Diversity and ecological aspects of aquatic insect communities from montane streams in southern Brazil

Abstract

AIMS: In this study, the diversity of Ephemeroptera, Plecoptera, Trichoptera and Coleoptera communities was surveyed in the Toropi River basin, a watershed localized in a slope region, in southernmost Brazil. The influence of some local abiotic factors on the most common genera was also analyzed. METHODS: Samplings were conducted at 40 sites in 1st-4th order streams, along a short elevation gradient (70-500 m), with a Surber sampler. Water physico-chemical factors, as well as substrate type, were obtained at each site. RESULTS: At all, 5,320 specimens were collected, belonging to 18 families and 52 genera. The caddisflies Austrotinodes and Celaenotrichia, and an undescribed Elmidae, Genus M, are new records for the region. The caddisfly Smicridea was the most frequent genus in the study area. The mayflies Camelobaetidius, Paracloeodes and Americabaetis were influenced by stream order. Smicridea was related to air temperature, while the mayfly Thraulodes was influenced by high levels of electrical conductivity. CONCLUSIONS: The high diversity found in the study area, compared to other Brazilian regions, reflects the environmental heterogeneity in the region. These data show that hydrographic basins in slope areas from extreme Southern Brazil sustain high levels of diversity of aquatic insect communities.

Potential distribution of riffle beetles (Coleoptera: Elmidae) in southern Brazil

“…The main variables were related to climate (precipitation of driest month and precipitation seasonality) and landscape (forest cover, ecoregions and slope) ( Table 2). Montane regions with higher declivity, in turn, promote water oxygenation, an important environmental driver of Elmidae assemblages at local spatial scales (Braun et al 2014a). For instance, precipitation (precipitation of driest month and precipitation seasonality) and variables associated with terrain slope strongly influence water level and discharge.…”

“…In addition, similar subsets of environmental factors were the main drivers of the predicted distribution of most genera. Neoelmis showed high resemblance with Microcylloepus and Heterelmis, and their individuals could be found in litter and inorganic substrates, occurring in shallow waters with high water velocity (Passos et al 2003a(Passos et al ,b, 2007Braun et al 2014aBraun et al , 2014b. niche) similarity among Elmidae taxa in Rio Grande do Sul.…”

“…Thus, a permanent water supply in streams throughout the year promote more diversified Elmidae assemblages. Montane regions with higher declivity, in turn, promote water oxygenation, an important environmental driver of Elmidae assemblages at local spatial scales (Braun et al 2014a). Additionally, a permanent water current downstream is known to contribute to Elmidae dispersal though drift, as well as to other aquatic insects (Bispo et al 2004;Elliott 2008).…”

“…niche) similarity among Elmidae taxa in Rio Grande do Sul. Hexacylloepus and Heterelmis were registered in sites showing large fragments of riparian vegetation, as well as the presence of more than one substrate type (organic and inorganic substrates) (Passos et al 2003a,b;Braun et al 2014aBraun et al , 2018b. Microcylloepus and Macrelmis were also influenced by similar environmental drivers.…”

“…Elmidae taxa have been considered important indicators of environmental integrity, because they are sensitive to changes in the habitat structure and physicochemical conditions of aquatic ecosystems (Brown 1987;Jäch & Balke 2008). In fact, the community structure and the occurrence of many genera are influenced by the presence of native vegetation, water temperature and oxygen content values (Passos et al 2003a,b;Braun et al 2014aBraun et al ,b, 2018a. Studies conducted at restricted spatial scales (i.e.…”