Odonate Assemblages Research Articles

Dragonflies (Odonata) from the Taquari River valley region, Rio Grande do Sul, Brazil

A survey of Odonata was carried out in the central region of the state of Rio Grande do Sul: the Taquari River valley. This region was originally covered by deciduous and Semi-deciduous Atlantic Forest, which today only exist in a highly fragmented environment mainly due to agricultural activities. Our survey was conducted in 12 municipalities from this region, between March 2011 and April 2013. Aiming a general overview of the species composition, our sampling sites included lakes, bogs, small streams and river sections, all inside or surrounded by small forest fragments or forest areas. Fifty species of Odonata were collected comprising 29 genera and seven families. The dominant families were Libellulidae (40%) and Coenagrionidae (36%), while Aeshindae, Gomphidae and Lestidae each only comprise 6% of the total number of species. The findings revealed the presence of a highly diverse odonate assemblage, mainly represented by generalist species in human disturbed fragments and a few forest specialist species in the best preserved remnants only.

Neotropical dragonflies (Insecta: Odonata) as indicators of ecological condition of small streams in the eastern Amazon

AbstractSensitive and cost‐effective indicators of aquatic ecosystem condition in Amazon streams are necessary to assess the effects of anthropogenic disturbances on those systems in a viable and ecologically meaningful manner. We conducted the present study in the municipality of Paragominas, state of Pará, northern Brazil, where we sampled adult dragonflies in 50 100‐m‐long wadeable stream sites in 2011. We collected 1769 specimens represented by 11 families, 41 genera and 97 species. The suborder Zygoptera contributed 961 individuals and Anisoptera 808. Among the 97 recorded species, nine were classified as useful indicators of ecological condition, with four species being associated with more degraded streams (three Anisoptera, one Zygoptera) and five with more preserved streams (all were Zygoptera). Anisoptera (dragonflies) tend to provide more useful indicators of more degraded environments because they have more efficient homeostatic mechanisms and are more mobile, enabling them to tolerate a wider range of environmental conditions. By contrast, Zygoptera (damselflies) tend to provide a more useful role as indicators of more preserved environments and high levels of environmental heterogeneity because of their smaller body sizes and home ranges and greater ecophysiological restrictions. We conclude from our assessment of this low‐order Amazonian stream system that (i) the occurrence of specific odonate species is strongly associated with the configuration of riparian vegetation, (ii) agricultural activities appear to be the main factor determining changes in the composition of odonate assemblages and (iii) these insects can act as useful indicators of the ecological consequences of riparian habitat loss and disturbance. Because generalist species invade moderately degraded areas, those areas may have high species richness but host few species of Zygoptera. Therefore, preserving dense riparian vegetation is necessary to maintain aquatic ecological condition, and that condition can be rehabilitated by planting new trees. Both require enforcing existing environmental regulations, various types of incentives and educating local communities.

Does the damming of streams in the southern Amazon basin affect dragonfly and damselfly assemblages (Odonata: Insecta)? A preliminary study

Our goal was to investigate whether the loss of riparian forests alters the structure of assemblages and populations of dragonflies and damselflies. We tested the hypothesis that the composition of the odonate assemblages found upstream from dams are significantly different from those found downstream of these barriers. To test the hypothesis, we investigated stream sectors upstream and downstream of three dams located at the extreme of the southern Amazon basin, in the Brazilian state of Mato Grosso. We collected 111 adult odonates, 45 upstream and 69 downstream, representing 18 species, 12 upstream and 10 downstream. The most abundant species was Epipleoneura williamsoni Santos, 1957 (n = 41, 36.9%), followed by Epipleoneura metallica Racenis, 1955 (n = 20, 18%) and Hetaerina curvicauda Garrison, 1990 (n = 17, 15.3%). Statistical ordination separated the different sectors, with the greatest dissimilarity being found between the upstream and downstream I (DS I), and our hypothesis was further supported b...

Changes in occurrence, richness, and biological traits of dragonflies and damselflies (Odonata) in California and Nevada over the past century

Increases in water demand, urbanization, and severity of drought threaten freshwater ecosystems of the arid western United States. Historical assessments of change in assemblages over time can help determine the effects of these stressors but, to date, are rare. In the present study, we resurveyed 45 sites originally sampled in 1914–1915 for Odonata (dragonflies and damselflies) adults throughout central California and northwestern Nevada, USA. We examined changes in species occurrence rates, taxonomic richness, and biological trait composition in relation to climate changes and human population increases. While species richness at individual sites did not change significantly, we found that odonate assemblages have become more similar across sites. Homogenization is a result of the expansion of highly mobile habitat generalists, and the decline of both habitat specialists and species with an overwintering diapause stage. Using a multi-species mixed-effects model, we found that overall occurrences of Odonata increased with higher minimum temperatures. Habitat specialists and species with a diapause stage, however, occurred less often in warmer regions and more often in areas with higher precipitation. Habitat specialists occurred less often in highly populated sites. Life history traits of Odonata, such as dispersal ability, habitat specialization, and diapause, are useful predictors of species-specific responses to urbanization and climate change in this region.

Aquatic insects indicate terrestrial habitat degradation: changes in taxonomical structure and functional diversity of dragonflies in tropical rainforest of East Kalimantan

As a group of freshwater invertebrates, dragonflies (Odonata) are commonly used as ecological indicators of freshwater ecosystems. Despite earlier studies suggesting that adult odonates may be good indicators for complex changes in a landscape, the utility of odonates as suitable indicators to indicate health of non-aquatic (forest) habitats remains poorly understood. This study analyses the adult dragonfly assemblage pattern against spatial and temporal disturbance characteristics in Indonesia's Sungai Wain Protection Forest. The core of this reserve comprises one of the few remaining fragments of primary rain forest along the East Kalimantan coast, whereas the rest of the reserve is covered by secondary forest, scrub, grassland, and farmland. Adult dragonfly assemblages at individual sampling sites were analysed in relation to (1) their intensity, (2) frequency of human-caused disturbances, and (3) the time since the last such disturbance, while controlling random variables (type of aquatic and terrestrial habitat) were removed. This study tests the effect of these factors on (1) species richness, (2) proportion of Zygoptera, (3) proportion of forest specialists, and (4) proportion of Borneo's endemics. The human-induced disturbances in the rain forest resulted in pronounced changes in the taxonomical composition and functional diversity of the odonate fauna. Results reported here demonstrate that gradual changes in the odonate assemblages correspond to the degree of anthropogenic influences on forest environments. Adult odonates comprise an appropriately sensitive and versatile indicator group for identifying changes in terrestrial forest environments as well as in freshwater habitats.

Associations of Dragonflies (Odonata) to Habitat Variables within the Maltese Islands: A Spatio-Temporal Approach

Relatively little information is available on environmental associations and the conservation of Odonata in the Maltese Islands. Aquatic habitats are normally spatio-temporally restricted, often located within predominantly rural landscapes, and are thereby susceptible to farmland water management practices, which may create additional pressure on water resources. This study investigates how odonate assemblage structure and diversity are associated with habitat variables of local breeding habitats and the surrounding agricultural landscapes. Standardized survey methodology for adult Odonata involved periodical counts over selected water-bodies (valley systems, semi-natural ponds, constructed agricultural reservoirs). Habitat variables relating to the type of water body, the floristic and physiognomic characteristics of vegetation, and the composition of the surrounding landscape, were studied and analyzed through a multivariate approach. Overall, odonate diversity was associated with a range of factors across multiple spatial scales, and was found to vary with time. Lentic water-bodies are probably of high conservation value, given that larval stages were mainly associated with this habitat category, and that all species were recorded in the adult stage in this habitat type. Comparatively, lentic and lotic seminatural waterbodies were more diverse than agricultural reservoirs and brackish habitats. Overall, different odonate groups were associated with different vegetation life-forms and height categories. The presence of the great reed, Arundo donax L., an invasive alien species that forms dense stands along several water-bodies within the Islands, seems to influence the abundance and/or occurrence of a number of species. At the landscape scale, roads and other ecologically disturbed ground, surface water-bodies, and landscape diversity were associated with particular components of the odonate assemblages. Findings from this study have several implications for the use of Odonata as biological indicators, and for current trends with respect to odonate diversity conservation within the Maltese Islands.

Odonata communities in retrodunal ponds: a comparison of sampling methods

Dragonflies are commonly used as indicators of environmental quality and different methods have been employed to monitor odonate assemblages, such as surveys of all adults, evaluations based on breeding adults, sampling of larvae and collection of exuviae. Results obtained with different sampling methods may not be interchangeable, as the different life stages (e.g. larvae, adults) differ in mobility (aquatic, aerial) and as they are subjected to different ecological constraints. Therefore generalization about habitat quality based on only one survey method might be questionable. Additionally, detectability of species might vary when different methods are used. In this study, nine retrodunal ponds in the Migliarino, San Rossore, Massaciuccoli Regional Park (Tuscany, Italy) were repeatedly and contemporaneously sampled during May–September 2008 with the following methods: all adults, breeding adults, larvae and exuviae. In total, 22 species were detected and the results showed that the four methods were no...

Congruence of biodiversity measures among larval dragonflies and caddisflies from three Canadian rivers

Summary1. Scientists tasked with collecting taxon richness and assemblage variation data for conservation purposes have identified biomonitoring studies as potential sources of information. This approach assumes that biodiversity patterns revealed by biomonitoring reflect those of the wider community, an assumption not thoroughly tested in riverine ecosystems.2. We compared patterns of taxon richness and assemblage variation in an important biomonitoring group (Trichoptera) with a group with high conservation significance (Odonata) at 34 sites across three fifth‐order catchments. We also explored the effect of abundance on observed patterns by rarefying the larval Trichoptera data set.3. Our results indicate that Trichoptera do not fully reflect site‐scale taxon richness or assemblage variation in Odonata. The magnitude of odonate assemblage variation was much greater than that of Trichoptera for one of the catchments. Odonata and Trichoptera richness was moderately correlated in two catchments, while assemblage variation was strongly correlated in another pair of catchments. However, comparisons based on rarefied data eliminated differences in the magnitude of assemblage variation and strengthened correlations in richness and assemblage variation, suggesting the lack of congruence in these measures might be due to differences in abundance among groups. Further, incomplete taxonomy may mask additional assemblage variation, particularly in Trichoptera.4. Conservation planning in riverine ecosystems based on proxies derived from biomonitoring data should proceed cautiously until we understand how well the resulting information reflects biodiversity patterns in under‐sampled taxa and habitats. Future studies of biodiversity congruence should consider both richness and assemblage variation as each provides valuable information for conservation‐related decisions. The taxonomic resolution and relative abundance of comparison groups can potentially impact the strength, direction and statistical significance of patterns. Researchers should employ species‐level taxonomy and account for differences in abundance among groups through rarefaction where at all possible and DNA‐based taxonomy methods can support this.

Environmental Characteristics accounting for Odonate Assemblages in Rural Reservoir Ponds in Japan

To clarify the effect of environmental factors on odonate assemblages in rural reservoir ponds, we surveyed the odonate adults (Zygoptera and Anisoptera) in 70 study ponds in Ibaraki Prefecture, Japan, during three sampling periods in 2005. Cluster analysis, indicator species analysis (INSPAN), and non-metric multidimensional scaling (NMDS) were used in combination to determine the relationship between odonate assemblages and environmental variables, i.e., biotic, physicochemical, and regional variables (the types of land use surrounding the ponds). A total of 41 odonate species were recorded in the study ponds, and 24 of them, excluding rare species, were used for each analysis. The study ponds were classified into six groups, and significant indicator species were selected from four of these groups. Examination of the correlation between each environmental variable and NMDS axes 1 and 2 revealed the profound effects of the presence of forest, paddy field, or open area around the ponds on the indicator species composition of each group. It was also revealed that the aquatic vegetation and forests around the ponds provide desirable conditions for the odonates and, in contrast, concrete revetment has a detrimental effect. These results suggest that the recent decrease of forests around ponds and the reconstruction with concrete revetment will have a negative effect on the odonate assemblages in ponds.

Odonata Richness and Abundance in Relation to Vegetation Structure in Restored and Native Wetlands of the Prairie Pothole Region, USA

Over the past couple decades, 2,200,000 ha wetlands and grasslands have been restored in the prairie pothole region, USA. However, many restored and remnant wetlands in the region are dominated by two invasive plant species, reed canary grass ( Phalaris arundinacea ) and cattail ( Typha spp.), which form dense monotypic stands. These restorations are usually evaluated as habitat for waterfowl and other birds; however, there is a need to evaluate their success for invertebrates. Odonata (dragonflies and damselflies) are ideal organisms to include in our evaluations restored wetland habitat quality for both ecological and practical reasons. To examine the association between vegetation structure and odonate assemblages in shoreline vegetation prairie pothole wetlands, we compared odonate richness and abundance in dense, monotypic stands to that vegetation with diverse vertical structure. We also observed the use these two different habitats by odonate species classified as of conservation in Iowa. Odonate species richness was substantially greater in the mixed-structure vegetation than in monotypic stands. A similar trend was found in odonate species with a vulnerable or uncommon conservation status. The number occurrences species conservation concern was four times greater in mixed than in monotypic vegetation. A comparison our data to those collected in the 1990s for one monotypic vegetation site further supported this conclusion. Many odonate species are targets for conservation and can readily benefit from wetland restoration and reconstruction if the sites are managed for proper vegetation structure.

Efficiency of buffer zones around ponds to conserve odonates and songbirds in mined peat bogs

Patch isolation resulting from habitat loss and fragmentation generally has detrimental effects on associated species. Peatlands may be especially sensitive to such effects because peat mining results in drastic changes in the hydrology of natural remnants. This study aimed to assess the efficiency of conservation zones surrounding ponds in mined bogs for two taxa: songbirds and odonates. We compared songbird distribution and odonate assemblages between ponds isolated by peat mining (n=6–12) and control ponds (n=11–13) located in natural bogs. Birds did not show major responses to pond isolation, whether in terms of their relative abundance or reproductive activity. However, longer‐term data would be required to confirm this trend. In contrast, odonate abundance, as estimated from exuviae, was higher in natural ponds than in isolated ones. Some taxa, especially bog specialists, were more sensitive than others. Hence, pond isolation by peat mining significantly altered the structure of odonate assemblages. Pond size also influenced odonate abundances and distribution. Effective conservation of bog ponds should account not only for variations in the response of different taxa, but also for pond structural diversity, which influence species response to isolation.

Community assemblage patterns of odonates inhabiting a wetland complex influenced by anthropogenic disturbance

Abstract. Many wetland complexes around the world are highly influenced by human activity (chiefly land conversion for agriculture). Measuring the impact of such activity hinges not only upon using appropriate wetland indicator taxa but also upon metrics that are sensitive enough to capture subtle effects. Over a 5‐year period, we quantified the distribution and community structure of odonates (dragonflies and damselflies) occupying a wetland complex in Texas. When using traditional community metrics, there were no significant differences in diversity or evenness in the odonate assemblages in wetlands surrounded by the two dominant regional forms of land use (tilled cropland and grassland). Similarity analyses likewise failed to detect any significant differences in odonate community composition with land use. Discriminant function analysis, however, revealed that species co‐occurrences could be distinguished on the basis of surrounding land use, which indicates that odonate assemblages in these wetlands are structured in a manner that typical community metrics fail to adequately describe. Differences between the approaches are discussed, particularly with regard to the use of presence–absence data.

Relative importance of within‐habitat environment, land use and spatial autocorrelations for determining odonate assemblages in rural reservoir ponds in Japan

AbstractTo clarify the major factors affecting odonate assemblages in rural reservoir ponds among within‐habitat environments, land use around ponds and spatial autocorrelation, we surveyed odonate adults (Zygoptera and Anisoptera) in 70 study ponds in Ibaraki Prefecture, Japan, during three sampling periods in 2005. Redundancy analyses (RDA) for these three factor groups were executed to determine their strength in explaining the odonate species composition. Their relative contributions were also evaluated by the method of variation partitioning. A total of 41 odonate species were recorded in the study ponds, and 24 of them, excluding rare species, were used for our analysis. Summed effects including all three factor groups explained approximately 39% of the variation in odonate species composition. We found that spatial autocorrelation was the most important, though the within‐habitat environment and land use had comparable effects. We conclude that spatial autocorrelation should be considered in this type of analysis, though we could not clearly explain what caused such a spatial structure. Pond area and debris that had accumulated at the bottom of ponds were selected as the within‐habitat environment, and the forests and paddy fields around ponds were selected for land use after the procedure of forward stepwise selection. These results suggest that the recent decrease of forests around the ponds has had a negative effect on the odonate assemblages.

The Odonata of newly constructed ponds with life history and production of dominant species

The species composition of an odonate assemblage from six new ponds in Virginia, USA, was documented, and life histories and production of three dominant odonate taxa (Anax junius (Drury), Gomphus exilis Selys, and Enallagma civile (Hagen)) were determined. The assemblage consisted of 19 species and was numerically dominated by A. junius, G. exilis, E. civile, and libellulids. Production of A. junius, G. exilis, and E. civile was 795 mg DW m−2 yr−1, 27 mg DW m−2 yr−1, and 236 mg DW m−2 yr−1, respectively. Coefficients of variation for production of each species were 50 – 77%, which suggests that variance should be considered in production estimates, especially if results are to be compared across studies or habitats. Low density and production of the dominant species in this study may be a result of inadequate densities of food items and limited availability of preferred habitat in the newly created ponds.

Reduction in odonate phylogenetic diversity associated with dam impoundment is revealed using taxonomic distinctness

Taxonomic distinctness is a highly useful index combining species richness and taxonomic (phylogenetic) diversity to detect changes in the taxonomic structure of communities and assemblages. While analysis of an odonate assemblage before and after construction of a hydroelectric impoundment in the state of Hidalgo, Mexico, revealed no significant increase in average monthly species richness (although annual counts were slightly higher for the latter survey), taxonomic distinctness and its variation were reduced. The impoundment converted natural lotic conditions into lentic habitat with more littoral vegetation. Such conditions favored plant-dependent species (mostly in the Zygoptera) with more species per genus and genera per family relative to those not dependent (mostly in the Anisoptera). High ratios reduce the average risk of losing higher taxonomic structure with loss of a species. Reduced taxonomic distinctness and its variation occurred at the expense of the Gomphidae and Corduliidae, and several genera in the Libellulidae having non-plant dependent species that favor inorganic substrate in flowing waters. The results contrast with the common assumption that higher odonate diversity occurs in lentic habitats. Seasonal patterns of taxonomic distinctness appeared similar between surveys and may reflect reproductive and emergence cycles. The results support the use of taxonomic distinctness and its variation over species richness in ecological assessments and its application in further freshwater research. We encourage its use with aquatic insects, but recommend frequent sampling intervals to account for effects from emergence and reproductive behaviors. These results suggest new and added breadth to the value of taxonomic distinctness in ecological research regarding habitat change.

Odonate assemblage structure in relation to basin and aquatic habitat structure in Pantanal wetlands

Structural properties of aquatic habitats are the basis of several theories produced to explain the functioning of aquatic environments. We predicted a longitudinal change of ecosystem properties along the river, and also that potamal areas of the river are similar to lakes. In rivers with periodic floods we also expect a high degree of similarity due to increased environmental similarity and increase dispersal of component species. Otherwise, rivers must be conceived as a landscape element with an intrinsic hierarchical nature and dispersal among its parts are constrained by this structure. Under this view, we also could expect that different basin or different “micro-basin” could present communities that are historically different in their general properties. Here, we aimed to describe odonate larval communities in the Pantanal Mortes-Araguaia river basin in Brazil comparing the composition, species richness and community structure between lakes and rivers, and also the possible differences among river basins. The field work was done in three rivers and three lakes chosen to conform to a paired experiment, each pair in a different river basin. An aggregated sampling unit was used based on Ekman dredge and D-nets replicated on each site. We sampled 936 individuals distributed in 30 genera and a total of 34 morphotypes. There was no difference in species richness among lakes and rivers, but a marked difference among basins. Samples from the same basin present a higher similarity of the species abundance relations than among river or lake samples. We also did not observed differences in composition and community structure between large rivers and lakes, in the same basin. The results supported the concept of structural similarity between large rivers and lakes and the differences observed among basins could indicate historical events in colonization that are shaping communities characteristics.

Assessing Riparian Quality Using Two Complementary Sets of Bioindicators

Biological indicators are being increasingly used to rapidly monitor changing river quality. Among these bioindicators are macroinvertebrates. A short-coming of macroinvertebrate rapid assessments is that they use higher taxa, and therefore lack taxonomic resolution and species-specific responses. One subset of invertebrate taxa is the Odonata, which as adults, are sensitive indicators of both riparian and river conditions. Yet adult Odonata are not necessarily an umbrella taxon for all other taxa. Therefore, we investigated whether the two metrics of aquatic macroinvertebrate higher taxa and adult odonate species might complement each other, and whether together they provide better clarity on river health and integrity than one subset alone. Results indicated that both metrics provide a similar portrait of large-scale, overall river conditions. At the smaller spatial scale of parts of rivers, Odonata were highly sensitive to riparian vegetation, and much more so than macroinvertebrate higher taxa. Odonate species were more sensitive to vegetation structure than they were to vegetation composition. Landscape context is also important, with the odonate assemblages at point localities being affected by the neighbouring dominant habitat type. Overall, benthic macroinvertebrates and adult Odonata species provide a highly complementary pair of metrics which together provide large spatial scale (river system) and small spatial scale (point localities) information on the impact of stressors such as riparian invasive alien trees. As adult Odonata are easy to sample and are sensitive to disturbance at both small and large spatial scales, they are valuable indicators for rapid assessment of river condition and riparian quality.

Comparison of two Odonata communities from a natural and a modified rainforest in Papua New Guinea

Abstract The Odonata fauna of Papua New Guinea is species-rich, but human population growth and resulting modification of primary rainforests may lead to a loss of valuable habitat and species diversity. In this study, I compared the odonate assemblages of a natural tropical rainforest and a modified forest in order to assess the loss that could result from human forest alteration. I collected odonates and recorded habitat use at both study sites for several weeks. The assemblages were compared with similarity indices, and total species richness was estimated using a jackknife procedure. The natural forest community, with 61 species, had both a higher diversity and evenness than the village community, with 38 species. Altogether I found 78 species of 13 families, of which 21 were shared between the two areas. Among the families with more than one species, Megapodagrionidae and Libellulidae had the highest similarity between the two sites, whereas Coenagrionidae and Platycnemididae had fairly dissimilar co...

Distribution of Adult Odonata Among Localized Wetlands in East-central Mississippi

We measured species richness and composition of adult Odonata and inferred habitat preferences among man-made wetland sites and surrounding tracts of natural bottomland forest. Cumulative species richness and composition were described by proportion coefficients and beta diversity indices. The three man-made sites provided open space resources, and more species were observed in each than in the floodplain forest. Twenty-nine of 42 species documented over a four-month period were observed in only one or two of the four wetlands studied. Large differences in species assemblages between the immediately adjacent ditch and marsh sites were the best evidence for high habitat affinity because distance and structural barriers to movement were absent. Such compositional asymmetry may reflect differential vegetative and reproductive suitability of the habitats. Results suggest that the open-canopy wetlands supported higher diversity of adult Odonata, and that distinct odonate assemblages were found among different habitat types in this flood-plain wetland complex.

Biodiversity of Larval Damselflies and Dragonflies (Insecta: Odonata) in the Lower Mobile/Tensaw Delta, Alabama

Abstract Sixteen species of odonates, representing 9.2% of Alabama's odonate fauna, were collected from flowing waters 10–450 m wide in the poorly surveyed Mobile/Tensaw Delta of Baldwin County over a one-year period. The number of species was positively correlated with the number of specimens per site, with sites nearest Mobile Bay having fewer species, possibly reflecting higher salinities. Odonate assemblages in large flows of the Delta are unpredictable in terms of species co-occurrence, and fit a model of non-equilibrium community structure.