On November 2015, one of Brazil's most important watersheds was impacted by the mine waste from Fundão dam collapse in Mariana. The mine waste traveled over 600 km along the Doce River before ...reaching the sea, causing severe devastation along its way. Here we assessed trace element concentrations and cytogenotoxic effects of the released mine waste. Water samples were collected along the Doce River ten days after the disaster in two impacted sites and one non-impacted site. Sampling points were located hundreds of kilometers downstream of the collapsed dam. Water samples were used for trace element quantification and to run an experiment using Allium cepa to test cytogenotoxicity. We found extremely high concentrations of particulate Fe, Al, and Mn in the impacted sites. We observed cytogenotoxic effects such as alterations in mitotic and phase indexes, and enhanced frequency of chromosomal aberrations. Our results indicate interferences in the cell cycle in impacted sites located hundreds of kilometers downstream of the disaster. The environmental impacts of the dam collapse may not only be far-reaching but also very likely long-lasting, because the mine waste may persist in the Doce River sediment for decades.
•Higher concentrations of particulate metals were found in impacted sites.•Cytogenotoxic effects were found in the impacted sites.•Mining waste affected genetic aspects of Allium cepa.•Impacts of the tragedy are far-reaching and long-lasting.
Caffeine is one of the most consumed substances, and it has been largely detected in aquatic ecosystems. We investigated the trends in caffeine consumption over three decades and its relationships ...with gross domestic product (GDP) and human development index (HDI) to understand global patterns and to identify potential hotspots of contamination. The total caffeine consumption is increasing mainly due to population growth. Moreover, caffeine consumption per capita is also increasing in some countries, such as Brazil, Italy, and Ethiopia. A high positive correlation between caffeine consumption per capita with HDI and GDP was found for coffee-importing countries in Europe, while a high negative correlation was found for coffee-exporting countries in Africa. The literature review showed that the highest caffeine concentrations coincide with countries that present an increasing caffeine consumption per capita. Also, approximately 35% of the caffeine concentrations reported in the literature were above the predicted no-effect concentration in the environment and, again, overlaps with countries with increasing per capita consumption. Despite the high degradation rate, caffeine consumption tends to increase in a near future, which may also increase the overall amount of caffeine that comes into the environment, possibly exceeding the thresholds of several species described as tolerant to the current environmental concentrations. Therefore, it is essential to prevent caffeine from reaching aquatic ecosystems, implementing sewage treatment systems, and improving their efficiency.
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•The global patterns and trends in caffeine consumption over time were investigated.•Caffeine concentration in the aquatic ecosystems may increase in the coming years.•Positive correlations between caffeine consumption and time were found in Europe.•Negative correlations between caffeine consumption and time were found in Africa.•Increasing caffeine consumption coincides with high environmental concentrations.
Caffeine concentrations in the environment may increase in the near future due to increasing consumption, especially in countries lacking sanitation.
Invasive alien species are considered one of the main threats to marine biodiversity. We used a BACI design to investigate the changes in rocky reef benthic communities related to the invasion of the ...octocoral Latissimia ningalooensis in the Southwest Atlantic. Drastic changes in benthic community structure were restricted to the invaded site and associated with the growth of L. ningalooensis on turf algae. Conversely, the zoanthid Palythoa caribaeorum remained stable coverage along the 9-year study period, indicating a greater biotic resistance against the octocoral. Latissimia ningalooensis spread from large and well-established patches to new areas of the reef, increasing turf-octocoral interactions. This study warns of the great invasive potential of the octocoral, due to its high abundance, competitive and expansion ability. The decline in abundance of turf-forming algae following the emergence of L. ningalooensis threatens the structure and functioning of macroalgal-dominated rocky reefs.
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•The alien octocoral was largely associated with changes in the benthic community.•Changes were associated with the growth of the invader on turf algae.•Zoanthid cover remained stable indicating a greater biotic resistance.•The invader is spreading through turf-octocoral interactions.•Invasive octocorals threatens macroalgal-dominated rocky reefs.
Understanding how species are structured in space and time and how they are functionally related to environmental conditions is still a challenge in ecology. In this study, we assessed the predictive ...power of lake morphometry, physical and chemical conditions of the water, and zooplankton density in relation to phytoplankton taxonomic and functional diversity in Amazonian floodplain lakes during low- and high-water periods. We also examined to what extent taxonomic and functional indexes were coupled. Taxonomic diversity was evaluated by species richness and Shannon index, and functional diversity by functional richness (FRic) and community-weighted mean trait value (CWM). The relative importance of predictive factors was evaluated by model selection, multi-model inference and correlations. We found that phytoplankton taxonomic and functional diversity indexes were mostly related to the same factors within the low- and high-water periods. Total phosphorus was the main driving factor in the low water, while euphotic zone depth and zooplankton density were the main driving factors in the high water. Taxonomic and functional diversity indexes were weakly coupled in the low water, but strongly coupled in the high water. Our results highlight that phytoplankton taxonomic and functional diversity can differ between periods, but respond similarly to environmental driving factors.
Accelerated eutrophication reduces water quality and shifts plankton communities. However, its effects on the aquatic food web and ecosystem functions remain poorly understood. Within this context, ...functional ecology can provide valuable links relating community traits to ecosystem functioning. In this study, we assessed the effects of eutrophication and cyanobacteria blooms on zooplankton functional diversity in a tropical hypereutrophic lake. Phytoplankton and zooplankton communities and limnological characteristics of a tropical Brazilian Lake (Southeast, Brazil) were monitored monthly from April 2013 to October 2014. Lake eutrophication indicators were total phosphorus, total chlorophyll-a, and chlorophyll-a per group (blue, green, and brown). The variation of major phytoplankton taxonomic group biomass was calculated and used as a proxy for changes in phytoplankton composition. Zooplankton functional diversity was assessed through functional dispersion and the community-weighted mean trait value. Regressions were performed between the lake eutrophication indicators, the phytoplankton biomass variation, and zooplankton functional dispersion. Our results suggest that eutrophication and cyanobacterial dominance change the composition of zooplankton traits and reduce functional dispersion, leading to zooplankton niche overlap. These findings are important because they provide a meaningful view of phytoplankton-zooplankton trophic interactions and contribute to an improved understanding their functional effects on aquatic ecosystems.
Freshwater sediments are important sites of organic carbon (OC) burial and mineralization. Previous studies indicate that warming can increase rates of OC mineralization, implying more CO₂ release ...from sediments and, consequently, less OC burial, but temperatures typical of tropical ecosystems are poorly represented in the models of temperature and OC mineralization. We measured OC mineralization rates in 61 Brazilian tropical systems, including rivers, streams, lakes, coastal lagoons, and reservoirs from different regions (Pantanal, Amazonia, Atlantic Forest, and coastal areas). Oxygen consumption and dissolved inorganic carbon production in sediment core incubations were used for estimating OC mineralization rates. Multiple regression models were used to investigate the importance of temperature and other variables to predict OC mineralization. The average OC mineralization rate for all systems was 1223 ± 950 mg C m−2 d−1. Rates increased significantly with increasing temperature and varied across system types and regions. In addition, salinity, total nitrogen, and chlorophyll a were important factors controlling OC mineralization in tropical sediments. The pattern of increasing mineralization with temperature was remarkably consistent with theoretical and empirical expectations. The explanatory power of previous temperature vs. mineralization models is confirmed and enhanced by the addition of the tropical data that substantially extended the temperature range.
ABSTRACT
Schistosomiasis, a neglected parasitic tropical disease that has plagued humans for centuries, remains a major public health burden. A primary challenge to understanding schistosomiasis is ...deciphering the most remarkable pathological feature of this disease, the granuloma – a highly dynamic and self‐organized structure formed by both host and parasite components. Granulomas are considered a remarkable example of how parasites evolved with their hosts to establish complex and intimate associations. However, much remains unclear regarding life within the granuloma, and strategies to restrain its development are still lacking. Here we explore current information on the hepatic Schistosoma mansoni granuloma in the light of Ecology and propose that this intricate structure acts as a real ecosystem. The schistosomal granuloma is formed by cells (biotic component), protein scaffolds, fibres, and chemical compounds (abiotic components) with inputs/outputs of energy and matter, as complex as in classical ecosystems. We review the distinct cell populations (‘species’) within the granuloma and examine how they integrate with each other and interact with their microenvironment to form a multifaceted cell community in different space–time frames. The colonization of the hepatic tissue to form granulomas is explained from the point of view of an ecological succession whereby a community is able to modify its physical environment, creating conditions and resources for ecosystem construction. Remarkably, the granuloma represents a dynamic evolutionary system that undergoes progressive changes in the ‘species’ that compose its community over time. In line with ecological concepts, we examine the granuloma not only as a place where a community of cells is settled (spatial niche or habitat) but also as a site in which the functional activities of these combined populations occur in an orchestrated way in response to microenvironmental gradients such as cytokines and egg antigens. Finally, we assert how the levels of organization of cellular components in a granuloma as conventionally defined by Cell Biology can fit perfectly into a hierarchical structure of biological systems as defined by Ecology. By rethinking the granuloma as an integrating and evolving ecosystem, we draw attention to the inner workings of this structure that are central to the understanding of schistosomiasis and could guide its future treatment.
Mining is an important economic activity that can have severe impacts on aquatic ecosystems. Plankton communities are commonly used as bioindicators of human‐related threats to freshwater ...environments due to their rapid response to environmental conditions changes. Here, we used zooplankton functional diversity to understand the recovery patterns of an Amazonian lake impacted by mining activity (input of bauxite tailings) after 30 years of natural attenuation and active restoration processes. Zooplankton species richness and functional diversity (Rao's quadratic entropy—FDQ and community‐level weighted means of trait values—CWM) were compared in impacted and reference areas during the flood period, in March 2015. We found a significant negative influence of turbidity on zooplankton FDQ, and similar FDQ and CWM values between the active restoration area and the reference area. These results suggest a positive effect of vegetation restoration efforts for the zooplankton community of Batata Lake. We demonstrated the utility of zooplankton functional diversity metrics as bioindicators of freshwater restoration, the response of the aquatic ecosystem to vegetation restoration and, consequently, water quality.
•Water hyacinth is an effective CO2-to-biomass-to-CH4 converter.•Increased coverage and rooting enhance CH4 emission to the atmosphere.•Water hyacinth plant-mediated CH4 transport strongly affect net ...GHG balance.
Water hyacinth stands are known to affect both nutrient concentrations in the water and carbon exchange with the atmosphere. However, both enhanced and reduced greenhouse gas (GHG) emissions have been reported in relation to water hyacinth presence. This controversy may be explained by variation in plant density and rooting. High growth rates indicate its capacity to mobilize and store nutrients in the tissues, and assimilate large amounts of carbon dioxide (CO2). Simultaneously the plant can stimulate methane (CH4) emission. This may occur when plants are rooting in the sediment due to CH4 shuttling from the sediment, through the plant, into the atmosphere. To unravel the potential influences of water hyacinth on nutrient dynamics and GHG fluxes, we performed an experiment in which plant coverage and root access to the sediment were manipulated. Plants reduced phosphorus concentrations in water and pore-water, independent of coverage and rooting, also rooting plants grown at high coverage showed higher plant N:P ratios. CH4 emissions were highest at high coverage and were further increased by rooting, indicating that plant-mediated transport indeed takes place. However, the overall GHG budget in terms of CO2 equivalents still resulted in the water hyacinth vegetation being near neutral, or even a net sink with respect to GHG exchange. The plant-induced enhancement of CH4 emissions suggests that the plant can be an effective CO2-to-biomass-to-CH4 converter. Our results show that plant coverage and water depth – regulating sediment-root contact – should be taken into account when estimating water hyacinth’s effect on GHG emissions.
Artificial reservoirs likely accumulate more carbon than natural lakes due to their unusually high sedimentation rates. Nevertheless, the actual magnitude of carbon accumulating in reservoirs is ...poorly known due to a lack of whole-system studies of carbon burial. We determined the organic carbon (OC) burial rate and the total OC stock in the sediments of a tropical hydroelectric reservoir by combining a seismic survey with sediment core sampling. Our data suggest that no sediment accumulation occurs along the margins of the reservoir and that irregular bottom morphology leads to irregular sediment deposition. Such heterogeneous sedimentation resulted in high spatial variation in OC burial—from 0 to 209 g C m⁻² y⁻¹. Based on a regression between sediment accumulation and OC burial rates (R ² = 0.94), and on the mean reservoir sediment accumulation rate (0.51 cm y⁻¹, from the seismic survey), the whole-reservoir OC burial rate was estimated at 42.2 g C m⁻² y⁻¹. This rate was equivalent to 70% of the reported carbon emissions from the reservoir surface to the atmosphere and corresponded to a total sediment OC accumulation of 0.62 Tg C since the reservoir was created. The approach we propose here allows an inexpensive and integrative assessment of OC burial in reservoirs by taking into account the high degree of spatial variability and based on a single assessment. Because burial can be assessed shortly after the survey, the approach combining a seismic survey and coring could, if applied on a larger scale, contribute to a more complete estimate of carbon stocks in freshwater systems in a relatively short period of time.
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