Drivers and ecological consequences of dominance in periurban phytoplankton communities using networks approaches

Abstract

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Community Compositions of Phytoplankton and Eukaryotes during the Mixing Periods of a Drinking Water Reservoir: Dynamics and Interactions

“…Among these modules, modules I and II were the largest co-occurrence modules in the whole networks, and each module revealed different composing characteristics in a different co-occurrence network. For each co-occurrence With respect to vertical variation within the phytoplankton community composition, Bacillariophyta and Chlorophyta were most dominant at depths of 5, 10, and 0, 2 m. Due to the lack of a self-regulating mechanism, Chlorophyta prefer living at the optimal light intensity in the reservoir, while diatoms are mainly distributed in the lower layer as a result of disliking light [55].…”

“…Seasonal variation in the phytoplankton community composition is significant. Recently, Escalas et al [55] investigated the impact of dominant phytoplankton across four summer campaigns from 50 contrasted environmental waterbodies in the Île-de-France region, and found that Chlorophyta and Cyanobacteria were widespread in summer communities, representing most of the cases of dominance with a relative abundance of 35.5-40.6% and 30.3-36.5%, respectively. However, by investigating the effects of environmental changes on dominant phytoplankton composition, diversity, and community stability in theŘímov reservoir (Czech Republic) over 32 years, Znachor et al [57] found that the phytoplankton of the reservoir underwent a substantial compositional shift towards diatoms, and that the most significant predictors of phytoplankton-composition structure driving the overall phytoplankton assemblage were TN, inflow rate, and surface level.…”

“…Nematoda, Ciliophora, and Cercozoa are also affiliated with zooplankton, inducing a decrease of algal density by predation and altering the structure of phytoplankton communities by selecting specific algae [31]. Several studies have reported that variations in zooplankton species distribution and abundance may alter ecosystems via cascading effects, and found that climate variability can be indicated by zooplankton [55,56,63]. Freshwater fungi are ubiquitous and diverse, occupying an important position as saprotrophs or parasites in the function of freshwater ecosystems [24].…”

“…Co-occurrence networks provide synthetic and clear representations of the microbial community for a better understanding of its structure and function [25,55]. Here, we assessed the co-occurrence patterns of eukaryotic organisms at the genus level from October to December to explore interactions between different eukaryotes.…”

“…Network density was highest in December, while the October and December networks exhibited lower and similar density. The indices of average clustering coefficient and average path length represent the size of the networks [55], which decreased and increased from October to December, respectively, and reached their minimum and maximum in December (Table 4). In November, all nodes were clearly parsed into seven different modules, of which modules I-III dominated in the network, accounting for 36.11%, 20.83%, and 13.89% of the whole network, respectively (Figure 9).…”