Leidiane Pereira Diniz

We investigated the impact of forest fires on species richness and β-diversity of a zooplankton resting egg bank in a high-altitude temporary pond in the Neotropical region. We hypothesized that (i) species richness and (ii) total β-diversity (β _total ) would be higher before forest fires than during and after fire; (iii) β _total would be driven by species replacement (β _repl ) before and after fires; and (iv) during fires, β _total would be mainly driven by richness differences (β _rich ). We used historical data from studies conducted in the same pond in 2014 and 2018 (i.e., before the fires), together with experimental hatching simulations during (2024) and after (2025) fire. Zooplankton species richness was higher before the fires. However, total β-diversity was highest during the fire period and was driven by richness differences, revealing a marked loss of species. Our findings indicate that forest fires acted as an environmental filter, reducing zooplankton viability and diversity and promoting species loss, thereby highlighting the negative effects of forest fire events and their implications for the future structure of communities. Predicted scenarios of increasing temperatures and higher fire frequency in tropical regions may modulate the establishment and selection of zooplankton species in temporary aquatic ecosystems.

The relationships between the functional diversity of phytoplankton and environmental conditions offer insights into phytoplankton community structure under environmental gradients in basins influenced by anthropogenic disturbances, including mining residues. Thus, we aimed to identify the main environmental drivers of the functional diversity of phytoplankton by considering three types of ecosystems and two distinct seasonal periods. We hypothesized that (1) ecosystems with higher hydrological stability and lower contamination—particularly deep lakes—support greater phytoplankton functional diversity, and (2) seasonal effects on functional diversity are more pronounced in rivers. Sampling was conducted between October 2018 and September 2021 in the Doce River and in shallow lakes and deep lakes of the floodplain. Functional diversity indices were measured based on seven functional traits comprising species volume, silica demand, heterocyst presence, mixotrophy potential, aerotope presence, flagella presence, and life form. Deep lakes exhibited higher functional diversity due to lower eutrophication conditions, metal contamination, and greater light availability. In the river, the increase in functional diversity during the dry season suggested an attenuation of anthropogenic pressures, considering the improvement in environmental conditions. Our results showed a dependence of the functional diversity of phytoplankton on the type of environment, and that the environments experienced distinct effects according to seasonality. Additionally, we demonstrated that resource availability, lower levels of metal contamination, and reduced grazing pressure resulted in greater functional diversity of the phytoplankton. We thus emphasize the importance of assessing functional aspects of phytoplankton in the biomonitoring of areas strongly impacted by anthropogenic activities.

Tragic incidents involving mine tailings spills have impacted many aquatic ecosystems around the world. The massive mine tailings dam collapse of Fundão, which occurred in Brazil in 2015, affected several aquatic ecosystems, including shallow and deep lakes in the lower Doce River basin. Until now, the effects of mine tailings on the functional diversity of zooplankton remain poorly understood. We investigated the functional diversity of zooplankton (functional groups, functional richness [FRic] and functional evenness [FEve]) in shallow and deep lakes, exploring the influence of environmental variables and metals. In addition, trends in functional redundancy and functional vulnerability were also assessed to understand patterns of resilience in mining‐impacted ecosystems. Surveys were performed monthly on three deep and three shallow lakes affected by the dam failure, from October 2018 to September 2019. In the deep lakes, the zooplankton community was dominated by smaller filter‐feeders and omnivorous species, associated with cyanobacteria density and chlorophyll‐a. Medium‐sized filters were associated to iron, suspended particulate organic matter and total organic carbon in shallow lakes. The smaller filter‐feeders and omnivorous trophic groups had a higher contribution to increasing the functional diversity of zooplankton than medium‐sized filter‐feeders in both deep and shallow lakes. FRic and FEve were higher in deep lakes than in shallow lakes. Shallow lakes were highly vulnerable to species loss and functional diversity was modulated by environmental changes and metal pollution. Tropical shallow lakes impacted by mining tailings should receive particular attention in conservation plans, as a consequence of their high level of pollutant retention in comparison with deep lakes. In addition, we highlight the importance of using a functional approach to better understand the ecosystem changes resulting from the impacts of mine tailings on aquatic environments.