Responses of Functional and Taxonomic Phytoplankton Diversity to Environmental Gradients in Subtropical and Tropical Reservoirs

Understanding the influence of environmental conditions on biodiversity is a major task in ecology. We investigated how phytoplankton taxonomic (TD) and functional (FD) diversities vary with environmental factors in eight subtropical and tropical reservoirs. We hypothesized that i) environmental variables affect phytoplankton TD and FD; ii) FD provides better relationships to environmental changes than TD, and; iii) indices based on biomass are better related to the environment than those based on identities. The relationships between phytoplankton diversities and environmental drivers were assessed through generalized linear models. Our hypotheses were partly confirmed. TD and FD were, in fact, dependent on the environment, with higher values occurring in warmer, clearer, and more enriched systems, under lower zooplankton grazing pressure; but FD based on identities was not predicted better from environmental conditions than TD based on identities. As expected, indices based on biomass are better related to the environment than their counterpart based on identities

Downstream transport processes modulate the effects of environmental heterogeneity on riverine phytoplankton

Environmental heterogeneity (EH) in space and time promotes niche-partition, which leads to high variation in biological communities, such as in algae. In streams, EH is highly related to the intensity of the water flow and may lead to community variation mainly during the low flow conditions. Despite the wide knowledge on the responses of phytoplankton communities to EH in lentic and semi-lentic systems, studies of riverine phytoplankton community variation are still scarce. Here, we first investigated the relationship between phytoplankton community variation and EH in different courses of the river and between seasons. We expected that under low or intermediate flow conditions, there is a positive correlation between community variation and EH. Alternatively, we did not expect any relationship between EH and community variation under high flow condition because stronger downstream transport would mask environmental filtering. We sampled nine sites monthly (May 2012 to April 2013) in a tropical river of Brazilian Southeast. We calculated EH from abiotic data whereas for community variation, here community distinctiveness (CD), we used Sorensen (CDSor) and Bray-Curtis (CDBray) dissimilarities. Differences in EH, CDSor and CDBray were tested at between-season and among-course levels. We found lower distinctiveness during the dry season when EH was the highest. Contrastingly, phytoplankton CD was the highest even when EH was low during the wet season. We found that this pattern raised from the increasing in individuals dispersal during the wet season, promoting mass effects. Finally, our results thus reject the first hypothesis and show a negative relationship between EH and distinctiveness. However, results support our alternative hypothesis and show that during the wet season, distinctiveness is not driven by EH. These results provide new insights into how EH drives community variation, being useful for both basic research about riverine algal communities and biomonitoring programs using phytoplankton communities as bioindicators. (C). 2019 Elsevier B.V. All rights reserved.Peer reviewe

PHYTOPLANKTON BIOMASS INCREASES IN A SILT-IMPACTED AREA IN AN AMAZONIAN FLOOD-PLAIN LAKE OVER 15 YEARS

Funding Information: We thank Mineração Rio do Norte S.A. and Limnologia/UFRJ for fieldwork support, Dr. Janet W. Reid (JWR Associates) for language revision, and Leonardo Preza Rodrigues for map charting. VLMH, JCN, FAE, RLB, and FR are partially supported by the National Council for Scientific and Technological Development (CNPq), Brazil, RLB, and FAE by FAPERJ, Brazil, and CGR financially supported by Sakari Alhopuro Foundation, Finland. Publisher Copyright: © 2022, Universidade Federal do Rio de Janeiro. All rights reserved.Tailings from bauxite mining in Porto Trombetas (Pará state, Central Amazonia, Brazil) was discharged (1979–1989) into Batata Lake affecting about 30% of its area. The lake belongs to a clear-water flood-plain system along the Trombetas River, a tributary of the Amazon River. Siltation is the main perceived factor impacting aquatic and flooded communities. Besides natural regeneration, a program to restore a section of igapó forest in the impacted area (IA) has been conducted since 1991. Decreased light is the main factor reducing total phytoplankton biomass (PhyBM) in IA. We hypothesized that PhyBM in IA increases over time because of the improvement of the underwater light conditions due to the natural regeneration and restoration. We sampled quarterly PhyBM and limnological variables (depth, transparency, temperature, pH, conductivity, dissolved oxygen, turbidity, suspended solids, total Kjeldahl nitrogen, and total phosphorus), over 15 years (2005–2019) at eight sampling sites in the two areas (N = 349). We also obtained daily climatic and hydrologic data. PhyBM was higher in NIA than in IA. The temporal trend in the annual mean of PhyBM increased significantly over time only in the IA, approximating the NIA values, confirming our general hypothesis. The increase of PhyBM in the IA was negatively related to the residual light attenuation caused by non-phytoplankton turbidity and to total phosphorus, and positively to air temperature and site depth (p < 0.05; Marginal r2 = 0.18; Conditional r2 = 0.29). Instead, in NIA, PhyBM was explained only by the increase in air temperature (p < 0.05; Marginal r2 = 0.15; Conditional r2 = 0.34). We concluded that the PhyBM in the IA positively responds to the synergy between increasing light availability, air temperature, and site depth, and decreasing total phosphorus concentrations, regardless of hydrologic phase.Peer reviewe

Naturschutz, Wildschutz und Jagdwesen in der T\ufcrkei

Volume: 24Start Page: 227End Page: 23

Reynolds Functional Groups: a trait-based pathway from patterns to predictions

Reynolds Functional Groups (RFG) were designed to represent the diversity of phytoplankton assemblages of freshwater ecosystems and are among the most enduring legacies of C. S. Reynolds to freshwater phytoplankton ecologists. The RFG concept summarises a rich base of knowledge, clustering species according to functional criteria. RFG allow researchers to organise information, understand community and ecosystem functioning, and identify future outcomes, also contributing to construct hypotheses and define community assembly. This approach represents the environmental requirements, tolerances and sensitivities of species, organizing them into diagnostic environmental axes representing the habitat template of phytoplankton communities. In this contribution, we highlight the importance of this trait-based approach for phytoplankton ecology, and summarise its history and usage for phytoplankton species classifications and prediction based on environmental gradients. We present some of the applications of the approach, to describe patterns, explain mechanisms and predict new situations. We hope that this review will contribute both to describe the trajectory and practice of RFG and to encourage its use in addressing new ecological questions and in generating new avenues of research.Fil: Kruk, Betina Claudia. Universidad de la Republica. Centro Universitario Regional del Este; UruguayFil: Devercelli, Melina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Huszar, Vera L.. Universidade Federal Do Rio de Janeiro. Museu Nacional; Brasi

Phytoplankton and its biotic interactions: Colin Reynolds’ legacy to phytoplankton ecologists

The 18th workshop of the International Association for Phytoplankton Taxonomy and Ecology (IAP), the first ‘‘tropical’’ IAP ever, the third one outside Europe, and the first one in South America, was held in Natal, Brazil, from August 27 to September 3, 2017, and its main ecological theme was the Phytoplankton and its biotic interactions. The taxonomic topic of the workshop was chosen based on function instead of phylogeny, and to link to the ecological theme of the workshop, the taxonomic theme was therefore centered on mixotrophic microalgae