Mateus Marques Pires

Diversity of Odonata (Insecta) larvae in streams and farm ponds of a montane region in southern Brazil

This study presents an inventory of the genera of Odonata found in streams and artificial farm ponds in a montane region, with temperate climate, in southern Brazil. Differences in richness of lotic and lentic environments were also investigated. The diversity of odonate families and genera in southernmost Brazil is lower than in warmer, either tropical or subtropical, regions of the country. Nine genera are new records for the region and six genera had their geographical ranges extended to regions with temperate climate of the Neotropics. The overall richness and especially the overall abundance recorded in the studied area are possibly determined by the occurrence of numerous farm ponds because natural standing waters are scarce in the region. The presence of macrophytes in these artificial ponds allowed the establishment of a diversified odonatofauna, typical of lentic environments.

Responses of Odonate Communities to Environmental Factors in Southern Brazil Wetlands

Abstract Odonate larvae play an important role in wetland systems, providing food for many fish species and birds. Besides, they are important predators in these ecosystems. However, studies of factors that determine odonate species richness and distribution in wetlands are scarce in the Neotropical region. The objectives of this study were to: 1) conduct a survey of the diversity of odonate larvae in southern Brazil wetlands, and 2) determine how much variation in odonate richness, abundance and composition is explained by wetland area, altitude, water conductivity and nitrate, hydroperiod, and dominant aquatic vegetation in 140 wetlands in an extensive area of the Neotropical region (~280,000 km2, southern Brazil). A total of 4,039 individuals distributed among five families and 28 genera were collected. Libellulidae, Coenagrionidae and Aeshnidae were the families that showed the greatest richness. Erythrodiplax was observed in more than 70% of the sampled wetlands, and comprised 61% of individuals collected. Richness was negatively associated with wetland area and nitrate concentration. Odonate abundance was negatively associated with water conductivity and nitrate, and it was higher in aquatic beds than in emergent wetlands. Richness and abundance were higher in permanent than in intermittent wetlands. Variation in odonate composition was correlated with wetland altitude, area and water conductivity. Hydroperiod and dominant aquatic vegetation also influenced composition. Our results showed that southern Brazil wetlands are important habitats for 28 odonate genera, and that richness, abundance and composition are influenced mainly by hydroperiod, nitrate, and aquatic vegetation type. These results should be seen as important to determine the environmental factors that shape and maintain odonate diversity in southern Brazil wetlands.

Diversity and distribution of riffle beetle assemblages (Coleoptera, Elmidae) in montane rivers of Southern Brazil

The diversity and spatio-temporal distribution of Elmidae (Coleoptera) assemblages in montane rivers and streams of southernmost Brazil (Rio Grande do Sul state) were studied. Six genera were found, represented mostly by larval specimens. Austrolimnius and Macrelmis are new occurrences in the region. Assemblages’ genera composition and dominance were related to the presence of the macrophyte Podostemum. Also, water temperature and stream depth and velocity were the most important drivers related to the assemblages’ distribution. Richness and abundance were positively related to high water velocity and negatively to stream depth. Temporal patterns were detected especially in assemblage abundance, yet a slight pattern in richness was also observed. The seasonal structure was related to warm temperatures, but temporal distribution of Elmidae assemblages appears to be related to the dominant genera life cycles. The studied area shows an overall Elmidae richness similar to that found in some tropical areas and the role of mountainous environments in sustaining high rates of regional diversity in the Neotropics is stated.

Diversity and ecological aspects of aquatic insect communities from montane streams in southern Brazil

AIMS: In this study, the diversity of Ephemeroptera, Plecoptera, Trichoptera and Coleoptera communities was surveyed in the Toropi River basin, a watershed localized in a slope region, in southernmost Brazil. The influence of some local abiotic factors on the most common genera was also analyzed. METHODS: Samplings were conducted at 40 sites in 1st-4th order streams, along a short elevation gradient (70-500 m), with a Surber sampler. Water physico-chemical factors, as well as substrate type, were obtained at each site. RESULTS: At all, 5,320 specimens were collected, belonging to 18 families and 52 genera. The caddisflies Austrotinodes and Celaenotrichia, and an undescribed Elmidae, Genus M, are new records for the region. The caddisfly Smicridea was the most frequent genus in the study area. The mayflies Camelobaetidius, Paracloeodes and Americabaetis were influenced by stream order. Smicridea was related to air temperature, while the mayfly Thraulodes was influenced by high levels of electrical conductivity. CONCLUSIONS: The high diversity found in the study area, compared to other Brazilian regions, reflects the environmental heterogeneity in the region. These data show that hydrographic basins in slope areas from extreme Southern Brazil sustain high levels of diversity of aquatic insect communities.

Comparative assessment of aquatic macroinvertebrate diversity in irrigated rice fields and wetlands through different spatial scales: an additive partitioning approach

The role of rice fields as refuges for wetland macroinvertebrates was assessed at multiple spatial scales, and macroinvertebrate diversity was compared between fields and natural wetlands. Because irrigated rice fields are highly disturbed environments, and have lower environmental complexity and heterogeneity in the irrigated phase than do wetlands, we hypothesised that the fields would sustain lower diversity than do wetlands, especially at broader spatial scales. Wetlands and rice fields from three regions in southern Brazil were simultaneously sampled. In wetlands, the broadest scale (hydrographic basin) contributed the most to macroinvertebrate diversity. In rice fields, besides hydrographic basin level, narrower scales (site level) also contributed to macroinvertebrate γ diversity. Different cultivation and management systems may be responsible for the contribution of narrower scales to γ diversity in rice fields. Differences in community structure in both environments were determined by wetland drainage practices, and they were affected by the ENSO climatic phenomenon, which influenced macrophyte diversity in wetlands. Wetland communities were characterised by macrophyte-associated, passive-dispersing taxa, whereas rice fields contained short-lived, active-dispersing macroinvertebrates. The present study demonstrated that rice fields do not represent suitable refugia for wetland-expelled macroinvertebrates because they do not support similar community structure, at least under some management practices and climatic conditions influenced by ENSO.

Diversity and Spatiotemporal Distribution of Larval Odonate Assemblages in Temperate Neotropical Farm Ponds

Abstract Farm ponds help maintain diversity in altered landscapes. However, studies on the features that drive this type of property in the Neotropics are still lacking, especially for the insect fauna. We analyzed the spatial and temporal distribution of odonate larval assemblages in farm ponds. Odonates were sampled monthly at four farm ponds from March 2008 to February 2009 in a temperate montane region of southern Brazil. A small number of genera were frequent and accounted for most of the dominant fauna. The dominant genera composition differed among ponds. Local spatial drivers such as area, hydroperiod, and margin vegetation structure likely explain these results more than spatial predictors due to the small size of the study area. Circular analysis detected seasonal effect on assemblage abundance but not on richness. Seasonality in abundance was related to the life cycles of a few dominant genera. This result was explained by temperature and not rainfall due to the temperate climate of the region studied. The persistence of dominant genera and the sparse occurrence of many taxa over time probably led to a lack in a seasonal pattern in assemblage richness.

Spatial and Temporal Distribution of Non-Biting Midge Larvae Assemblages in Streams in a Mountainous Region in Southern Brazil

Abstract The spatial and temporal structure of non-biting midge (Diptera: Chironomidae) larvae assemblages and some environmental factors that affect their distribution were analyzed in a montane river and its tributaries in a temperate climate region of southernmost Brazil. In total, 69 taxa were recorded after four seasonal samplings (winter, spring, summer, and autumn). The dominant taxa were Rheotanytarsus sp. 1, Rheotanytarsus sp. 2, Cricotopus sp. 2, and Polypedilum (Polypedilum) sp., although dominance varied among the four sampling sites. The variations in dominance, abundance, and richness among the different sites were affected by environmental characteristics, such as the presence of marginal vegetation and a heterogeneous substratum, and also by human activities. Strictly environmental factors, such as altitude, and factors related to annual weather patterns, such as mean temperature and precipitation, influenced the spatial and temporal distribution of certain taxa and the structure of faunal assemblages. The influence of the riparian vegetation and riverbed heterogeneity on the composition, richness, and abundance of the chironomid larvae assemblages indicates that human activities, such as deforestation and the construction of dams, constitute a serious threat to the conservation of these insects and to the fauna that depends on them for food.

Effects of riparian vegetation width and substrate type on riffle beetle community structure: Effect of riparian vegetation on Elmidae

Riffle beetle community structure is influenced by the preservation condition of stream riparian vegetation. Though, the width of riparian vegetation required to ensure conservation of stream insect communities is still controversial. Effects of alterations in riparian vegetation widths on stream insect community structure can be overcame by other environmental variables, like substrate type, hindering accurate assessments. We tested the effects of different riparian vegetation widths (>40, 30–15, 15–5 and <5 m) along with different substrate types (inorganic and organic) on riffle beetle community structure in southern Brazilian 4th‐ to 5th‐order streams. Riparian buffer widths and substrate types influenced riffle beetle community structure, but no interaction between them was observed. Reduced riparian vegetation widths downstream were associated with changes in riffle beetle dominant genera (Macrelmis predominated only in streams with narrowest riparian widths). Additionally, communities in organic substrates had lower equitability and different dominant genera (Hexacylloepus and Heterelmis) than inorganic ones. Our results showed that reductions in riparian vegetation were associated with water pollution and changes in riffle beetle community structure, suggesting that buffer strips narrower than 5 m are not adequate to maintain environmental integrity of southern Brazilian streams. These results have special importance for the conservation of stream insects in Brazil, as reductions up to less than 5 m in stream banks of small properties are allowed by the new Brazilian Forest Code, independently of stream order.

Partitioning beta‐diversity through different pond hydroperiod lengths reveals predominance of nestedness in assemblages of immature odonates

Patterns of freshwater invertebrate assemblage structure in the transition from permanent to non‐permanent lentic habitats are well described in the literature. However, the effects of small changes in the hydroperiod of non‐permanent ponds on invertebrate assemblage structure remain less studied, especially on β‐diversity. Thus, we tested the effects of different pond hydroperiod lengths on the assemblage structure of immature odonates, in terms of both α‐ and β‐diversity. Small high‐altitude ponds with different hydroperiod lengths (assigned to ‘short’, ‘medium’ and ‘long’ hydroperiods) were sampled in southern Brazil between 2013 and 2014. Based on the hypothesis that shorter hydroperiods filter constituents of lentic fauna, i.e. that long‐living species cannot inhabit shorter‐hydroperiod ponds, we expected to find higher α‐ and β‐diversity in longer hydroperiods, as well as predominance of the nestedness component in β‐diversity. Restricted occurrence of some genera and higher α‐diversity of immature odonate assemblages was detected in long‐hydroperiod ponds. Within‐hydroperiod β‐diversity values did not vary among hydroperiods, because the occasional occurrence of some genera with high dispersal ability of adults in short‐hydroperiod ponds yielded similar values of the β‐diversity among hydroperiods. Partitioning of β‐diversity among hydroperiods revealed a significant higher contribution of the nestedness component rather than turnover. This pattern is explained by the occurrence of some generalist genera across the whole gradient of hydroperiod, as a subset of fauna in longer‐hydroperiod ponds. Thus, our results suggest that reduction in hydroperiod length, if occurring in the future climate change, would favor habitat‐generalist taxa in lentic ecosystems.

Drivers of beta diversity of Odonata along a forest–grassland transition in southern Brazilian coastal ponds

Assessment of β diversity patterns in relation to environmental and spatial drivers can provide useful insights into the underlying mechanisms structuring communities (deterministic and dispersal limitation). However, the relative importance of each mechanism and driver of β diversity patterns in freshwater communities is assumed to change with ecosystem type, scale of observation, and among groups with different dispersal abilities. We assessed β diversity patterns of assemblages of odonate larvae in relation to geographical distances and scale-specific environmental drivers in southern Brazilian coastal ponds along a latitudinal gradient. We expected to find similar contributions of deterministic and dispersal limitation mechanisms to odonate assemblages and distinct patterns of β diversity between suborders Anisoptera and Zygoptera. We found low values of β diversity (probably related to distribution of generalist taxa and environmental conditions constituted by temporary ponds). Mantel and partial Mantel tests detected distinct relationships between dissimilarity in scale-specific drivers and geographical distances with β diversity of Odonata. Zygoptera was influenced by dissimilarity in local- (presence of riparian vegetation and connectivity) and regional-level (climate) variables, whereas Anisoptera was influenced by geographical distances. Our results supported our hypothesis that changes in the composition of assemblages of odonate larvae in temporary ponds were jointly driven by deterministic and dispersal limitation mechanisms. Furthermore, the similar contributions of nestedness and replacement components and the differing responses of Anisoptera and Zygoptera to local- and regional-level environmental drivers and geographical distances indicate that the relative importance of environmental and spatial drivers to β diversity patterns in ponds is scale-specific.