Nestedness of stream insects in Subtropical region: importance of inter-annual temporal scale

Abstract

Stream insects use in different ways the stream habitats which affect patterns of species occurrence on stream. The nestedness is one of these patterns being an ecological mechanism that generates beta diversity. In this study, we verify the effects of temporal environmental variations on nestedness patterns of Chironomidae assemblages on subtropical streams. We collected chironomid larvae during winter and summer during three years (2010, 2011 and 2012) in Brazilian Subtropical low-order streams (Erechim, state of Rio Grande do Sul, Brazil). We measured environmental variables in each stream. To assess if assemblages will show nested patterns intra-and interannual we used a NODF metric. We observed nestedness only in one year, this pattern was due to variation of limnological factors, which are directly associated with climatic conditions (precipitation and water temperature) and agricultural management (e.g. dissolved oxygen and nutrients). Climatological events affect Chironomidae community through the time. The variations on precipitation values could be one of the mainly factors that influence nestedness for this community. Finally, studies on nesting on time scales should consider inter-annual comparisons, as climatic variations are more evident.

Agriculture affects functional diversity of aquatic insects in Subtropical Atlantic Forest streams

“…The dominance of few taxa is a common pattern in biological communities; however, the dominance of some taxa is more evident when the environment is impacted. Studies demonstrate that changes in areas adjacent to streams can cause chemical changes in the water (for example, through the transport of sediments or chemicals) favoring the dominance of tolerant organisms (Hepp et al, 2010;Huiñocana et al, 2020;Hepp et al, 2021). Among the Trichoptera genera, Smicridea and Itaura are widely observed in streams with agricultural use (Breda et al, 2020), while Caenis has been reported as an Ephemeroptera genus tolerant to anthropogenic disturbances (Arimoro & Muller, 2010).…”

Land-use effects on aquatic macroinvertebrate diversity in subtropical highland grasslands streams

“…Overall, macroinvertebrates are a well-studied group in subtropical steams, with the diversity of the group being (i) negatively affected by anthropogenic land use (Barbola et al, 2011;Galeti et al, 2020;Tonello et al, 2021); (ii) pos-itively affected by oxygen concentration and high granulometry heterogeneity (Baptista et al, 2014); (iii) influenced by inter-annual temporal factors (Hepp et al, 2021); (iv) negatively affected by the input of leaf litter chemical compounds resulting from anthropogenic land uses (Loureiro et al, 2018(Loureiro et al, , 2021; and (v) highly similar between neighboring areas (i.e., local scale; Hepp & Melo, 2013;Hepp et al, 2021). It is noteworthy that most of these studies focused on forest streams and only a few studied the macroinvertebrate fauna of subtropical grasslands (Baptista et al, 2014;Hepp & Melo, 2013;Hepp et al, 2021;Loureiro et al, 2018Loureiro et al, , 2021Tonello et al, 2021), few of which were in highland grasslands (Galeti et al, 2020;, Montilla et al, 2022Principe et al, 2015). Similarly, subtropical highland grasslands have been understudied compared to tropical highland grasslands (Callisto et al, 2016(Callisto et al, , 2021Castro et al, 2019).…”

“…Similarly, subtropical highland grasslands have been understudied compared to tropical highland grasslands (Callisto et al, 2016(Callisto et al, , 2021Castro et al, 2019). In general, areas with highly connected environments tend to have similar physical-chemical habitat characteristics, resulting in the same specific macroinvertebrate composition (Rezende et al, 2014b;Hepp et al, 2021). Furthermore, landscapes with low permeability and a disconnected matrix tend to present high dissimilarity in macroinvertebrate composition, thus increasing β diversity (Rezende et al, 2019a).…”