Insetos Aquáticos Associados a Macrófitas Submersas com Diferentes Complexidades Morfológicas

The aim of the study was to analyze the diversity and community structure of aquatic insects associated with species of submersed macrophytes with different morphological complexity in relation to leaf structure. Sampling occurred in raining and dry periods at Ribeirão das Anhumas, Américo Brasiliense/SP. Four macrophytes were analyzed: Vallisneria sp., Eleocharis sp., Egeria najas and Ottelia sp. The entomological community was identified up to the family level, and at tribe level for Chironomidae. The community structure was analyzed using diversity indices of Simpson, Equitability evenness, relative participation of functional category and taxa dominance. The dispersion of faunal composition between the different collection periods was analyzed using a n-MDS with Morisita index. The structure of the insect community associated with macrophytes with different structural morphologies was analyzed using structural similarity calculated by the Bray-Curtis index. Seventeen families were identified from five orders, a total of 1642 specimens. The family Hydropsychidae (Trichoptera) presented eudominance (52.6%), followed by the tribe Pentaneurini (Chironomidae) (13.8%) and family Trichoryithidae (Ephemeroptera) (10%). The results showed that there were no large diversity variations in the analyzed macrophyte species and the sampling periods. The predator and collector functional groups were predominant. The n-MDS analysis indicated the absence of seasonal variation and, the similarity analysis indicated that macrophyte E. najas and Otellia sp., presented similar fauna structure, differing from other analyzed species. The results demonstrated that the morphological structure of macrophytes may have different structures of aquatic insect communities.O objetivo deste estudo foi analisar a diversidade e a estrutura da comunidade de insetos aquáticos associadas à macrófitas aquáticas submersas com diferentes complexidades morfológicas com relação às estruturas foliares. As coletas ocorreram em períodos seco e chuvoso, no Ribeirão das Anhumas, Américo Brasiliense/SP. Foram analisadas quatro espécies de macrófitas submersas: Vallisneria sp., Eleocharis sp., Egeria najas e Ottelia sp. A entomofauna coletada foi identificada até o nível de família, com exceção de Chironomidae, identificada até nível de tribo. A estrutura da comunidade foi analisada através dos índices de diversidade de Simpson, Equitabilidade de Pielou, participação relativa de categoria funcional e dominância de táxons. A composição faunística entre os diferentes períodos de coleta foi analisada por meio de uma n-MDS com índice de Morisita. A estrutura da comunidade de insetos associada a macrófitas, com diferentes morfologias estruturais, foi analisada por meio da similaridade, calculada pelo índice de Bray-Curtis. Foram identificadas 17 famílias pertencentes a cinco ordens, de um total de 1642 espécimes. A família Hydropsychidae (Trichoptera) apresentou eudominância (52,6%), seguidas pela tribo Pentaneurini (Chironomidae) (13,8%) e da família Trichoryithidae (Ephemeroptera) (10%). Os resultados demonstram que não houve grandes variações da diversidade entre as espécies de macrófitas analisadas e períodos de coleta. Os grupos funcionais predadores e coletores foram predominantes. A análise de n-MDS indicou ausência de variação entre os períodos de coleta. A análise de similaridade indicou que as macrófitas E. najas e Otellia sp. possuem estrutura faunística similar, diferenciando-se das demais espécies analisadas. Os resultados demonstraram que a estrutura morfológica das macrófitas pode apresentar distintas estruturas de comunidades de insetos aquáticos

Forecasting the impact of an invasive macrophyte species in the littoral zone through aquatic insect species composition

ABSTRACT Invasive macrophytes threaten freshwater ecosystem biodiversity. We analyzed the impact of the invasive white ginger lily (Hedychium coronarium J. König, Zingiberaceae) on aquatic insect assemblages living in the littoral zone of a tropical reservoir. We took aquatic insect samples in the littoral zone on four main vegetal profile banks: white ginger monotypic bank, forest partially invaded, native macrophyte monotypic bank and riparian forest. At each vegetal bank, we measured abiotic variables such as dissolved oxygen, pH, water temperature and depth. We analyzed the aquatic insects through abundance, richness and Simpson diversity. We used the non-Metric Multidimensional Scaling (nMDS) analysis to analyze the spatial distribution of each assemblage, and Analysis of similarities (ANOSIM) to verify differences amongst dissimilarity distances. Additionally, we analyzed the main taxa associated with invasive macrophytes through indicator species analyses using IndVal index. We observed that the invasive macrophyte banks presented higher abundance of associated specimens, as well as lower dissimilarity of aquatic insect assemblages. Additionally, invasive macrophytes shifted the water pH and littoral depth of reservoir banks. The IndVal index indicated eight aquatic insects as indicator species. Labrundinia unicolor Silva, 2013, Ablabesmyia depaulai Neubern, 2013 and Diastatops Rambur, 1842 were indicator species on banks. We concluded that invasion of white ginger lily caused loss of shallow littoral habitat and altered the pH of the surrounding water probably by high decomposition rate and high production of plant biomass. We suggest the use of species of aquatic insects as indicator species to monitor white ginger lily impact in freshwater systems