Fabio de Oliveira Roque

A comparative analysis reveals weak relationships between ecological factors and beta diversity of stream insect metacommunities at two spatial levels

The hypotheses that beta diversity should increase with decreasing latitude and increase with spatial extent of a region have rarely been tested based on a comparative analysis of multiple datasets, and no such study has focused on stream insects. We first assessed how well variability in beta diversity of stream insect metacommunities is predicted by insect group, latitude, spatial extent, altitudinal range, and dataset properties across multiple drainage basins throughout the world. Second, we assessed the relative roles of environmental and spatial factors in driving variation in assemblage composition within each drainage basin. Our analyses were based on a dataset of 95 stream insect metacommunities from 31 drainage basins distributed around the world. We used dissimilarity-based indices to quantify beta diversity for each metacommunity and, subsequently, regressed beta diversity on insect group, latitude, spatial extent, altitudinal range, and dataset properties (e.g., number of sites and percentage of presences). Within each metacommunity, we used a combination of spatial eigenfunction analyses and partial redundancy analysis to partition variation in assemblage structure into environmental, shared, spatial, and unexplained fractions. We found that dataset properties were more important predictors of beta diversity than ecological and geographical factors across multiple drainage basins. In the within-basin analyses, environmental and spatial variables were generally poor predictors of variation in assemblage composition. Our results revealed deviation from general biodiversity patterns because beta diversity did not show the expected decreasing trend with latitude. Our results also call for reconsideration of just how predictable stream assemblages are along ecological gradients, with implications for environmental assessment and conservation decisions. Our findings may also be applicable to other dynamic systems where predictability is low.

A Metacommunity Framework for Enhancing the Effectiveness of Biological Monitoring Strategies

Because of inadequate knowledge and funding, the use of biodiversity indicators is often suggested as a way to support management decisions. Consequently, many studies have analyzed the performance of certain groups as indicator taxa. However, in addition to knowing whether certain groups can adequately represent the biodiversity as a whole, we must also know whether they show similar responses to the main structuring processes affecting biodiversity. Here we present an application of the metacommunity framework for evaluating the effectiveness of biodiversity indicators. Although the metacommunity framework has contributed to a better understanding of biodiversity patterns, there is still limited discussion about its implications for conservation and biomonitoring. We evaluated the effectiveness of indicator taxa in representing spatial variation in macroinvertebrate community composition in Atlantic Forest streams, and the processes that drive this variation. We focused on analyzing whether some groups conform to environmental processes and other groups are more influenced by spatial processes, and on how this can help in deciding which indicator group or groups should be used. We showed that a relatively small subset of taxa from the metacommunity would represent 80% of the variation in community composition shown by the entire metacommunity. Moreover, this subset does not have to be composed of predetermined taxonomic groups, but rather can be defined based on random subsets. We also found that some random subsets composed of a small number of genera performed better in responding to major environmental gradients. There were also random subsets that seemed to be affected by spatial processes, which could indicate important historical processes. We were able to integrate in the same theoretical and practical framework, the selection of biodiversity surrogates, indicators of environmental conditions, and more importantly, an explicit integration of environmental and spatial processes into the selection approach.

Chironomid species richness in low-order streams in the Brazilian Atlantic Forest: a first approximation through a Bayesian approach

Abstract The Atlantic Forest of Brazil has been identified as a biodiversity hotspot of global significance. We assessed chironomid (Diptera:Chironomidae) taxa richness in 2 vegetation types in this region: the Atlantic Rain Forest and the Atlantic Semi-deciduous Forest. Taxa were collected from 15 low-order streams across multiple habitats. A total of 191 morphospecies were recognized (125 Chironominae, 28 Tanypodinae, and 38 Orthocladiinae). We estimated chironomid richness using a Bayesian statistical approach. Species-richness estimates ranged from 200 (credibility interval, 195–207) to 267 (248–288). These results place low-order streams from Atlantic Forest among the most chironomid speciose areas in the world.

Sponge-dwelling chironomids in the upper Paraná river (Brazil): little known but potentially threatened species

In this paper, we provide a checklist of chironomids living in freshwater sponges in the upper Paraná River (Brazil) and we call attention to the problem of complete substitution of extensive areas covered by freshwater sponges by banks of the invasive alien species Limnoperna fortunei (golden mussel). We describe a new species of Oukuriella based on male adults and also describe an unusual larva of Chironomidae that probably belongs to the Stenochironomus complex.

The effect of riparian deforestation on macroinvertebrates associated with submerged woody debris

Riparian deforestation is one of the main causes of change in freshwater ecosystems, resulting in the reduction of biological integrity and the loss of ecosystem functions. Our goal was to understand how a gradient of deforestation may affect abundance and richness of specialist and generalist macroinvertebrates associated with submerged woody debris in Neotropical streams. We conducted an observational study sampling mixed-species woody debris from 16 streams along a deforestation gradient. We also conducted an incubation study with known woody debris species (Cecropia pachystachya Trécul) in six streams. We collected 781 specimens and identified 50 taxa in the observational study, and we found 99 individuals belonging to 17 taxa in incubation study. Results from the two complementary studies indicate that the effect of riparian deforestation was more pronounced for wood specialists than generalists. Deforestation decreased the abundance and richness of wood specialists, and some taxa were locally extinct. The incubation study showed that sedimentation, which leads to the burying of woody debris, is an important process impeding macroinvertebrate colonization. Our study highlights the importance of woody debris as habitat for aquatic communities and as a structural component of streams, with important implications for conservation and biomonitoring. We suggest that wood specialists could be a potential group for use in biomonitoring programs aimed at assessing the impact of deforestation.

Systematics of Oukuriella Epler, 1986, including a revision of the species associated with freshwater sponges

Oukuriella has been recorded only in the Neotropical region. Larvae of some species of the genus have associations with freshwater sponges and immersed wood. In this study we performed a phylogenetic analysis to test the hypothesis that species that inhabit freshwater sponges form a monophyletic group. Including the six species described here, the number of species in the genus now is 21. Our findings do not support the subgroups previously proposed within Oukuriella based on the morphology of adult males. The most parsimonious cladograms obtained indicate that Oukuriella is a monophyletic group and the inhabitants of freshwater sponges form a monophyletic group within Oukuriella.

Predictive Modelling of Insect Metacommunities in Biomonitoring of Aquatic Networks

Aquatic insects are used extensively in freshwater bioassessment because they are good indicators of human impact. The most successful bioassessment initiatives have focused mainly on comparing insect communities from potential impacted sites to those predicted by empirical correlative models that occur in pristine sites. The theoretical scope that underpins the use of these models is derived from a deterministic view of ecology, particularly based on niche theory – i.e., predicting taxa occurrence from environmental conditions. In recent years, however, the development of new concepts (e.g., the metacommunity concept), use of new techniques (e.g., artificial neural networks) and availability of better datasets (e.g., geographic information system layers) could change this scenario. In this chapter, we explore the use of metacommunity models, the geometry of riverine networks and organism dispersal conceptually with a simulation exercise to discuss the challenges of modelling metacommunities in biomonitoring aquatic networks.

Incorporating resilience and cost in ecological restoration strategies at landscape scale

The restoration of deforested or degraded areas can contribute to biodiversity conservation and global resilience given the current and projected impacts of climate change. In recent years, a robust array of ecological restoration frameworks have been generated to address restoration challenges at large scales in different ecosystems around the world. Unfortunately, the costs associated with restoration at such scales greatly challenges the implementation of such frameworks. We used landscape ecology principles with multicriteria optimization of landscape resilience and agricultural productivity as a way to mitigate the trade-offs between production and restoration. We used the Cerrado biome in Mato Grosso do Sul State, Brazil, as a case study to apply our framework. We compared three scenarios: minimal legal compliance (MLC); selection by ecological resilience (SER); and selection by restoration cost (SRC). Our results show that increasing the restoration target from MLC (25%) to SER (30%) means moving from 968,316 to 1592 million hectares, which can represent a huge opportunity cost for agricultural lands. However, because costs and resilience are not homogeneously distributed throughout landscapes, we can select areas of intermediate ecological resilience and low cost, for the same restoration area target. This process can reduce potential conflicts and make restoration a more viable process. Our results also reveal some areas that can be particularly important for reconciling agriculture and landscape restoration. Those areas combined high and intermediate resilience and an above average profitability. This could mean that increasing restoration in this area could be very expensive, assuming that our proxy roughly represents the restoration implementation cost. However, there is another important message here, that some areas can be productive at the same time that they maintain levels of resilience above the legal compliance, which facilitates win-win scenarios in human-dominated landscapes.

Short-term effects of visitor trampling on macroinvertebrates in karst streams in an ecotourism region.

In order to evaluate the potential risks of human visitation on macroinvertebrate communities in streams, we investigated the effect of trampling using two short-term experiments conducted in a Brazilian ecotourism karst region. We asked three questions: (a) Does trampling increase the drift rate of aquatic macroinvertebrates and organic matter? (b) Does trampling change the macroinvertebrate community organization? (c) If trampling alters the community structure, is a short time (5xa0days, a between weekends intervalu2009-u2009peaks of tourism activities) sufficient for community restructuring? Analysis of variance of richness, total abundance, abundance of the most abundant genus (e.g., Simothraulopsis and Callibaetis), and community composition showed that trampling immediately affects macroinvertebrate community and that the intervals between the peaks of visitation (5xa0days) are not sufficient to complete community restructuring. Considering that bathing areas receive thousands of visitors every year and that intervals of time without visitation are nearly nonexistent, we suspect that the negative effects on the macroinvertebrate community occur in a cumulative way. Finally, we discuss some simple procedures that could potentially be used for reducing trampling impacts in lotic environments.

What Shapes the Phylogenetic Structure of Anuran Communities in a Seasonal Environment? The Influence of Determinism at Regional Scale to Stochasticity or Antagonistic Forces at Local Scale

Ecological communities are structured by both deterministic and stochastic processes. We investigated phylogenetic patterns at regional and local scales to understand the influences of seasonal processes in shaping the structure of anuran communities in the southern Pantanal wetland, Brazil. We assessed the phylogenetic structure at different scales, using the Net Relatedness Index (NRI), the Nearest Taxon Index (NTI), and phylobetadiversity indexes, as well as a permutation test, to evaluate the effect of seasonality. The anuran community was represented by a non-random set of species with a high degree of phylogenetic relatedness at the regional scale. However, at the local scale the phylogenetic structure of the community was weakly related with the seasonality of the system, indicating that oriented stochastic processes (e.g. colonization, extinction and ecological drift) and/or antagonist forces drive the structure of such communities in the southern Pantanal.