Correction to: A Water Quality Binning Method to Infer Phytoplankton Community Structure and Function

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

Microbial communities play critical roles in ecosystem functioning across a wide range of environmental conditions. The physiological stress imposed by temperature, pH and resource levels can shape the structure and function of microbial communities; however, while often tested independently, factors influencing physiological stress on a community rarely occur in isolation from each other. Controlled experiments simultaneously testing multiple interactive stressors allow researchers to better assess the dynamical responses of microbial communities to rapidly changing environments. Using a full factorial, controlled experiment, we tested three hypotheses for how independent and interactive effects of abiotic stresses impact bacterial community composition, structure and function in a model system. We utilised an aquatic, pitcher plant-associated bacterial community in which microbial nutrient cycling is essential to the host plant and ecosystem. Temperature, pH and resource (food) concentration had strong independent and interactive effects on bacterial community composition, structure and function. Community functions did not respond to interactive stressors in the same way. Chitinase and protease enzymatic activities had opposite responses to temperature and pH changes, indicating that diverse functional measures are necessary for understanding the varied effects of interacting stressors. The most extreme abiotic stress combination (high temperature, lowest pH and excess food) resulted in the lowest enzyme activity and reduced species richness as compared to the other treatments. Stressful conditions, especially high temperature, strengthened correlations between community structure and function. Higher phylogenetic dispersion under abiotic extremes suggested selection for diverse taxa adapted to similar conditions through convergent evolution. These interactive effects highlight the often greater-than-additive impact of multiple stressors and demonstrate that environmental filtering and trait convergence shape microbial responses to stress.

The composition and intensity of land use significantly influence the aquatic ecological environment, further affecting the physicochemical attributes of the water body, and indirectly modulating the phytoplankton community structure. This study centers around the Danjiangkou Reservoir, investigating the correlation between land use, water environment, and phytoplankton alongside varying intensities of anthropogenic activities, based on the review of land use, phytoplankton, and water quality data of 2021. Firstly, an analysis was conducted over five circular buffer zones generated around sampling points with radii set at 500 m, 1000 m, 1500 m, 2000 m, and 2500 m, wherein the intensity of human activity was categorized into low, medium, and high, in accordance with the human activity intensity level score (HAILS). This study proceeded to explore the correlation between land use and the water environment across different scales, compared phytoplankton density and community structure differences across varied levels of human activity, and analyzed the association between phytoplankton communities in the Danjiangkou Reservoir and environmental variables under various intensities. The findings showed: The land use within the 500 m circular buffer zone has the greatest impact on the water quality of the Danjiangkou Reservoir, especially with the increase in human activities leading to elevated nutrient levels in the water, thereby promoting the growth and reproduction of algae, and increasing the risk of algal blooms. This research scrutinizes the relationship between land use, water environment, and plankton under varying human activity intensities, serving as a foundation for environmental management sectors to make informed decisions and promote the sustainable development of the catchment water environment.

We examined the effects of different forms of nitrogen and mixed versus static conditions on the structure and function of natural Neuse River estuary phytoplankton communities incubated in 66-liter microcosms in March, May, August, and November 1999. Significant differences were found between effects of mixed versus static treatments in three of four experiments, but no differences were observed between effects of different forms of nitrogen. Mixed incubations resulted in higher contributions of diatoms to total community biomass (measured as chlorophyll a) than in static tanks in May. Significantly higher rates of carbon fixation were also observed, likely due to increased suspension of diatoms in surface (illuminated) layers of the tanks. In August, we found significantly higher abundances of cyano- bacteria, total community biomass, and rates of carbon fixation in static tanks than in tanks that were mixed. In Novem- ber, static incubations showed significantly higher abundances of cryptophytes resulting in higher total community bio- mass and rates of carbon fixation in static tanks than in mixed tanks. Nitrogen additions significantly increased total community biomass relative to controls in May and August, indicating that the communities were nitrogen-limited at these times. We conclude that while nitrogen additions may result in increases in phytoplankton biomass when nitrogen is limiting, phytoplankton community structure in the Neuse River Estuary may be determined more by the hydrodynam- ics of the system (mixing versus stratification) than by the form of nitrogen available for growth.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 442:37-57 (2011) - DOI: https://doi.org/10.3354/meps09378 Environmental forcing of phytoplankton community structure and function in the Canadian High Arctic: contrasting oligotrophic and eutrophic regions Mathieu Ardyna1,5,*, Michel Gosselin1, Christine Michel2, Michel Poulin3, Jean-Éric Tremblay4 1Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada 2Freshwater Institute, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba R3T 2N6, Canada 3Research Division, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada 4Département de biologie et Québec-Océan, Université Laval, Québec, Québec G1V 0A6, Canada 5Present address: Takuvik Joint International Laboratory, Laval University (Canada) - CNRS (France), Département de biologie et Québec-Océan, Université Laval, Québec, Québec G1V 0A6, Canada *Email: mathieu.ardyna@takuvik.ulaval.ca ABSTRACT: We assessed phytoplankton dynamics and its environmental control across the Canadian High Arctic (CHA). Environmental (hydrographic, atmospheric, sea ice conditions) and biological variables (phytoplankton production, biomass, composition) were measured along 3500 km transects across the Beaufort Sea, the Canadian Arctic Archipelago, and Baffin Bay during late summer 2005, early fall 2006 and fall 2007. Phytoplankton production and chlorophyll a (chl a) biomass were measured at 7 optical depths, including the depth of subsurface chl a maximum (ZSCM). Phytoplankton taxonomy, abundance, and size structure were determined at the ZSCM. Redundancy analyses and non-metric multidimensional scaling were used to assess relationships between phytoplankton composition in relation to biological and environmental variables. In late summer/fall, the CHA was characterized by (1) an oligotrophic flagellate-based system extending over the eastern Beaufort Sea, the peripheral Amundsen Gulf, and the central region of the Canadian Arctic Archipelago; and (2) a eutrophic diatom-based system located in Baffin Bay, Lancaster Sound, and in a hotspot in the central Amundsen Gulf. The oligotrophic regions were characterized by low production and biomass of large phytoplankton cells (>5 µm) and relatively high abundance of eukaryotic picophytoplankton (<2 µm) and unidentified nanoflagellates (2−20 µm). The eutrophic regions were characterized by high production and biomass of large cells and relatively high abundance of centric diatoms, mainly Chaetoceros spp. The distinction between the 2 regimes was explained by differences in stratification (density gradient) and nitrate concentrations at the ZSCM. This study demonstrates the key role of vertical mixing and nutrient input in shaping the structure and function of phytoplankton communities in the CHA, showing how ongoing environmental changes have the capacity to alter the diversity of biogeographic regions in the CHA. KEY WORDS: Primary production . Phytoplankton communities . Biogeographic regions . Sea ice cover . Stratification . Nutrients . Climate change . Canadian High Arctic Full text in pdf format PreviousNextCite this article as: Ardyna M, Gosselin M, Michel C, Poulin M, Tremblay JÉ (2011) Environmental forcing of phytoplankton community structure and function in the Canadian High Arctic: contrasting oligotrophic and eutrophic regions. Mar Ecol Prog Ser 442:37-57. https://doi.org/10.3354/meps09378 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 442. Online publication date: December 05, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

The Ross Sea is a critical region for understanding phytoplankton dynamics and their role in polar marine ecosystems in the west Antarctica, particularly in the context of rapid environmental change. Investigating the spatial variability of phytoplankton biomass and community structure is essential for assessing ecosystem productivity and biogeochemical cycling in this vulnerable area. From January to February 2023, a field survey of the Ross Sea was conducted onboard the icebreaker research vessel Araon, utilizing high-resolution, continuous observations of surface seawater with the Algae Online Analyzer and Imaging FlowCytoBot. These observations provided precise spatial distribution data on phytoplankton biomass and species abundance. The results revealed intricate spatial variability in phytoplankton community structure and biomass across the eastern and western Ross Sea, spanning coastal to offshore gradients, and in the dynamic waters near polynyas and ice shelves. The phytoplankton community was predominantly composed of diatoms, especially Fragilariopsis spp., and/or Phaeocystis spp., with their dominance varying across spatial gradients. The observed patterns suggest that multiple interacting environmental factors, including sea ice concentrations, water masses, and ocean currents, influence on phytoplankton distribution in the region. These findings highlight the critical role of physical and biological interactions in phytoplankton distributions and offer valuable insights into their potential responses to environmental changes in the Ross Sea ecosystem.

Phytoplankton are an ecologically important and diverse group of organisms whose distribution, abundance, and population dynamics vary significantly over small spatial (cm) and temporal (minutes) scales in the coastal ocean. Our inability to observe phytoplankton community structure and function at these small scales has severely limited our understanding of the fundamental ecological and evolutionary mechanisms that drive phytoplankton growth, mortality, adaptation and speciation. The goal of this dissertation was to enhance our understanding of phytoplankton ecology by improving in situ observational techniques based on the optical properties of cells, colonies, populations, and communities. Field and laboratory studies were used to determine the effects of phytoplankton species composition, morphology, and physiology on the inherent optical properties of communities and to explore the adaptive significance of bio-optically important cellular characteristics. Initial field studies found a strong association between species composition and the relative magnitude and shape of particulate absorption (ap), scattering (bp), and attenuation (cp) coefficient spectra. Subsequent field studies using scanning flow cytometry to directly measure optically important phytoplankton and non-algal particle characteristics demonstrated that the size and pigment content of large (>20 μm) phytoplankton cells and colonies vary significantly with the slope of particulate attenuation and absorption spectra, and with the ratio of particulate scattering to absorption. These relationships enabled visualization of phytoplankton community composition and mortality over small spatial and temporal scales derived from high resolution optical measurements acquired with an autonomous profiling system. Laboratory studies with diverse uni- algal cultures showed that morphological and physiological characteristics of cells and colonies can account for ~30% of the optical variation observed in natural communities and that complex morphologies and low intracellular pigment concentrations minimize pigment self-shading that could otherwise limit bio-optical fitness. These results demonstrate that optical properties reveal detailed information about the distribution, abundance, morphology, and physiology of phytoplankton that can help explain their ecological dynamics over small spatial scales and the bio-optical function of diverse forms in the ocean.

A cruise was conducted in the summer of 2023 from the Pearl River Estuary (PRE) to the adjacent waters of the Xisha Islands in the northern South China Sea (NSCS) to investigate the distribution, community structure, and assembly patterns of eukaryotic and prokaryotic phytoplankton using high-throughput sequencing (HTS) and microscopic observation. Dinophyta were the most abundant phylum in the eukaryotic phytoplankton community based on HTS, accounting for 92.17% of the total amplicon sequence variants (ASVs). Syndiniales was the most abundant order among eukaryotic phytoplankton, whereas Prochlorococcus was the most abundant genus within cyanobacteria. The alpha diversity showed the lowest values in the PRE area and decreased gradually with depth, while cyanobacteria exhibited higher alpha diversity indices in the PRE and at depths ranging from 75 m to 750 m. The morphological results were different from the data based on HTS. Diatoms (37 species) dominated the phytoplankton community, with an average abundance of 3.01 × 104 cells L-1, but only six species of dinoflagellate were observed. Spearman correlation analysis and redundancy analysis (RDA) showed that the distribution and community structure of phytoplankton were largely influenced by geographical location and environmental parameters in the NSCS. The neutral community model (NCM) and null model indicated that deterministic processes played a significant role in the assembly of eukaryotic phytoplankton, with heterogeneous selection and homogeneous selection accounting for 47.27 and 29.95%, respectively. However, stochastic processes (over 60%) dominated the assembly of cyanobacteria and undominated processes accounted for 63.44%. In summary, the formation of eukaryotic phytoplankton was mainly influenced by environmental factors and geographic location, but the assembly of cyanobacteria was shaped by both stochastic processes, which accounted for over 60%, and environmental selection in the NSCS.

Dimethyl sulfide (DMS), primarily produced by marine organisms, contributes significantly to sulfate aerosol loading over the ocean after being oxidized in the atmosphere. In addition to exerting a direct radiative effect, the resulting aerosol particles act as cloud condensation nuclei, modulating cloud properties and extent, with impacts on atmospheric radiative transfer and climate. Thus, changes in pelagic ecosystems, such as phytoplankton physiology and community structure, may influence organosulfur production, and subsequently affect climate via the sulfur cycle. A fully coupled Earth system model, including explicit marine ecosystems and the sulfur cycle, is used here to investigate the impacts of changes associated with individual phytoplankton groups on DMS emissions and climate. Simulations show that changes in phytoplankton community structure, DMS production efficiency, and interactions of multielement biogeochemical cycles can all lead to significant differences in DMS transfer to the atmosphere. Subsequent changes in sulfate aerosol burden, cloud condensation nuclei number, and radiative effect are examined. We find the global annual mean cloud radiative effect shifts up to 0.21 W/m2, and the mean surface temperature increases up to 0.1 °C due to DMS production changes associated with individual phytoplankton group in simulations with radiative effects at the 2,100 levels under an 8.5 scenario. However, changes in DMS emissions, radiative effect, and surface temperature are more intensive on regional scales. Hence, we speculate that major uncertainties associated with future marine sulfur cycling will involve strong region‐to‐region climate shifts. Further understanding of marine ecosystems and the relevant phytoplankton‐aerosol‐climate linkage are needed for improving climate projections.

The phytoplankton community composition, structure, and biomass were investigated under stratified and oligotrophic conditions during summer for three consecutive years in the Mediterranean Sea. Our results reveal that the phytoplankton community structure was strongly influenced by vertical stratification. The thermocline separated two different phytoplankton communities in the two layers of the euphotic zone, characterized by different nutrient and light availability. Picoplankton dominated in terms of abundance and biomass at all the stations sampled and throughout the photic zone. However, the structure of the picoplanktonic community changed with depth, with Synechococcus and heterotrophic prokaryotes dominating in surface waters down to the base of the thermocline, and Prochlorococcus and picoeukaryotes contributing relatively more to the community in the deep chlorophyll maximum (DCM). Light and nutrient availability also influenced the communities at the DCM layer. Prochlorococcus prevailed in deeper DCM waters characterized by lower light intensities and higher picophytoplankton abundance was related to lower nutrient concentrations at the DCM. Picoeukaryotes were the major phytoplankton contributors to carbon biomass at surface (up to 80%) and at DCM (more than 40%). Besides, contrarily to the other phytoplankton groups, picoeukaryotes cell size progressively decreased with depth. Our research shows that stratification is a major factor determining the phytoplankton community structure; and underlines the role that picoeukaryotes might play in the carbon flux through the marine food web, with implications for the community metabolism and carbon fate in the ecosystem.

The excessive nutrients in freshwater have been proven to promote eutrophication and harmful algae blooms, which have become great threats to water quality and human health. To elucidate the responses of the plankton community structure and function to total phosphorus (TP) at environmental concentrations in the freshwater ecosystem, a microcosm study was implemented. The results showed that plankton communities were significantly affected by the TP concentration ≥ 0.1 mg/L treatments. In terms of community structure, TP promoted the growth of Cyanophyta. This effect was transmitted to the zooplankton community, resulting in the promotion of Cladocera growth from day 42. The community diversities of phytoplankton and zooplankton had been continuously inhibited by TP. The principal response curve (PRC) analysis results demonstrated that the species composition of phytoplankton and zooplankton community in TP enrichment treatments significantly (p ≤ 0.05) deviated from the control. For community function, TP resulted in the decline in phytoplankton photosynthesis. The chlorophyll fluorescence parameters were significantly inhibited when TP concentration reached 0.4 mg/L. In TP ≥ 0.1 mg/L treatments, the reductions in total phytoplankton abundances led to a continuous decrease in pH. This study can directly prove that the plankton community changes significantly when TP concentrations are greater than 0.1 mg/L and can help managers to establish specific nutrient management strategies for surface water.

Global change may introduce fundamental alterations in phytoplankton biomass and community structure that can alter the productivity of northern lakes. In this study, we utilized Swedish and Finnish monitoring data from lakes that are spatially (135 lakes) and temporally (1995-2019, 110 lakes) extensive to assess how phytoplankton biomass (PB) of dominant phytoplankton groups related to changes in water temperature, pH and key nutrients [total phosphorus (TP), total nitrogen (TN), total organic carbon (TOC), iron (Fe)] along spatial (Fennoscandia) and temporal (25 years) gradients. Using a machine learning approach, we found that TP was the most important determinant of total PB and biomass of a specific species of Raphidophyceae - Gonyostomum semen - and Cyanobacteria (both typically with adverse impacts on food-webs and water quality) in spatial analyses, while Fe and pH were second in importance for G. semen and TN and pH were second and third in importance for Cyanobacteria. However, in temporal analyses, decreasing Fe and increasing pH and TOC were associated with a decrease in G. semen and an increase in Cyanobacteria. In addition, in many lakes increasing TOC seemed to have generated browning to an extent that significantly reduced PB. The identified discrepancy between the spatial and temporal results suggests that substitutions of data for space-for-time may not be adequate to characterize long-term effects of global change on phytoplankton. Further, we found that total PB exhibited contrasting temporal trends (increasing in northern- and decreasing in southern Fennoscandia), with the decline in total PB being more pronounced than the increase. Among phytoplankton, G. semen biomass showed the strongest decline, while cyanobacterial biomass showed the strongest increase over 25 years. Our findings suggest that progressing browning and changes in Fe and pH promote significant temporal changes in PB and shifts in phytoplankton community structures in northern lakes.

Knowledge on microbial community shifts during ecosystem succession from bare surfaces resulting from massive landscape stripping is extremely limited. Here we took advantage of an artificially created experimental catchment (6 ha) to assess structural and functional changes of microbial communities in ephemeral stream sediments and adjacent soils between 3 and 13 years after catchment construction. The catchment has since developed in undisturbed conditions, with major transformations in its morphology, hydrology and vegetation reflected by changes in microbial community structure and function. Initially dominated by cyanobacteria (42% of 16S rRNA reads in 2008 and 0.3% in 2018), the bacterial community shifted to an essentially heterotrophic composition within 10 years, when Alphaproteobacteria (12 vs 21%) and Planctomycetes (3 vs 16%), in particular, gained in importance. Similarly, Sordariomycetes (5% of ITS reads in 2008 and 27% in 2018) replaced Dothideomycetes (53 vs 14%) as the prevailing fungal class. Microbial respiration rates increased tenfold, from an average of 0.5–4.4 μg CO 2 g −1 DM h −1 , accompanied by an increase in potential enzyme activities. Seasonal patterns of microbial community functions were accentuated over a decade of catchment development, whereas structural community changes were less pronounced. Spatial variation of community composition also increased, with differences between soils and sediments intensifying over time. However, a striking disconnect between microbial community structure and function in 2008 had vanished by 2018. Thus, a decade of ecosystem succession resulted in fundamental shifts in microbial community structure and function, highlighting the intricate interplay between changing environmental conditions and microbial responses. • Re-connection of microbial community structure and function within a decade. • Shift in bacterial community composition from autotroph to heterotroph dominance. • Increased spatial heterogeneity of microbial communities during catchment succession. • Amplified seasonal variation in microbial function but not community structure.

During the 1995 monsoons, phytoplankton biomass was low over large areas of the Arabian Sea in spite of often high concentrations of inorganic nutrients, characteristics typical of high‐nutrient, lowchlorophyll (HNLC) areas. The objective of this study, a part of the Arabian Sea U.S. JGOFS program, was to elucidate controls of phytoplankton biomass and community structure in these areas, using primarily pigment‐based methods. Unlike other HNLC areas, phytoplankton biomass and growth rates in the monsoonal Arabian Sea were not likely limited by the availability of trace nutrients but rather controlled by grazers. Evidence for this conclusion is high concentrations of iron, the nutrient likely limiting phytoplankton biomass in other HNLC areas; phytoplankton growth rates clearly not limited by concentrations of inorganic nutrients; blooms during grow‐out experiments in the absence of mesozooplankton; rates of microzooplankton and mesozooplankton grazing that approached rates of primary production; and the absence of blooms in situ in spite of persistently high concentrations of inorganic nutrients. A more detailed look at shifts of phytoplankton community structure with increasing levels of phytoplankton biomass, in situ and during grow‐out experiments, shows that diatoms were the only group of organisms capable of blooming in the absence of mesozooplankton, i.e., their abundance in situ was likely controlled by mesozooplankton grazing. Changes in the abundance of different picoautotroph taxa with increasing levels of phytoplankton biomass suggest that their biomass was controlled within tight bounds by microzooplankton grazing, rather than by the availability of resources. Thus, these results are consistent with the hypothesis that phytoplankton abundance and community structure in the HNLC areas of the monsoonal Arabian Sea are controlled by top‐down forces, grazing, rather than bottom‐up forces, availability of resources.

The Qinghai-Tibet Plateau is an ecologically fragile region. The changes in physicochemical parameters of water quality [PPOWQ] and land use types [LUT] in different regions will affect the phytoplankton community in rivers, thus threatening the ecosystem. Taking the phytoplankton community as an indicator variable, it is of great significance to study the relative influence of symbiotic factors on regulating human activities and river ecological protection. The results showed that the proportions of Bacillariophyta, Cyanophyta, and Chlorophyta were &amp;gt;84% in the phytoplankton community of taxa composition. The abundance of the phytoplankton community varied from 1.47 × 105 to 7.58 × 105 cells/L. Bacillariophyta had the highest average abundance (&amp;gt;82%). The results of the variance partitioning analysis showed that PPOWQ was the main variable affecting the changes in the phytoplankton community. Redundancy analysis showed that local factors (total nitrogen, salinity, water temperature) and regional factors (forestland, grassland, unused land) (p &amp;lt; 0.05) were the main factors causing the changes in community structure and abundance of dominant algae. The analysis of structural equation models showed that LUT had the least direct impact on the abundance of the phytoplankton community, mainly through changing nutrients and physical parameters. Water temperature and nutrients are still the main factors affecting phytoplankton community abundance. Farmland and forestland are the main sources of total nitrogen in rivers. In general, in the ecologically vulnerable area, it is of guiding significance for the ecological monitoring and management of plateau rivers. In addition to considering water quality, it is also necessary to reasonably plan the LUT around rivers.