Las áreas verdes urbanas con vegetación mixta favorecen la riqueza y abundancia de aves en Ciudad Victoria, Tamaulipas, México

Introducción: La presencia y estructura de la vegetación en áreas urbanas tiene un impacto en la composición de las comunidades de aves. Las áreas verdes con una mayor proporción de vegetación introducida tienden a presentar una homogeneización de avifauna, mientras que las áreas verdes con alta proporción de vegetación nativa presentan mayor diversidad de aves. En varios trabajos realizados en áreas urbanas de México, estos factores no son tomados en cuenta. Por lo tanto, se desconocen las respuestas de las especies en términos de riqueza y diversidad. Objetivo: Analizar la composición de especies de aves en las áreas verdes de Ciudad Victoria, Tamaulipas y evaluar la respuesta de las comunidades de aves en tres áreas verdes con diferente composición de vegetación. Así como analizar la relación entre los gremios tróficos de aves con los elementos de la vegetación en las áreas urbanas. Métodos: El estudio se llevó a cabo en tres sitios de muestreo de Ciudad Victoria, Tamaulipas, México, con base en dos criterios: área similar de muestreo (ha) y diferencias en las características de la vegetación. Los monitoreos se realizaron de enero a diciembre de 2020, con tres visitas mensuales en cada sitio para un total de 108 visitas, utilizando el método visual directo. Resultados: Identificamos 98 especies (11 órdenes, 28 familias). Las especies más abundantes fueron Quiscalus mexicanus y Molothrus aeneus. Hubo diferencias en la riqueza de especies para cada sitio. Las insectívoras y granívoras fueron las dominantes. Se determinó una asociación entre los gremios y los sitios de estudio, donde la mayoría están relacionados con la vegetación mixta, comparado con la vegetación homogénea o introducida. Conclusiones: Las áreas urbanas estudiadas mantuvieron un número notable de aves, y varias de ellas presentaron alguna categoría de riesgo o endemismo. Esto demuestra la importancia de estas áreas verdes como refugio de aves y resalta la necesidad de conservar y proteger dichas áreas dentro de Ciudad Victoria y ciudades similares.

Introduction: The presence and structure of vegetation in urban areas have an impact on the composition of bird communities. Green areas with a higher ratio of introduced vegetation tend to have a greater homogenization of avifauna, whereas green areas with a high ratio of native vegetation have a greater diversity of birds. In several studies carried out in urban areas of Mexico, the factors of vegetation are not considered. Therefore, the responses of the species to vegetation types in terms of richness and diversity are unknown. Objective: To analyze the composition of bird species in the green areas of Ciudad Victoria, Tamaulipas, and evaluate the response of bird communities in areas with differences in vegetation composition. As well as to analyze the relationship between the trophic guilds in birds and vegetation in urban areas. Methods: Three sampling sites were established in Ciudad Victoria, Tamaulipas, Mexico, based on two criteria: similar sampling area (ha) and differences in vegetation characteristics. Monitoring took place between January and December 2020, with three monthly visits in each site for a total of 108 visits, using the direct visual method. Results: We identified 98 species (11 orders, 28 families). The most abundant species were Quiscalus mexicanus and Molothrus aeneus. Differences in species richness were found for each site. The insectivorous and granivorous were the dominant guilds. An association between the guilds and the study sites was determined, where most were linked to mixed native vegetation, compared to homogeneous or introduced vegetation. Conclusions: The urban areas studied maintained a notable number of birds, and several of them presented some category of risk or endemism. This demonstrates the importance of these green areas composed of native vegetation as a refuge for birds and highlights the need to conserve and protect these areas within Ciudad Victoria and similar cities.

Fish species of the Paraiba River estuary, northeastern Brazil / Espécies de peixes do estuário do Rio Paraíba, nordeste do Brasil

Abstract The Paraiba River estuary is the largest and most important estuary of Paraiba state, northeastern Brazil. It is under intense environmental degradation by the surrounding human population, and possibly several fish species are at risk in this habitat. Scientific sampling of the ichthyofauna started in the late 1970's and proceeded until recently. We present a list of fish species captured in this estuary, based on voucher specimens housed at the Federal University of Paraiba collection. Four orders of Chondrichthyes and 26 orders of Osteichthyes were identified. A total of 187 fish species, including eight species of Chondrichthyes and 179 Osteichthyes, with 123 genera and 57 families were identified. Perciformes dominated in terms of richness (32 species), followed by Acanthuriformes and Clupeiformes. Comparing estuaries along the Brazilian northeastern coast and considering our large time sampling span, a higher richness would be expected. According to the IUCN Red List, Urotrygon microphthalmum is considered Critically Endangered and more seven species are classified as Vulnerable: Rhizoprionodon porosus, Rhinoptera bonasus, Megalops atlanticus, Epinephelus itajara, Hyporthodus niveatus, Lutjanus cyanopterus, and Cynoscion acoupa. Three of these species also appear in the same category in the threatened Brazilian list, all of which have declining population trends. Concerning the Elasmobranchii, Carcharhinus porosus is listed as Critically Endangered in our country and globally. This inventory organizes and broadens knowledge on the fish community that occurs in this important ecosystem, with inferences about life habits, ecological guilds and conservation status of the fish species.

Resumo O estuário do Rio Paraíba, maior e mais importante do estado da Paraíba, nordeste do Brasil, sofre intensa degradação ambiental pela população humana no seu entorno, e possivelmente várias espécies de peixes estão ameaçadas neste habitat. Nós apresentamos uma lista de espécies de peixes capturadas neste estuário, com base em espécimes tombados na coleção da Universidade Federal da Paraíba. Quatro ordens de Chondrichthyes e 26 ordens de Osteichthyes foram identificadas. Um total de 187 espécies de peixes foi registrado, incluindo oito espécies de Chondrichthyes e 179 Osteichthyes, com 123 gêneros e 57 famílias. Em relação à riqueza, Perciformes dominou com 32 espécies, seguido por Acanthuriformes e Clupeiformes. Comparando estuários ao longo do nordeste brasileiro e considerando nosso longo período de amostragens, seria esperada uma riqueza maior. De acordo com a lista vermelha da IUCN, Urotrygon microphthalmum é tida como Criticamente Ameaçada e mais sete espécies são classificadas como Vulnerável: Rhizoprionodon porosus, Rhinoptera bonasus, Megalops atlanticus, Epinephelus itajara, Hyporthodus niveatus, Lutjanus cyanopterus e Cynoscion acoupa. Três dessas espécies também aparecem na mesma categoria na lista brasileira de espécies ameaçadas, tendo todas elas, suas populações em declínio. Em relação aos Elasmobranchii, Carcharhinus porosus é listada como Criticamente Ameaçada em nosso país e globalmente. Esse inventário abrange e organiza o conhecimento acerca da comunidade de peixes que ocorre nesse importante ecossistema, com inferências sobre hábitos de vida, guildas ecológicas e status de conservação das espécies de peixes.

Vertical stratification of arthropods in the dry ecosystems of Colombian Guyana: morphological patterns and their ecological implications / Estratificación vertical de artrópodos en ecosistemas secos de la Guayana colombiana: patrones morfológicos y sus implicaciones ecológicas

Abstract Introduction: Despite growing interest by the ecosystems derived from the Guyanese formations, the vertical structure of the communities and relationships of the biota with the climatic conditions in these ecosystems are unknown. Objective: Characterize the structure and vertical composition of the arthropod fauna associated with three of the most representative ecosystems of the Northern area of the serranía de La Lindosa in Colombia based on morphological and ecological parameters. Methods: The arthropod fauna was sampled, from the subsurface soil level to the shrub and tree stratum. The fauna was determined up to the level of family or supraspecific group and the values of Alfa and Beta diversity were determined. Body length measurements were made, and the coloration and trophic level of each group were determined. Results: The composition and diversity of the arthropod fauna was different in each ecosystem and vertical stratum and most of the groups in all the ecosystems studied present low abundances. Groups of phytophagous and predatory habits were frequent in all ecosystems and the highest biomass of arthropod fauna comes from groups of polyphagous habits, of medium size and great abundance. Light and dark colorations are the most frequent in landscape-scale. Conclusion: The ecosystems studied are characterized by the low values of diversity and replacement and the large number of non-shared groups that apparently respond to the microclimatic characteristics; however, there are some generalities on a landsc ape scale such as the greater richness and abundance of groups in the intermediate strata, the greater proportion of groups with phytophagous habits and medium body sizes, and the predominance of dark colorations in the lower strata.

Resumen Introducción: A pesar del interés que despiertan los ecosistemas derivados de las formaciones guyanesas, se desconoce la estructura vertical de las comunidades y las relaciones de la biota con las condiciones climáticas. Objetivo: Caracterizar la estructura y composición vertical de la artropofauna asociada a tres de los ecosistemas más representativos de la zona norte de la serranía de La Lindosa en Colombia, con base en parámetros morfológicos y ecológicos. Métodos: Se muestreó la artropofauna, desde el nivel del suelo subsuperficial hasta los estratos arbustivos y arbóreos, y se identificó hasta el nivel de familia o grupo supraespecífico. Se determinaron los valores de diversidad Alfa y Beta, se realizaron mediciones de la longitud corporal y se determinó la coloración y el nivel trófico de cada grupo. Resultados: La composición y diversidad de la artropofauna fue diferente en cada ecosistema y estrato vertical y la mayoría de los grupos de artrópodos en todos los ecosistemas estudiados presentan abundancias bajas. Los grupos de hábitos fitófagos y depredadores fueron frecuentes en todos los ecosistemas y la mayor biomasa de artropofauna proviene de grupos de hábitos polífagos, de tamaño medio y de gran abundancia. Las coloraciones claras y oscuras son las más frecuentes a escala de paisaje. Conclusión: Los ecosistemas estudiados se caracterizan por los bajos valores de diversidad y recambio y por la gran cantidad de grupos no compartidos que aparentemente responden a las características microclimáticas; sin embargo, existen algunas generalidades a escala de paisaje como la mayor riqueza y abundancia de grupos en los estratos intermedios, la mayor proporción de grupos de hábitos fitófagos y tallas corporales medianas y el predominio de coloraciones oscuras en los estratos inferiores.

Bat (Mammalia: Chiroptera) biodiversity in a subtropical inselberg ecosystem of Northeastern Argentina / Biodiversidad de murciélagos (Mammalia: Chiroptera) en un ecosistema inselberg subtropical del Noreste de Argentina

Abstract Introduction: Rocky outcrops influence both micro and macro habitat for plants and animals by increasing the availability and predictability of food, providing shelter, and unique microclimatic conditions. Objective: We describe the bat assemblage in three isolated rocky outcrops and their surrounding pediments, adding new data about trophic guilds and roosts. Methods: We surveyed the bat fauna of Paraje Tres Cerros, Corrientes Province, Argentina, exploring 13 sites during 26 field trips, using mist nets and search of roosts. We made an accumulation species curve and calculate inventory completeness. The similarity and composition of different habitats was compared by a Non-Metric Multidimensional Scaling (NMDS) and an ANOSIM test. Results: We reported 13 species, with a completeness inventory of the 80 % (Jacknife1), corresponding to the families Vespertilionidae, Molossidae and Phyllostomidae. The insectivorous bats were the best represented guild. We found nine types of roost for eight species in different sites. The analysis expressed low differences in the species composition between both types of habitats in the area. Conclusions: The rocky outcrops and their pediments are important ecosystems for the conservation and diversity of the bats in the region, since their assemblages are regionally unique.

Resumen Introducción: Los afloramientos rocosos influyen tanto en el micro como en el macro hábitat de plantas y animales al incrementar la disponibilidad de alimentos, proporcionar refugios y brindar condiciones microclimáticas únicas. Objetivo: Describir el ensamble de murciélagos en tres afloramientos rocosos aislados y sus pendientes circundantes, incorporando nuevos datos sobre gremios tróficos y refugios. Métodos: Muestreamos la fauna de murciélagos del Paraje Tres Cerros, provincia de Corrientes, Argentina, exploramos 13 sitios durante 26 viajes de campo, usando redes de niebla y búsqueda de refugios. Realizamos una curva de acumulación de especies y calculamos la completitud del inventario. La similitud y composición de diferentes hábitats se comparó mediante un escalado multidimensional no métrico (NMDS) y una prueba ANOSIM. Resultados: Reportamos 13 especies, con una completitud del 80 % del inventario (Jacknife1), correspondientes a las familias Vespertilionidae, Molossidae y Phyllostomidae. Los gremios mejor representados fueron los insectívoros. Encontramos nueve tipos de refugios para ocho especies en diferentes sitios. Los análisis expresaron bajas diferencias en la composición de especies entre ambos tipos de hábitats en el área. Conclusión: Los afloramientos rocosos y pendientes son ecosistemas importantes para la conservación y diversidad de los murciélagos en la región, ya que sus comunidades son regionalmente únicas.

Birds of Parque Estadual Ilha do Cardoso: ecology, conservation and natural history / Aves do Parque Estadual Ilha do Cardos: ecologia, conservação e história natural

Abstract: The Parque Estadual Ilha do Cardoso (PEIC), located on extreme South of São Paulo's cost, in Brazil, holds an important Atlantic Forest remnant which still in a good state of conservation, but lack a deepen study about the avian community that habits the island. This study aimed to elaborate a census of avian species that occur in the park approaching richness, occurrence frequency, occurrence status and the structure of trophic guilds. A total of 25 field expedictions occurred between September 2015 and September 2017 during five days each, the field work included different ecosystems as mangrove, restinga, forest, sandbank, beach and marine. The census was made combine three different techniques used in ornithological studies: visual identification, auditory identification and catch by mist-nets (with five fixed sites in mangrove, restinga and forest). Were recorded 335 avian species, with 28 of them endemic from Brazil and 33 being threatened with extinction. Seventy-three species were recorded in all sampled months (FO 100%), while 46 were recorded in just one month (FO = 4%). About occurrence status, 55% of species are residents, 20% occasional visitors, 13% unusual residents, 6% migratory and 6% visitors. According the recorded species were recognized 25 trophic guilds based on food items, corporal size and strata that commonly forage, which of most representative in the community, the guild of "of insectivorous of medium-strata" (N = 55), "canopy omnivorous" (N = 33), "aquatic invertebrates consummers" and "piscivorous" (N = 31). Finally, with the current study, we aimed through a significative field effort bring a better knowledge about avifauna of PEIC, which could be a good base when is necessary take actions that aim to park management and the Conservation Unities around it.

Resumo: O Parque Estadual Ilha do Cardoso (PEIC), localizado no estremo sul do litoral paulista, reúne um importante remanescente de Floresta Atlântica em bom estado de conservação, carecendo, porém, de um estudo aprofundado sobre a comunidade de aves que habita a ilha. Diante disso, o presente estudo visou a elaborar um inventário das espécies de aves do parque abordando a riqueza, frequência de ocorrência, status de ocorrência e divisão das espécies em guildas. Foram realizadas entre setembro de 2015 e setembro de 2017, 25 expedições de campo com cinco dias de duração cada, incluindo os ecossistemas de manguezal, restinga, floresta, baixio, praia e marinho. O inventário foi realizado combinando três técnicas para estudos ornitológicos: identificação visual, identificação auditiva e captura com redes-de-neblina (cinco pontos fixos no manguezal, restinga e floresta). Foram registradas 335 espécies de aves, sendo 28 espécies consideradas endêmicas para o Brasil e 33 com algum grau de risco de extinção. Setenta e três espécies foram registradas em todos os meses amostrados (FO = 100%), enquanto que 46 apresentaram registros em apenas um mês (FO = 4%). No que se refere ao status de ocorrência, 55% das espécies são residentes, 20% visitantes ocasionais, 13% residentes incomuns, 6% migratórias e 6% visitantes. As espécies registradas permitiram o reconhecimento de 25 guildas com base nos itens alimentares, tamanho corporal e estrato em que comumente forrageiam, sendo as mais representativas na comunidade, as guildas de "Insetívoros de estrato médio" (N = 55), "Onívoros de copa" (N = 33), "Consumidores de Invertebrados Aquáticos" e "Piscívoros" (N = 31). Por fim, com o presente estudo, buscamos através de um significativo esforço em campo trazer um melhor conhecimento no que diz respeito a avifauna do PEIC, que pode vir a servir de base na hora de traçar ações visando ao manejo do parque bem como das unidades de conservação que se distribuem no seu entorno.

Composición y estructura del ensamblaje de hormigas en diferentes usos del suelo en Santa Fe de Antioquia, Colombia / Ant assemblage composition and structure in different land uses in Santa Fe de Antioquia, Colombia

RESUMEN La Estación Agraria Cotové está ubicada en Santa Fe de Antioquia, zona de bosque seco tropical, en la que se han desarrollado actividades agropecuarias por más de 40 años, transformado sus ecosistemas originales y modificando las condiciones ambientales. Por lo anterior, este estudio tiene por objetivo evaluar la composición y la estructura de las hormigas en cinco sitios, con diferentes usos del suelo de la Estación Agraria: frutales, sistema silvopastoril, bosque secundario, pastos de corte y pastoreo con baja densidad de árboles. En cada uso del suelo, se ubicaron tres transectos de 100m cada uno, al interior, interior-borde y borde, tomando una muestra cada 20m, a una profundidad de 10cm. Se identificaron las hormigas presentes, a nivel de morfoespecies y se clasificaron por gremios tróficos y por grupos funcionales. Se recolectaron 5.239 individuos, agrupados en 253 colonias, pertenecientes a 23 géneros y 37 morfoespecies de las subfamilias Myrmicinae, Ponerinae, Formicinae y Ecitoninae. La diversidad fue más alta en bosque secundario y frutales, mientras que la dominancia fue mayor en el sistema silvopastoril y en pastoreo con baja densidad de árboles. Entre bosque secundario y frutales, se encontró el mayor valor de morfoespecies compartidas. Los gremios tróficos mejor representados fueron omnívoros y depredadores y, por grupo funcional, se presentó una mayor proporción de Especialistas de Clima Tropical y de Myrmicinae Generalistas.

ABSTRACT The Agrarian Station Cotové is located in Santa Fe de Antioquia, an area of tropical dry forest in which agricultural activities have been carried out for more than 40 years, which have transformed their original ecosystems and modified the environmental conditions. Therefore, this study aims to evaluate the composition and structure of ants in five sites with different land uses: fruit trees, silvopasture, secondary forest, grass for cutting, and pastures with low density of trees. In each land use, three transects of 100m each were located, inside, inside-edge, and edge, taking a sample every 20m to a depth of 10cm. In each site, the ants were identified to morphospecies, and classified by trophic guilds and by functional groups. The diversity index for each land uses were determined. We collected 5239 ants, grouped in 253 colonies, belonging to 23 genera and 37 morphospecies of subfamilies Myrmicinae, Ponerinae, Formicinae y Ecitoninae. Species diversity was highest in secondary forest and fruit trees, while the dominance was higher in silvopasture and pastures with low density of trees. Secondary forest and fruit trees showed the highest value of shared morphospecies. The omnivorous and predator's trophic guilds were the best represented, and regarding functional groups, we found a high proportion of tropical climate specialists and Myrmicinae generalists.

Composición y fluctuación poblacional de la araneofauna en el algodonero de la Universidad Nacional Agraria La Molina, Lima, Perú / Composition and population fluctuation of the spider community in a cotton field at Universidad Nacional Agraria La Molina, Lima, Peru

En el presente trabajo, se evaluó la araneofauna durante todo el periodo fenológico del cultivo de algodón, utilizando dos técnicas de muestreo (búsqueda directa y trampas de caída). Se registraron 2304 individuos, agrupados en 50 especies y 18 familias. Las arañas estuvieron presentes durante todo el periodo del cultivo, relacionándose positivamente a su desarrollo fenológico, y donde las prácticas agronómicas, la temperatura y humedad no fueron influyentes en su abundancia, excepto por la cosecha, actividad que sí influenció negativamente sus poblaciones.

In this work, the spider community was assessed during the whole phenological period of a cotton crop using two sampling techniques (direct search and pitfall traps). 2304 individuals were registered, grouped into 50 species and 18 families. The spiders were present during the whole crop’s period; positively related to its phenological development; agronomic practices, temperature and humidity were not influential in their abundance, except for harvest, which negatively influenced their population.

Houseflies speaking for the conservation of natural areas: a broad sampling of Muscidae (Diptera) on coastal plains of the Pampa biome, Southern Brazil

ABSTRACT The Brazilian Coastal Plain of the Pampa Biome (CPPB), has suffered fragmentation caused by resource extraction and cattle raising. In turn, conservation proposals are needed to prevent the anthropisation of Pampa natural areas. The first step towards conservation proposals by using insects is fauna inventories, providing data support for legislators. Thus, we undertook a regional and broad-scale sampling survey to investigate the diversity of Muscidae flies in protected and non-protected areas of CPPB. In addition, we carried out an ecological guild diversity analysis as a metric approach of bioindication. The Muscidae sampling resulted in 6314 specimens, 98 species taxa in 31 genera. Based on diversity estimators, our sampling represents 70-86% of all muscids of CPPB. The highest diversity occurs in Pelotas streams (non-protected) and Taim Ecological Station (a huge protected area). Despite the fact these areas are more diversified and present more predatory muscid species than others, invasive species associated with livestock were observed at a higher level, providing evidence of the impact of livestock proximity to protected areas. Based on biological characters of Muscidae species and ecological guild analysis, we were able to identify: (i) high diversity of carnivorous species associated with forested and more preserved areas and (ii) a high level of a few saprophagous species as indicator of anthropisation process. In general, our results represent a significant step towards understanding Muscidae in Southern Brazil, and we demonstrate how the population ecology of muscid flies supports data to conservation proposals.

Relaciones entre la diversidad de aves y la estructura de vegetación en cuatro etapas sucesionales de bosque secundario, antioquia, colombia / Relationships between bird diversity and vegetation structure in four secondary forest successional stages, antioquia, colombia

RESUMEN Se estudió la relación entre la diversidad taxonómica y funcional del ensamblaje de aves y la estructura de vegetación, en cuatro estadios de sucesión secundaria de bosque, realizando cinco muestreos, entre junio de 2016 y febrero de 2017, en los que se registraron las aves, mediante puntos de conteo de radio fijo y se caracterizó la estructura de la vegetación de cada sucesión. Se estableció la abundancia, la preferencia, la especificidad de hábitat y el gremio trófico, así como la riqueza y la diversidad de las especies de aves y las relaciones entre la composición de las especies y los gremios tróficos con las variables del hábitat. Se registraron 9.516 individuos de 187 especies, pertenecientes a 42 familias y 15 órdenes. Se determinaron dos agrupaciones, separando los estadios sucesionales SS1 y SS2, de los estadios SS3 y SS4, con una similitud entre los dos grupos del 10%, a nivel taxonómico y del 32%, a nivel funcional. La regeneración natural posterior al abandono de prácticas agropecuarias, permiten un incremento de áreas de bosque secundario que, en la medida en que obtienen mayor complejidad estructural, se asocian con una mayor cantidad de especies con preferencia de hábitat de interior de bosque y un aumento de los gremios tróficos nectarívos y frugívoros.

ABSTRACT The relationships between taxonomic and functional diversity of bird assemblage and vegetation structure in four stages of secondary forest succession were studied. Five field samplings were carried out between June 2016 and February 2017, in which birds were recorded using fixed radius point counts, and the vegetation structure of each successional stage was characterized. Bird species were identified and their habitat preference, specificity and trophic guilds were established. The abundance, preference, habitat specificity and trophic guild, and the richness and diversity of species of birds and relationships between species composition and trophic guilds with habitat variables in the four sequences was established. 9516 individuals from 187 bird species belonging to 42 families and 15 orders were registered. Two clusters separating the SS1 and SS2 of SS3 and SS4 successional stages, were determined, with a similarity between both of 10% at taxonomic level and 32% at functional level. The natural regeneration subsequent to the abandonment of agricultural practices allow an increase in secondary forest areas, which to the extent they get greater structural complexity, are associated with increased number of forest interior species, and an increase of nectarivorous and frugivorous guilds.

Trophic structure of a floodplain fish assemblage in the upper Amazon basin, Bolivia / Estructura trófica de un ensamblaje de peces en la cuenca alto-Amazónica, Bolivia

Abstract Amazonian fish assemblages are typically high in species diversity and trophic complexity. Stable isotopes are valuable tools to describe the trophic structure of such assemblages, providing useful information for conservation and ecological management. This study aimed at estimating the relative contribution of the different basal carbon sources to the diet of primary consumer fishes (herbivores and detritivores), and determining the trophic position (TP) of the dominant fishes from each trophic guild (herbivores, detritivores, invertivores and piscivores). For this purpose we analyzed stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) in potential food sources, and muscle tissue of fishes in five oxbow lakes located in the floodplain of River Ichilo, Bolivia. Terrestrial plants and C3 aquatic macrophytes were the major carbon source contributing to the diet of herbivorous fishes, whereas particulate organic matter (POM) contributed more to the diet of detritivore fishes. In general, C4 aquatic macrophytes contributed little to the diet of herbivores and detritivores. However, we found a relatively high contribution of C4 macrophytes (28 %) to the diet of the herbivores Mylossoma duriventre and Schizodon fasciatus. We found a good agreement between our estimated TP values and the trophic group assigned based on diet composition from literature. The herbivore M. duriventre was at the bottom of the food web, being the baseline organism (TP = 2). The remaining primary consumers (herbivores and algivore/detritivores) exhibited relatively high TP values (2.3-2.9), probably due to their opportunistic feeding behavior. Omnivore/invertivore species studied displayed TP values near the 3.0 value expected for secondary consumers. Piscivore fishes were at the top TP, with TP values varying from 3.3 (Serrasalmus spilopleura and Serrasalmus rhombeus) to 3.8 (Pseudoplatystoma fasciatum). The fact that detritivore fishes, the most abundant food source for piscivores, occupy relatively high TPs determines that food chains in these particular Amazonian floodplains are longer than previously thought. Rev. Biol. Trop. 66(3): 1258-1271. Epub 2018 September 01.

Resumen Los ensamblajes de peces amazónicos presentan alta diversidad y complejidad trófica. La descripción de su estructura trófica proporciona información útil para su manejo. Con el fin de estimar la contribución de las fuentes básicas de carbono en la dieta de los consumidores primarios, y determinar la posición trófica (PT) de las especies dominantes de peces de cada gremio, analizamos isótopos estables de carbono (δ13C) y nitrógeno (δ15N) en las fuentes de carbono y en músculo de peces, de la llanura de inundación del río Ichilo. Las plantas terrestres y las macrófitas C3 fueron las mayores fuentes de carbono en la dieta de los peces herbívoros, mientras que la materia orgánica particulada contribuyó más a la dieta de los detritívoros. Las macrófitas C4 contribuyeron poco a la dieta de herbívoros y detritívoros, excepto para Mylossoma duriventre y Schizodon fasciatus, en las que encontramos una contribución relativamente alta (28 %). Encontramos una buena relación entre los valores estimados de PT y el gremio trófico asignado en la literatura. El herbívoro M. duriventre estuvo en la base de la red trófica (PT = 2). Los restantes consumidores primarios mostraron valores de PT relativamente altos (2.3 - 2.9), probablemente debido a sus hábitos alimenticios oportunistas. Las especies omnívoras/invertívoras mostraron valores cercanos a 3. Los peces piscívoros estuvieron en la cima de la red trófica, con PT que variaron entre 3.3 (Serrasalmus spilopleura y Serrasalmus rhombeus) y 3.8 (Pseudoplatystoma fasciatum). Estos datos sugieren que las cadenas tróficas en llanuras de inundación amazónicas, son más largas de lo que se suponía.

Hábitos alimentarios de quironómidos (Diptera: Chironomidae) en lagos del páramo de Chingaza, Colombia / Feeding habits of chironomids (Diptera: Chironomidae) of paramo lakes, Chingaza, Colombia

Resumen Los lagos tropicales de alta montaña presentan condiciones ambientales únicas donde los quironómidos tienen un papel importante en el funcionamiento del ecosistema. Las características de estos ambientes podrían favorecer el solapamiento de dietas y por ende una alta competencia interespecífica. En este estudio se describen los hábitos alimentarios de géneros de quironómidos, se identifica si los hábitos alimenticios son especializados o generalistas y se analiza el solapamiento en la dieta de los géneros. Entre abril y mayo de 2016 se colectaron larvas de Chironomidae de cuatro lagos del páramo de Chingaza. Se evaluó la dieta de larvas, mediante el análisis de contenido estomacal. Se ubicó cada género en gremios tróficos (carnívoro, detritívoro y alguívoro) y se estimó el solapamiento de las dietas entre los géneros mediante el índice de Pianka. Se colectó un total de 1 003 individuos y se identificaron nueve géneros. Las larvas consumieron principalmente materia orgánica particulada fina (MOPF), algas, fragmentos de macrófitas, macroinvertebrados y tejido animal. La MOPF fue la fuente principal de alimento de detritívoros. El análisis de dietas mostró una alta afinidad de cada género con un único gremio trófico y la mayor parte de los géneros son generalistas en el uso de recursos. En todos los lagos se observaron valores altos de solapamiento en la dieta entre los géneros y los gremios tróficos, principalmente entre los detritívoros. Los resultados sugieren que las larvas de Chironomidae presentan hábitos tróficos bien diferenciados, ocurriendo un moderado solapamiento de dietas entre géneros de detritívoros y carnívoros.

Abstract Tropical high mountain lakes show unique environmental conditions where chironomids play an important role in ecosystem functioning. The characteristics of these environments could favor diet overlap and therefore a high interspecific competition. This study described the dietary habits of chironomid genera, identified whether the dietary habits were specialized or generalist, and analyzed the diet overlap in the genera. Chironomidae larvae were collected from four lakes of the Chingaza paramo during the dry season, between April and May of 2 016. The feeding habits of larvae were evaluated by analyzing gut contents following standard methods. Each genus was assigned to trophic guilds (carnivore, detritivore and algivore) and the diet overlap was estimated using the Pianka's index. A total of 1 003 individuals were collected and nine genera were identified. Larvae consumed mainly fine particulate organic matter (FPOM), algae, macrophyte fragments, macroinvertebrates, and animal tissues. FPOM was the main feeding resource of detritivores. The analysis of diets showed a high affinity of each genus for a single trophic guild and most of the genera were generalist in the use of resources. For all lakes, high levels of diet overlap were observed among genera and trophic guilds, mainly among detritivores. Our results suggested that Chironomidae larvae of these lakes presented well differentiated trophic habits, and showed a moderate diet overlap within detritivores and carnivores. Rev. Biol. Trop. 66(1): 136-148. Epub 2018 March 01.

Los agroecosistemas cafetaleros modernos y su relación con la conservación de mariposas en paisajes fragmentados / Modern coffee agroecosystems and their relationship with butterflies conservation in fragmented landscapes

Resumen El cambio de uso del suelo por la intensificación de la agricultura contribuye a la fragmentación de los bosques tropicales y la pérdida de la biodiversidad. En este sentido, a diferencia de los sistemas agroforestales (SAF) tradicionales, los SAF modernos son considerados de poca importancia para la conservación de la biodiversidad de los fragmentos de bosque. Sin embargo, existe una tendencia al establecimiento de SAF modernos. Debido a la sensibilidad a los cambios ambientales, se evaluó la diversidad de mariposas en SAF modernos de Coffea arabica y Erythrina poeppigiana (CP) y en combinación con Musa spp. (CPM) o Cordia alliodora (la única especie nativa de los SAF) (CPL), además de fragmentos de bosque muy húmedo premontano (FR) en el Corredor Biológico Volcánica Central-Talamanca, Costa Rica. En seis sitios representativos de cada sistema se establecieron tres transectos paralelos de 80 m cada uno y distanciados a 25 m entre los mismos. Cada cafetal y fragmento de bosque fue muestreado durante 1.5 horas en total para el registro de mariposas. Durante tres fechas de muestreo, se obtuvo un esfuerzo de muestreo de 4.5 horas/sitio y 27 horas en cada SAF y en FR. CP y CPM juntos tuvieron una composición de especies de mariposas diferente a la de CPL y FR. CP y CPM juntos resultaron con las especies de áreas abiertas Hermeuptychia hermes y Anartia jatrophae como indicadoras. CPL resultó con las especies de bosques secundarios Heliconus erato petiverana y Pareuptychia ocirrhoe como indicadoras. Por el contrario, FR resultó con diversas especies indicadoras típicas de bosques continuos tales como Pierella helvina incanescens, Caligo eurilochus y Morpho peleides limpida. Además, la riqueza de especies en FR fue mayor en relación a los SAF. Sin embargo, entre los SAF, CPL resultó con la mayor diversidad (Exp(H')) de especies de áreas cerradas que CP. Así mismo, CPM tuvo una mayor abundancia de mariposas frugívoras que CP y CPL. En bosques fragmentados, los cafetales con sombras exóticas pueden ser mejores hábitats para mariposas de bosques si se combinan con árboles nativos y/o frutales.

Abstract Land use change by the intensification of agriculture contributes to tropical forest fragmentation and biodiversity loss. In this sense, in comparison with traditional agroforestry systems (AFS), modern AFS are considered irrelevant for the conservation of biodiversity of tropical forest fragments. However, there is an increasing trend toward the establishment of different types of modern AFS. Owing to the sensitivity to environmental changes, we evaluated the biodiversity of butterflies in AFS with Coffea arabica and Erythrina poeppigiana (CP), and intermixed with Musa spp. (CPM) or Cordia alliodora (the only native species of AFS) (CPL), as well as premontane very humid forest fragments in the Volcánica Central-Talamanca Biological Corridor, Costa Rica. In six representative sites of each system we set up three parallel 80 m line-transects, separated by a distance of 25 m. Each coffee farm and forest fragment (FR) was surveyed during 1.5 hours to record butterflies. All sites were sampled once a month from May to July 2007. We obtained 4.5 hours of sampling/site, and 27 hours of sampling/habitat. Both CP and CPM together had a butterflies' species composition which differed from CPL and FR. The indicator species of both CP and CPM together were Hermeuptychia hermes and Anartia jatrophae which are typical of open areas. CPL resulted with the species of secondary forests Heliconius erato petiverana and Pareuptychia ocirrhoe as indicators. In contrast, FR resulted with several indicator species typical of closed canopy forests such as Pierella helvina incanescens, Caligo eurilochus, and Morpho peleides limpida. Moreover, the richness of species was similar among coffee AFS. Furthermore, the richness of species of each coffee AFS was lower in comparison with FR. However, among coffee AFS, CPL harbored higher diversity (Exp(H')) of forest butterflies than CP. Also, CPM was higher in abundance of frugivorous butterflies in relation with CP and CPL. In fragmented forests, coffee farms with exotic shade species combined at least with a native tree or fruit species, can be a better habitat for forest butterflies than those dominated by an exotic monospecific shade. Rev. Biol. Trop. 66(1): 394-402. Epub 2018 March 01.

Fish beta diversity responses to environmental heterogeneity and flood pulses are different according to reproductive guild

In floodplain communities, beta diversity is influenced by different factors; however, environmental heterogeneity and floods are believed to be particularly influential. The influence of environmental heterogeneity and floods on beta diversity may vary among guilds that present different ecological traits. This study evaluated the correlation between the environmental heterogeneity and flood periods and the beta diversity of trophic and reproductive guilds of fish assemblages. Sampling was conducted quarterly between 2000 and 2012 in the upper Paraná River floodplain. The environmental heterogeneity and period (i.e., dry or flood) were associated with the beta diversity of each guild based on the results of generalized least squares linear models. Only guilds with parental care were influenced by the interaction between environmental heterogeneity and period. The beta diversity of the other guilds presented no relationship between environmental heterogeneity and period. It is likely that species with parental care presented less dispersal capacity, which increased the dissimilarity among assemblages. The higher dispersion rates of the other guilds may be responsible for the lack of relationship between the beta diversity and the environmental heterogeneity and period. In sum, these results suggest that reproductive guilds influence how environmental heterogeneity and floods affect beta diversity variation.(AU)

A diversidade beta é influenciada por diferentes fatores em comunidades de planícies de inundação; contudo, acredita-se que a heterogeneidade ambiental e inundações sejam particularmente influentes. A influência da heterogeneidade ambiental e inundações na diversidade beta podem variar entre guildas que apresentam diferentes características ecológicas. Este estudo avaliou a correlação entre heterogeneidade ambiental, os períodos de inundação e a diversidade beta de guildas tróficas e reprodutivas de peixes. A amostragem foi realizada trimestralmente entre 2000 e 2012 na planície de inundação do Alto rio Paraná. Heterogeneidade ambiental e o período (i.e., seca ou cheia) foram associados à diversidade beta de cada guilda por modelos lineares de quadrados mínimos generalizados. Somente guildas com cuidados parentais foram influenciadas pela interação entre heterogeneidade ambiental e período. A diversidade beta das outras guildas não apresentou relação com heterogeneidade ambiental e período. É provável que espécies com cuidados parentais apresentem menor capacidade de dispersão, o que aumenta a diferença entre as assembleias. As maiores taxas de dispersão de outras guildas podem ser responsáveis pela ausência de relação entre a diversidade beta e heterogeneidade ambiental e o período. Em suma, os resultados sugerem que as guildas reprodutivas influenciam a forma como a heterogeneidade ambiental e as inundações afetam a variação da diversidade beta.(AU)

Seed Dispersal by Bats Over Successional Gradients in the Colombian Orinoquia (San Martin, Meta, Colombia) / Murciélagos dispersores de semillas en gradientes sucesionales de la orinoquia (san martín, meta, colombia)

RESUMEN La dispersión de semillas por fauna juega un papel fundamental en la reproducción vegetal. Los murciélagos son unos de los dispersores de semillas más importantes en los ecosistemas neotropicales. El objetivo en esta investigación fue describir la comunidad de murciélagos y las semillas que potencialmente dispersan, en el gradiente sucesional (sabana, arbustal, borde de bosque y bosque ripario), de una localidad de la altillanura colombiana. Se midió abundancia, riqueza, diversidad de murciélagos y las semillas de sus heces. Se capturaron 534 individuos pertenecientes a cuatro familias y 39 especies. Las especies más abundantes fueron Carollia perspicillata, Artibeus obscurus y Molossus molossus. C. perspicillata y A. obscurus presentaron los mayores valores en el índice de dispersión de semillas (DII). Los registros pertenecen a seis gremios, siendo más abundantes los frugívoros (sedentarios y nómadas). El hábitat con mayor abundancia y riqueza de especies de murciélagos fue el borde de bosque. Se recolectaron un total de 11808 semillas, siendo Cecropia engleriana la especie más abundante. Los estados sucesionales difieren significativamente en abundancia de semillas, mas no en riqueza; mostrando dominancia de determinados géneros de semillas. Se resalta el arbustal como dinamizador de la sucesión, con un flujo potencial de semillas diversas, donde los murciélagos juegan un papel clave para su dispersión, pues aquellos que vuelan sobre las áreas abiertas tienen la misma carga de semillas para dispersar que los hallados en el bosque, evidenciando un potencial de regeneración coadyuvado por una comunidad de murciélagos con una estructura diversa en grupos tróficos y especies.

ABSTRACT Faunal seed dispersal plays a fundamental role in plant reproduction. Bats are one of the most important seed dispersers in Neotropical ecosystems. The objective of this research was to describe the bat community and seeds that are potentially dispersed in a successional gradient (savanna, woods, forest edge and riparian forest) in a locality of the Colombian Altillanura. We measured abundance, richness, and diversity of bats and the seeds found in their feces. 534 individuals belonging to four families and 39 species were captured. The most abundant species were Carollia perspicillata, Artibeus obscurus and Molossus molossus. C. perspicillata and A. obscurus presented the highest values in the seed dispersion index (DII). The records belong to six guilds, the most abundant being frugivores (sedentary and nomadic). The habitat with the greatest bat abundance and richness of species was the forest edge. A total of 11808 seeds with Cecropia engleriana were collected as the most abundant species. Successional states differed significantly in seed abundance but not in wealth, and certain genera showed dominance. Shrubs were highlighted for their dynamic succession and a potential flow of diverse seeds. Here bats play a fundamental role in seed dispersal since those flying over open areas have the same seed load for dispersal as those found in forest, exhibiting a regeneration potential that is contributed to by a bat community having a diverse structure in trophic groups and species.

Comunidades de aves de bosques y pastizales en los afloramientos rocosos aislados del Paraje Tres Cerros, Corrientes, Argentina / Bird communities of forests and grasslands on isolated rocky outcrops in Paraje Tres Cerros, Corrientes, Argentina

ResumenLos afloramientos rocosos aislados se describen como paisajes destacados en biodiversidad debido a la gran variedad de microhabitats, presencia de taxones restringidos y al alto recambio de especies con la matriz circundante. Particularmente los afloramientos rocosos aislados del Paraje Tres Cerros (ARPTC), Corrientes, Argentina, representan un paisaje único en la región, biológicamente fueron poco explorados. Se estudió la comunidad de aves de bosques y pastizales de los ARPTC mediante 136 listas de Mackinnon de diez especies durante la temporada reproductiva y no reproductiva. Se evaluó la diversidad, riqueza estimada y completitud de inventarios, abundancia de gremios tróficos y fenología de las especies. Se comparó estos atributos entre los bosques y pastizales. Se registraron 107 especies donde el bosque es 1.3 veces más diverso que el pastizal. La completitud de inventarios varió de 83 a 90 % en el pastizal y de 88 a 99 % en el bosque. Los hábitats se complementaron en un 62 % indicando una elevada ocurrencia de especies exclusivas. Las aves insectívoras fueron abundantes en ambos ambientes, mientras que las frugívoras en bosques y las granívoras en pastizales. Ambos hábitats son significativamente más ricos en especies en la estación reproductiva por la llegada de los migrantes estivales. Los resultados concuerdan con los patrones generales conocidos para las comunidades de aves y con otros específicos para las comunidades de aves de afloramientos rocosos. El presente estudio resalta la importancia de los afloramientos rocosos aislados de Paraje Tres Cerros para la protección de la biodiversidad de aves a nivel local y regional y representa una herramienta de manejo para la conservación de estos ecosistemas.

AbstractIsolated rocky outcrops can act as patch habitats that host great biodiversity through the diversity of microhabitats, presence of restricted taxa and the high turnover of species in the patch matrix. The isolated rocky outcrops of Paraje Tres Cerros (ARPTC), Corrientes, Argentina, are a unique landscape in the region and biologically little explored. We conducted a study to describe for the first time the bird community of the forest and grassland of the ARPTC, using 136 lists following the ten species Mackinnon method from the breeding and non-breeding seasons. We evaluated the diversity, trophic guilds and phenology of the species, and compared attributes of grassland and forest communities. The total species richness was 107, with the forest being 1.3 times more diverse than the grassland. Completeness of inventories ranged from 83-90 % in the grassland and 88 to 99 % in the forest. The habitat complementarity was 62 %, indicating the presence of several species exclusive of forest and grassland habitats. The trophic structure of communities showed a good representation of insectivorous birds in both habitats. Frugivorous birds were more frequent in the forest and granivorous birds were more frequent in the grasslands. Due to the arrival of migrant species, both habitats had significantly higher richness in the breeding season than in the non-breeding season. Our results showed similar general aspects and patterns for bird communities and with specific studies for bird communities of rocky outcrops. The present study highlights the importance of the isolated rocky outcrops of Paraje Tres Cerros for the protection of local and regional bird biodiversity and represents a benchmark for the management and the protection of these ecosystems.

Isotopic profile and mercury concentration in fish of the lower portion of the rio Paraíba do Sul watershed, southeastern Brazil

The aim of this study was to evaluate the isotopic profile and mercury (Hg) concentrations in fish (carnivores, omnivores and detritivores) in the lower portion of the rio Paraíba do Sul watershed, southeastern Brazil. Carbon (δ13C) isotopic analyses revealed that pelagic and benthonic sources are part of the feeding of the fish from the different guilds (-14.0 to -24.8 ‰). The benthic sources are usually enriched in δ13C (-16.9‰, from watershed runoff) compared to pelagic sources because the phytoplankton, important primary producer that supports several pelagic chains, has δ13C signature lighter (-23.9‰). The nitrogen (δ15N) isotopic signatures indicated that most guilds were at the same trophic position (10.0 to 15.5 ‰), except for pelagic omnivorous fish, which had a lower trophic position. Niche overlap was observed among pelagic and demersal carnivorous fish, demersal omnivorous fish, and demersal detritivorous fish. The lower isotopic niche breadth of pelagic carnivorous fish reveals the specialized resource use by this guild. Hg concentrations (ng g-1 dry weight) differed significantly between demersal carnivorous fish (185.3 dry weight; 27.8 wet weight) and demersal omnivorous fish (277.9 dry weight; 41.7 wet weight) and between pelagic omnivorous fish (197.2 dry weight; 29.6 wet weight) and demersal omnivorous fish due to (1) differences in food sources: guilds that fed on bottom resources were more affected by contamination because the sediment is an important Hg accumulator in the study area, and (2) because of its trophic positions. Considering that the fish consumed prey of similar trophic positions, the guilds did not show a well-defined food hierarchy. Therefore, in this study, there was no clear relationship between Hg and δ15N.

O objetivo deste estudo foi avaliar o perfil isotópico e as concentrações de mercúrio (Hg) em peixes (carnívoros, onívoros e detritívoros) na bacia inferior do rio Paraíba do Sul, sudeste do Brasil. As análises isotópicas de carbono (δ13C) revelaram participação de fontes pelágica e bentônica na alimentação dos peixes das diferentes guildas (-14,0 a -24,8 ‰). As fontes bentônicas são usualmente mais enriquecidas em δ13C (-16,9‰, derivado do escoamento superficial da bacia de drenagem) comparadas às fontes pelágicas pois, o fitoplâncton, importante produtor primário que suporta inúmeras cadeias pelágicas, tem assinatura de δ13C mais leve (-23,9‰). As assinaturas isotópicas de nitrogênio (δ15N) indicaram que a maioria das guildas estava no mesmo nível trófico (10,0 a 15,5 ‰), exceto os peixes onívoros pelágicos cuja posição trófica foi inferior. Observou-se sobreposição de nicho entre peixes carnívoros pelágicos e demersais, onívoros demersais, e detritívoros demersais. A menor amplitude de nicho isotópico dos peixes carnívoros pelágicos revela o uso de recursos especializados por esta guilda. A concentração de Hg (ng g-1 peso seco) diferiu significativamente entre peixes carnívoros demersais (185,3 peso seco; 27,8 peso úmido) e onívoros demersais (277,9 peso seco; 41,7 peso úmido), e entre peixes onívoros pelágicos (197,2 peso seco; 29,6 peso úmido) e onívoros demersais devido a (1) diferenças nas fontes alimentares: guildas que utilizaram recursos de fundo foram mais afetadas pela contaminação pois o sedimento é um importante acumulador de Hg na área de estudo, e (2) por causa das suas posições tróficas. Tendo em vista que os peixes consumiram presas com níveis tróficos semelhantes, as guildas não apresentaram uma hierarquia alimentar definida. Desse modo, no presente estudo não se verificou uma relação clara entre Hg e δ15N.

Temporal dynamic of foraging of epigeic ants in an urban forest fragment / Dinâmica temporal do forrageamento de formigas epigéicas em um fragmento florestal urbano

The present study aimed to investigate the foraging dynamic of an ant community in an urban semideciduous mesophitic forest. A total of 4,297 individuals, distributed in 23 species, seven genera and four subfamilies were sampled in January, April, July and October of 2010. Four ant species guilds were found: leaf cutters, soil-dominant omnivores, soil and vegetation opportunists and large-sized epigaeic predators. There were no significant differences in total of species richness and abundance of individuals in samples among the months evaluated. However, there was a clear substitution (turnover) of species over the months. Nine species were sampled exclusively in the rainy period and five species were present only during the dry period. Thus, the species turnover over the months support the hypothesis that ant communities present a temporal dynamics in their foraging activities even in an urban forest fragment. In general, the abundance of ants foraging on soil was greatest during the months with greater rainfall. However, two species belonging to the guild of opportunistic ants from soil and vegetation doubled the number of foraging individuals in period during the months with less precipitation. These findings support that ant communities, independent of isolation and environment (urban or natural), have temporal dynamics that arise from factors relating to the biology and behavior of the group.

O presente estudo teve como objetivo investigar a dinâmica temporal do forrageamento da comunidade de formigas de um fragmento de mata mesófila semidecídual urbana. Um total de 4.297 indivíduos, distribuídos em 23 espécies, sete gêneros e quatro subfamílias foram coletados nos meses de janeiro, abril, julho e outubro de 2010. Quatro guildas de espécies de formigas foram encontradas: Cortadeiras, Onívoras dominantes de solo, Oportunistas de solo e vegetação e Predadoras epigéicas grandes. Não houve diferenças significativas na riqueza de espécies e na abundância de indivíduos encontrados nas amostras entre os meses avaliados. Entretanto, houve uma clara substituição (turnover) de espécies ao longo dos meses. Nove espécies foram amostradas exclusivamente no período chuvoso e cinco espécies no período seco. Assim, a substituição das espécies ao longo dos meses reforça a hipótese de que comunidades de formigas apresentam uma dinâmica temporal em suas atividades de forrageamento mesmo em um fragmento florestal em área urbana. No geral, a abundância de formigas forrageando no solo foi maior durante os meses de maior pluviosidade. Entretanto, duas espécies da guilda de formigas oportunistas de solo e vegetação dobraram o número de indivíduos forrageando no período de menor precipitação. Estes resultados comprovam que as comunidades de formigas, independente do isolamento e ambiente (urbano ou natural), possuem uma dinâmica temporal na atividade de forrageamento que surgem a partir de fatores relacionados com a biologia e o comportamento de cada grupo e espécie.

Differences in ichthyofauna feeding habits among lateral lagoons and the river channel in a large reservoir / As diferenças nos hábitos alimentares da ictiofauna entre lagoas laterais e o canal do rio em um grande reservatório

In this study, we investigated differences in feeding habits of small-sized ichthyofauna among lateral lagoons and the river channel in a large reservoir. The study was performed in four lagoons and in one sampling site of the main channel in Rosana Reservoir, Paranapanema River, Brazil. The samples were taken in September and November of 2004 and in January, March, May, and August of 2005. Fish were sampled with a 7.5 m2 hand net. Five manual throws were made toward aquatic macrophytes stands. The sampling design favored the collection of small-sized fish fauna (juveniles/small-sized species). The stomach contents of 42 species were analyzed. A total of 183 different items were consumed by fish. These items were grouped in 11 food categories, which were used to classify fish into seven trophic guilds. Aquatic insects were consumed by 32 species and were the predominant feeding item. In the river, the most consumed items were aquatic insects, cladocerans, and phytoplankton, whereas in the lagoons aquatic insects, copepods, and cladocerans were the main items. By comparing each trophic guild, the number of insectivores, algivores, and zooplanktivores species was higher in the lagoons than in the river, and the opposite was found only for omnivore fish. Low niche width in all sites indicates high trophic specialization and low niche overlap between pairs of species. Fish assemblage in the lateral lagoons presents feeding habits distinct from those of the river species, indicating that the coexistence and high abundance of small-sized fish in the sampling sites are explained by their high feeding adaptability, which includes a tendency toward dietary specialization, low feeding overlap, and resource partitioning, along with different temporal resource uses.

O objetivo deste estudo foi avaliar a diferença no hábito alimentar da ictiofauna entre lagoas laterais e o canal do rio num reservatório de grande porte. O estudo foi realizado em quatro lagoas e um ponto no reservatório de Rosana, rio Paranapanema, Brasil. As amostras foram coletadas em setembro e novembro de 2004 e janeiro, março, maio e agosto de 2005. Foram realizados cinco arrastos manuais com uma rede de 7,5m2, junto aos bancos de macrófitas aquáticas. O desenho amostral favoreceu a coleta de peixes juvenis e espécies de pequeno porte. Os conteúdos estomacais de 42 espécies foram analisados. Um total de 183 diferentes itens foi consumido, que foram agrupados em 11 categorias alimentares. Sete guildas tróficas foram estabelecidas. Insetos aquáticos foram consumidos por 32 espécies de peixes, sendo o item alimentar predominante. O padrão alimentar da ictiofauna no rio foi diferente quando comparado as lagoas, como demonstrado na Análise de Correspondência Destendenciada. No rio, os principais itens alimentares foram insetos aquáticos, cladóceros e fitoplâncton, enquanto que nas lagoas os principais itens foram insetos aquáticos, copépodes e cladóceros. Comparando-se cada guilda trófica, o número de espécies de insetívoros, algívoros e zooplanctívoros foi maior nas lagoas do que no rio e o oposto foi encontrado somente para os onívoros. Foram registrados baixos valores de amplitude de nicho, indicando que as espécies apresentam alta especialização trófica, e baixa sobreposição de nicho trófico entre os pares de espécies. Finalmente, este estudo mostra que a coexistência e alta abundância das espécies de peixe de pequeno porte encontrada nas lagoas laterais são explicadas pela adaptabilidade alimentar, o uso temporal dos recursos pelos peixes e pela ampla disponibilidade de alimento existente nas lagoas.

Factors influencing the structure and spatial distribution of fishes in the headwater streams of the Jaú River in the Brazilian Amazon

The aim of this study was to investigate the influence of spatial variation in river channels and habitats on the distribution of fish communities in the headwater streams of the Jaú River System, a blackwater tributary of the Negro River. Collections and measurements were made in 34 headwater streams during the period of November- December, 1998. Fish were captured with fish traps and hand nets along standard reaches of two meanders. Data on benthic habitat structure, stream depth and width were collected along lateral transects in each sample reach. A total of 66 fish species from 24 families were collected and classified into seven trophic guilds: allocthonous insectivore, autochthonous insectivore, general insectivore, piscivore, detritivorous planktivore, detritivorous insectivore and insectivorous piscivore. Variations in the distribution and diversity of bottom substrates were important factors influencing fish community structures in these systems. Also, variation in stream size explained the observed variability in fish communities.

O objetivo desse estudo foi investigar a influência da variação espacial de características físicas do canal dos igarapés e habitats na distribuição das comunidades de peixes em igarapés de cabeceira no sistema do rio Jaú. O rio Jaú é um tributário de águas pretas do rio Negro. Coletas e medidas foram realizadas em 34 igarapés de cabeceira durante os períodos de novembro a dezembro de 1998. Os peixes foram capturados com armadilhas e puçás ao longo de dois meandros em cada local. Um total de 66 espécies de peixes de 24 famílias foram coletados e classificados em sete guildas tróficas: insetívoro alóctone, insetívoro autóctone, insetívoro em geral, piscívoro, detritívoro algívoro, detritívoro insetívoro e insetívoro piscívoro. Variações na distribuição e diversidade do substrato de fundo foram importantes fatores influenciando a estrutura da comunidade nesses sistemas. Sendo assim, variações no tamanho dos igarapés mostraram reflexos nas comunidades de peixes.

Factors influencing the structure and spatial distribution of fishes in the headwater streams of the Jaú River in the Brazilian Amazon / Fatores influenciando a estrutura e distribuição espacial dos peixes nos Igarapés de cabeceira do Parque Nacional do Jaú, Amazônia Central

The aim of this study was to investigate the influence of spatial variation in river channels and habitats on the distribution of fish communities in the headwater streams of the Jaú River System, a blackwater tributary of the Negro River. Collections and measurements were made in 34 headwater streams during the period of November- December, 1998. Fish were captured with fish traps and hand nets along standard reaches of two meanders. Data on benthic habitat structure, stream depth and width were collected along lateral transects in each sample reach. A total of 66 fish species from 24 families were collected and classified into seven trophic guilds: allocthonous insectivore, autochthonous insectivore, general insectivore, piscivore, detritivorous planktivore, detritivorous insectivore and insectivorous piscivore. Variations in the distribution and diversity of bottom substrates were important factors influencing fish community structures in these systems. Also, variation in stream size explained the observed variability in fish communities.

O objetivo desse estudo foi investigar a influência da variação espacial de características físicas do canal dos igarapés e habitats na distribuição das comunidades de peixes em igarapés de cabeceira no sistema do rio Jaú. O rio Jaú é um tributário de águas pretas do rio Negro. Coletas e medidas foram realizadas em 34 igarapés de cabeceira durante os períodos de novembro a dezembro de 1998. Os peixes foram capturados com armadilhas e puçás ao longo de dois meandros em cada local. Um total de 66 espécies de peixes de 24 famílias foram coletados e classificados em sete guildas tróficas: insetívoro alóctone, insetívoro autóctone, insetívoro em geral, piscívoro, detritívoro algívoro, detritívoro insetívoro e insetívoro piscívoro. Variações na distribuição e diversidade do substrato de fundo foram importantes fatores influenciando a estrutura da comunidade nesses sistemas. Sendo assim, variações no tamanho dos igarapés mostraram reflexos nas comunidades de peixes.