Seasonal and spatial patterns of eukaryotic phytoplankton communities in an urban river based on marker gene

The seasonal and spatial eukaryotic phytoplankton composition in the Fenhe River was investigated based on the 18S rDNA V4 region. The relationship between phytoplankton functional groups and environmental factors was explored to effectively capture the responses of these taxa to environmental gradients and their effects on ecosystem function. Our results indicated that the Chlorophyta and Bacillariophyta had higher relative abundance than other taxa, and their diversity and richness indices in spring were higher than those in other seasons. The linear discriminant analysis effect size (LEfSe) analyses detected that the potential seasonal biomarkers included Desmodesmus, Cyclotella, Pseudoschroederia, Discostella, Scenedesmus, Monoraphidium, and Nannochloropsis; the spatial biomarkers included Amphora, Neochloris, Hindakia, Pseudomuriella, Coccomyxa, Chloroidium, Scherffelia, Chromochloris, and Scotinosphaera. The systemic evolution and distribution characteristics of the first 50 representative sequences showed that the dominant genus included Desmodesmus in spring, Pseudopediastrum in summer, Mychonastes in autumn, and Monoraphidium in winter. Main seasonal variation of phytoplankton functional groups was as follows: spring (J + F + C + X1) → summer (J + F + X1 + X2) → autumn (J + F + X1 + C) → winter (X1 + J + B + X2). Pearson correlation, redundancy analysis, and variance partitioning analysis showed temperature and phosphate were the determining factors causing the changes of phytoplankton functional groups and community composition in the Fenhe River.

Ecological assessment of water quality in an urban river replenished with reclaimed water: the phytoplankton functional groups approach

Comprehensive water quality assessment plays a vital role in decision making for the sustainable management of urban rivers, and thus the exploration of integrated ecological assessment methods for water quality has become a major requirement. This study assessed the water quality of the North Canal River on the basis of its ecological status using the phytoplankton functional groups (PFGs) approach. The river runs through the megacities of the Beijing-Tianjin-Hebei region in China, and is mainly replenished with reclaimed water. The results showed that the PFGs approach is much better for evaluating the water quality of urban rivers than the conventional physicochemical index method and phytoplankton diversity metrics, because the PFGs approach is more sensitive to the spatiotemporal variations in the water quality of urban rivers. The average Qr index, for ecological status estimation in rivers, based on the PFGs of the North Canal River was 3.30, indicating “good” water quality. In the dry season, the dominant PFG upstream was group D (Cyclotella spp.), whereas the major downstream PFGs had changed to group Y (Glenodinium spp., Cryptomonas ovata, and Cryptomonas erosa) and W1 (Euglena spp. and Gonium pectoral). While the dominant PFG throughout the river changed to TB: Melosira spp. in the wet season. The Qr at each site was one to two grades lower during the wet season than the dry season, indicating that water quality was worse in the wet than the dry season.

Temporal Stability of Phytoplankton Functional Groups Within Two Agricultural Irrigation Ponds in Maryland, USA

Phytoplankton functional groups and their influence on water quality have been studied in various types of water bodies but have yet to be studied in agricultural irrigation ponds. Freshwater sources (e.g., lakes, rivers, and reservoirs) have been previously shown to exhibit high spatial and temporal variability in phytoplankton populations. Improvements in the monitoring of phytoplankton populations may be achieved if patterns of stable spatial variability can be found in the phytoplankton populations through time. The objective of this work was to determine if temporally stable spatial patterns in phytoplankton communities could be detected in agricultural irrigation ponds using a functional group approach. The study was performed at two working agricultural irrigation ponds located in Maryland, USA over two summer sampling campaigns in 2017 and 2018. Concentrations of four phytoplankton groups, along with sensor-based and fluorometer based water quality parameters were measured. Temporal stability was assessed using mean relative differences between measurements in each location and averaged measurements across ponds on each sampling date. Temporally stable spatial patterns of three phytoplankton functional groups were found for both ponds over the two sampling seasons. Both ponds had locations where specific phytoplankton functional group concentrations were consistently higher or lower than the pond's average concentration for each sampling date. Zones of consistently higher or lower than average concentrations were associated with flow conditions, pond morphology, and human activities. The existence of temporally stable patterns of phytoplankton functional group concentrations can affect the outcome of a water quality assessment and should be considered in water quality monitoring designs.

Phytoplankton functional groups as environmental indicators at a high neotropical mountain reservoir in Colombia

Phytoplankton is a fundamental productive component of lentic ecosystems, which also directly reflects environmental variability. This study evaluated the dynamics of phytoplankton in response to the monthly variability of physicochemical properties of a neotropical high Andes reservoir, El Neusa, from July to October 2004. Samples were collected and analyzed for taxonomic identification to species or the lowest possible level and categorized in functional groups (FGs). A total of 111 species of phytoplankton belonging to nine classes and 20 FGs were recorded. Among these phytoplankton classes, Chlorophyceae (36 species), Euglenophyceae (13 species), Bacillariophyceae, (14 species), and Conjugatophyceae (25 species) were the most species-rich and highest in abundance. The overall phytoplankton abundance was largest in August (8.5×104 ±2.7 ×104 ind.L-1) and September (8.9×104 ±4.6×104 ind.L-1); however, the distribution of phytoplankton classes was not statistically different among sampling sites (Friedman-ANOVA; p>0.01) Chlorella sp. (2.4×104 ±2.0×104 ind.L-1), and Chloromonas grovei (2.5×104 ±4.4×103 ind.L-1), belonging to functional group X1, were dominant, representing together between 54% and 78% of the average monthly abundance. Simple correlations and multivariate analysis between physicochemical variables and phytoplankton revealed that conductivity, pH, and total suspended solids had a key influence on the distribution of both dominant species and FGs. These analyses indicated that hydrological (precipitation and runoff) and water stability (stratification and mixing) conditions determined environmental changes and the selection of phytoplankton functional groups. The main features of the dominant FGs and the trophic state of El Neusa were also discussed.

Structure of phytoplankton functional groups in shallow lakes with different equilibrium states

Changes in equilibrium states in shallow lakes are associated with disturbances and resilience. The study evaluated the structure and composition of phytoplankton functional groups in two lakes, Lagoa do Paó (turbid waters) and Santa Lúcia (clear waters). Monthly collections of limnological variables and phytoplankton occurred between August 2014 and June 2015 in the pelagic region. The lakes shared five functional groups: K, S1 , X1 , W2 and P, formed by coccoid and filamentous cyanobacteria, coccoid chlorophytes and euglenophytes, and desmids, respectively. The canonical correspondence analysis evidenced a clear separation, highlighting the groups TD, N, W2 and S1 in Santa Lúcia and functional groups composed of potentially toxic cyanobacteria in Lagoa do Paó (SN, Lo), indicating that the submerged macrophyte coverage can act promoting the phosphorous stabilization in the sediment in Santa Lúcia, reducing its contribution to the water column and inhibiting the dominance of the mentioned species. Temperature, pH, phosphorus and light attenuation coefficient influenced the occurrence of H1 , SN, S1 , W2 , X1 , D, and Lo , in the Lagoa do Paó. The composition and structure of the functional groups responded in the two lakes with some functional groups associated with toxic cyanobacteria occurring exclusively in Lagoa do Paó, having also been observed the sharing of some functional groups.