Resumen: La evaluación de los cambios a nivel edáfico debido a la implementación de diferentes prácticas de manejo requiere el análisis de variables de distinta naturaleza. El objetivo de este trabajo fue determinar las variaciones anuales en propiedades y macrofauna del suelo, y las interacciones entre ambas, en secuencias rotacionales con y sin cultivos de cobertura (CC). Se trabajó en un experimento instalado en la localidad de Zavalla (Santa Fe, Argentina) y los tratamientos estudiados incluyeron CC (vicia y triticale) y barbecho químico como antecesores de maíz y soja, respectivamente. Se determinó carbono orgánico total (COT) y particulado (COP), porcentaje de agregados estables al agua (AEA), pH, parámetros comunitarios de macrofauna hipogea del suelo y abundancia de grupos tróficos. Los CC generaron valores superiores en COP y porcentaje de AEA en comparación con los de barbecho, en tanto que el COT presentó una tendencia de incremento anual en todos los tratamientos. En cuanto a las comunidades de macrofauna, el CC de vicia introdujo cambios favorables en abundancia, riqueza y diversidad luego de su ciclo de crecimiento, mientras que el triticale presentó una respuesta similar al barbecho y con valores inferiores a los de vicia. Los grupos tróficos registraron variaciones estacionales en su abundancia y cambios vinculados con las características de las secuencias rotacionales. Los CC causaron modificaciones en el corto plazo sobre propiedades y macrofauna del suelo debido a la cobertura generada y el aporte de materiales orgánicos.

Abstract: The assessment of edaphic changes due to the adoption of different management practices requires the analysis of different types of variables. The aim of this study was to determine annual variations on soil properties and macrofauna, and the interactions between them, in cropping sequences with and without cover crops (CC). The work was carried out on an experiment installed in Zavalla (Santa Fe, Argentina) and the treatments included CC (vetch and triticale) and fallow before corn and soybean, respectively. We determined soil organic carbon (SOC) and particulate organic carbon (POC), percentage of water stable aggregates (WSA), pH and macrofauna communities’ parameters and trophic groups abundance. Treatments which included CC showed higher values of POC and WSA as compared to fallow ones, while SOC presented an annual increment in all treatments. As regard to macrofauna communities’ parameters, CC of vetch made favorable changes in abundance, richness and diversity after its cycle, while CC of triticale showed a similar response to fallow and values were lower than vetch ones. Trophic groups abundance showed seasonal variations and changes associated with crop sequences characteristics. CC caused short-term changes on soil properties and macrofauna due to the coverage and the contribution of organic materials.

Abstract Data obtained by direct observation of organisms in their natural habitats can provide valuable contributions regarding intra- and inter-specific interactions, as well as spatial distribution and trophic relationships. However, relatively few such data are available for the Neotropical ichthyofauna relative to the great species diversity of this region. We present data on the ichthyofauna in karst environments of the Serra da Bodoquena, Upper Paraguay River basin regarding their categorization into functional trophic groups. We used direct observations that focused on the most frequent feeding tactics and their spatial (vertical and horizontal) distribution in the channel. We observed 83 fish species in 17 functional trophic groups. The greatest species richness was concentrated in the Characidae and Loricariidae in the categories Diurnal Backwater Drift Feeders and Grazers, respectively. Regarding horizontal depth stratification, we found a positive relationship between the association of small fish with the shallow marginal habitats. This work represents a contribution to a region known for its high tourist potential and to the important diversity of the entire ichthyofauna of the Upper Paraguay basin region that requires proper conservation strategies for sustaining these species.

Resumo Dados obtidos pela observação direta dos organismos em seus hábitats naturais podem fornecer valiosas contribuições com relação a interações intra e inter-específicas, além de distribuição espacial e relações tróficas. Entretanto, relativamente poucos dados estão disponíveis no que diz respeito à ictiofauna neotropical dada à grande diversidade dessa região. Apresentamos dados sobre a ictiofauna em ambientes cársticos da Serra da Bodoquena, bacia do alto rio Paraguai e a categorização das mesmas em grupos tróficos funcionais baseada em observações diretas relacionadas às táticas alimentares mais frequentes e à sua distribuição espacial (vertical e horizontal) no canal. Assim sendo, observamos 83 espécies de peixes alocadas em 17 grupos tróficos funcionais. A maior riqueza de espécies concentrou-se nas famílias Characidae e Loricariidae, abrangendo as categorias Catadores Diurnos de Itens Arrastados pela Corrente e Pastadores, respectivamente. Com relação à estratificação horizontal, encontramos a relação positiva entre a associação de peixes de pequeno porte com relação aos hábitats marginais. Esse trabalho representa uma contribuição a uma região conhecida pelo seu alto potencial turístico e à importante diversidade da ictiofauna da região da bacia do alto Paraguai que requer estratégias de conservação adequadas para sustentar essas espécies.

Resumen: Introducción: el ejercicio reduce el dolor y mejora la funcionalidad en pacientes con dolor crónico lumbar y espondilolistesis degenerativa. Sin embargo, no existe a la fecha un consenso sobre la superioridad de algún programa de ejercicio para inducir cambios tróficos de los músculos estabilizadores lumbares, por lo que el objetivo fue comparar el trofismo de estos músculos mediante ultrasonido, con dos programas de ejercicio distintos: estabilización vertebral versus ejercicios flexores. Material y métodos: estudio prospectivo, longitudinal y comparativo, en veintiún pacientes mayores de 50 años, con dolor crónico lumbar y espondilolistesis degenerativa. Se entrenó a los pacientes para la ejecución diaria de ejercicio: estabilización lumbar o ejercicios flexores, los cuales fueron asignados por aleatorización como parte de un ECA en desarrollo. El trofismo muscular fue evaluado mediante ultrasonido al inicio y a tres meses. Las pruebas de U de Mann-Whitney y prueba de Wilcoxon se usaron para comparaciones entre grupos y para correlaciones se usaron los coeficientes de correlación de Spearman. Resultados: todos los pacientes presentaron ganancia en el trofismo de los músculos multífidos a tres meses, pero sin diferencias entre grupos de tratamiento. No se detectaron cambios significativos en el resto de los músculos evaluados. Conclusión: no encontramos diferencia significativa entre los ejercicios de estabilización lumbar y los ejercicios flexores, a tres meses de seguimiento, en términos de los cambios tróficos medidos por ultrasonido de los músculos estabilizadores lumbares.

Abstract: Introduction: exercise programs can reduce pain and improve functionality in patients with degenerative spondylolisthesis and chronic low back pain. However, there is still no consensus surrounding the superiority of any specific routine for exercise-induced trophic changes of lumbar muscles. The aim was to compare the changes in the primary lumbar stabilizing muscle thickness after spine stabilization exercises and flexion exercises in patients with spondylolisthesis and chronic low back pain. Material and methods: prospective, longitudinal and comparative study was carried out. Twenty-one treatment-naive patients with a diagnosis of both chronic low back pain and degenerative spondylolisthesis over the age of 50 were included. A physical therapist taught participants either spine stabilization exercises or flexion exercises to execute daily at home. The thickness of the primary lumbar muscles was measured through ultrasound (at rest and contraction) at baseline and three months. A Mann-Whitney U test and Wilcoxon signed-rank test were performed for comparisons, and Spearman’s rank correlation coefficients were calculated for associations. Results: we did not find statistically between the exercise programs: all patients presented significant changes in the thickness of the multifidus muscle but in none of the other evaluated muscles. Conclusion: there is no difference between spine stabilization exercises and flexion exercises after three months in terms of the changes in muscle thickness evaluated by ultrasound.

Resumen El Bosque Tropical Caducifolio (BTC) es un importante bioma amenazado por el cambio climático y la invasión humana. Los nematodos del suelo pueden ser indicadores de la perturbación del suelo debido a las actividades humanas. Nuestro objetivo fue presentar un primer inventario sobre la biodiversidad de los nematodos en siete sitios sometidos actualmente a diferentes usos del suelo, o con usos anteriores no perturbados durante diez años. Estos sitios están localizados en el BTC cerca de Copala en la región de la Costa Chica de Guerrero, México. Los paisajes del BTC son especialmente heterogéneos en muchos parámetros de suelo y microclima, mientras que los sistemas agrícolas de subsistencia en este bioma son muy diversos y presentan grandes desafíos para el muestreo con replicación. Debido a esto decidimos observar la fauna de nematodos del suelo como un primer paso antes de empezar el análisis de todos los parámetros abióticos potencialmente relevantes. La diversidad a nivel de género osciló entre 12 y 18 taxones para los usos del suelo muestreados, o 27 taxones en total. Las pruebas estadísticas para el análisis de datos sin replicación revelaron diferencias significativas entre los usos del suelo en la diversidad de nematodos, la estructura trófica y la abundancia. Cuatro sitios dejados en descanso por una década después de varios usos fueron estadísticamente diferentes entre sí y con el sitio forestal no perturbado por veinte años. A pesar de las limitaciones metodológicas inherentes a este estudio inicial, planteamos la hipótesis de que, en el BTC, algunos efectos en las comunidades de nematodos pueden persistir durante más de una década después de los impactos antropogénicos de la agricultura de subsistencia. Por lo tanto, las futuras encuestas de nematodos de los ecosistemas derivados de un BTC no solo deberían analizar las propiedades actuales de los sitios de muestreo, sino también documentar los datos relacionados con factores de las actividades humanas en el pasado. Entre estos factores, sugeridos por los resultados de nuestro estudio, se deben incluir niveles de pisoteo humano y pastoreo, así como estimaciones de cantidades de deposición de desechos vegetales acumuladas por cosecha o deshierbe.

Abstract Tropical Deciduous Forest (TDF) is an important biome threatened globally by climate change and human encroachment. Changes in diversity and abundance of soil nematodes can serve as indicators of soil disturbance due to human activities. Our objective was to present a first inventory of the generic biodiversity of soil nematodes in seven TDF sites subjected to different current or decade-old land uses, located near Copala in the Costa Chica region of Guerrero, Mexico. TDF landscapes are especially heterogeneous in many soil and microclimate parameters, while subsistence agriculture systems in this biome are highly diverse and present great challenges for sampling design with replication. We therefore chose to focus on characterizing the soil nematode fauna, as a first step before undertaking detailed analyses of all potentially relevant biotic and abiotic factors. Genus-level diversity ranged from 12 to 18 taxa for the sampled land uses, or 27 total taxa for all samples combined. Statistical tests for data analysis without replication revealed significant differences in nematode diversity, trophic structure, and abundance between land uses. Four sites, left as fallows for ten years after prior human uses, were statistically different from each other as well as from a forest site undisturbed for at least twenty years. Despite the methodological limitations inherent in this initial study, we hypothesize that some effects on nematode communities may persist for more than a decade after the anthropogenic impacts of subsistence farming in TDF. Thus, future nematode surveys in the TDF biome should not only analyze the current properties of sampling sites, but also document data related to factors from past human use activities. Example factors, suggested by the pattern of nematode abundance from the seven sites in our study, include past levels of trampling by human traffic and grazing, as well as estimates of past amounts of plant debris deposition accumulated by harvesting or weeding.

Abstract: The benthic communities of Chilean Patagonia present a high biodiversity in response to the variability of environmental conditions, food sources and habitats. In this study, the epibenthic communities associated with different characteristics of the benthic habitat in the Puyuhuapi fjord were characterized. The information was registered through underwater videos with a remotely operated vehicle (ROV) along the fjord. The results show an epibenthic community with high values of species richness, dominated by suspension feeders. Where the characteristics of the habitat such as depth, inclination and type of substrate were determining factors in the composition and distribution of the epifauna. In this fjord, suspension feeders represent a key trait associated with important ecosystem functions linked to carbon and nutrient cycles. For this reason, the spatiotemporal and functional information of these communities is a fundamental tool for monitoring these ecosystems, especially in fjords with a high impact of anthropic activities such as salmon farming.

Resumen: Las comunidades bentónicas de la Patagonia chilena presentan una alta biodiversidad en respuesta a la variabilidad de las condiciones ambientales, fuentes de alimentos y hábitats. En este estudio se caracterizaron las comunidades epibentónicas asociadas a diferentes características del hábitat bentónico en el fiordo Puyuhuapi. La información se levantó mediante filmaciones realizadas con un robot submarino (ROV) a lo largo del fiordo. Los resultados muestran una comunidad epibentónica con altos valores de riqueza de especies, dominadas por los suspensívoros. Donde las características del hábitat como la profundidad, la inclinación y tipo de sustrato fueron determinantes en la composición y distribución de la epifauna. En este fiordo, los alimentadores en suspensión representan un rasgo clave asociado a importantes funciones ecosistémicas vinculadas a los ciclos del carbono y de los nutrientes. Razón por la cual, la información espaciotemporal y funcional de estas comunidades son una herramienta fundamental para el monitoreo de estos ecosistemas, especialmente en fiordos con alto impacto de actividades antrópicas como la salmonicultura.

Abstract Fish are often used as bioindicators of the presence of potentially toxic metals in aquatic ecosystems. The objective of these study was to quantify the levels of Cd, Cr, Cu, Hg, Pb and Zn in water and sediment samples from the Sorocaba River and musculature and gill samples of seven species of fish (Hoplosternum littorale, Pterygoplichthys ambrosettii, Hypostomus ancistroides, Geophagus iporangensis, Prochilodus lineatus, Psalidodon cf. fasciatus, and Rhamdia quelen. In addition, the Bioaccumulation factor and Bioconcentration factor were obtained. The water and sediment analysis indicates average concentrations of metals below the maximum limit allowed by Brazilian legislation. Results above the legislation were found for chromium, in 18 samples: eight gills and 10 muscles. The trophic group that presented the highest contamination was the iliophages, followed by insectivores. There were no significant differences between the trophic groups in the absorption of the analyzed metals except for Zn and Hg in fish gills. The bioaccumulation factor in the gills and muscles showed that Hg and Zn had the highest values for the sediment in most species studied. Future research is needed to broaden the assessment as fish are consumed and water collection for supply has recently started downstream of the studied area.

Resumo Peixes são frequentemente usados como bioindicadores da presença de metais potencialmente tóxicos em ecossistemas aquáticos. O objetivo deste estudo foi quantificar as concentrações de Cd, Cr, Cu, Hg, Pb e Zn em amostras de água e sedimento do rio Sorocaba e em amostras de musculatura e brânquias de sete espécies de peixes (Hoplosternum littorale, Pterygoplichthys ambrosettii, Hypostomus ancistroides, Geophagus iporangensis, Prochilodus lineatus, Psalidodon cf. fasciatus e Rhamdia quelen), pertencentes a diferentes níveis tróficos. Além disso, foi obtido o fator de bioacumulação e o fator de bioconcentração. A análise de água e sedimento indicaram concentrações médias de metais abaixo do limite máximo permitido pela legislação brasileira. Foram encontrados valores acima da legislação principalmente para o cromo: oito brânquias e 10 músculos. O grupo trófico que apresentou maior contaminação foi o iliófago, seguido pelos insetívoros. Não foi verificado diferenças significativas entre os grupos tróficos na absorção dos metais analisados, exceto para zinco e mercúrio em brânquias de peixes. O fator de bioacumulação nas brânquias e músculos mostrou que Hg e Zn apresentaram os maiores valores para o sedimento na maioria das espécies estudadas. Pesquisas futuras são necessárias para ampliar a avaliação à medida que os peixes são consumidos e a coleta de água para abastecimento começou recentemente a jusante da área de estudo.

Abstract In this study, we assessed the effects of multiple land uses and local habitat variables on the composition of fish functional trophic groups (FTG’s) and on the ecomorphological traits of fish in Amazonian streams. We evaluated land use types and local habitat variables in 26 streams distributed within a land use gradient. Land use and habitat variables affected the composition of FTG’s, as evidenced by the increased abundance of diurnal channel drift feeders in areas with high dissolved oxygen and deeper thalweg. At the same time, diurnal surface pickers, as well as diggers, and ambush and stalker predators were more abundant in streams with higher canopy density. Only habitat variables affected the ecomorphological characteristics of the species. Fish with higher values of relative caudal peduncle length were positively associated with high canopy density, while fish with greater relative mouth width were negatively associated with the variables impact in the riparian zone and cover of fish shelter. The stream fish functional structure was mainly affected by the impacts caused to the local habitat resulting from different land uses. Thus, preserving forest remnants, as well as recovering degraded areas, is essential for the maintenance of aquatic biodiversity in the region.

Resumo Neste estudo, avaliamos os efeitos dos múltiplos usos da terra e de variáveis do habitat local sobre a composição de grupos tróficos funcionais (FTG’s), e nos traços ecomorfológicos, de peixes em riachos amazônicos. Analisamos os tipos de uso da terra e variáveis da estrutura do habitat local em 26 riachos distribuídos dentro de um gradiente de uso da terra. O uso da terra e as variáveis de habitat afetaram a composição de FTG’s, evidenciado pelo aumento na abundância de peixes diurnos que se alimentam de organismos em suspensão na água em áreas com maiores valores de oxigênio dissolvido e profundidade do talvegue. Ao passo que os peixes diurnos catadores de superfície, bem como os escavadores e predadores de emboscada foram mais abundantes em riachos com maior densidade florestal. Apenas as variáveis do habitat afetaram as características ecomorfológicas das espécies. Peixes com maiores valores de comprimento relativo do pedúnculo caudal foram associados positivamente com alta densidade do dossel, enquanto peixes que apresentam maior largura relativa da boca foram associados negativamente com as variáveis impacto na zona ripária e abrigo para peixes. A estrutura funcional da comunidade de peixes de riachos foi afetada principalmente pelos impactos causados ao habitat decorrentes de diferentes usos da terra. Portando, preservar os remanescentes florestais, bem como recuperar áreas já degradadas, é fundamental para a manutenção da biodiversidade aquática na região.

Resumen Objetivo. Con el fin de fortalecer el conocimiento y producción de la granadilla de quijos Passiflora popenovii (Passifloraceae) como una especie promisoria, se evalúo la riqueza, abundancia y composición de los insectos. Alcance. Analizar diversidad y grupos tróficos de la entomofauna, diferenciando los posibles insectos considerados plaga y los benéficos. Metodología. Los muestreos fueron realizados en tres fincas de la vereda Santa María, municipio de Timbío, departamento del Cauca, utilizando trampas tipo Van SomerenRydon, red entomológica y recolección manual. Resultados principales. Se obtuvieron 180 morfoespecies de insectos de ocho órdenes y 55 familias. El orden Díptera presentó la mayor abundancia con un 96,3% del total de los órdenes, mientras que Hymenoptera mostró la mayor riqueza. Se diferenciaron seis grupos tróficos. Conclusiones. El 56,53% de las familias recolectadas fueron fitófagas, considerando que los dípteros Lonchaeidae son potenciales plagas de los botones florales, y están causando pérdidas que sin un manejo adecuado podría incrementarse. El 33,92% fueron enemigos naturales (depredadores, parásitos, parasitoides) y el 7,14% fueron insectos polinizadores, siendo Centris sp., el principal polinizador.

Abstract Objective: In order to strengthen the knowledge and production of the granadilla de quijos Passiflora popenovii (Passifloraceae) as a promising species, the richness, abundance and composition of the insects were evaluated. Scope: Analysis of the diversity and trophic groups of the entomofauna, differentiating the possible insects considered plagues from the beneficial ones. Methodology: The samplings were carried out in three farms in the Santa María village, municipality of Timbío, department of Cauca, using Van Someren-Rydon type traps, the entomological network, and manual collection. Main results: A total of 180 morphospecies of insects of eight orders and 55 families were obtained. The Diptera order presented the highest abundance with 96.3% of the total orders, while Hymenoptera showed the highest richness. Six trophic groups were differentiated. Conclusions: 56.53% of the collected families were phytophages considering that Lonchaeidae Diptera are potential pests of flower buds and are causing losses that without proper management could increase. Natural enemies were 33.92% (predators, parasites, parasitoids) and pollinating insects were 7.14%, being Centris sp., the main pollinator.

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.

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.

ABSTRACT. This work constitutes an effort to evaluate benthic biodiversity in Bahía de Los Ángeles, Gulf of California, Mexico. To characterize macrofauna at the family level, 2 sampling campaigns took place during summer 2013 and winter 2014 at 6 coastal stations. A total of 18,403 invertebrates were collected, 7,880 in summer and 10,523 in winter. These invertebrates were grouped into 6 phyla and 110 families, comprising 39 mollusks, 33 crustaceans, 30 polychaetes, 5 echinoderms, 2 cnidarians, and 1 cephalochordate. In both sampling periods, mollusks were the dominant group, especially in summer, followed by polychaetes and crustaceans, which were more abundant in winter. Ten new records were established for the area. The most abundant trophic groups were deposit feeders and carnivores. This research could be used to evaluate future changes in benthic assemblages in Bahía de Los Ángeles.

RESUMEN. Este trabajo constituye un esfuerzo para evaluar la biodiversidad bentónica en bahía de Los Ángeles, golfo de California, México. Para caracterizar la macrofauna a nivel de familia, se realizaron 2 campañas de muestreo durante el verano de 2013 y el invierno de 2014 en 6 estaciones costeras. Se recolectaron un total de 18,403 invertebrados, 7,880 en verano y 10,523 en invierno. Los invertebrados estuvieron representados por 6 filos y 110 familias, que estaban compuestas por 39 moluscos, 33 crustáceos, 30 poliquetos, 5 equinodermos, 2 cnidarios y 1 cefalocordado. En ambos periodos de muestreo, los moluscos fueron el grupo dominante, especialmente en verano, seguido de los poliquetos y los crustáceos, los cuales fueron más abundantes en invierno. Se establecieron 10 nuevos registros para el área. Los grupos tróficos más abundantes fueron organismos detritívoros y carnívoros. Esta investigación podría ser utilizada para evaluar cambios futuros en ensamblajes bentónicos en bahía de Los Ángeles.

Resumo As barragens reduzem a conectividade longitudinal dos rios e interrompem a migração e a distribuição espacial das espécies, configurando impactos pouco estudados para alguns rios Neotropicais megadiversos. Investigamos a distribuição espacial de espécies de peixes com diferentes características tróficas e reprodutivas para avaliar como grupos funcionais responderam a uma cascata de reservatórios no rio Uruguai, sul do Brasil. Abundância de peixes, biomassa e composição de espécies foram avaliadas em oito locais ao longo do gradiente longitudinal. A assembleia de peixes no trecho superior foi caracterizada principalmente por espécies de pequeno e médio porte em níveis tróficos mais elevados, enquanto que os ambientes localizados mais a jusante apresentaram mais espécies de médio e grande porte, incluindo muitas espécies carnívoras. Espécies com alta fecundidade, migradores sazonais e bagres com fertilização interna foram comuns no curso médio e inferior. Espécies detritívoras dominaram áreas distantes das barragens. A diversidade funcional das assembleias de peixes locais foi maior nas partes inferiores. A cascata de barragens impactou a distribuição dos grupos funcionais das assembleias de peixes locais no rio Uruguai. A alteração da diversidade funcional no curso superior do rio tem consequências potenciais para a dinâmica e serviços do ecossistema, como ciclagem de nutrientes e pesca.

Abstract Dams reduce the longitudinal connectivity of rivers and thereby disrupt fish migration and the spatial distribution of species, impacts that remain poorly studied for some Neotropical rivers from mega-diverse basins. We investigated the spatial distribution of fish species with different trophic and movement/reproductive/size characteristics to assess how functional groups have responded to a cascade of dams on the Uruguai River in southern Brazil. Fish abundance, biomass, and species composition were evaluated at eight locations along the longitudinal gradient. The fish assemblage in the upper stretch was mainly characterized by small and medium-sized species at higher trophic levels, whereas the sites located furthest downstream displayed more medium and large-sized species, including many carnivorous species. Species with high fecundity, seasonal migrants, and catfishes with internal fertilization were common in the river´s middle and lower reaches. Detritivorous species dominated areas distant from the dams. Overall, functional diversity of local fish assemblages was greater in lower reaches. The cascade of dams has impacted the distribution of functional groups of local fish assemblages of Uruguai River. The alteration of functional groups in upper reaches of the river has potential consequences for ecosystem processes and services, such as nutrient cycling and fisheries.

Resumo O tamanho corporal influencia o efeito de indivíduos e assembleias no funcionamento dos ecossistemas e define como estes respondem à alterações ambientais. Investigamos como a estrutura do tamanho corporal de assembleias e grupos funcionais de peixes responde ao uso da terra quantificado em três escalas espaciais (sub-bacia, ripária e local), em 40 riachos do Pampa, sul do Brasil. Para tanto, calculamos média, coeficiente de variação, assimetria e kurtose usando biomassa individual em nível de assembleia e grupo funcional. As respostas do tamanho corporal dependeram da métrica utilizada, do grupo funcional e da escala de uso da terra. Entre os 11 grupos funcionais identificados, apenas cinco mostraram uma resposta clara ao uso da terra. Em geral, a maioria dos grupos mostrou uma assimetria na distribuição em favor de menores tamanhos corporais e uma concentração de tamanhos em uma distribuição estreita e central (alta kurtose) em resposta ao uso da terra quantificado nas três escalas espaciais. Entretanto, as respostas foram complexas e variaram entre grupos funcionais. A consideração de atributos ecomorfológicos e tróficos separadamente por grupo funcional e a avaliação de múltiplas métricas contribuem de forma importante para detectar a influência do uso da terra no tamanho corporal de peixes.

Abstract Body size influences the effect of individuals and assemblages on ecosystem functioning and defines how they respond to ecosystem changes. We evaluated how body size structure of fish assemblages and functional groups respond to human modifications at catchment, riparian and local scales in 40 streams of the Pampa grasslands, southern Brazil. To describe body size structure, we calculated the mean, coefficient of variation, skewness, and kurtosis, using individual biomass data for the entire fish assemblages and separately by functional group. The results suggested that body size response depends on body size metrics, functional group, and the spatial scale of land use. From 11 functional groups, only five showed a clear response to land use. In general, most functional groups had a higher concentration of small sizes (left-skewed) in response to increased land use measured at distinct spatial scales (local, riparian, and catchment), and a greater concentration of sizes in a narrow and central distribution (higher kurtosis). However, the responses were complex and varied between the functional groups. We conclude that considering ecomorphological and trophic features separately by functional group and assessing multiple body size metrics contributed greatly to detecting the influence of land use on fish body size.

Resumo Objetivo Nosso estudo avaliou os efeitos de eventos climáticos extremos e condições ambientais sobre os grupos tróficos (herbívoros e onívoros) de copépodes na planície de inundação do alto rio Paraná. Métodos O zooplâncton foi coletado e copépodes e rotíferos foram analisados em nove ambientes da planície de inundação do alto rio Paraná, durante os anos de 2000 e 2010, períodos que ocorreram os eventos climáticos La Niña (seca) e El Niño (cheia), respectivamente. Resultados Os resultados sugerem que em períodos de seca extrema (La Niña) as variáveis associadas a produtividade atuem como forças determinantes sobre a abundância de grupos tróficos de copépodes devido a contração dos ecossistemas aquáticos. As respostas entre as abundâncias dos grupos tróficos divergem apesar de estarem associados a produtividade do sistema, uma vez que a abundância de herbívoros está associada a clorofila-a e ao fósforo total e dos onívoros à abundância de rotíferos. No período de cheia extrema (El Niño) não foi encontrada relação significativa entre as variáveis ambientais e grupos tróficos. Conclusões Acredita-se que em períodos de extrema seca as variáveis associadas à produtividade atuam como forças determinantes na abundância de grupos tróficos de copépodes devido à contração dos ecossistemas aquáticos. De acordo com os resultados encontrados, sugere-se que outros trabalhos sejam realizados com maior número de eventos extremos para corroborar com nossos resultados e, ainda para extrapolar para outras comunidades aquáticas.

Abstract Aim Our study evaluated the effects of extreme weather events and environmental conditions on the trophic groups of copepods (herbivores and omnivores) in the upper Paraná River floodplain. Methods The zooplankton were collected and Copepods and Rotifers were analyzed in nine environments of the upper Paraná River floodplain during 2000 and 2010, during which time the La Niña (drought) and El Niño (flood) climatic events occurred, respectively. Results The results suggest that in periods of extreme drought productivity-related variables act as determining forces on abundance of copepod trophic groups due to the contraction of aquatic ecosystems. Although the abundance of trophic groups is associated with system productivity, the responses between them differ, since herbivore abundance was associated with chlorophyll-a and total phosphorus and omnivores with rotifer abundance. In extreme flood (El Niño), no significant relationship was found between environmental variables and any trophic group. Conclusions In general, it is believed that in periods of extreme drought the variables associated with productivity act as determining forces on the abundance of trophic groups of copepods due to the contraction of aquatic ecosystems. According to the results found, it is suggested that other works be carried out with a greater number of extreme events to corroborate our results and, and also to extrapolate to other aquatic communities.

Resumen Introducción: El Pacífico Norte de Costa Rica generalmente se considera rico en hábitats y especies marinas. Sin embargo, algunas zonas están sujetas a presiones de pesca que pueden degradar los ecosistemas. El Golfo de Papagayo comprende zonas protegidas y desprotegidas con diversos grados de impacto. Objetivos: Nuestro objetivo fue evaluar el estado de conservación de las comunidades de peces e invertebrados en los arrecifes rocosos y las zonas arenosas de dos bahías desprotegidas del Golfo de Papagayo. Métodos: El estudio se llevó a cabo en las bahías de Cabuyal y Zapotillal, al sur del Parque Nacional Santa Rosa. Desde diciembre 2017 hasta abril 2018, se realizaron un total de 35 transectos paralelos a la costa entre 3-10 m de profundidad. Se identificaron especies de peces e invertebrados y se estimó la biomasa por grupo trófico en los peces, y la densidad en los invertebrados. Resultados: Encontramos un alto número de especies de peces (81) e invertebrados (70) en arrecifes rocosos, lo que indica un ecosistema biodiverso, pero pocas especies de peces en zonas arenosas. La composición de especies difirió entre las dos bahías. La densidad de peces juveniles fue elevada en la bahía de Zapotillal, lo que sugiere que la zona podría ser importante para el reclutamiento y la reproducción. La biomasa de peces fue mayor en zonas arenosas que en arrecifes rocosos y todos los grupos tróficos tuvieron menores biomasas que en otras zonas desprotegidas de la región. En promedio, la biomasa de peces de arrecifes fue de 1.57 ± 0.67 (s.e.) t ha-1, similar a lo reportado anteriormente en el Pacífico Norte de Costa Rica. Por grupo trófico, los piscívoros y planctívoros tuvieron la biomasa más alta en las zonas arenosas y los piscívoros y carnívoros en los arrecifes rocosos. La cobertura media de coral fue baja con 4.09 % ± 2.51 (s.e.), similar a la reportada anteriormente para la región. Conclusiones: Las bahías Cabuyal y Zapotillal en el Golfo de Papagayo son biodiversas en peces e invertebrados. Sin embargo, la zona puede verse afectada por las pesquerías locales y otras actividades humanas, lo que afecta a las poblaciones de peces e invertebrados y formaciones coralinas. Nuestro estudio llena algunos vacíos de conocimiento de la biodiversidad marina en el Golfo de Papagayo que pueden contribuir a la conservación de la vida marina en el Pacífico Norte de Costa Rica.

Abstract Introduction: North Pacific Costa Rica is generally considered rich in marine habitats and species. However, some areas are subject to fishing pressures that could degrade ecosystems. The Gulf of Papagayo comprises protected and unprotected areas with various degrees of impact. Objectives: Our aim was to evaluate the conservation status of fish and invertebrate communities in rocky reefs and sandy areas in two unprotected bays of the Gulf of Papagayo. Methods: The study was conducted at Cabuyal and Zapotillal Bays, south of Santa Rosa National Park. From December 2017 to April 2018, a total of thirty-five transects were done parallel to the coast at 3-10 m depth. We identified fish and invertebrate species and estimated biomass by trophic group in fish, and density in invertebrates. Results: We found a high number of species of fish (81) and invertebrates (70) in rocky reefs, which indicates a biodiverse ecosystem, but few species of fish in sandy areas. Species composition differed between the two bays. Density of juvenile fishes was high in Zapotillal Bay, suggesting that the area could be important for recruitment and breeding. Fish biomass was higher in sandy areas than in rocky reefs and all trophic groups had lower biomass than in other unprotected areas of the region. On average, reef fish biomass was 1.57 ± 0.67 (s.e.) t ha-1, similar to previous reports for Costa Rican North Pacific. By trophic group, piscivorous and planktivorous had the highest biomass in sandy areas and piscivorous and carnivorous in rocky reefs. Mean coral cover was low with 4.09 % ± 2.51 (s.e.), similar to previously reported for the region. Conclusions: Cabuyal and Zapotillal Bays in the Gulf of Papagayo are biodiverse in fish and invertebrates. However, the area may be impacted by local fisheries and other human activities, affecting fish and invertebrate populations, and coral formations. Our study fills some gaps in knowledge of marine biodiversity in the Gulf of Papagayo that can contribute to the conservation of marine life in North Pacific Costa Rica.

Resumen Introducción: Describir los patrones de biodiversidad y los mecanismos que los subyacen es indispensable para afrontar las desenfrenadas presiones sobre los ecosistemas de agua dulce en el trópico. Esto es particularmente relevante en regiones escasamente estudiadas como el escudo guayanés colombiano Objetivo: Describir la estructura taxonómica y funcional de las comunidades de macroinvertebrados, y evaluar su variación a lo largo de escalas espaciales y temporales Métodos: Las comunidades de macroinvertebrados de cuatro ríos fueron muestreadas durante la época seca del 2017 y 2018. Adicionalmente, se evaluaron los patrones de diversidad dentro y entre los ríos y entre diferentes meses de muestreo en uno de los cursos hídricos. Los patrones de diversidad fueron evaluados mediante la comparación de los patrones entre y dentro de los ríos de la diversidad alfa (diferencias en la riqueza y abundancia de taxones entre comunidades) y de la diversidad beta (diferencias en la composición de taxones entre comunidades). La diversidad alfa fue estimada usando los números de Hill, mientras que la diversidad beta se estimó usando los índices de Sørensen y Morisita-Horn y comparada usando un análisis de similaridad (ANOSIM). Resultados: La composición de taxones fue distinta dentro (escala de mesohábitat) y entre los ríos (escala regional). Sin embargo, la composición de FFG cambió entre, pero no dentro de los ríos. La comparación de los números de Hill y de la composición de taxones sugiere que el tipo de mesohábitat es un factor determinante de la diversidad taxonómica pero no de la diversidad de FFG en distintas escalas. En la escala temporal, la diversidad alfa fue baja para los meses con altas precipitaciones (febrero-abril) y alta para la temporada seca (enero). La diversidad beta temporal fue alta para los periodos muestreados y los procesos de anidamiento fueron el componente más notable de la diversidad beta a lo largo del año. Conclusión: Los ríos de la Serranía de la Lindosa albergan una alta diversidad de macroinvertebrados acuáticos. La estacionalidad y las diferencias en la heterogeneidad del hábitat dentro de los ríos parecen determinar los patrones de diversidad observados a diferentes escalas temporales y espaciales. Profundizar en su estudio es necesario para entender el funcionamiento de estos ecosistemas y mejorar la habilidad para generar estrategias de manejo y conservación.

Abstract Introduction: Describing biodiversity patterns and the underlying drivers is relevant for tackling the rampant pressures on tropical freshwaters. This is particularly relevant in scarcely studied regions, such as in the Colombian Guiana shield. Objective: To describe the taxonomic and functional structure of macroinvertebrate communities and assess their variability across spatial and temporal scales. Methods: We sampled the invertebrate communities in four streams during the dry seasons of 2017 and 2018. Additionally, we assessed diversity patterns within and among streams and between different sampling months in one stream. To assess diversity patterns, we compared alpha (differences in taxon richness and abundance within communities) and beta (differences in taxon composition among communities) diversity patterns among and within rivers. Alpha diversity was estimated using the numbers of Hill, while beta diversity was estimated using the Sørensen and Morisita-Horn indices and compared using a similarities analysis (ANOSIM). Results: The taxon composition of the communities was different within (mesohabitat scale) and among streams (regional scale). However, the composition of FFGs changed among but not within streams. The comparison of the numbers of Hill and the taxon composition suggested that the mesohabitat type is a determining factor of the taxonomic but not FFG diversity across scales. At the temporal scale, alpha diversity was low for months with high precipitation (February-April) and high for the dry season (January). The temporal beta diversity was high among sampling periods, being nestedness processes driving beta diversity among years and turnover processes driving beta diversity within years. Conclusion: Streams from Serranía de la Lindosa host a high diversity of freshwater macroinvertebrates. Seasonality and differences in the in-stream habitat heterogeneity seem to determine the diversity patterns observed at different temporal and spatial scales. A deeper study is needed to understand the functioning of these ecosystems and improve the ability to generate management and conservation strategies.