The changes in land use caused by human activities have directly impacted aquatic ecosystems, making these environments some of the most threatened places on the planet. It is increasingly necessary ...and urgent to develop tools to identify and assess the effects of human impacts on ecosystems and biodiversity. This study aimed to evaluate whether the Zygoptera/Anisoptera ratio can be an effective tool to measure ecological changes in Atlantic Forest streams. Adult Odonata were collected in 42 streams. An environmental integrity index was used as a measure of environmental change. The Zygoptera/Anisoptera ratio was efficient in classifying the state of preservation of streams; therefore, habitats with a proportion equal to or greater than 67 and 52% of richness and abundance of the suborder Anisoptera can be considered altered. Meanwhile, streams representing a proportion of 54 and 67% of richness and abundance of the suborder Zygoptera can be considered little altered or preserved. The proportions of responses were close to the proposals for streams in the Amazon rainforest region. The ease of identifying the specimens in the different suborders of Odonata is practical, enabling the implementation of participatory monitoring with quick responses for monitoring in the aquatic ecosystems assessed in the region. It is important to test the Zygoptera/Anisoptera ratio for a broader validation in biomes where this evaluation has not yet been carried out. In the future, this will enable the implementation of networks for monitoring the integrity of aquatic environments quickly, effectively and at a low cost.
Biodiversity conservation has faced many challenges, especially the conversion of natural areas that compete with use for agriculture, energy production and mineral extraction. This problem is ...further aggravated by lack of knowledge of the biodiversity that exists and the geographical distribution of different groups. The objectives of our study were to examine the distributional pattern of Gerromorpha diversity in Brazil, create a map of conservation priority areas, estimate the degree of protection that the current network of protected areas guarantees to this insect group, and identify the size thresholds in geographical distributions that would allow species to be protected. We used species occurrences from the Water Bugs Distributional Database, and we used 19 bioclimatic variables to build models of the potential distributions of species using the MaxEnt program. Using the potential model results, we calculated diversity metrics and overlapped them with the current state and federal "conservation units" (protected areas for biodiversity) in Brazil. Total beta diversity and turnover portions were separated into two faunistic groups, one in northern and the other in southern Brazil. The Amazon has higher beta diversity than what was predicted by the null models. We detected a positive relationship between species distribution area and occurrence in conservation units. Conservation units with less than 250 km
do not protect Gerromorpha species. Our results reinforce the necessity of formulating new conservation strategies for this group, contemplating species with both restricted and ample distributions, because rare and specialist species are the most harmed by habitat reduction, given that they are more sensitive to environmental disturbance.
•The scarcity of studies on the assessment of biotic integrity in tropical regions was confirmed;•The macrobenthos is the main taxa used as an indicator of disturbances in estuaries;•The most used ...metrics in the biotic evaluation in estuaries correspond to assembly structure and abiotic parameters;•The application of integrity indices without justification or proper adaptation can result in mistaken evaluations.
In this study, we conducted a scientometric analysis of studies on the assessment of ecological conditions in estuaries using biotic indicators. We aimed (1) to describe the current landscape of the scientific production on the topic; (2) to characterize the most productive/influential authorships and the organization of scientific collaboration; (3) to analyze the most used biotic integrity indices, metrics and methods. After the survey process, separation, and analysis, 334 publications were selected between the years 1990 and 2021 that met all stablished criteria. The results indicated an increase in the number of publications along the years, but there are still few researchers working on the subject. European countries (mainly Spain and Portugal) and the USA dominate the scientific production, possibly due to the promulgation of legal guidelines in these countries regarding environmental assessments in estuaries. In this context, a concentrated scientific collaboration linked to European authors stands out. The Spanish author Angel Borja is the author with the most influential scientific production, with participation in the development of two of the biotic indexes most used (AMBI and M−AMBI). Among the most used indicators are the benthic macroinvertebrates, followed by the fish. We found that the most used metrics are related to community composition (e.g., richness, abundance, biomass), abiotic parameters (e.g., salinity, temperature), and pollutants (e.g., metals). Our results indicate that methodological issues are still of great concern, given the absence of standardization among studies. Another relevant aspect is the large gap of studies in tropical countries, which keep applying indices not developed for their regional particularities. The results of this study highlight the need for more studies in tropical regions, on the sensitivity of the species and about methodological aspects, which can greatly contribute for the development of the field.
We assessed how the variation in environmental factors influences mayfly assemblages in conserved streams of different Amazonian interfluves. We hypothesized that environmental variables, mayfly ...assemblages, and the influence of environmental factors vary among these interfluves, given their distinct evolutionary and ecological histories, and patterns of human interference. We also expected that the effects of environmental variation on species richness and composition would be greater among interfluves than among streams within the same interfluve. Our hypotheses were corroborated, reflecting the considerable heterogeneity of the Amazonian biome, where streams vary naturally among interfluves, determining broad scale divergences in species composition. The environment affected mayfly diversity in different ways among interfluves, reflecting the influence of historical processes that resulted in the formation of centers of endemism delimited by major Amazonian rivers, in which distinct biotic and abiotic factors have prevailed. These regional effects have resulted from the heterogeneity of environmental gradients, which affect mayfly diversity. The results of the present study indicate that, depending on the scale and topography of the interfluve, environmental predictors of the structure of mayfly assemblages vary considerably. This has important implications for the definition of control sites for the assessment and monitoring of environmental quality.
Understanding the role of abiotic and biotic factors on biological communities is a challenge for ecologists. Individuals of the order Odonata have a close connection with these factors, which can ...influence the establishment of each stages of live. This study evaluated the relationship between habitat complexity and limnological variables on the diversity of Libellulidae larvae and adults. Our hypotheses were that (i) limnological variables would have a greater influence than habitat complexity on larvae and (ii) habitat complexity would influence more adults. Forty-six sampling sites were evaluated in the Brazilian Amazon region. Our results indicated the effects of limnological variables and habitat complexity on both life stages, with higher influence of the first on larvae and the second on adults, mainly for species composition. The abundance of the
Eichhornia azurea
, which has enormous morphological plasticity, together with the presence of a range of other macrophyte species provides different habitat architectures, with more suitable microhabitats for different odonates. The habitat complexity metrics had combined effects on the larvae, presumably because of the greater availability of refuges from predators and food sources. In contrast, in the adults, the relationship with habitat complexity is associated with the availability of ovipositing sites and perches.
•The family-level provides an effective tool for the biomonitoring of streams using odonates.•The use of family-level keeps essential ecological information of the species-level community.•Aggregate ...measures such as abundance can be very useful when higher taxonomic levels are used in biomonitoring.•The use of family-level could be advantageous in terms of time and financial resources.
The insects of the order Odonata have been widely used as bioindicators of environmental quality in different types of ecological research. In general, the taxonomic level used is the species, but higher taxa, such as the family, have received less attention. Assuming that higher taxa can reproduce the impacts that occur at the species level, we use facets of diversity at the community to assess if Odonata families could be an efficient tool for the assessment of environmental impact in Amazon streams. We first assessed to what extent each family retains ecological information from the ecological diversity of the species of the suborder (Anisoptera or Zygoptera). We then quantified the degree of congruence between different taxonomic levels in the Odonata. Next, we evaluated the effects of environmental integrity on the facets of diversity of the families. Finally, we evaluated whether ecological thresholds can be detected using a family-level approach. We sampled adult odonates in 98 streams in the eastern Amazon, in the municipalities of Paragominas, Santarém, and Belterra, in the Brazilian state of Pará. The habitat integrity index (HII) was used to assess the environmental integrity of each stream. The congruence between the different taxonomic levels was evaluated using a Procrustes analysis. The degree of correlation of diversity facets was evaluated between families and each suborder. Linear mixed models and matrix regressions were used to measure the influence of environmental integrity on the diversity facets of the families. Higher-level ecological thresholds were detected using the TITAN analysis. The results of the analyses indicated a high degree of congruence between species-level and higher levels (family and suborder). The ability of the families to represent the diversity facets of the suborder is influenced by the abundance of individuals and the number of species in the family. The environmental integrity of the streams affects the facets of diversity of the families systematically, although cumulative measurements, such as abundance, appeared to be more advantageous as biomonitoring tools. The similarity of the responses observed at species and family levels supports the use of odonate families for the detection of ecological thresholds in stream environments. The sum of the evidence indicates that a family-level approach is effective for the identification of alterations in the environmental integrity of streams, providing valuable insights into the facets of diversity of the odonate community. The adoption of a family-level approach in environmental monitoring programs could optimize the investment of resources, in particular through the identification of specimens by non-specialists, permitting a significant increase in sampling effort and replication.
The odonates are insects that have a wide range of reproductive, ritualized territorial, and aggressive behaviors. Changes in behavior are the first response of most odonate species to environmental ...alterations. In this context, the primary objective of the present study was to assess the effects of environmental alterations resulting from shifts in land use on different aspects of the behavioral diversity of adult odonates. Fieldwork was conducted at 92 low-order streams in two different regions of the Brazilian Amazon. To address our main objective, we measured 29 abiotic variables at each stream, together with five morphological and five behavioral traits of the resident odonates. The results indicate a loss of behaviors at sites impacted by anthropogenic changes, as well as variation in some morphological/behavioral traits under specific environmental conditions. We highlight the importance of considering behavioral traits in the development of conservation strategies, given that species with a unique behavioral repertoire may suffer specific types of extinction pressure.
Freshwater assessment studies have been used changes on individuals and populations of Chironomidae assemblages as bioindicators to assay aquatic ecosystems changes and environmental quality. To ...assess the contribution of the studies with this family to response aquatic environmental changes, we carried out a scientometric analysis of the papers published from 1992 to 2012. We imported papers from ISI Web of Knowledge database (Thomson Reuters) in November 2013. A total of 2967 papers were evaluated and we carried out descriptive analysis to assay the main trends on Chironomidae research in freshwater assessments. The main ideas and approaches in these studies were related to the impact of human influence on aquatic ecosystems and the status of conservation of this environments, as well as to limitations and difficulties in the applications of the assessments. In view of our results, we suggest some ideas to contribute to the conservation of aquatic ecosystems, mainly in threatened environments in southern Hemisphere countries. However, Chironomidae identification for assessing aquatic environments, as well as the limitations of suitable tools and metrics, which still are strong issues that need more attention to make more robust approaches to assay aquatic ecosystems.
Protecting riparian vegetation around streams is vital in reducing the detrimental effects of environmental change on freshwater ecosystems and in maintaining aquatic biodiversity. Thus, identifying ...ecological thresholds is useful for defining regulatory limits and for guiding the management of riparian zones towards the conservation of freshwater biota.
Using nationwide data on fish and invertebrates occurring in small Brazilian streams, we estimated thresholds of native vegetation loss in which there are abrupt changes in the occurrence and abundance of freshwater bioindicators and tested whether there are congruent responses among different biomes, biological groups and riparian buffer sizes.
Mean thresholds of native vegetation cover loss varied widely among biomes, buffer sizes and biological groups: ranging from 0.5% to 77.4% for fish, from 2.9% to 37.0% for aquatic invertebrates and from 3.8% to 43.2% for a subset of aquatic invertebrates. Confidence intervals for thresholds were wide, but the minimum values of these intervals were lower for the smaller riparian buffers (50 and 100 m) than larger ones (200 and 500 m), indicating that land use should be kept away from the streams. Also, thresholds occurred at a lower percentage of riparian vegetation loss in the smaller buffers, and were critically lower for invertebrates: reducing only 6.5% of native vegetation cover within a 50‐m riparian buffer is enough to cross thresholds for invertebrates.
Synthesis and applications. The high variability in biodiversity responses to loss of native riparian vegetation suggests caution in the use of a single riparian width for conservation actions or policy definitions nationwide. The most sensitive bioindicators can be used as early warning signals of abrupt changes in freshwater biodiversity. In practice, maintaining at least 50‐m wide riparian reserves on each side of streams would be more effective to protect freshwater biodiversity in Brazil. However, incentives and conservation strategies to protect even wider riparian reserves (~100 m) and also taking into consideration the regional context will promote a greater benefit. This information should be used to set conservation goals and to create complementary mechanisms and policies to protect wider riparian reserves than those currently required by the federal law.
Resumo
Proteger a vegetação no entorno de riachos é vital para reduzir os efeitos das mudanças ambientais sobre os ecossistemas aquáticos e para a manutenção de sua biodiversidade. Assim, a identificação de limiares ecológicos é útil para regular os limites de uso e para orientar o manejo de zonas ripárias, visando a conservação da biota aquática.
Usando dados de peixes e invertebrados aquáticos de pequenos riachos do Brasil, nós estimamos os limiares de perda de vegetação nativa nos quais ocorrem mudanças abruptas na ocorrência e abundância de bioindicadores aquáticos. Também testamos se existem respostas congruentes entre os diferentes biomas, grupos biológicos e áreas de vegetação ripária (buffers).
Os valores médios dos limiares de perda de vegetação nativa variaram marcadamente entre biomas, tamanhos de buffer e grupos biológicos: entre 0,5% e 77,4% para peixes, entre 2,9% e 37,0% para invertebrados aquáticos e entre 3,8% e 43,2% para um subconjunto de invertebrados aquáticos. Os intervalos de confiança dos limiares foram amplos, mas os valores mínimos dos intervalos foram reduzidos para os menores buffers ripários (50 e 100 m) em comparação com os maiores (200 e 500 m), indicando que o uso do solo deve ser mantido longe dos riachos. Além disso, os limiares ocorreram em menores porcentagens de perda de vegetação ripária nos buffers menores, e foram criticamente baixos para invertebrados aquáticos: uma redução de apenas 6,5% da cobertura de vegetação nativa no buffer ripário de 50 m é suficiente para ultrapassar os limiares de perda de invertebrados.
Síntese e aplicações. A elevada variabilidade dos limiares de declínio abrupto da biodiversidade aquática em resposta a perda de vegetação ripária nativa sugere cautela no uso de uma largura única de proteção ripária para ações de conservação e definição de políticas nacionais. Os bioindicadores mais sensíveis podem ser usados como sinais precoces que alertam a aproximação de mudanças abruptas na biodiversidade aquática. Na prática, manter reservas ripárias (áreas de preservação permanente—APP) de pelo menos 50 m de largura, em ambos os lados dos riachos, parece ser mais efetivo em proteger a biodiversidade de água doce do Brasil. Contudo, incentivos e estratégias de conservação que protejam reservas ripárias ainda maiores (~100 m de largura) e que levem em consideração o contexto regional podem promover um maior benefício. Essas informações podem ser usadas para definir metas de conservação e para criar mecanismos e políticas complementares para proteger reservas ripárias (APP) ainda maiores do que aquelas atualmente requeridas pela lei federal.
The high variability in biodiversity responses to loss of native riparian vegetation suggests caution in the use of a single riparian width for conservation actions or policy definitions nationwide. The most sensitive bioindicators can be used as early warning signals of abrupt changes in freshwater biodiversity. In practice, maintaining at least 50‐m wide riparian reserves on each side of streams would be more effective to protect freshwater biodiversity in Brazil. However, incentives and conservation strategies to protect even wider riparian reserves (~100 m) and also taking into consideration the regional context will promote a greater benefit. This information should be used to set conservation goals and to create complementary mechanisms and policies to protect wider riparian reserves than those currently required by the federal law.
The present study evaluated the effects of habitat quality on the alpha and beta diversity of odonate larvae under conditions of reduced impact and conventional logging. We hypothesized that the ...variation in the abiotic conditions found in areas of conventional logging would result in a greater loss of alpha and beta diversity in these areas in comparison with areas of reduced-impact logging and native forest. The study area was located in northeastern Pará state, in northern Brazil. We analyzed data from 10 control streams, located in areas of preserved native forest, 11 streams in forest harvested by reduced-impact logging, and nine streams in areas that had been logged conventionally. Environmental factors such as dissolved oxygen, woody debris, water temperature, sediments, and canopy cover were the principal predictors of the diversity of the Odonata. Our results showed that turnover was the principal component structuring beta diversity in the three areas (native forest, reduced impact and conventional logging). The results of the present study indicate that management initiatives based on reduced-impact logging techniques could be adopted to guarantee socio-economic benefits while minimizing the impacts of logging on local biodiversity.
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