciclo de vida das espécies assim como a atividade alimentar e movimentos de pequena escala. Resultados no subestuário Pando denotam um uso de juvenis e padrões sazonais semelhante aos dos estuários. Mais pesquisas no papel das áreas de berçário e dinâmicas juvenis ao longo do ano são recomendadas para compreender melhor o papel ecológico dos subestuários.

ESTUARIES AS NURSERY HABITATS FOR THE HORSE-EYE JACK (Caranx latus) IN NORTH-ASTERN BRAZIL

Compreender a importância dos habitats costeiros para a manutenção das populações de peixes explotados é fundamental para delinear estratégias sustentáveis para a pesca e o manejo do ecossistema. Os xaréus são peixes marinhos tropicais muito apreciados. A maioria deles completa todo o seu ciclo de vida no mar, porém alguns utilizam os estuários na fase juvenil antes de retornarem ao mar e adentrarem ao estoque adulto explotado pela pesca. Este é o caso do aracimbora (Caranx latus), uma espécie explotada mas pouco estudada e que pode ser encontrada com frequência em estuários no Nordeste do Brasil, pelo menos no estágio juvenil. Entretanto, pouco se sabia sobre a ecologia da espécie nestes habitats costeiros, assim como a importância destes locais para a manutenção do estoque exlpotado localmente. Esta tese combina três eixos de pesquisa complementares para começar a preencher esta lacuna de conhecimento. O primeiro deles investigou o comprimento por idade e o crescimento de C. latus na região com base nos dados de tamanho e na leitura dos otólitos de 282 espécimes capturados no mar e em diversos habitats costeiros. Isto permitiu especificar a idade dos peixes nos habitats colonizados pela espécie e inferir os parâmetros de crescimento para o estoque explotado. O segundo eixo investigou as variações locais na dieta e nos recursos alimentares dos indivíduos juvenis nos estuários através de uma análise conjunta do conteúdo estomacal e razão isotópica (13C e 15N) de 439 indivíduos juvenis de C.latus e uma outra espécie simpátrica de xaréu (C. hippos), em três estuários vizinhos e com características morfológicas e biológicas contrastantes. Isso demonstrou a plasticidade no uso de recursos das espécies de acordo com as configurações ambientais de cada estuário, permitindo-lhes limitar a competição trófica entre elas, com potenciais consequências em seus respectivos tamanhos e abundâncias. Por fim, o terceiro eixo de pesquisa visou quantificar a importância dos estuários da região para a manutenção do estoque adulto de C. latus explotado pela pesca ao analisar os elementos químicos incorporados na porção do otólito referente ao estágio juvenil de 183 otólitos de indivíduos juvenis e adultos capturados em diversos ambientes estuarinos e marinhos da região. Isso revelou que 75% dos indivíduos sub-adultos e adultos explotados pela pesca ao largo da costa do estado de Pernambuco passaram seu primeiro ano de vida crescendo em estuários próximos da região, particularmente naqueles sob forte influência marinha. Esses resultados avançam significativamente os conhecimentos pretéritos sobre a ecologia de C. latus e demonstram que os estuários desempenham um papel fundamental na manutenção da população de C. latus no nordeste do Brasil. No entanto, as diferenças locais nas condições ambientais as quais os juvenis da espécie estão sujeitos durante sua estadia nos estuários modulam fortemente o respectivo valor desses habitats para a renovação do estoque, com fortes implicações no manejo pesqueiro e do ecossistema.

Evaluating the importance of inshore coastal habitats for the maintenance of exploited coastal fish populations is key to delineate sustainable strategies for both fishery and ecosystem management. Jacks are highly prized tropical marine fishes. Most of them complete their whole life cycle at sea, but some use estuaries at the juvenile stage before moving back to coastal waters and joining offshore adult exploited stocks. This is the case of the horse-eye jack (Caranx latus), an exploited yet poorly studied species frequently found in estuaries in North-Eastern Brazil, at least at the juvenile stage. However, little was known on the species' ecology in these inshore habitats, nor on their importance for the maintenance of its local exploited stock. To start filling this knowledge gap, this thesis combined three complementary research axes. The first one investigated the local size-at-age and growth of C. latus using size data and otolith readings from 282 specimens captured both at Sea and in varied inshore habitats. This allowed to specify fish ages in all the environments colonised by the species in the area and to infer the growth parameters for its local exploited stock. The second axis investigated local variations in the diet and food resources of C. latus juveniles in estuaries and their causes, by a combined analysis of the stomach contents and stable isotopes (13C and 15N) signatures of 439 juveniles of both C. latus and another sympatric jack species (C. hippos), in three neighboring estuaries with contrasted morphological and biological features. It highlighted a plasticity in local resources use by juvenile jacks according to the estuarine environmental settings, allowing them to limit the trophic competition among them, with potential consequences on their respective sizes and abundances. Finally, the third research axis aimed to quantify the importance of local estuaries for sustaining the adult stock of C. latus exploited offshore, by analysing different chemical elements incorporated in the juvenile part of 183 otoliths of juveniles and adults captured in varied estuarine and marine habitats in this area. This revealed that 75% of the sub-adults and adults exploited by the fisheries off the coast of the Pernambuco state have spent their first year of life growing in local estuaries, particularly those under strong marine influence. These findings significantly advance previous knowledge on C. latus ecology and demonstrate that estuaries play a key role in the maintenance of the C. latus population in North-Eastern Brazil. Yet, local differences in the abiotic and biotic environmental conditions experienced by juvenile jacks during their estuarine stay strongly modulate the respective value of these inshore habitats for the renewal of the stock fished at Sea, with strong implications in terms of local fishery and ecosystem management.

Feeding ecology of three juvenile mojarras (Gerreidae) in a tropical estuary of northeastern Brazil

Distributions and feeding ecology of mojarra species from shallow water of a tropical estuary in Northeastern Brazil were observed aiming to investigate differences in distribution and resource partitioning among juveniles of three species of mojarras. Fishes were collected with a beach seine across four sites along a salinity gradient from January to December of 2011. Highest abundances were recorded during the rainy season in the upper and middle estuary. Microcrustaceans, mainly copepods, were the preferential prey items of all mojarras, irrespective of size or hydrological season, suggesting these areas may be important nursery habitats. Juveniles of mojarra used two important mechanisms for exploitation of resources: (1) spatial segregation along the salinity and temperature gradient, such as abundance of Eucinostomus melanopterus increased from downstream to upstream estuary, while Eugerres brasilianus displayed an opposite pattern; (2) differences related to the volumetric proportion of the main prey items, with indications that E. melanopterus and Diapterus rhombeus fed predominantly on Calanoida and Cyclopoida, while the diet of E. brasilianus was dominated by items of infauna. Such strategies were important for resource partitioning, favouring the coexistence of these three species in the estuary.(AU)

A distribuição e a ecologia alimentar de gerreídeos capturados em águas rasas de um estuário tropical no nordeste do Brasil foram abordados com o objetivo de investigar diferenças na distribuição e partição de recursos entre três espécies de gerreídeos juvenis. Arrastos de praia foram realizados ao longo de quatro locais ao longo do gradiente de salinidade entre janeiro e dezembro de 2011. Maiores abundâncias foram registradas durante a estação chuvosa na zona superior e média do estuário. Microcrustáceos, principalmente copépodos, foram as principais presas para as três espécies, independente do tamanho ou do período hidrológico, sugerindo que essas áreas são importantes para o recrutamento. Gerreídeos juvenis usaram dois importantes mecanismos para exploração dos recursos: (1) segregação espacial no uso dos habitats ao longo do gradiente de salinidade e temperatura, com a abundância de Eucinostomus melanopterus aumentando em direção a parte inferior para porção superior do estuário, enquanto Eugerres brasilianus apresentou um padrão oposto; e (2) diferenças relacionadas com a proporção volumétrica das principais presas ingeridas, com indicações que E. melanopterus e Diapterus rhombeus alimentaram-se principalmente de Calanoida e Cyclpoida, enquanto a dieta de E. brasilianus foi dominada por itens da infauna. Tais estratégias foram importantes para partição dos recursos, favorecendo a coexistência dessas três espécies no estuário.(AU)