The aim of the present study was to evaluate how environments modified by conventional logging (CL), reduced-impacted logging (RIL), and pastures (PST) surrounding streams affect environmental ...characteristics and semiaquatic bugs assemblages (Gerromorpha), in the eastern Amazon. The following hypotheses were tested: (i) environmental heterogeneity in streams is lower in areas with more intensive practices (e.g. CL and PST); (ii) species richness and abundance are also lower in streams located in areas with more intensive practices, while more preserved areas have higher richness and abundance; and (iii) species composition shall be affected by changes in forestry practices, thus causing differences between treatments according to species tolerances. We observed that although PST and CL have higher environmental heterogeneity and alpha diversity, respectively, these treatments are associated with the presence of tolerant species and are different from the forest regarding composition (species identity) and species distribution pattern. On the other hand, forest and RIL areas did not have differences regarding habitat characteristics, environmental heterogeneity, alpha diversity, composition and species distribution pattern. This indicates that RIL can maintain a considerable part of habitat integrity and Gerromorpha assemblage composition.
Carnivores have long been used as model organisms to examine mechanisms that allow coexistence among ecologically similar species. Interactions between carnivores, including competition and ...predation, comprise important processes regulating local community structure and diversity. We use data from an intensive camera-trapping monitoring program across eight Neotropical forest sites to describe the patterns of spatiotemporal organization of a guild of five sympatric cat species: jaguar (Panthera onca), puma (Puma concolor), ocelot (Leopardus pardalis), jaguarundi (Herpailurus yagouaroundi) and margay (Leopardus wiedii). For the three largest cat species, we developed multi-stage occupancy models accounting for habitat characteristics (landscape complexity and prey availability) and models accounting for species interactions (occupancy estimates of potential competitor cat species). Patterns of habitat-use were best explained by prey availability, rather than habitat structure or species interactions, with no evidence of negative associations of jaguar on puma and ocelot occupancy or puma on ocelot occupancy. We further explore temporal activity patterns and overlap of all five felid species. We observed a moderate temporal overlap between jaguar, puma and ocelot, with differences in their activity peaks, whereas higher temporal partitioning was observed between jaguarundi and both ocelot and margay. Lastly, we conducted temporal overlap analysis and calculated species activity levels across study sites to explore if shifts in daily activity within species can be explained by varying levels of local competition pressure. Activity patterns of ocelots, jaguarundis and margays were similarly bimodal across sites, but pumas exhibited irregular activity patterns, most likely as a response to jaguar activity. Activity levels were similar among sites and observed differences were unrelated to competition or intraguild killing risk. Our study reveals apparent spatial and temporal partitioning for most of the species pairs analyzed, with prey abundance being more important than species interactions in governing the local occurrence and spatial distribution of Neotropical forest felids.
Changes in riparian vegetation directly affect the entry of allochthonous material into aquatic systems, which is the main source of food and energy for different functional feeding groups (FFG) of ...aquatic insects that play important ecological roles in these ecosystems. Thus, reducing the fragmentation of organic matter affecting the energy flow and food network, interfering with important ecosystem processes that sustain biodiversity. We assess the effects of landscape changes on the composition of the FFG of Ephemeroptera, Plecoptera and Trichoptera (EPT) communities in streams from the Eastern Amazon, a region that exhibits a mosaic of multiple land uses with the prevalence of pastures. We expected that shredders and collectors (gatherers and filterers), naturally prevalent in preserved first-order streams, would be more affected by the loss of riparian vegetation due to their higher dependence on allochthonous food sources than other FFG. We sampled 30 Amazonian streams (1st to 3rd orders) located in the Capim River Basin, Paragominas, Pará, Brazil. The environmental predictors affected the FFG of EPT. Shredders, collector-gatherer, and predators were predominant in streams with more forests that had more living trees in the channel. On the other hand, collector-filter were predominant in streams with more exposed soil and higher water temperatures. We conclude that the preservation of riparian zones is important for the preservation of FFG of EPT and highlighting the effectiveness of using these groups as a tool for biomonitoring environmental quality.
Implications for insect conservation
Our results show that FFG of EPT are affected by environmental conditions. Therefore, the landscape changes caused by the deforestation of the riparian zone imply changes in the composition of the FFG of EPT communities.
•Odonata order contains distinct species groups that share similar responses to environmental change.•Response patterns were related to phylogeny structure and morphology similarity.•The mentioned ...above relationship appears to be complex and no clear.•We believe that other factors as land use historical can effect these Odonata.•Despite this the response patterns had presented some differences between the areas.
A range of factors may determine the structure of ecological communities in time and space, in particular niches, dispersal limits, and the evolutionary history of the species. In the last decades, the traditional focus of community ecology on species diversity and composition have been supplemented by approaches incorporating functional traits and phylogeny. Following this perspective, we evaluated the response pattern of adult damselflies and dragonflies (Odonata) along a gradient of environmental disturbance in Brazilian Amazonia, with the objective of identifying subgroups of species that respond in a similar manner to environmental filters. The study tested the hypothesis that the subgroups of species with similar responses to the environmental gradient are structured phylogenetically and will be morphologically more similar to one another than they are to the other species. Adult odonates were sampled in 98 Amazonian streams, 48 in the region of Santarém and Belterra and 50 in the municipality of Paragominas, both located in the Brazilian state of Pará. The study was based on an ecological niche modeling approach and statistical significance testing methods to identify groups of species. These species groups (latent classes) were then associated with their morphological characteristics (Abdomen Length and Thorax Length) and phylogenetic relationships. Four latent classes, containing 34 species, were generated for each region. The latent classes of the Odonata formed along the gradient of anthropogenic impact had effects of phylogenetic proximity and the species' morphological similarity. Therefore, species belonging to the same latent class are more morphologically similar and have greater similarities in evolutionary history. It seems likely, however, that other processes may be important for the understanding of the structuring of the latent classes, such as intra- and interspecific relationships, environmental plasticity, and the history of land use. Both morphology and phylogeny are important for understanding species' responses to environmental gradients.
•We assessed environmental factors driving larvae and adults of odonates.•We evaluated the congruency between and within life-history stages.•Larvae vs. adult and adult genera vs. species were ...congruent.•Environmental variables were important to explain the congruence pattern.•For operational reasons, adult genera are recommended in biomonitoring programs.
Odonates are suggested as bioindicators of human impact. However, their complex life cycles add additional challenges in the practical use as bioindicators, because the level of taxonomic identification could be dependent on life-history stage and, during their ontogeny, dramatic changes occur in their niche (ontogenetic niche shifts). Considering that larvae and adults have different biological characteristics, which could interfere in their performance as bioindicators, we first sought to understand how similar or different environmental factors affect larval and adult life stages in the Odonata. Second, we assessed the level of congruence between (larvae and adult) and within (adult genera and species) life-history stages, considering the taxonomic and numerical resolution. We sampled larvae and adults in 44 streams distributed along a riverine network in southwest Brazil. Larvae samples constituted 20 sampling units of 1m length each, using the kick sampling method; adults were collected for 1h at each site with a hand net along a 100-m transect parallel to the stream/river banks. The influence of environmental factors on larvae and adult was assessed by redundancy analysis coupled with forward selection. The congruence level between response matrices was determined by Procrustes analysis. Our results revealed that a set of environmental variables explained a portion of larvae and adults distribution and some environmental factors affect both between (larvae and adults) and within (adult genera and species) life-history stages. Larvae and adult were about 54% congruent, regardless of taxonomic level of adults. Abundance of adult genera and species were 94% congruent, but numerical resolution (abundance vs. incidence) decreased the congruency by 10%. Environmental variables could influence larvae and adults individually or via carry-over effects, i.e., larval environmental conditions that could affect adult fitness components or vice versa. In addition, some odonate behaviors, such as female selection of more appropriate habitats for laying their eggs, could also help us to explain our results, because it could determine larvae distribution. In a biomonitoring perspective, considering the cost-benefit of taxonomic level and sampling of larvae and adults, our results suggest that abundance of adult genera could be used in biomonitoring programs since they capture, respectively, 94% and 54% of the information carried by adult species and larvae.
The evaluation of the effects of environmental factors on natural communities has been one of the principal approaches in ecology; although, over the past decade, increasing importance has been given ...to spatial factors. In this context, we evaluated the relative importance of environmental and spatial factors for the structuring of the local odonate communities in preserved and altered streams. Adult Odonata were sampled in 98 streams in eastern Amazonia, Brazil. The physical features of each stream were evaluated and spatial variables were generated. Only environmental factors accounted for the variation in the Odonata community. The same pattern was observed in the suborder Zygoptera. For Anisoptera, environmental factors alone affect the variation in the community, considering all the environments together, and the altered areas on their own. As the two Odonata suborders presented distinct responses to environmental factors, this partitioning may contribute to an improvement in the precision of studies in biomonitoring. We thus suggest that studies would have a greater explanatory potential if additional variables are included, related to biotic interactions (e.g., competition). This will require further investigation on a finer scale of environmental variation to determine how the Odonata fauna of Amazonian streams behaves under this analytical perspective.
Anthropic activities are one of the main drivers of change in the environmental characteristics of streams and the diversity of aquatic macroinvertebrates. We evaluated the influence of an anthropic ...gradient (varying degrees of impact) on the genera level alpha and beta diversity of the Ephemeroptera, Plecoptera, and Trichoptera (EPT) in 48 eastern Amazonian streams. These insects were sampled using a dipnet, and the anthropic gradient was represented by the activities observed in the channel and the catchment of each stream. We found that increasing anthropic impact reduced the alpha diversity of the EPT. The Total Beta Diversity (BD
Total
) showed a moderate degree of variation in streams. The streams with the greatest Local Contribution to Beta Diversity (LCBD) had the lowest alpha diversity of EPT, while the genera with the greatest Species Contribution to Beta Diversity (SCBD) were the most abundant and widely distributed among the streams. Thus, the increase in anthropic impacts reduced the alpha diversity of the EPT and indirectly influenced the uniqueness, emphasizing the importance of using different components of the diversity to understand the effects of anthropic impacts on Amazonian streams.
Since early studies about aquatic ecology, it has been found that changes in environmental conditions alter aquatic insect communities. Based on this, the combined study of environmental conditions ...and aquatic insect communities has become an important tool to monitor and manage freshwater systems. However, there is no consensus about which environmental predictors and facets of diversity are more useful for environmental monitoring. The objective of this work was to conduct a scientometric analysis to identify the main environmental predictors and biological groups used to monitor and manage lotic freshwater systems. We conducted a scientometric study on the Web of Science platform using the following words: stream, river, aquatic insect, Ephemeroptera, Plecoptera, Trichoptera, Odonata, Heteroptera, Chironomidae, bioindicator, environmental change, anthropic, and land use. Although most of the environmental predictors employed are local, intrinsic of freshwater systems using local environmental and associated landscape variables is a better strategy to predict aquatic insect communities. The facets of diversity most used are composition and richness of species and genera, which are not efficient at measuring the loss of ecosystem services and extinction of phylogenetic lineages. Although very important, these functional and phylogenetic facets are poorly explored for this purpose. Even though tropical regions are the most diverse globally and are experiencing major losses of native vegetation, these ecosystems are the least studied, a knowledge gap that needs addressing to better understand the effect of anthropogenic activities on the diversity of aquatic insects.
The increasing land use in the Amazon region has resulted in the widespread substitution of forest areas with pasture and bauxite mining. These land uses reduce the forest cover of streams and modify ...their characteristics, reducing the diversity of aquatic insect assemblages. In the present study, we aimed to identify the threshold of the assemblages of the larvae of insects of the orders Ephemeroptera, Plecoptera, and Trichoptera (collectively known as EPT), and adults of the order Odonata, along an environmental gradient of land use and land cover (LULC). We sampled 30 streams along an environmental gradient determined by the proportion of forest, pasture, and bauxite mining observed within the catchment of each stream. We identified 12 taxa associated with forest (nine positively and three negatively) and four negatively associated with pasture. However, no taxa were associated explicitly with the bauxite mining gradient. As forest is converted to pasture, the abundance and frequency of occurrence of the taxa sensitive to pasture are reduced, reflecting their environmental sensitivity and their potential as sentinels of preserved streams. The identification of the thresholds of the EPT and odonates taxa allowed us to determine which of these organisms are positively or negatively associated with the environmental gradient of LULC in Amazonian streams. We hope that the results of the present study can be applied in future biomonitoring programs, particularly for monitoring the response of aquatic insects to the degradation of streams.
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