RESUMEN El cambio de uso de la tierra con áreas de bosques nativos convertidas a la agricultura, la ganadería y las plantaciones de bosques exóticos, es el factor principal que afecta la vegetación ribereña y las comunidades acuáticas. El objetivo del estudio fue evaluar las respuestas del ensamblaje de macroinvertebrados acuáticos al cambio en la cobertura ribereña en el bosque protector Murocomba, Valencia, Ecuador. Se realizaron muestreos en las temporadas seca (de junio a diciembre 2014) y de lluvias (diciembre hasta abril 2015) en tres quebradas con diferentes coberturas riparias: bosques nativos Q1-CBN, pastos para agricultura y ganadería Q2-CAG y plantaciones forestales Q3-CPF, en las que se recolectaron muestras de macroinvertebrados acuáticos y se midieron diferentes variables fisicoquímicas in situ. Según el IBF y el BMWP/Col, la mejor condición ecológica se presentó en la quebrada Q1-CBN, y el EPT disminuyó en la quebrada Q2-CAG en la estación lluviosa. El índice de Shannon-Weaver mostró valores más altos en Q1-CBN y Q3-CPF en el período seco, y la dominancia aumentó en Q3-CPF en la temporada de lluvias. Un total de 6 583 macroinvertebrados fueron recolectados. El orden Coleoptera mostró una mayor abundancia en Q1-CBN y Diptera en Q2-CAG, mientras que Hemiptera mostró la menor abundancia en Q3-CPF. Los taxones Psephenidae, Chironomidae, Leptophlebiidae, Veliidae, Simuliidae, Baetidae y Leptohyphidae se asociaron con los valores más altos de sólidos disueltos y pH, así como valores más altos de IBF y valores más bajos de los índices EPT, BMWP y profundidad del canal en Q2-CAG, mientras que Leptoceridae, Elmidae, Ptilodactylidae y Philopotamidae, se asociaron con valores más altos de EPT y BMWP y con mayor profundidad en Q1-CBN y Q3-CPF. Se evidenció una influencia negativa de las actividades antrópicas en las variables fisicoquímicas y la estructura del ensamblaje de macroinvertebrados. Esto indica que la vegetación ribereña es un factor determinante para el establecimiento y la estructura de las comunidades acuáticas.

Abstract Land-use change from native forests to agriculture, livestock and exotic forest plantations is a main factor affecting riparian vegetation and aquatic communities. The aim of this study was to assess responses of aquatic macroinvertebrate assemblages to riparian cover change in Murocomba protective forest, Valencia, Ecuador. Aquatic macroinvertebrates were collected and physicochemical variables were measured during dry (June-October 2014) and rainy (December-April 2015) seasons along three creeks with different riparian cover: native forests Q1-CBN, pasture for agricultural and livestock activities Q2-CAG, and exotic forest plantations Q3-CPF. According to the Macroinvertebrate Family Biotic Index (FBI) and the Biological Monitoring Working Party Index (BMWP/Col) the best conditions existed in the creek Q1-CBN, while the Ephemeroptera, Plecoptera and Trichoptera Index (EPT) decreased in the creek Q2-CAG during the rainy season. The Shannon-Weaver index showed higher values in Q1-CBN and Q3-CPF in the dry period, and the dominance increased in the Q3-CPF in rainy season. A total of 6 583 macroinvertebrates were collected. Trichoptera was the most abundant order and Hidropsychidae the most abundant family. The Coleoptera order showed greater abundance in Q1-CBN and Diptera in Q2-CAG, while Hemiptera showed the lowest abundance in Q3-CPF. Psephenidae, Chironomidae, Leptophlebiidae, Veliidae, Simuliidae, Baetidae and Leptohyphidae were associated with the highest values of total dissolved solids and pH, as well as higher values of IBF and lower values of EPT, BMWP, and depth of the channel in Q2-CAG, whereas Leptoceridae, Elmidae, Ptilodactylidae and Philopotamidae were associated with higher values of EPT, BMWP and depth of the channel in Q1-CBN and Q3-CPF. A negative influence of anthropic activities on the physicochemical variables and structure of the macroinvertebrate assemblages was evidenced. This indicates that the riparian vegetation is a factor that determines the establishment and structure of aquatic communities.

Resumo: Objetivo O foco do presente estudo foi a aplicar dois índices biológicos, baseados nos macroinvertebrados bentônicos (BMWP e ICB RES-P), utilizando o Reservatório de Itupararanga como modelo para determinar as vantagens e desvantagens na aplicação de cada índice nesse ambiente. Métodos A metodologia consistiu em três etapas: 1) coleta de macroinvertebrados bentônicos, determinação in situ das variáveis limnológicas e triagem dos organismos em laboratório, 2) identificação taxonômica dos organismos e 3) determinação dos graus de saprobidade para os pontos de coleta e a eficácia da aplicação do Índice BMWP (Biological Monitoring Working Party score system) e do Índice de Comunidade Bentônica de região profundal (ICB RES-P) criado pela CETESB (Companhia de Tecnologia de Saneamento Ambiental do Estado de São Paulo). Resultados O estudo foi desenvolvido em dois períodos (primavera/verão e outono/inverno) onde 8.841 organismos foram coletados e divididos em 17 famílias. As famílias Chaoboridae (gênero Chaoborus), Chironomidae (subfamílias Chironominae e Tanypodinae) e Tubificidae foram os táxons mais abundantes. O grau de saprobidade obtido para a região do reservatório de Itupararanga, no geral, classificou o reservatório como as β-α mesasaprobic (βms- αms), considerado crítico quanto o teor de matéria orgânica. O índice BMWP foi adaptado para os pontos de coleta e subsequentemente as pontuações foram obtidas classificando o reservatório como de categoria V (qualidade muito ruim). O índice ICB RES-P classificou a qualidade da água nos pontos de coleta do período de primavera/verão como regular, e no período de outono/inverno como boa. Conclusões A partir dos resultados obtidos pode-se concluir que são necessários mais estudos e refinamentos dos componentes de ambos os índices para determinar com eficiência a qualidade da água em reservatórios.

Abstract: Aim The aim of the present study, was to apply two biological indexes based on benthic macroinvertebrates (BMWP and ICB RES-P) using as model the Itupararanga Reservoir to know what the advantages and disadvantages of the application of each index in that environment. Methods The methodology consisted on three stages: 1) macroinvertebrates sampling and determination of limnological variables in situ, and sorting of the organisms in laboratory, 2) taxonomic identification of organisms and 3) determination of the saprobic degree for the collection sites and effectiveness of the application of the BMWP (Biological Monitoring Working Party score system) index and the Benthic Community Index created by CETESB (Environmental Sanitary Company of State of São Paulo) for deep regions (ICB RES-P index). Results The study was performed over two periods (spring/summer and autumn/winter), and 8,841 organisms were sampled and divided in 17 families. The Chaoboridae (genus Chaoborus), Chironomidae (subfamilies Chironominae and Tanypodinae) and Tubificidae families had the most abundant taxa. The saprobic degree of the Itupararanga reservoir region resulted in the general classification of the reservoir as β-α mesasaprobic (βms- αms), considered critical due to its organic charge content. The BMWP index was adapted to the sample points and the scores subsequently obtained ranked the reservoir as category V, representing very poor water quality. The ICB RES-P index classified the sample points in the spring/summer period as having regular water quality, and the autumn/winter period as having good water quality. Conclusions From previous findings, it can be concluded that further study and refinement of the components of both indexes are required in order to effectively assess the quality of water in reservoirs.