Effects of land use and limnological variables on the dissimilarity of common and rare aquatic insects in Atlantic Forest streams

Abstract

Lotic ecosystems are altered at various spatial scales leading to the simplification of water bodies and the dominance or exclusion of certain organisms. In streams, species may have limitations generated by the environment that result in a more abundant or rare occurrence. Thus, the aim of this study was to evaluate the influence of water physical-chemical variables and land use in the drainage basin on the composition of Ephemeroptera, Plecoptera and Trichoptera (EPT) assemblages in the streams of Atlantic Forest. We collected water samples and aquatic insects from 18 streams in Atlantic Forest in southern Brazil. We evaluated the relationship between physical-chemical variables of water and land use and the dissimilarity of EPT assemblages in three different situations: (i) matrix with all organisms collected, (ii) matrix containing only common genera and (iii) matrix containing only the rare genera. We collected 6 023 EPT larvae from 41 genera; 62 % of the individuals belonged to the order Trichoptera, 32 % to the order Ephemeroptera and 6 % to the order Plecoptera. The most common organisms (10 genera) accounted for 86 % of the total abundance of identified individuals. On the other hand, rare genera corresponded to 76 % of the total richness, but only 6 % of the total abundance. For the three matrices studied, the pH, electrical conductivity and riparian vegetation were correlated with the dissimilarity matrix of the three biological datasets used. In our study, we observed that the pH, electric conductivity, exposed soil and riparian vegetation variables were the most important for the dissimilarity of the EPT assemblages. In addition, our results demonstrated that variables at different scales (stream and riparian zone) structure stream insect assemblages.

Effects of spatial distances on the assemblage dissimilarity of macroinvertebrates with different dispersal pathways and abilities in southern Brazilian streams

“…For the total macroinvertebrate assemblage, the partial Mantel tests detected stronger associations between environmental and compositional dissimilarities rather than geographic distances. In general, our results agree with those of previous authors that found that environmental conditions can play a major role rather than spatial distance in structuring the composition of stream macroinvertebrates (Astorga et al, 2012; Brown & Swan, 2010; Cañedo‐Argüelles et al, 2015; Maloney & Munguia, 2011; Ongaratto et al, 2018). In fact, reviews on the metacommunity organization of stream macroinvertebrates stress that environmental conditions are the main drivers of their composition, while spatial structure accounted by dispersal limitation can be related to specific features of the study region (Brown et al, 2011; Brown & Swan, 2010; Heino et al, 2015).…”

“…The composition of Chironomidae and Ephemeroptera larvae is highly responsive to local environmental conditions. Several studies conducted in southern Brazil showed that water quality (pH, EC), land use and substrate type are important drivers of composition of their assemblages (Floss, Kotzian, & Spies, 2012;Ongaratto et al, 2018;Salvarrey, Kotzian, Spies, & Braun, 2014). In addition, adult Chironomidae have an active flight in the adult stage, and overland dispersal can occur through wind (Johnson, 1969).…”

“…The observed effect of WD and OD can also vary among study areas with different environmental settings. For instance, in watersheds with reduced or absent riparian vegetation cover, insects can fly laterally and thus farther away, reducing the similarity in community composition (Ongaratto et al, 2018). In turn, in streams running through deep valleys or with wide riparian vegetation, insect dispersal will most likely be confined to the riparian corridors (Petersen et al, 2004).…”

Effects of Environmental Variables and Habitat Integrity on the Structure of the Aquatic Insect Communities of Streams in the Cerrado-Caatinga Ecotone in Northeastern Brazil

“…The pH was an important filter of the structure of the EPT community, and gradients of this variable are known to be an important factor determining the formation of the communities of other groups of aquatic insects (Brasil et al 2018, Ongaratto et al 2018, Ridl et al 2018. Gradients in the pH of the water have been associated with alterations in rainfall patterns, which may change the amount of dissolved solid matter added to the water, which is also dependent on the conditions in the area surrounding the stream (Pérez 2003, Juen et al 2016).…”

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

“…Environmental assessment of aquatic invertebrate responses to anthropogenic disturbance helps to understand which factors drive community structure changes (Hepp et al, 2016;Castro, Dolédec, & Callisto, 2018;Ongaratto, Loureiro, Restello, & Hepp, 2018). Aquatic ecosystems in subtropical Brazil are presently under intense environmental pressure due to riparian vegetation suppression and allochthonous inputs from watercourses' surroundings (Ferreira, Cyrino, Duarte-Neto, & Martinelli, 2012).…”