Plankton Community Research Articles

Structural characteristics of plankton community in Dongting Lake and its relationship with water environmental factors.

The plankton community structure and environmental factors in Dongting Lake were investigated during four seasons from September 2020 to August 2021. The results revealed 147 species from 58 genera and 7 phyla of phytoplankton and 84 species from 56 genera and 4 phyla of zooplankton in Dongting Lake. The characteristics of plankton communities varied with time and space. The temporal variation of phytoplankton abundance ranged from 43.5201 × 104 to 120.7968 × 104cells/L and the spatial variation ranged from 18.6707 × 104 to 247.5542 × 104cells/L. The temporal variation of zooplankton abundance ranged from 18 to 42ind/L and the spatial variation ranged from 19 to 62ind/L. The temporal and spatial variations of the abundance range values were much larger for phytoplankton than for zooplankton, with phytoplankton dominating. However, environmental factors in Dongting Lake vary more temporally than spatially, and drive more temporal than spatial variations in planktonic organisms. Based on the redundancy analysis WT, DO, and CODMn were the main environmental factors affecting the distribution of phytoplankton, while WT, CODMn, NO2-N, and Chl-a were the main factors affecting the distribution of zooplankton. WT and CODMn were the common key influencing factors.

Diversity of eukaryote plankton and phycotoxins along the West Kalaallit Nunaat (Greenland) coast

The West Kallaallit Nunaat (Greenland) coast, characterized by a variety of fjords, bays, and channels influenced by glacier melting and Atlantic and Arctic waters, is one of the most affected ecosystems by climate change. Here, we combine oceanography, optics, microscopy, high throughput sequencing, microalgal strain establishments, and state-of-the-art analytical methods to fully characterize the diversity, community composition, and toxin repertoire of the eukaryotic plankton members of the coast of the West Kalaallit Nunaat (Greenland). Results indicate that the West Kalaallit Nunaat (Greenland) coast is a complex and oceanographically challenging system, where the superimposition of water masses of different origins, the penetration of light and its repercussions, generate mainly vertical, rather than horizontal heterogeneity in nutrient concentration and plankton biomass. Nevertheless, our molecular data reveal a strong homogeneity and a high diversity in the plankton community along the Greenland coast. We confirmed the presence of five phycotoxin groups: domoic acid and paralytic shellfish toxins were most abundant along the transect from Qeqertarsuup Tunua (Disko Bay) to the northern Baffin Bay, while spirolides, yessotoxins and pectenotoxins were predominant in Nuup Kangerlua (GodthaabFjord) and Qeqertarsuup Tunua (Disko Bay). Concentrations of these phycotoxins correlate differently to temperature, salinity and nutrients, reflecting the ecological differences of their producers. Patterns of paralytic shellfish and spirolide toxins suggest the presence of genetically distinct populations of Alexandrium along the Western Kalaallit Nunaat (Greenland). Phytoplankton strains isolated during this oceanographic campaign resemble, in most cases, the toxin profiles of the respective field stations. Overall, this work shows the diversity and community composition of the plankton at the Western Kalaallit Nunaat coast and reveals a distinct spatial distribution of phycotoxins, with certain toxin groups restricted to specific areas.

Resilience of Phytoplankton and Microzooplankton Communities under Ocean Alkalinity Enhancement in the Oligotrophic Ocean.

Ocean alkalinity enhancement (OAE) is currently discussed as a potential negative emission technology to sequester atmospheric carbon dioxide in seawater. Yet, its potential risks or cobenefits for marine ecosystems are still mostly unknown, thus hampering its evaluation for large-scale application. Here, we assessed the impacts OAE may have on plankton communities, focusing on phytoplankton and microzooplankton. In a mesocosm study in the oligotrophic subtropical North Atlantic, we investigated the response of a natural plankton community to CO2-equilibrated OAE across a gradient from ambient alkalinity (2400 μmol kg-1) to double (4800 μmol kg-1). Abundance and biomass of phytoplankton and microzooplankton were insensitive to OAE across all size classes (pico, nano and micro), nutritional modes (autotrophic, mixotrophic and heterotrophic) and taxonomic groups (cyanobacteria, diatoms, haptophytes, dinoflagellates, and ciliates). Consequently, plankton communities under OAE maintained their natural chlorophyll a levels, size structure, taxonomic composition and biodiversity. These findings suggest a high tolerance of phytoplankton and microzooplankton to CO2-equilibrated OAE in the oligotrophic ocean. However, alternative application schemes involving more drastic perturbations in water chemistry and nutrient-rich ecosystems require further investigation. Nevertheless, our study on idealized OAE will help develop an environmentally safe operating space for this climate change mitigation solution.

Estimating nutrient stoichiometry and cascading influences on plankton in thermokarst lakes on the Qinghai-Tibet Plateau

Thermokarst lakes play a critical role in global biogeochemistry. Here we delved into nutrient stoichiometry and its cascading effects on plankton communities across thermokarst lakes on the Qinghai-Tibet Plateau. Our findings revealed significant variability in nutrient concentrations and stoichiometric ratios in both water and seston, indicating heterogeneous nature of thermokarst lakes. Phytoplankton communities were dominated by cyanobacteria. Zooplankton communities, though simple, varied significantly and responded distinctly to the prevailing nutrient stoichiometry, and particularly shown competitive interactions between copepods and Cladocera. Structural Equation Modeling revealed a complex web of interactions, underscoring the bottom-up influences from nutrient stoichiometry in water to phytoplankton/seston, and finally to zooplankton, although there were no direct relationships between phytoplankton and zooplankton communities. Water nutrient stoichiometry positively affected eukaryotic algae but negatively impacted seston stoichiometry, which. had a negative influence on copepods. Our study highlighted the intertwined relationships between nutrient stoichiometry and plankton communities within thermokarst lakes.

Ecological Assessment of Phytoplankton Diversity and Water Quality to Ensure the Sustainability of the Ecosystem in Lake Maybalyk, Astana, Kazakhstan

Microalgae in planktonic communities are the main producers of biomass in lake ecosystems; however, their stability is influenced by many environmental factors. This study aims to assess the ecological state of Lake Maybalyk, located in Astana (Kazakhstan), based on the study of the taxonomic diversity and structure of phytoplankton, zooplankton, and the physico-chemical properties of the water. From 2019 to 2021, samples were taken for phytoplankton analysis, hydrochemical analysis of the water, zooplankton, and saprobiological analysis of the algocenosis. The study also investigated the main morphometric parameters of the lake, as well as the composition of hydrobionts, such as zooplankton, zoobenthos, and ichthyofauna. The analysis of phytoplankton revealed the presence of 97 species and intraspecific taxa of microalgae, with 71 types of microalgal indicators indicating water saprobity. The planktonic algoflora in Lake Maybalyk is predominantly composed of diatoms (Bacillariophyta) and green algae (Chlorophyta), which play a vital role in oxygen production and the food chain within the reservoir. Based on the Pantle–Buck saprobity index (2.15–2.5), the water quality in Lake Maybalyk is classified as moderately polluted. The assessment of the water quality, considering the number and composition of indicator phytoplankton species, places Lake Maybalyk in class III (β-mesosaprobic). The hydrochemical indicators align with the hydrobiological indicators, confirming the water quality as class III. The trophic status of the reservoir, during the study period, can be described as average. The obtained data on both the hydrobiological and hydrochemical indicators correlate, suggesting satisfactory water quality and the ability of the reservoir to purify itself. This study contributes to the sustainable management of water resources, by providing essential data on the ecological state of Lake Maybalyk. The results underscore the importance of continuous biomonitoring, with microalgae as indicators of water quality, which is crucial for developing effective ecosystem conservation strategies.

Effect of a tropical cyclone on the pelagic ecosystem of a continental shelf

AbstractThis study aimed to comprehend the effects of Typhoon Maria on the pelagic ecosystem in the southern East China Sea. Shipboard measurements were conducted at eight sampling stations before (2–4 d) and after (3–6 d) the typhoon, which enabled the evaluation of the potential impacts of the typhoon on this pelagic ecosystem, with particular focus on carbon dynamics. Following the typhoon's passage, there was a slight drop in sea surface temperature. The response of the variables to the typhoon, however, exhibited variations at different sampling stations. For further analysis, t‐tests compared variables, while type II regression assessed the linear correlation between two variables. Overall, during the post‐typhoon period, concentrations of nitrate, chlorophyll a, primary production, bacterial biomass and production, plankton community respiration, and abundance of large phytoplankton (> 2 μm) and the relative abundance of picophytoplankton among larger‐sized picoeukaryotes were higher compared to the pre‐typhoon period. The mean value of fugacity of CO2 was similar to or slightly lower than pre‐typhoon period. Although the typhoon‐induced vigorous primary production might have absorbed a significant amount of CO2, the decrease in fugacity of CO2 could have been offset by the plankton community respiration. The findings suggest that the typhoon enhanced physical disturbance and increased water column mixing, which, in turn, augmented nutrient availability and promoted plankton growth in the shallow water column. Overall, this study sheds light on the complex interactions between typhoons and marine ecosystems and highlights the importance of further investigating these phenomena to better understand their ecological implications.

Prickly postglacial pioneers: freshwater plankton community composition influences fatty acid desaturase (FADS2) copy number in southern Greenland threespine sticklebacks

The adaptation of marine fish to freshwater environments includes prodigious examples of rapid evolution.Given the scarcity of ω‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA) in freshwater, we expect selection to be strong on fish transitioning to freshwater habitats and yet the underlying ecological causes of genomic and phenotypic differentiation are poorly understood for traits associated with lipid content and composition. Threespine stickleback Gasterosteus aculeatus have repeatedly colonized, and adapted to, freshwater habitats across the Northern Hemisphere. These freshwater populations often show elevated copy number of the fatty acid desaturase 2 gene (FADS2), which increases the biosynthetic capacity of LC‐PUFA. The starkly lower content of LC‐PUFA in freshwater compared to marine prey, especially docosahexaenoic acid (DHA), likely imposes strong positive selection on freshwater fish for either increased biosynthesis or greater dietary acquisition of LC‐PUFA. The recently colonized and relatively undisturbed threespine stickleback populations in postglacial coastal lakes of southern Greenland offer an exceptional opportunity to study how variation in the copy number of FADS2 is related to abiotic and biotic conditions of lakes and their morphometry. As expected, given its position on the stickleback X chromosome, we found strong sexual dimorphism in FADS2 copy number in all populations (19 freshwater, 1 marine and 1 brackish), and an increased dimorphism in some freshwater populations. We also found that FADS2 copy number was negatively correlated, for both males and females, with the abundance of copepods, which are a DHA‐rich food source in the zooplankton community. Overall, our results suggest that the prey community context of lakes might influence the process of metabolic adaptation of marine fish colonizing freshwater ecosystems.

Exploring phyto- and zooplankton community structure, spatial variation, and driving forces shaping the community from a large-scale freshwater dominated estuary

Abstract Plankton is essential to estuarine food webs, providing key food for species like fish larvae, and understanding their dynamics helps us comprehend ecological interactions and energy transfer in aquatic ecosystems. This study examined the plankton community structure, diversity, variability and the environmental variables of water that influenced these communities in a freshwater-dominated estuary along the Northern Bay of Bengal during the dry season. A variety of tools were employed, including a dissecting microscope, a Sedgwick-Rafter cell, and a Hanna multi-parameter meter, to obtain detailed and comprehensive data. From the analyses, in total 37 genera of phytoplankton belonging to 11 classes such as Bacillariophyceae (66%), Coscinodiscophyceae (28%), Fragilariophyceae (1%), Euglenophyceae (1%), Cyanophyceae (1%), others (3%) were recorded. Zooplankton, consisting of multicellular organisms, was represented by 11 genera across five classes, with Monogononta (53%) and Insecta (29%) being the most prevalent. Phytoplankton exhibited a mean abundance of 180,000 ± 20,200 cells L⁻¹ whereas zooplankton showed a mean abundance of 3,000 ± 200 cells L⁻¹. The diversity indices (H’), evenness (J’) and dominance (D) ranged from 1.188 ± 0.015 to 0.19 ± 0.006, 0.9377 ± 0.002 to 0.5118 ± 0.006, 0.365 ± 0.001 to 0.143 ± 0.002 respectively, suggested low to moderate plankton diversity with a suppressed community and moderate to high dominance in the river water. Based on the similarity percentage (SIMPER) and analysis of similarity (ANOSIM), Phytoplankton and zooplankton varied significantly between stations while non-metric multi-dimensional scaling (nMDS) indicated greater consistency in phytoplankton communities across stations compared to zooplankton. Furthermore, Pearson's correlation coefficient (rs) and canonical correspondence analysis (CCA) identified transparency, sulfates, dissolved oxygen, conductivity, TDS, pH, and salinity as major influencers of plankton abundance; nitrate had a moderate effect. Spearman's rank correlations showed significant positive (p < 0.05) correlations between diversity indices and environmental variables.

Latitudinal patterns in ocean C:N:P reflect phytoplankton acclimation and macromolecular composition

The proportions of carbon (C), nitrogen (N), and phosphorus (P) in surface ocean particulate matter deviate greatly from the canonical Redfield Ratio (C:N:P = 106:16:1) in space and time with significant implications for global carbon storage as this matter reaches the deep ocean. Recent work has revealed clear latitudinal patterns in C:N:P, yet the relative importance of ecological, physiological, or biochemical processes in creating these patterns is unclear. We present high-resolution, concurrent measurements of particulate C:N:P, macromolecular composition, environmental conditions, and plankton community composition from a transect spanning a subtropical-subpolar boundary, the North Pacific Transition Zone. We find that the summed contribution of macromolecules to particulate C, N, and P is consistent with, and provides interpretation for, particulate C:N:P patterns. A decline in particulate C:N from the subtropical to subpolar North Pacific largely reflects an increase in the relative contribution of protein compared to carbohydrate and lipid, whereas variation in C:P and N:P correspond to shifts in protein relative to polyphosphate, DNA, and RNA. Possible causes for the corresponding trends in C:N and macromolecular composition include physiological responses and changes in community structure of phytoplankton, which represented approximately 1/3rd of particulate C across the transect. Comparison with culture experiments and an allocation-based model of phytoplankton macromolecular composition suggest that physiological acclimation to changing nutrient supply is the most likely explanation for the latitudinal trend in C:N, offering both a mechanistic interpretation and biochemical basis for large-scale patterns in C:N:P.

Parasitic taxa are key to the vertical stratification and community variation of pelagic ciliates from the surface to the abyssopelagic zone.

An increase in upper-ocean thermal stratification is being observed worldwide due to global warming. However, how ocean stratification affects the vertical profile of plankton communities remains unclear. Understanding this is crucial for assessing the broader implications of ocean stratification. Pelagic ciliates cover multiple functional groups, and thus can serve as a model for studying the vertical distribution and functional strategies of plankton in stratified oceans. We hypothesize that pelagic ciliate communities exhibit vertical stratification caused by shifts in functional strategies, from free-living groups in the photic zone to parasitic groups in deeper waters. 306 samples from the surface to the abyssopelagic zone were collected from 31 stations in the western Pacific and analyzed with environmental DNA (the V4 region of 18S rDNA) metabarcoding of pelagic ciliates. We found a distinct vertical stratification of the entire ciliate communities, with a boundary at a depth of 200m. Significant distance-decay patterns were found in the photic layers of 5m to the deep chlorophyll maximum and in the 2,000m, 3000m and bottom layers, while no significant pattern occurred in the mesopelagic layers of 200m - 1,000m. Below 200m, parasitic Oligohymenophorea and Colpodea became more prevalent. A linear model showed that parasitic taxa were the main groups causing community variation along the water column. With increasing depth below 200m, the ASV and sequence proportions of parasitic taxa increased. Statistical analyses indicated that water temperature shaped the photic communities, while parasitic taxa had a significant influence on the aphotic communities below 200m. This study provides new insights into oceanic vertical distribution, connectivity and stratification from a biological perspective. The observed shift of functional strategies from free-living to parasitic groups at a 200m transition layer improves our understanding of ocean ecosystems in the context of global warming.

Benthic Microbes on the Shore of Southern Lake Taihu Exhibit Ecological Significance and Toxin-Producing Potential Through Comparison with Planktonic Microbes

Water quality and aquatic ecosystems along lakeshores are vital for ecological balance and human well-being. However, research has primarily focused on plankton, with benthic niches being largely overlooked. To enhance understanding of benthic microbial communities, we utilized 16S and 18S rRNA sequencing alongside multivariate statistical methods to analyze samples from the shoreline of Lake Taihu in Huzhou City, Zhejiang Province. Our results reveal a marked difference in species composition between benthic and planktonic microorganisms, with benthic cyanobacteria predominantly comprising filamentous genera like Tychonema, while 95% of planktonic cyanobacteria were Cyanobium. The β-diversity of benthic microorganisms was notably higher than that of planktonic counterparts. The neutral community model indicated that stochastic processes dominated planktonic microbial assembly, while deterministic processes prevailed in benthic communities. Null models showed that homogeneous selection influenced benthic community assembly, whereas planktonic communities were affected by undominated processes and dispersal limitation. Network analysis indicated that planktonic networks were more stable than benthic networks. Importantly, dominant benthic cyanobacterial genera posed potential toxin risks, highlighting the need for enhanced monitoring and ecological risk assessment. Overall, these findings enhance our understanding of benthic and planktonic microbial communities in lakeshores and offer valuable insights for aquatic assessment and management in eutrophicated environments.

Is in-situ burning an acceptable mitigation option after a major oil spill? Impact on marine plankton

Major oil spills can impose a significant environmental hazard on the marine ecosystem, and a promising mitigation measure is in-situ oil burning (ISB). However, our knowledge of the impact of the burned residues and soot deposition on the marine ecosystem is still limited. We investigated the effects of burned oil residue and soot deposition on the marine plankton communities of the oligotrophic Eastern Mediterranean Sea with a mesocosm experiment. Three triplicated treatments were tested: (1) Iranian crude oil was added and burned (Burned treatment); (2) soot was collected and deposited with artificial rain (Soot); and (3) a non-contaminated Control. Results revealed that Low Nucleic Acid heterotrophic bacteria, Synechococcus spp., and pigmented pico-nano Eukaryotes (pnEuk) were negatively affected in the Burned and Soot treatments. Viruses, heterotrophic pnEuk and ciliates (in Soot) were crucial for controlling the High Nucleic Acid bacteria. Ciliates and most dinoflagellates showed a negative response to the burned residues but were less affected or were even favored when exposed to soot. Our results show that ISB affected the structure and dynamics of the plankton food web through burned residues and soot depositions. However, since the effects appeared at least three days after the ignition, ISB could be combined with subsequent burned residue collection to minimize its impact on the pelagic ecosystem.

Vertical exchange versus horizontal dispersal in structuring local planktonic and sedimentary bacterial communities in polluted lotic ecosystems

Elucidating the mechanisms underlying community assembly remains a central question in community ecology, especially in aquatic ecosystems disrupted by human activities. Understanding the causes and consequences of community responses to changing environmental conditions is essential for revealing the ecological effects of anthropogenic disturbances and proposing practical strategies for ecological restoration. While stochastic dispersal and species sorting are known to influence local biological communities, most studies have focused on horizontal dispersal, often neglecting the vertical exchange of organisms between planktonic and sedimentary communities when studying stochastic dispersal. We used a highly disturbed urban river in Beijing as a model system to investigate the relative roles of stochastic dispersal versus species sorting driven by local pollution, as well as two components of stochastic dispersal, vertical exchange and horizontal dispersal, in structuring local bacterial communities. Our integrated analyses of planktonic and sedimentary bacterial communities revealed that, despite different spatial patterns along the river, both types of bacterial communities were primarily shaped by stochastic dispersal processes rather than species sorting influenced by the environmental gradient. Notably, in addition to the effect of horizontal dispersal along the river, the vertical exchange between planktonic and sedimentary bacterial communities significantly contributed to the formation of local communities. These findings suggest that both vertical exchange and horizontal dispersal should be considered when assessing the role of stochastic dispersal in shaping local community structure in microbial communities.

Spatiotemporal Topic Modeling Reveals Storm‐Driven Advection and Stirring Control Plankton Community Variability in an Open Ocean Eddy

AbstractPhytoplankton communities in the open ocean are high‐dimensional, sparse, and spatiotemporally heterogeneous. The advent of automated imaging systems has enabled high‐resolution observation of these communities, but the amounts of data and their statistical properties make analysis with traditional approaches challenging. Spatiotemporal topic models offer an unsupervised and interpretable approach to dimensionality reduction of sparse, high‐dimensional categorical data. Here we use topic modeling to analyze neural‐network‐classified phytoplankton imagery taken in and around a retentive eddy during the 2021 North Atlantic EXport Processes in the Ocean from Remote Sensing (EXPORTS) field campaign. We investigate the role physical‐biological interactions play in altering plankton community composition within the eddy. Analysis of a water mass mixing framework suggests that storm‐driven surface advection and stirring were major drivers of the progression of the eddy plankton community away from a diatom bloom over the course of the cruise.

Influence of environmental parameters on marine plankton diversity in the southern coastal waters of Korea: Emphasis on thermal stratification

Plankton are fundamental to aquatic ecosystems, forming the base of the marine food web and playing a crucial role in the global carbon cycle. While the impact of environmental factors on marine plankton ecosystems has been widely studied, the seasonal variability in plankton diversity has received comparatively less attention. Here, we investigated the complexity and distribution of plankton species in Korean coastal waters in relation to seasonal environmental changes, particularly those linked to water mass characteristics and the presence of a thermocline, using alpha and beta diversity indices. A thermocline was observed at all stations in July, coinciding with the lowest diversity and richness, but was absent in September, when diversity indices peaked. In the upper layer above the thermocline, diatom species such as Pseudo-nitzschia delicatissima and Skeletonema costatum were dominant. Analysis of the Shannon index suggested that planktonic ecosystems in the South Sea of Korea from May to September 2021 were well-balanced. These findings enhance our understanding of the potential effects of environmental variability and thermal stratification on plankton biodiversity and community dynamics in Korean coastal waters.

A rapid and parallel Late Pleistocene/Holocene morphological radiation in a predaceous planktonic water flea: the case of Bythotrephes (Cladocera: Cercopagididae)

Abstract The predatory cladoceran Bythotrephes is one of North America’s most successful and impactive invasive species in freshwater plankton communities. The taxonomic status of the genus Bythotrephes Leydig, 1860 (Crustacea: Cladocera: Cercopagididae) has remained unclear and a subject of intensive debate for over 150 years. We applied an integrative taxonomy approach with multi-gene analysis (mitochondrial COI and 12S genes, and nuclear 18S and 28S genes) on 80 individuals (representing at least four morphospecies) from various regions spanning the genus distribution (North America, Europe, and Asia) to resolve the taxonomic status of species within Bythotrephes. The results of our study strongly support the hypothesis of a single species—Bythotrephes longimanus Leydig, 1860, and ecological morphs should be accepted as junior synonyms. Our work also elucidates the very recent radiation of Bythotrephes, which may have begun rapidly and parallel during the Late Pleistocene, or even after the last glaciation. Finally, we provide a comprehensive biogeographic reconstruction of Bythotrephes dispersal within the Holarctic realm. Europe likely served as a dispersal centre for Bythotrephes from where they spread relatively recently (possibly, less than 10 kyr) and we distinguish five possible dispersal events in its evolutionary history.

The Potential Role of Phytoplankton Functional Groups Under Anthropogenic Stressed Wetlands: Characterizing The Environmental Sensitivity.

Anthropogenic and climatic changes are continuously altering the freshwater plankton, necessitating an evaluation of the complex structure of plankton communities to understand and mitigate these impacts. In this context, the present study focuses on evaluating the structure of plankton communities, specifically Phytoplankton Functional Groups (FGs) for assessing the environmental sensitivity of wetlands under changing scenario. These FGs are defined by shared adaptive features rather than taxonomic traits. Over the period from 2016 to 2018, two ecologically distinct wetlands were examined, analysing their phytoplankton FGs and their relationship with water quality parameters. Ecohydrological data revealed significant seasonal variations (p ≤ 0.05) in key parameters such as water depth, temperature, pH, electrical conductivity, dissolved oxygen, total alkalinity, total hardness, NO3-N, and PO4-P. Notably, there were no significant differences observed among the sampling stations within each wetland. A total of 125 phytoplankton genera/species were classified into 23 FGs in the open wetland and 22 FGs in the closed wetland. Spatial and seasonal analyses of dominant FGs suggested both wetlands were experiencing pollution pressures. This study highlights the powerful role of phytoplankton functional groups (FGs) as bioindicators of wetland health, uncovering pollution pressures. In open wetlands, 15 phytoplankton FGs with 36 key taxa (Indicator Value ≥ 40%) emerged as critical indicators, while in closed wetlands, only 10 FGs with 17 taxa were identified. To assess eutrophication, the occurrence of these indicator species was evaluated using BVSTEP function analysis. The study recommends pollution reduction in catchment areas and restoration of riverine connectivity to enhance FG diversity. Phytoplankton FG methodologies are deemed effective for assessing the environmental sensitivity of wetlands significantly impacted by human activities. This research offers a scientific foundation for the evaluation and restoration of wetland ecosystems.

Driving mechanism of land use and landscape pattern to phytoplankton and zooplankton community and their trophic interactions in river ecosystems

The trophic interactions between phytoplankton and zooplankton communities are essential for maintaining river ecosystem integrity and health. However, the driving mechanisms of land use and landscape patterns (LULP) affecting their trophic interactions are not fully understood. Therefore, the research objective of this study was to reveal the driving mechanisms of LULP on the interaction of phytoplankton with zooplankton through remote sensing interpretation of LULP in different buffer scales (500 m, 1000 m, 1500 m, and catchment), combined with water environment factors and plankton community structures analyzed. Results showed that LULP had the most significant effect on the phytoplankton and the zooplankton community structure at 500 and 1500 m buffer scales, respectively. Construction land (CON) and edge density (ED) most influenced phytoplankton and zooplankton community structure and their influence mechanisms were identified, i.e., CON increased the species (S) of phytoplankton by increasing the concentration of NO3-N in river water at the 500 m buffer scale. ED reduced the biological density (BD) of zooplankton by decreasing the concentration of heavy metal (HM) in river water at the 1500 m buffer scale. The water area (WAT) and ED showed the most significant influence on plankton interaction. Three pathways were found to explain their influence mechanisms, i.e., ED decreased the BD or Shannon-Weiner index (H’) of zooplankton by increasing the dissolved oxygen (DO) to enhance BD of phytoplankton in river water at the 1500 m buffer scale; the WAT increased the BD of phytoplankton by increasing water temperature to reduce the H' of zooplankton at the 500 m buffer. These findings have implications for effective ecological planning of future human activities in the stream domain and maintaining river ecosystem health.

Water-surface photovoltaic systems have affected water physical and chemical properties and biodiversity

The implementation of water-surface photovoltaic systems as a source of renewable power has expanded rapidly worldwide in recent decades. Water-surface photovoltaic avoids negative impacts on terrestrial ecosystems, while the impacts on aquatic physical and chemical properties and biodiversity are unclear. To understand the ecological and environmental impacts of water-surface photovoltaic systems, here we conducted a field survey on water physical and chemical properties, plankton and bird communities of 26 water-surface photovoltaic systems in the Yangtze River basin in China during the winter and summer of 2022. We found that water-surface photovoltaic systems decreased water temperature, dissolved oxygen saturation and uncovered area of the water surface, which caused a reduction in plankton species and individual density, altering the community composition. Water-surface photovoltaic systems also caused an overall decrease in bird diversity and changed bird community compositions. These findings suggested that water-surface photovoltaic systems have impacts on the water environment and ecology. Since water-surface photovoltaic systems will continue to expand in the future, our results emphasize that rational planning is critical for the sustainable development of water-surface photovoltaic systems and the protection of the aquatic environment and biodiversity.

Effects of filter-feeding bivalves in benthic and pelagic habitats on plankton community and water quality in shallow systems: implications for lake rehabilitation

Effects of filter-feeding bivalves in benthic and pelagic habitats on plankton community and water quality in shallow systems: implications for lake rehabilitation