No abstract

The production of oil palm is expected to increase in the Amazon region. However, expansion of oil palm plantation leads to significant changes in the physical structure of aquatic ecosystems, mainly through the reduction of riparian vegetation that is essential for aquatic biodiversity. Here, we evaluated the effects of oil palm on the physical habitat structure of Amazonian stream environments and assemblages of Plecoptera and Trichoptera (PT), ​both found in these streams. We compared streams sampled in oil palm plantations (n = 13) with natural forest areas ("reference" streams, n = 8), located in the eastern Amazon, Brazil. Our results showed that oil palm streams were more likely to be in close proximity to roads, had higher pH values, and higher amounts of fine substrate deposited in the channel than reference streams. Further, these environmental changes had important effects on the aquatic invertebrate assemblages, reducing the abundance and richness of PT. Nevertheless, the genera composition of the assemblages did not differ between reference and oil palm (PERMANOVA, pseudo-F = 1.891; p = 0.111). We conclude that oil palm production has clear negative impacts on aquatic environments and PT assemblages in Amazonian streams. We recommend that oil palm producers invest more in planning of road networks to avoid the construction of roads near to the riparian vegetation. This planning can minimize impacts of oil palm production on aquatic systems in the Amazon.

No abstract

Environmental and spatial heterogeneity affects the distribution of aquatic insects, determining or influencing the variation in local species composition. Dragonflies and damselflies (Odonata) have different strategies for oviposition site selection that depend on environmental conditions. However, Land Use and Land Cover (LULC) can reduce the availability of suitable sites for Odonata oviposition through environmental homogenization. We investigated the relationship between environmental and spatial heterogeneity and variation in species composition of Odonata with different oviposition strategies (endophytic, epiphytic and exophytic) in Amazonian streams in a gradient of LULC. We used the Jaccard and Bray‐Curtis coefficients and the Manhattan distance to estimate a continuum of variation in species composition. Variation in the composition of endophytic and epiphytic species was explained by spatial heterogeneity. Using abundance data and the Manhattan distance, we found a relationship between variation in species composition and environmental heterogeneity. Endophytic species composition was related to perch heterogeneity, while exophytic species composition was related to perch and canopy cover heterogeneity. Exophytic and endophytic species could be used in biomonitoring as they respond to specific environmental predictors and because exophytic species do not have spatial patterns across the landscape. Different dissimilarity coefficients provide complementary information about the responses of multispecies communities to land use, as some will represent strong effects (presence‐absence indexes) while others will represent more subtle effects (abundance‐based indexes). Land use can increase the environmental heterogeneity of some predictors (perches and canopy cover). Physical changes in streams such as hydromorphological alterations can modify specific habitats, affecting oviposition strategies and supporting tolerant species.

A Amazônia vem sofrendo ao longo dos anos com diferentes impactos ambientais, dentre eles, no Estado do Pará, a palma de dendê é a terceira atividade agrícola em expansão, estando atrás da soja e do açaí. Os impactos ambientais resultantes dessa atividade se estendem aos ecossistemas aquáticos, principalmente aos pequenos riachos, que apresentam alta dependência do ambiente terrestre. Neste capítulo apresentamos os resultados dos efeitos da palma de dendê sobre a biodiversidade de riachos da Amazônia Oriental. Foram analisadas as assembleias de peixes e insetos aquáticos e semiaquáticos em áreas com diferentes proporções de usos da terra para o plantio de dendê. Os estudos registraram alteração na riqueza e abundância de peixes e de insetos entre ambientes afetados pela monocultura de dendê e áreas florestadas, evidenciando uma substituição de espécies seguindo um gradiente florestal. Sendo assim, a monocultura de dendê provoca alterações na estrutura dos riachos, afetando a distribuição da biodiversidade, demonstrando a necessidade de monitoramento dos ecossistemas aquáticos para manutenção das características naturais e sua biodiversidade em áreas agrícolas.

Abiotic and biotic factors play an essential role in the structuring of natural communities. Aquatic ecosystems have complex interaction networks, encompassing predator/prey relationships and structural support. Among aquatic organisms, the order Odonata is a model group for understanding those relationships since they can be both predators and prey. Our hypotheses were that Zygoptera are (i) influenced positively by Ephemeroptera, Plecoptera and Trichoptera (EPT) and the Habitat Integrity Index (HII), and negatively by fish and macrophytes; and (ii) Anisoptera are affected positively by EPT and macrophytes, and negatively by fish and HII. We found that Zygoptera were affected by the fish functional trophic groups, while Anisoptera were affected by macrophytes, EPT, fish and HII. Macrophytes affected anisopterans positively because they provide perching sites for adults. The results for EPT and HII may be related since these organisms are also sensitive to environmental changes. More open areas have lower HII values and the negative relationship with Anisoptera may be explained by physiological constraints. The negative relationship between EPT and Anisoptera could be explained by the low occurrence of EPT in open sites, which are the sites that were highly rich in Anisoptera. Finally, the dominance of specific functional trophic groups of fish influences Odonata suborders in different ways. In conclusion, the results show the importance of ecological interactions for Odonata in Amazonian streams in both direct and indirect ways.

No abstract

A major challenge in using recovery techniques, for the different natural ecosystems affected by mining, is a mutual relationship between the habitat and its biota response. This study aimed to do a review to identify the number of publications, which countries are publishing more and which recovery techniques and taxonomic group are used in mining areas globally have contributed to the maintenance or recovery of the environment. We reviewed the literature on recovery in mining areas worldwide, between 1994 and 2016, using the Web of Science online database. We identified 9,000 publications, after the selection procedures, we analyzed the 467 remaining manuscripts. Of these, 34.26% were published between 1994 and 2004, and 65.74% between 2006 and 2016. The countries that contributed the most were the USA with 16.45%, Australia with 13.56% and China with 8.66%. Brazil contributed 6.9% of the publications. The recovery techniques using vegetation were the most reported in the literature and most used. The taxonomic group of terrestrial plants was the most cited and most used in the recovery of degraded areas. We found various techniques for recovering degraded areas can be established, but most of them did not show proper monitoring and without this the recovery processes may not achieve their objectives and studies that test the effect size of these recovery methods are still necessary.