Variation of benthic macroinvertebrate communities in streams of three landscapes of South Brazilian grasslands

Introduction: Aquatic ecosystems in southern Brazil are presently under great environmental pressure. Changes in land use result in negative impacts on the ecosystem, affecting the functioning of stream communities. Objective: To compare the benthic macroinvertebrate community richness, abundances and compositions in streams of three South Brazilian grassland landscapes and correlate community patterns with environmental and spatial variables. Methods: Fifteen streams along riparian forests were selected in three landscapes (mean geographical distance of 285.1 km) inserted in the Paraná and Uruguai river basins. Of the three landscapes, two are inserted in conservation units (State Park of Guartelá and Palmas Wildlife Refuge). Invertebrates were collected in 20 kick net points along 150 m of the streams between June and November 2015. Invertebrates were sorted in the laboratory with three sieves and were identified to the lowest taxonomic level possible. The taxa were classified in functional feeding groups of shredders/detritivores, predators, scrapers, collectors/filters and gatherers/collectors. For each stream, we measured the environmental variables width and velocity, pH, dissolved oxygen, and temperature; and the relative cover of forest, grassland, plantation and silviculture in the catchments. Results: We found a total of 1 058 individuals, divided in 53 morphospecies and 34 families. Lower abundance of benthic macroinvertebrates was found in the northernmost landscape with higher temperature, and forest in the catchment. These streams were described mainly by predator groups, while streams inserted in the other two landscapes showed a more diverse guild composition of shredders/detritivores, gatherers/collectors, collectors/filterers, and scrapers. Geographical distance was the main factor influencing differences in community compositions among landscapes. Conclusions: Lower abundance of the northernmost landscape may be explained by (i) the low habitat heterogeneity due to dominance of sandy substrates, and by (ii) the anthropogenic land use of agriculture and extensive cattle breeding in the region that is ongoing and started before the creation of the conservation unit. Additionally, composition of macroinvertebrates may be correlated with environmental differences among landscapes that, in turn, are related to the geographical distance. Therefore, macroinvertebrate community responses may reflect different biota biogeographical histories that can also be associated with historical land use practices.

Introducción: Los ecosistemas acuáticos en el sur deBrasil están actualmente bajo gran presión ambiental. Cambios en el uso de la tierra pueden tener impactos negativos en el ecosistema que afectan el funcionamiento de las comunidades de arroyos. Objetivo: Comparar la riqueza, abundancia y las composiciones de macroinvertebrados bentónicos en arroyos de tres paisajes de pastizales del sur de Brasil, y correlacionar los modelos patrones de comunidad con variables ambientales y espaciales. Metodología: Quince arroyos a lo largo de los bosques ribereños fueron seleccionados en tres paisajes (distancia geográfica media de 285.1 km) insertados en las cuencas fluviales de Paraná y Uruguai. De los tres paisajes, dos están insertados en unidades de conservación (Parque Estatal de Guartelá y Refugio de Vida Silvestre de Palmas). Los invertebrados fueron recolectados en 20 puntos con una red a lo largo de 150 m de las corrientes entre junio y noviembre 2015. En el 2016, fueron clasificados en el laboratorio, con tres tamices de mallas, identificándolos al nivel taxonómico más bajo posible. Así, los taxones se clasificaron en grupos funcionales alimentícios: trituradores/detritívoros, depredadores, raspadores, colectores/filtradores y colectores/recolectores. En cada arroyo fueron medidas las variables ambientales: anchura, velocidad, pH, oxígeno disuelto y temperatura; en las cuencas, la cubierta relativa de bosques, pastizales, plantaciones y silvicultura. Resultados: Encontramos un total de 1 058 individuos, divididos en 53 morfoespecies y 34 familias. Se encontró una menor abundancia de macroinvertebrados bentónicos en el paisaje más septentrional con mayor temperatura, y bosques en la cuenca. Esos arroyos fueron descritos principalmente por grupos de depredadores, mientras que los arroyos insertados en los otros dos paisajes mostraron una composición más diversa de trituradores/detritívoros, colectores/recolectores, colectores/filtradores y raspadores. La distancia geográfica fue el principal factor que influyó en las diferencias de las composiciones comunitarias entre los paisajes. Conclusiones: La menor abundancia encontrada en el paisaje más septentrional puede explicarse por (i) la baja heterogeneidad constatada en el hábitat, debido al dominio de los sustratos arenosos, y por (ii) el uso antropogénico de la tierra: la agricultura y la cría extensiva de ganado en la región que está en curso, la cual comenzó antes de la creación de la unidad de conservación. Además, la composición de los macroinvertebrados puede estar correlacionada con diferencias ambientales entre paisajes que, a su vez, están relacionadas con la distancia geográfica. Por lo tanto, las respuestas comunitarias de los macroinvertebrados pueden reflejar diferentes historias biogeográficas de biotas que también pueden estar asociadas a prácticas históricas de uso de la tierra.

Environmental factors associated to dengue fever occurrence in the Chapecó municipality, Santa Catarina State / Fatores ambientais associados à ocorrência de dengue no município de Chapecó, Estado de Santa Catarina

This study aimed to evaluate the influence of environmental factors on the occurrence of dengue and the spatial distribution of the cases in the municipality of Chapecó, Santa Catarina State. Dengue cases were obtained from the Epidemiological Surveillance Department of Santa Catarina and Epidemiological Surveillance of Chapecó. The data of positive containers for Aedes aegypti were obtained from the Environmental Health Surveillance of the municipality. In 2015 and 2016, Chapecó registered 819 autochthonous cases of dengue. It showed a significant relationship between the number of foci of the vector and the minimum and maximum temperatures, as well as the cases of dengue and the population size of the neighborhoods evaluated. This study indicated a multifactorial influence on mosquito proliferation and the occurrence of viral transmission of dengue in the municipality of Chapecó. It reinforces the need of an interdisciplinary approach to prevent and control this endemic disease (AU)

Epidemiológica de Chapecó. Os dados de recipientes positivos para Aedes aegypti na Vigilância em Saúde Ambiental do município. Em 2015 e 2016 Chapecó registrou 819 casos autóctones de dengue. Apresentou relação significativa entre o número de focos do vetor e as temperaturas mínimas e máximas, assim como os casos de dengue com o tamanho populacional dos bairros avaliados. Este estudo indicou influência multifatorial sobre a proliferação do mosquito e a ocorrência da transmissão viral de dengue no município de Chapecó. Reforça a necessidade de uma abordagem interdisciplinar de ações de prevenção e controle desta endemia (AU)

Effects of understory structure on the abundance, richness and diversity of Collembola (Arthropoda) in southern Brazil / Efeitos da estrutura do sub-bosque na abundância, riqueza e diversidade de Collembola (Arthropoda) no sul do Brasil

The purpose of this study was to investigate the effects of different landscape structures on the understory Collembola community. Four different forest physiognomies were compared: Pinus spp. plantation, Eucalyptus spp. plantation, Araucaria angustifolia plantation, and a remaining native Araucaria forest. Three areas containing two sampling units (25 m x 2 m each) were selected in each forest physiognomy. Understory Collembola collection was done with a 1 x 1m canvas sheet held horizontally below the vegetation, which was beaten with a 1m long stick, seasonally from September 2003 to August 2004. We evaluated the influence of forest physiognomies on the abundance, richness and diversity of Collembola communities. It was also verified if the habitat structure of each physiognomy was associated with the composition of the Collembola community. A total number of 4,111 individuals were collected belonging to the families Entomobrydae and Tomocerida (Entomobryomorpha), and Sminthuridae (Symphypleona), and divided in 12 morphospecies. Pinus plantation presented the highest richness, abundance and diversity of Collembola and it was associated to diverse understory vegetation. The abundance of Entomobrydae and Sminthuridae was associated to the presence of bushes, while Tomoceridae abundance was associated to the presence of trees. The habitat structure, measured through understory vegetation density and composition, plays an important role on the determination of the structure and composition of the Collembola community.

O propósito deste estudo foi investigar os efeitos da estrutura do sub-bosque na comunidade de colêmbolos. Foram comparados quatro ambientes florestais distintos: plantações de Pinus spp., plantações de Eucalyptus spp., plantações de Araucaria angustifolia e áreas de floresta ombrófila nativa remanescente. Para cada fisionomia vegetal houve três áreas com duas unidades amostrais de 25 m × 2 m cada. As coletas foram realizadas com guarda-chuva entomológico, medindo 1 m × 1 m, no período de setembro de 2003 a agosto de 2004. Investigou-se se a abundância, a riqueza e a diversidade da comunidade de colêmbolos foram influenciadas pelas fisionomias vegetais. Também verificou-se se a estrutura do habitat de cada tipo de floresta teve associação com a composição da comunidade de colêmbolos. Foram coletados 4111 indivíduos, pertencentes às famílias Entomobryidae, Tomoceridae e Sminthuridae, divididos em 12 morfoespécies. A plantação de Pinus spp. apresentou maior riqueza, abundância e diversidade de colêmbolos, devido à maior quantidade de vegetação disponível no sub-bosque. A composição de colêmbolos esteve associada aos tipos vegetacionais, com Entomobryidae e Sminthuridae associados aos arbustos, e Tomoceridade às árvores. A estrutura do habitat, medida através da densidade e composição da vegetação do sub-bosque mostrou-se um fator importante na determinação da estrutura e composição da comunidade de Collembola.