Impact of run-of-river damming on increasing phytoplankton biomass and species shift in a large Amazonian river.

Run-of-river (ROR) dams, often perceived as having minimal environmental impact, can induce significant hydrodynamic changes that alter aquatic ecosystems. We investigated the impacts of an ROR dam on the Madeira River, the largest Amazon tributary, focusing on phytoplankton communities, their ecological implications, and related environmental factors. Our study examined changes in biomass and environmental factors (using General Linear Mixed Models - GLMM), species composition (using PERMANOVA) before and after damming, in both the main channel and tributaries (N = 549 samples).

Experimental warming promotes phytoplankton species sorting towards cyanobacterial blooms and leads to potential changes in ecosystem functioning.

A positive feedback loop where climate warming enhances eutrophication and its manifestations (e.g., cyanobacterial blooms) has been recently highlighted, but its consequences for biodiversity and ecosystem functioning are not fully understood.

Understanding temporal variability across trophic levels and spatial scales in freshwater ecosystems.

A tenet of ecology is that temporal variability in ecological structure and processes tends to decrease with increasing spatial scales (from locales to regions) and levels of biological organization (from populations to communities). However, patterns in temporal variability across trophic levels and the mechanisms that produce them remain poorly understood. Here we analyzed the abundance time series of spatially structured communities (i.

Effects of warming on the structure of aquatic communities in tropical bromeliad microecosystems.

Freshwaters are among the most vulnerable ecosystems to climate warming, with projected temperature increases over the coming decades leading to significant losses of aquatic biodiversity. Experimental studies that directly warm entire natural ecosystems in the tropics are needed, for understanding the disturbances on aquatic communities. Therefore, we conducted an experiment to test the impacts of predicted future warming on density, alpha diversity, and beta diversity of freshwater aquatic communities, inhabiting natural microecosystems-Neotropical tank bromeliads.

Nutrients and not temperature are the key drivers for cyanobacterial biomass in the Americas.

Cyanobacterial blooms imperil the use of freshwater around the globe and present challenges for water management. Studies have suggested that blooms are trigged by high temperatures and nutrient concentrations. While the roles of nitrogen and phosphorus have long been debated, cyanobacterial dominance in phytoplankton has widely been associated with climate warming.

Effects of space and environment on phytoplankton distribution in subtropical reservoirs depend on functional features of the species.

Unlabelled: Environmental factors and dispersal can influence the structure of biological communities. Their effects can depend on the functional features of the species in the community. Since species belonging to the same trophic level, such as phytoplankton, may show functional differences, we investigated whether the effects of environment and dispersal differ among phytoplankton species from different functional groups.

Warming and top predator loss drive direct and indirect effects on multiple trophic groups within and across ecosystems.

The interspecific interactions within and between adjacent ecosystems strongly depend on the changes in their abiotic and biotic components. However, little is known about how climate change and biodiversity loss in a specific ecosystem can impact the multiple trophic interactions of different biological groups within and across ecosystems. We used natural microecosystems (tank-bromeliads) as a model system to investigate the main and interactive effects of aquatic warming and aquatic top predator loss (i.

Trophic downgrading decreases species asynchrony and community stability regardless of climate warming.

Theory and some evidence suggest that biodiversity promotes stability. However, evidence of how trophic interactions and environmental changes modulate this relationship in multitrophic communities is lacking. Given the current scenario of biodiversity loss and climate changes, where top predators are disproportionately more affected, filling these knowledge gaps is crucial.

Differently dispersing organism groups show contrasting beta diversity patterns in a dammed subtropical river basin.

Although it is widely known that dams can have large impacts on the environmental and biological characteristics of downstream rivers, there is a substantial lack of studies focusing on which ecological processes cause longitudinal changes in biological communities downstream of reservoirs. We investigated longitudinal patterns in the total beta diversity and its replacement and richness difference components for actively (fish) and passively (phytoplankton) dispersing biological groups. Our results, obtained from a 230 km sampling stretch, demonstrated the key role played by tributaries in the downstream direction from main river impoundment, which influenced local environmental conditions and beta diversity patterns of each biological group.

Main predictors of periphyton species richness depend on adherence strategy and cell size.

Periphytic algae are important components of aquatic ecosystems. However, the factors driving periphyton species richness variation remain largely unexplored. Here, we used data from a subtropical floodplain (Upper Paraná River floodplain, Brazil) to quantify the influence of environmental variables (total suspended matter, temperature, conductivity, nutrient concentrations, hydrology, phytoplankton biomass, phytoplankton species richness, aquatic macrophyte species richness and zooplankton density) on overall periphytic algal species richness and on the richness of different algal groups defined by morphological traits (cell size and adherence strategy).

Dispersal ability determines the role of environmental, spatial and temporal drivers of metacommunity structure.

Recently, community ecologists are focusing on the relative importance of local environmental factors and proxies to dispersal limitation to explain spatial variation in community structure. Albeit less explored, temporal processes may also be important in explaining species composition variation in metacommunities occupying dynamic systems. We aimed to evaluate the relative role of environmental, spatial and temporal variables on the metacommunity structure of different organism groups in the Upper Paraná River floodplain (Brazil).