Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Oxidative stress generation by microcystins in aquatic animals: Why and how

Microcystins (MICs) are potent toxins produced worldwide by cyanobacteria during bloom events.Phosphatases inhibition is a well recognized effect of this kind of toxins as well as oxidative stress. However, it is not fully understood why and how MICs exposure can lead to an excessive formation of reactive oxygen species (ROS) that culminate in oxidative damage. Some evidences suggest a close connection between cellular hyperphosphorylation state and oxidative stress generation induced by MICs exposure. It is shown,based on literature data,that MICs incorporation per se can be the first event that triggers glutathione depletion and the consequent increase in ROS concentration. Also, literature data suggest that hyperphosphorylated cellular environment induced by MICs exposure can modulate antioxidant enzymes,contributing to the generation of oxidative damage. This review summarizes information on MICs toxicity in aquatic animals, focusing on mechanistic aspects, and rise questions that in our opinion needs to be further investigated

A multi-tissues comparison of biomarkers in Serrasalmus rhombeus (Teleostei: Serrasalmidae) and Prochilodus nigricans (Teleostei: Prochilodontidae) from two Amazonian rivers with distinct levels of pollution

Aquatic ecosystems are often exposed to a complex mixture of pollutants that can have a negative influence on the health of the resident organisms. In this context, it is crucial to understand the biological responses of the different organisms that inhabit impacted areas to identify biomonitors that are representative of alterations in the local biota. In the present study, two fish, Serrasalmus rhombeus (red-eyed piranha) and Prochilodus nigricans (curimatã) were assessed as potential biomonitors for Amazonian rivers. A total of 121 fish of these two species were collected during the dry season from two rivers representing different extremes of pollution. One site was the Xingu River, which has low level of pollution, while the other was the Itacaiunas River, which is impacted by high levels pollution from multiple sources. Two exposure biomarkers (glutathione S-transferase activity and total antioxidant capacity) and one effect biomarker (lipid peroxidation) were evaluated in samples of both species extracted from various types of tissues (brain, liver, gills and muscle). The results of the analyses indicated the occurrence of both species-specific and tissue-specific responses. The responses of the biomarkers of the detritivorous species, P. nigricans, were more significant than those of the apex predator, S. rhombeus. In addition, the P. nigricans specimens from the polluted (Itacaiunas) river presented marked suppression of the responses related to the detoxification and antioxidant defences, which resulted in more significant oxidative damage (lipoperoxidation) in comparison with the less polluted (Xingu) river. These findings indicate that P. nigricans is the more sensitive of the two species and would thus be the better choice as a biomonitor for environmental monitoring. The results of the present study also indicate that a more integrated approach to the assessment of the response of biochemical biomarkers, including the analysis of a range of different types of tissue should be adopted to guarantee the robustness of analyses of environmental quality

Influence of a toxic Microcystis aeruginosa strain on glutathione synthesis and glutathione-S-transferase activity in common carp Cyprinus carpio (Teleostei: Cyprinidae)

We evaluated the effects of aqueous extracts of the cyanobacterium-producing microcystin(MC), Microcystis aeruginosa (strain RST9501), on detoxification capacity and glutathione (GSH) synthesis in liver, brain, gill, and muscle—as well as apoptotic protease (calpain)activity in liver and brain—in the common carp Cyprinus carpio (Teleostei: Cyprinidae). Experimental groups were defined as follows: (1) control (CTR); (2)carp treated with an aqueous extract from the toxic cyanobacteria M. aeruginosa in a final MC concentration of 25 lg/kg (MC 25); and (3) carp treated with an aqueous extract from the toxic cyanobacteria M. aeruginosa in a final MC concentration of 50 lg/kg (MC 50).Carp were gavaged with a cyanobacterial aqueous solution or MilliQ water (CTR group). The experiment was conducted for period of 48 h comprising two gavages with a 24-h interval between them. Some of the parameters analyzed in liver, brain, gill, and muscle included activity of the enzymes glutathione-S-transferase (GST), glutamate cysteine ligase (GCL), glutathione reductase (GR), and GSH concentration. We also evaluated GST pi concentration by Western blot as well as calpain activity in liver and brain samples. In carp liver from the MC 50 group,we obeserved a decrease in GST and GCL activity, which was accompanied by a decreased GSH concentration. In addition, liver calpain activity was highly induced in carp at both MC doses.Thus, MC ingestion affected the liver antioxidant status through decreasing the GSH concentration and the activity of the enzyme involved in its synthesis (GCL). It also decreased the MC detoxification capacity of the liver because total GST activity decreased, a result that cannot be ascribed to GST pi levels. Because GSH acts as an uncompetitive inhibitor of calpain, its decrease should explain the higher activity of this apoptotic enzyme. The main goal of this study was to show that a decrease in GSH concentration is related to decreased activity of GCL, the limiting enzyme involved in GSH synthesis. Because MCs are phosphatase inhibitors and GCL is allosterically inhibited by phosphorylation, the cellular hyperphosphorylation state induced by MC exposure could act as a modulator factor for antioxidant defenses

Biomarkers of exposure and effect in the Brazilian flounder Paralichthys orbignyanus (Teleostei: Paralichthyidae) from the Patos Lagoon estuary (Southern Brazil).

Biomarkers of exposure (liver metallothionein-like proteins content and catalase and glutathione S-transferase activities) and effect (liver lipoperoxidation and blood cell DNA damage) of contaminants were analyzed in the Brazilian flounder Paralichthys orbignyanus from the Patos Lagoon estuary (Southern Brazil). Flounders were collected for a year in two sites: ‘‘Coroa do Boi’’ (polluted site) and ‘‘Saco do Justino’’ (non-polluted site). Results indicated that micronucleated cells frequency was the best biomarker to distinguish flounders from the two sites. Taken together, data from DNA damage analyses (micronucleus test and comet assay) indicated that flounders from the non-polluted site efficiently repaired the DNA breaks, contrary to those from the polluted site, which probably had their DNA repair system inhibited or exhausted. Furthermore, data from enzyme activities (catalase and GST) and lipid peroxidation indicated that flounders from the polluted site were under oxidative stress in summer and autumn

Microzooplâncton como bioindicador da degradação ambiental na Amazônia

Federal University of Pará. Postgraduate Program in Aquatic Ecology and Fish. Belém, PA, Brazil / Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Federal University of Pará. Postgraduate Program in Aquatic Ecology and Fish. Belém, PA, Brazil.Federal University of Pará. Postgraduate Program in Aquatic Ecology and Fish. Belém, PA, Brazil / Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Abstract: Recent studies have assessed the impact of the discharge of untreated domestic and industrial effluents on aquatic ecosystems. In the 1980s, large industrial factories were set up in the municipality of Barcarena, Amazon, Brazil; however, this was not accompanied by investments to improve basic sanitation and housing structures in the region, resulting in deterioration of the surface water quality. The main aims of this study were to characterize the zooplankton community of surface water to elucidate the influence of unregulated territorial occupation and industrial development on ecosystem degradation of three rivers located near the industrial and port area of Barcarena. The physico-chemical and microbiological parameters linked to water quality assessment were also analyzed. In each river, three sites were selected for sampling, which was performed quarterly in 2012. The zooplankton community of the three rivers comprised 149 taxa, and the density of zooplankton varied among rivers; Arapiranga River had the lowest values, followed by Curuperê-Dendê and Murucupi Rivers. IndVal analyses show that Keratella lenzi and Anuraeopsis sp1 have elevated fidelity and specificity to the Curuperê-Dendê and Murucupi Rivers, both of which are strongly affected by anthropogenic forces. Difflugia distenda and Difflugia sp7 were associated with Arapiranga River, which has a well-conserved ecosystem

Microcystin-induced oxidative stress in Laeonereis acuta (Polychaeta, Nereididae)

Oxidative stress induced by microcystins was evaluated in an estuarine worm, Laeonereis acuta (Nereididae).Ten organisms were exposed to lyophilized cells of a toxic Microcystis aeruginosa strain RST9501 ( 2 lg/mL microcystins, MC); 10 were exposed to lyophilized cells of a nontoxic Aphanotece sp. strain RSMan92 and 10 were maintained without cyanobacterial cells. Exposure time was 48 h. The enzymatic antioxidant defenses, as well as the oxidative damage, were analyzed. Toxic and nontoxic cyanobacteria lowered catalase activity with no changes in glutathione reductase and glutathione-S-transferase activities. This may have led to toxin intracellular accumulation, which should favor oxidative stress generation,observed by the high lipid peroxide and DNA–protein crosslink levels in the group exposed to MC

Application of public-domain statistical analysis software for evaluation and comparison of comet assay data

A novel approach for statistical analysis of comet assay data (i.e.: tail moment) is proposed, employing public-domain statistical software, the R system. The analytical strategy takes into account that the distribution of comet assay data, like the tail moment, is usually skewed and do not follow a normal distribution. Probability distributions used to model comet assay data included: the Weibull, the exponential, the logistic, the normal, the log normal and log-logistic distribution. In this approach it was also considered that heterogeneity observed among experimental units is a random feature of the comet assay data. This statistical model can be characterized with a location parameter mij, a scale parameter r and a between experimental units variability parameter θ. In the logarithmic scale, the parameter mij depends additively on treatment and random effects, as follows: log(mij) = a0 + a1xij + bi, where exp(a0) represents approximately the mean value of the control group, exp(a1) can be interpreted as the relative risk of damage with respect to the control group, xij is an indicator of experimental group and exp(bi) is the individual risk effects assume to follows a Gamma distribution with mean 1 and variance θ. Model selection is based on Akaike’s information criteria (AIC). Real data coming from comet analysis of blood samples taken from the flounder Paralichtys orbignyanus (Teleostei: Paralichtyidae) and from samples of cells suspension obtained from the estuarine polychaeta Laeonereis acuta (Nereididae) were employed. This statistical approach showed that the comet assay data should be analyzed under a modeling framework that take into account the important features of these measurements. Model selection and heterogeneity between experimental units play central points in the analysis of these data