The Response of Neotropical Dragonflies (Insecta: Odonata) to Local and Regional Abiotic Factors in Small Streams of the Amazon

Abstract

Since the relative role of local and regional abiotic factors on the Odonata diversity in rainforest streams is still poorly understood, we evaluated the effects of these factors on adult Odonata (Insecta) from preserved and altered streams in the Amazonian region. Adult Odonata were sampled in 98 streams in the Eastern Amazon, Pará, Brazil. Six variables were used to measure local environmental factors: habitat integrity index; mean canopy over the channel; and four physical and chemical descriptors of the water. To measure regional environmental factors, six variables were also used: altitude gradient, three bioclimatic variables and two percentage forest variables. In partial redundancy analysis, both abiotic factors (local and regional) were important to explain the variation in the Odonata community. The Odonata community can be influenced by regional and local factors. The relationship between Odonata and the local (e.g., integrity, canopy cover, and physical and chemical descriptors of the water) and regional (e.g., bioclimatic and forest cover variables) environmental variables recorded in this study has important implications for the use of these organisms to monitor small streams of the Eastern Amazon. The scale at which habitat is measured is an important issue in community structuring studies considering the rapid environmental changes. It is of great importance to consider the different scales in studies assessing community structure, once an adequate habitat must meet the ecological needs of all stages of the life of the Odonata.

Aquatic Macrophyte Vegetation Promotes Taxonomic and Functional Diversity of Odonata Assemblages in Intermittent Karst Rivers in the Mediterranean

“…Lotic diversity tends to decrease with increasing flow intermittence, but in such habitats, there is often a compensation with an increase in lentic diversity, including Odonata [6,70]. This is not surprising, as higher numbers of European Odonata prefer lentic habitats or lotic ones with low water velocity, which are characterized by higher habitat heterogeneity [57,74]. One of the species recorded in our study, C. heros, is of international conservation concern.…”

Habitat conditions in streams influence Odonata larval assemblages in the eastern Amazon

“…The variation in Odonata larval assemblages is explained by the composition of the local habitat, supporting our hypothesis. This is a recurring pattern in studies that investigate the effects of environmental change on fish (Montag et al, 2019) and aquatic insect assemblages in tropical streams, such as mayfly, stonefly, and caddisfly assemblages (Siegloch et al, 2017), and adult odonate assemblages (Oliveira-Junior et al, 2019). Although changes in the landscape affect in-stream conditions (Leal et al, 2018), all the evidence cited above, together with our results, suggest that changes at small spatial scales (in-stream) are the ones that most directly affect aquatic diversity.…”

“…Our hypothesis is based on the premise that in-stream environmental conditions are altered in regions that experience anthropogenic pressures and that this affects aquatic insects (Martins et al, 2018;Castro et al, 2019). This is due to a hierarchical mechanism, where climate and dispersal affect metacommunities on a landscape scale, contributing to regional and biogeographic patterns (Brasil et al, 2019), whereas local habitat characteristics are important for the spatial organization on smaller scales (Montag et al, 2019;Oliveira-Junior et al, 2019).…”

A niche‐based gap analysis for the conservation of odonate species in the Brazilian Amazon

“…Outside protected areas, there is robust evidence that it is possible to preserve the diversity of odonates where timber is extracted, provided that logging minimizes the environmental impacts (Calvão, Nogueira, de Assis Montag, Lopes, & Juen , 2016). Even in areas of farming and cattle ranching, the diversity of odonates can be maintained provided the native riparian vegetation is maintained to block the sunlight and guarantee the preservation of the stream microclimate (De Marco et al , 2015; Oliveira‐Junior, Dias‐Silva, Teodósio, & Juen, 2019). Although there is no direct evidence on the potential of SUAs and ITs for the protection of dragonflies and damselflies, deforestation in these areas is typically lower than on private land (Nunes et al ., 2019), which is likely to benefit the more sensitive odonates, which are at a greater risk of extinction and require specific habitat conditions, in particular those found in forest and lotic ecosystems (M. F. A. Araújo, De Marco, Juen, & Torres, 2020; Clausnitzer et al , 2009; Paulson, 2006).…”