Odonate assemblage structure in relation to basin and aquatic habitat structure in Pantanal wetlands

Abstract

Structural properties of aquatic habitats are the basis of several theories produced to explain the functioning of aquatic environments. We predicted a longitudinal change of ecosystem properties along the river, and also that potamal areas of the river are similar to lakes. In rivers with periodic floods we also expect a high degree of similarity due to increased environmental similarity and increase dispersal of component species. Otherwise, rivers must be conceived as a landscape element with an intrinsic hierarchical nature and dispersal among its parts are constrained by this structure. Under this view, we also could expect that different basin or different ''micro-basin'' could present communities that are historically different in their general properties. Here, we aimed to describe odonate larval communities in the Pantanal Mortes-Araguaia river basin in Brazil comparing the composition, species richness and community structure between lakes and rivers, and also the possible differences among river basins. The field work was done in three rivers and three lakes chosen to conform to a paired experiment, each pair in a different river basin. An aggregated sampling unit was used based on Ekman dredge and D-nets replicated on each site. We sampled 936 individuals distributed in 30 genera and a total of 34 morphotypes. There was no difference in species richness among lakes and rivers, but a marked difference among basins. Samples from the same basin present a higher similarity of the species abundance relations than among river or lake samples. We also did not observed differences in composition and community structure between large rivers and lakes, in the same basin. The results supported the concept of structural similarity between large rivers and lakes and the differences observed among basins could indicate historical events in colonization that are shaping communities characteristics.

Composição e distribuição da fauna de Ephemeroptera (Insecta) em área de transição Cerrado-Amazônia, Brasil

“…Este resultado corrobora o trabalho de HEINO et al (2005), no qual o tamanho do córrego foi o principal fator influenciando a estrutura taxonômica de comunidades de macroinvertebrados. Além disso, com o aumento da largura, grandes rios funcionariam como sistemas lênticos, uma vez que grandes volumes de água acabariam homogeneizando o sistema e reduzindo o número de microhábitats (JUEN et al, 2007).…”

Estrutura e composição da comunidade de Trichoptera (Insecta) de rios e áreas alagadas da bacia do rio Suiá-Miçú, Mato Grosso, Brasil

“…A despeito de sua importância para a dinâmica energética dos ambientes onde vivem, levantamentos da entomofauna aquática são escassos na região leste de Mato Grosso (Juen et al, 2007;dias-silva et al, 2010;shiMano et al, 2010;nogueira & Cabette, 2011). Poucos estudos têm avaliado os efeitos dos impactos antrópicos sobre a composição e estrutura das comunidades de Trichoptera (oliveira & FroehliCh, 1997;oliveira & bisPo, 2001;bisPo et al, 2006), e um número ainda mais reduzido têm investigado a fauna de áreas alagadas (MaltChik et al, 2009).…”

Assemblage of immature Odonata (Insecta, Anisoptera) in streams of the Mato Grosso do Sul State: spatial implications

“…At the end of each stretch it were installed blocking nets (10.0 x 2.0 m; 5.0 mm mesh size) to capture the material carried by the flow. The use of these sampling methods is justified on the basis of differences in equipment efficiency on different substrates (Alves & Strixino, 2003;Juen et al, 2007).…”

“…Firstly, to local and regional historical colonization events, which according to Oliveira et al (1997), are the main responsible for the community characteristics, particularly its composition. Secondly, to physical and structural characteristics of the streams, particularly the nature of the substrate, which can control the distribution of immature Odonata (Juen et al, 2007).…”