Long-term changes in benthic communities following the invasion by an alien octocoral in the Southwest Atlantic, Brazil.

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.

Changing our view of the Schistosoma granuloma to an ecological standpoint.

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.

A global trend of caffeine consumption over time and related-environmental impacts.

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.

Far-reaching cytogenotoxic effects of mine waste from the Fundão dam disaster in Brazil.

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.

Viruses and bacteria in floodplain lakes along a major Amazon tributary respond to distance to the Amazon River.

In response to the massive volume of water along the Amazon River, the Amazon tributaries have their water backed up by 100s of kilometers upstream their mouth. This backwater effect is part of the complex hydrodynamics of Amazonian surface waters, which in turn drives the variation in concentrations of organic matter and nutrients, and also regulates planktonic communities such as viruses and bacteria. Viruses and bacteria are commonly tightly coupled to each other, and their ecological role in aquatic food webs has been increasingly recognized. Here, we surveyed viral and bacterial abundances (BAs) in 26 floodplain lakes along the Trombetas River, the largest clear-water tributary of the Amazon River's north margin. We correlated viral and BAs with temperature, pH, dissolved inorganic carbon, dissolved organic carbon (DOC), phosphorus, nitrogen, turbidity, water transparency, partial pressure of carbon dioxide (pCO2), phytoplankton abundance, and distance from the lake mouth until the confluence of the Trombetas with the Amazon River. We hypothesized that both bacterial and viral abundances (VAs) would change along a latitudinal gradient, as the backwater effect becomes more intense with increased proximity to the Amazon River; different flood duration and intensity among lakes and waters with contrasting sources would cause spatial variation. Our measurements were performed during the low water period, when floodplain lakes are in their most lake-like conditions. Viral and BAs, DOC, pCO2, and water transparency increased as distance to the Amazon River increased. Most viruses were bacteriophages, as viruses were strongly linked to bacteria, but not to phytoplankton. We suggest that BAs increase in response to DOC quantity and possibly quality, consequently leading to increased VAs. Our results highlight that hydrodynamics plays a key role in the regulation of planktonic viral and bacterial communities in Amazonian floodplain lakes.

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir.

Substantial amounts of organic matter (OM) from terrestrial ecosystems are buried as sediments in inland waters. It is still unclear to what extent this OM constitutes a sink of carbon, and how much of it is returned to the atmosphere upon mineralization to carbon dioxide (CO2). The construction of reservoirs affects the carbon cycle by increasing OM sedimentation at the regional scale. In this study we determine the OM mineralization in the sediment of three zones (river, transition, and dam) of a tropical hydroelectric reservoir in Brazil as well as identify the composition of the carbon pool available for mineralization. We measured sediment organic carbon mineralization rates and related them to the composition of the OM, bacterial abundance and pCO2 of the surface water of the reservoir. Terrestrial OM was an important substrate for the mineralization. In the river and transition zones most of the OM was allochthonous (56 and 48%, respectively) while the dam zone had the lowest allochthonous contribution (7%). The highest mineralization rates were found in the transition zone (154.80 ± 33.50 mg C m(-) (2) d(-) (1)) and the lowest in the dam (51.60 ± 26.80 mg C m(-) (2) d(-) (1)). Moreover, mineralization rates were significantly related to bacterial abundance (r (2) = 0.50, p < 0.001) and pCO2 in the surface water of the reservoir (r (2) = 0.73, p < 0.001). The results indicate that allochthonous OM has different contributions to sediment mineralization in the three zones of the reservoir. Further, the sediment mineralization, mediated by heterotrophic bacteria metabolism, significantly contributes to CO2 supersaturation in the water column, resulting in higher pCO2 in the river and transition zones in comparison with the dam zone, affecting greenhouse gas emission estimations from hydroelectric reservoirs.

Light microscopy in aquatic ecology: methods for plankton communities studies.

Planktonic organisms dominate waters in ponds, lakes and oceans. Because of their short life cycles, plankters respond quickly to environmental changes and the variability in their density and composition are more likely to indicate the quality of the water mass in which they are found. Planktonic community is formed by numerous organisms from distinct taxonomic position, ranging from 0.2 µm up to 2 mm. Despite others, the light microscopy is the most used apparatus to enumerate these organisms and different techniques are necessary to cover differences in morphology and size. Here we present some of the main light microscopy methods used to quantify different components of planktonic communities, such as virus, bacteria, algae and animals.