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A key control on the magnitude of coastal eutrophication is the degree to which currents quickly transport nitrogen derived from human sources away from the coast to the open ocean before eutrophication develops. In the Southern California Bight (SCB), an upwelling-dominated eastern boundary current ecosystem, anthropogenic nitrogen inputs increase algal productivity and cause subsurface acidification and oxygen (O 2 ) loss along the coast. However, the extent of anthropogenic influence on eutrophication beyond the coastal band, and the physical transport mechanisms and biogeochemical processes responsible for these effects are still poorly understood. Here, we use a submesoscale-resolving numerical model to document the detailed biogeochemical mass balance of nitrogen, carbon and oxygen, their physical transport, and effects on offshore habitats. Despite management of terrestrial nutrients that has occurred in the region over the last 20 years, coastal eutrophication continues to persist. The input of anthropogenic nutrients promote an increase in productivity, remineralization and respiration offshore, with recurrent O 2 loss and pH decline in a region located 30-90 km from the mainland. During 2013 to 2017, the spatially averaged 5-year loss rate across the Bight was 1.3 mmol m -3 O 2 , with some locations losing on average up to 14.2 mmol m -3 O 2 . The magnitude of loss is greater than model uncertainty assessed from data-model comparisons and from quantification of intrinsic variability. This phenomenon persists for 4 to 6 months of the year over an area of 278,40 km 2 ( ∼ 30% of SCB area). These recurrent features of acidification and oxygen loss are associated with cross-shore transport of nutrients by eddies and plankton biomass and their accumulation and retention within persistent eddies offshore within the SCB.

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 × 104 cells/L and the spatial variation ranged from 18.6707 × 104 to 247.5542 × 104 cells/L. The temporal variation of zooplankton abundance ranged from 18 to 42 ind/L and the spatial variation ranged from 19 to 62 ind/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. [ABSTRACT FROM AUTHOR]

Background: 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. Results: 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 18 S rDNA) metabarcoding of pelagic ciliates. We found a distinct vertical stratification of the entire ciliate communities, with a boundary at a depth of 200 m. Significant distance-decay patterns were found in the photic layers of 5 m to the deep chlorophyll maximum and in the 2,000 m, 3000 m and bottom layers, while no significant pattern occurred in the mesopelagic layers of 200 m – 1,000 m. Below 200 m, 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 200 m, 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 200 m. Conclusions: 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 200 m transition layer improves our understanding of ocean ecosystems in the context of global warming. [ABSTRACT FROM AUTHOR]

Aim: To determine the degree to which assemblages of planktonic foraminifera track thermal conditions. Location: The world's oceans. Time Period: The last 700,000 years of glacial–interglacial cycles. Major Taxa Studied: Planktonic foraminifera. Methods: We investigate assemblage dynamics in planktonic foraminifera in response to temperature changes using a global dataset of Quaternary planktonic foraminifera, together with a coupled Atmosphere–Ocean General Circulation Model (AOGCM) at 8000‐year resolution. We use 'thermal deviance' to assess assemblage responses to climate change, defined as the difference between the temperature at a given location and the bio‐indicated temperature (i.e., the abundance‐weighted average of estimated temperature optima for the species present). Results: Assemblages generally tracked annual mean temperature changes through compositional turnover, but thermal deviances are evident under certain conditions. The coldest‐adapted species persisted in polar regions during warming but were not joined by additional immigrants, resulting in minimal assemblage turnover. The warmest‐adapted species persisted in equatorial regions during cooling with similarly minimal assemblage change. Assemblages at mid‐latitudes mostly tracked temperature cooling and warming. Main Conclusions: Planktonic foraminiferal assemblages were generally able to track or endure temperature changes: as climate warmed or cooled, bio‐indicated temperature also became warmer or cooler, although to a variable degree. At polar sites under warming and at equatorial sites under cooling, the change in bio‐indicated temperature was less than, or even opposite to, what would be expected from estimated environmental change. Nevertheless, all studied species persisted across the study interval, regardless of thermal deviance—a result that highlights the resilience and inertia of planktonic foraminifera on an assemblage level to the last 700,000 years of climate change. [ABSTRACT FROM AUTHOR]

The problem with superintensive vannamei shrimp cultivation is the increase in N and P concentrations which can cause eutrophication and blooming algae. Therefore, this research aims to obtain data and information regarding plankton dynamics and water quality in super intensive vannamei shrimp cultivation at different densities. The research used 3 pond plots with a shrimp density of 750 individuals/m2 (A); 1,000 heads/m²; and 1,250 heads/m2. Plankton data was collected through observation by filtering pond water at five points using planktonnet no. 25, 20 liters at 5 sampling points or 100 liters of water per plot, and sampling was carried out every 7 days. The results of statistical analysis show spearman correlation analysis showed that shrimp density did not have a significant effect on plankton abundance, phytoplankton abundance, zooplankton abundance, TAN, NO2, NO3, PO4, and TSS because the sig value. 2-tailed P > 0.05. however, the abundance of phytoplankton had a significant influence on the abundance of zooplankton (P < 0.05). while zooplankton abundance was influenced by NO2 (P < 0.05). The close relationship between shrimp density and the abundance of plankton, phytoplankton, zooplankton, and water quality (TAN, NO2, NO3, PO4, and TSS) is very low (-0.85-2.79). positive and very close correlation between plankton density, phytoplankton density and zooplankton density (0.68-0.956), and negative correlation with water quality (TAN, NO2, NO3, PO4, and TSS). This causes the distribution of low levels of diversity (H) and evenness (E), so that the average dominance index is below 1, which indicates the absence of dominant individuals. Therefore, in the three treatments no dangerous plankton blooming was found. [ABSTRACT FROM AUTHOR]

Plankton play an indispensable role in the biogeochemical processes of marine ecosystem. However, unraveling the intricate interactions among biodiversity, trophic linkages, and biotic-abiotic interplay between phytoplankton-zooplankton remains a significant challenge. Here, we conducted field studies in the neritic area of the Bohai Sea during autumn 2023 and spring 2024 to explore seasonal variations of both phytoplankton and zooplankton through microscope. Our analysis revealed a sharp decline in trophic interactions across phytoplankton and zooplankton, with an abundance ratio in autumn 2023 being 5.5 times higher than in spring 2024. Additionally, dominant plankton species (Y ≥ 0.02) exhibited obvious differences between the two seasons, with higher species diversity observed in autumn. Moreover, each dominant zooplankton species had distinct preferred food items in both seasons, with Rhizosolenia setigera being favored by Noctiluca scintillans and Acartia pacifica. Furthermore, a multivariate biota-environment analysis indicated that each dominant plankton species had unique correlation with specific environmental parameters, highlighting how plankton can fully exploit external environmental conditions to survive in seasonal variations. Ultimately, our findings emphasize significant seasonal dynamics and provide a solid foundation for assessing the potential impacts of environmental changes on plankton in coastal marine realm. [ABSTRACT FROM AUTHOR]

Several experimental evidences and field data documented that zooplankton may alter its behavioral response in the presence of toxic phytoplankton, reducing its consumption to the point of starvation. This paper is devoted to the mathematical study of such interactions of toxic phytoplankton with grazer zooplankton. The non-toxic phytoplankton is assumed to adopt a density-dependent refuge strategy to avoid over-predation by zooplankton. Both groups of phytoplankton are assumed to suffer direct harm from anthropogenic toxicants, while zooplankton is affected indirectly by ingesting contaminated phytoplankton. We calibrate the proposed model with the field data from Talsari and Digha Mohana, India, and estimate some crucial model parameters consistent with the behavior of the observed data. Our results demonstrate that zooplankton grazing on toxic phytoplankton plays a key role in the emergence or mitigation of plankton blooms. We also highlight the system's potential to exhibit multiple stable configurations under the same ecological conditions. The plankton system experiences significant regime shifts, which are explored through various bifurcation scenarios, such as transcritical and saddle-node bifurcations. These shifts are influenced by changes in refuge capacity, species growth rates, and environmental carrying capacity. Furthermore, we incorporate environmental variations due to seasonal periodic or almost periodic changes, allowing the refuge parameter to be time-dependent. We observe that the forced system exhibits double periodic solutions. Moreover, stronger seasonal variations in the refuge pattern lead to irregular chaotic blooms. In conclusion, the results offer valuable insights into the sustainability of biodiversity, potentially shedding light on the origin of diverse plankton bloom phenomena. [ABSTRACT FROM AUTHOR]

This paper describes typical habitats of European river lamprey (Lampetra fluviatilis (L., 1758)) larvae in the rivers of Leningrad Oblast. The density of ammocoetes and abiotic components of biotopes, as well as the structure of benthic and planktonic algae communities, zooplankton, and macrozoobenthos, are estimated. It is shown that the preferred grounds for larvae are sands <0.25 mm. Oligochaeta and Chironomidae larvae reach high levels of quantitative development together with ammocoetes. Algae and zooplankton communities are not decisive for lamprey larvae and have expressed seasonal patterns with peaks of abundance in the spring. The part of lamprey larvae in the abundance of benthic coenoses can reach significant values—the part in the total biomass of macrozoobenthos is 30–80%. [ABSTRACT FROM AUTHOR]

Chlorophyceae is a class of plankton commonly discovered in aquaculture ponds in tropical aquatic regions. Therefore, this study aimed to analyze the abundance levels of Chlorophyceae in pen-culture ponds during the dry season using a dynamic modeling system. The method adopted was a causal ex-post facto design, and the observed parameters were water quality and plankton abundance. The results showed the presence of various plankton classes such as Chrysophyceae, Chyanophyceae, Chlorophyceae, Dynophyceae, and Oligotrichea, as well as the discovery of 17 plankton genera. Water quality parameters identified Total Dissolved Solids (TDS) concentrations, dissolved oxygen levels, temperature, pH levels, and salinity ranging from 3.06–7.37 mg·L-1, 4.39–6.30 mg·L-1, 26.21–31.17 °C, 7.7–8.1, and 10–25 ppt, respectively. The average plankton dominance index (D’) showed Chlorophyceae dominance at 4.55, followed by Chyanophyceae, Chrysophyceae, Dynophyceae, and Oligotrichea at 1.78, 0.08, 0.07, and 0.01, respectively, falling in the index category of 0.5 < D < 1. Furthermore, the average plankton abundance dominance level (pi) signified Chlorophyceae dominance at 7.11E-01, followed by Chyanophyceae, Chrysophyceae, Dynophyceae, and Oligotrichea at 4.68E-01, 1.30E-01, 8.05E-02, and 3.96–02, respectively. This implied that in pen-culture water, Chlorophyceae significantly dominated over other classes. Dynamic modeling results showed the abundance of Chlorophyceae in ponds A, C, and D to be relatively uniform (± 5.00E-02 cell/ ml) compared to pond B (± 0.10E-00 cell/ml). It was important to acknowledge that as Chlorophyceae dominance increased (0.10E-00–5.0E-02 cell/ml), the total plankton abundance in the water decreased contradictorily (0.01E00–100E-04 cell/ml) due to over-dominance. On the basis of the modeling description, Chlorophyceae sustained for 20 weeks during the culture period, with optimal growth observed from the 1st to the 5th week. In conclusion, this plankton class experienced dynamic fluctuations during the pen-culture cultivation period, and the life cycle stability was dependent on water quality and temperature. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new tritrophic food chain model. We address the conditions for the coexistence of two different zooplankton species and one phytoplankton species. The results of the numerical and analytical studies of the model show that the most relevant parameters influencing the plankton ecosystem, to maintain a stable coexistence equilibrium, are the: carrying capacity and the constant intrinsic growth rate of the phytoplankton population, and the conversion rate with a mortality rate of carnivorous zooplankton. We prove the existence and direction of Hopf bifurcation in non delay system. To account for the time delay in the conversion of herbivorous consumption to carnivorous zooplankton, we incorporate a discrete delay into the consume response function. Furthermore, we establish some adequate conditions to prove the occurrence of Hopf bifurcation induced by delay in the delayed model. We also plot two-parameter bifurcation diagrams. The numerical results support the analytical findings. [ABSTRACT FROM AUTHOR]

[Objective]To understand the structural characteristics of the plankton community and its key environmental impact factors in the rivers of Muli mining area, and to provide data support and reference basis for the management and protection of water resources in the mining area. [Method]Collection and analysis of water and plankton in the rivers (Duosuo and Mori) that surround the opencast mine in the town of Muli. [Result]6 Phylum (21 species) of phytoplankton and 2 Phylum (15 species) of zooplankton were collected in the Dosuo River and 6 Phylum (19 species) of phytoplankton and 2 Phylum (9 species) of zooplankton were collected in the Mori River. In both rivers diatoms, green algae and protozoa were the dominant species, and the density and biomass of plankton were quantitatively higher upstream and lower downstream. The Shannon-Wiener, Margalef and Pielou indices for phytoplankton and zooplankton in Duosuo River are 1. 64 and 0. 58, 0. 86 and 0. 33, 0. 69 and 0. 42, respectively;the Shannon-Wiener, Margalef and Pielou indices for phytoplankton and zooplankton in Mori River are 1. 86 and 0. 21, 0. 87 and 0. 24, 0. 79 and 0. 36. Water temperature, pH, and nitrogen nutrients were identified as the main environmental factors affecting the structure of the planktonic communities in the Dosso and Mojito Rivers by redundancy analysis (RDA) and correlation analysis. [Conclusion]The ecological protection of water in the Muli mining area should focus on nutrient pollution and strengthen the control of non-point source pollution caused by overgrazing. [ABSTRACT FROM AUTHOR]

Environmental DNA metabarcoding (eDNA metaB) is fundamental for monitoring marine biodiversity and its spread in coastal ecosystems. We applied eDNA metaB to seawater samples to investigate the spatiotemporal variability of plankton and small pelagic fish, comparing sites with different environmental conditions across a coast-to-offshore gradient at river mouths along the Campania coast (Italy) over 2 years (2020–2021). We found a marked seasonality in the planktonic community at the regional scale, likely owing to the hydrodynamic connection among sampling sites, which was derived from numerical simulations. Nonetheless, spatial variability among plankton communities was detected during summer. Overall, slight changes in plankton and fish composition resulted in the potential reorganization of the pelagic food web at the local scale. This work supports the utility of eDNA metaB in combination with hydrodynamic modelling to study marine biodiversity in the water column of coastal systems. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'. [ABSTRACT FROM AUTHOR]

The transport of plankton by highly dynamic (sub)mesoscale currents—often associated with fronts and eddies—shapes the structure of plankton communities on the same time scales as biotic processes, such as growth and predation (days–weeks). The resulting biophysical couplings generate heterogeneities in their finescale distributions (1–10 km), or "patchiness." Here, we test the hypothesis that cross‐frontal plankton patchiness at a front found 200–250 km offshore in the California Current System was influenced by wind‐driven upwelling conditions upstream of the front. We show that in situ Eulerian measurements (cross‐frontal transects) can be interpreted in a Lagrangian framework by using satellite‐derived current velocities to trace water parcels backward in time to their coastal origins. We find that the majority of the water parcels sampled at this front originated along the central California coast during different episodic wind‐driven upwelling pulses and followed various trajectories before converging temporarily at the front. In response to nutrient injections at the coast, plankton communities transformed during their journeys from the coast to the sampling zone, with a succession of phytoplankton and zooplankton blooms. The cross‐frontal sampling captured the convergence of these distinct water parcels at different points in their biological histories, which resulted in the observed spatial patchiness. Our results suggest that identifying the processes controlling frontal plankton communities requires understanding them in the context of their spatial and temporal histories. In particular, Lagrangian approaches should be more widely applied to understand critical ecological patterns in highly dynamic systems. [ABSTRACT FROM AUTHOR]

Aggregated clusters of acritarchs are relatively common among assemblages of organic‐walled microfossils, yet such associations have received relatively little attention. Here we report a new diversity of acritarch clusters from the early Cambrian Buen Formation of North Greenland. The aggregation patterns of four genera (Skiagia, Comasphaeridium, Asteridium and Synsphaeridium) are described together with their background population characteristics (presence of openings, inner bodies and overall disparity) in order to better understand the palaeobiology of these acritarchs. The majority of Skiagia clusters were found to be monospecific despite significant intraspecific variability, a pattern that is suggestive of a strong environmental influence on Skiagia morphologies and aggregation habits. Abundant small (<20 μm) Comasphaeridium vesicles were recovered in a broad range of chiefly monospecific clusters that are likely to have been formed under bloom conditions. A colonial habit is tentatively inferred from the tightly packed appearance of monogeneric Asteridium aggregates, and clearly evidenced by the highly conserved cellular structure of recovered Synsphaeridium clusters. A lack of excystment structures in Comasphaeridium and Asteridium vesicles suggest these taxa represent actively growing cells rather than resting cysts. Altogether, these findings shed new light on the diversity of cellular structures and lifestyles represented among Cambrian acritarchs, and illustrate a range of reproduction and defence strategies adopted by plankton in the face of novel environmental pressures. [ABSTRACT FROM AUTHOR]

Plankton size spectra are important indicators of the ecosystem state, yet such measurements are typically biased by the available sampling methods. Here, we combined individual size measurement from two zooplankton imaging approaches— in situ observation by the Underwater Vision Profiler5 and Multinet-collection supplemented by ex situ imaging via Zooscan—obtained in the global ocean, to calculate zooplankton normalized biovolume size spectra (NBSS) for all organisms larger than 1 mm. The reconstructed NBSS combining both datasets resulted in increased biomass estimates by adding organisms poorly sampled by either of the methods. The optimal values measured by both methods are used to reconstruct the zooplankton biovolume and biomass distributions. The reconstructed slopes appeared steeper and closer to those measured only by the UVP5 (+7.6%) and flatter than those obtained only from the Multinet (−20%), particularly in tropical and temperate latitudes. The main difference in tropical and temperate NBSS from the two devices is due to the fragile rhizarians that were not accounted for when using net data. When possible, we suggest using in situ and ex situ technologies together, and we provide potential indications on how to correct for missing components of the community when only one method is available. [ABSTRACT FROM AUTHOR]

The forty-year-old Long-Term Ecological Research MareChiara (LTER-MC) program started on 26 January 1984, with fortnightly oceanographic sampling until 1991 and then, from 1995, with weekly sampling up to the present time. LTER-MC produced >150 publications that have been cited by thousands of other studies. In this scoping review, we analyzed this corpus using a semantic approach based on topic modeling, a machine-driven procedure to identify and map topics and their interactions. Understanding the causes behind the evolution of scientific topics, their emergence, splitting, hybridization, or merging within a scientific community is an important step in science policy in managing collaborative research and bringing it into the future. Across different topics, mainly represented by studies on Natural History, Biodiversity, Phenology, Life Cycles, and Community Ecology, the LTER-MC work expanded the knowledge on planktonic organisms, describing in detail their lifestyles and delineating their relationships with environmental conditions. In presenting these results, the potential strengths, weaknesses, opportunities, and threats connected to the overall scientific dimension of LTER-MC are discussed. Finally, the upcoming effort is envisioned in reinforcing internal collaboration to integrate basic and applied research around scientific investigations suitable for establishing a stronger interaction between science and policy, as indicated by the United Nations Decade of Ocean Science for Sustainable Development. [ABSTRACT FROM AUTHOR]

A study of diatoms in eight watercourses (four spawning rivers and four streams) in the area of the Ozernovsky Mining and Metallurgical Complex (MMC) on the Kamchatka Peninsula was carried out for the first time. A total of 174 taxa were identified, and a comparative analysis of periphyton species diversity at the sampling stations was carried out. A new species for science was proposed: Gomphonema anissimovae Glushchenko, Kezlya & Kulikovskiy sp. nov. The composition and quantitative characteristics of plankton were analysed only in samples collected from rivers. It was shown that all rivers are oligotrophic in terms of phytoplankton biomass. The work includes lists of taxa with indication of their abundance, as well as illustrative material of found diatom taxa, which will provide an opportunity to monitor changes in planktonic and periphyton microalgae communities in the studied watercourses in the context of potentially high anthropogenic load from industry. [ABSTRACT FROM AUTHOR]

The perception of the importance of ciliate in freshwater has changed dramatically since the "microbial loop" conceptualisation, reflecting methodological attempts. The data from two decades (1994–2018) on the surface (0–3 m) ciliate assemblage in the Slapy reservoir (Vltava River, Czech Republic) during two different nutrient-load defined periods were analysed. We grouped the identified, quantified, and biomass-evaluated ciliates in the quantitative protargol-impregnated preparations according to their feeding behaviour. The sampling median and interquartile range data of the ciliates were plotted; the modelled water age, nutrients, bacteria, heterotrophic nanoflagellates, and Rhodomonas spp. were applied as the main explanatory background variables. We validated the differences between the periods, engaging multivariate analyses. The picoplankton-filtering species dominated the assemblages in an annual mean (halteriids and minute strobilidiids followed by peritrichs). Algae hunting urotrichs, Balanion planctonicum, and nanoplankton filtering tintinnids were significant before the spring phytoplankton peak when a maximum of ciliate biomass reflected mixotrophic nanoplankton filtering pelagostrombidiids. Only there did ciliate biomass tightly follow their quantified prey. Heterotrophic and mixotrophic Askenasia and Lagynophrya were typical raptorial/flagellate-hunting cilates; only Mesodinium spp. reached the maximum during autumn. The observed oligotrophication of the reservoir increased the ciliate assemblage biomass in the surface layer during stratification in concordance with the Plankton Ecology Group (PEG) model. [ABSTRACT FROM AUTHOR]

Although usually considered part of the plankton, cubozoans are strong swimmers. The aim of this study was to determine the influence of the active swimming ability of the box jellyfish Carybdea marsupialis on the spatial distribution of a well‐studied population in the NW Mediterranean where adults and juveniles do not overlap geographically. To accomplish this, we analyzed the swimming speed, effective velocity, effective displacement index (EDI), and proficiency of 27 individuals with diagonal bell widths (DBWs) ranging from 1.1 to 36 mm. The laboratory analysis utilized conventional video recordings and the video analysis tool Tracker. Mean swimming speed for small juveniles, medium juveniles and adults was 9.7 ± 0.8, 21.9 ± 2.3 and 43.1 ± 1.8 mm s−1 (mean ± se), respectively. Effective velocity was also proportional to size, ranging from 5.0 ± 0.7 to 38.8 ± 3.1 mm s−1 (mean ± se). The calculated EDI for each group was 0.51 ± 0.05, 0.84 ± 0.06 and 0.90 ± 0.05 (mean ± se), respectively. Proficiency showed an inverse trend, from 6.4 ± 0.6 s−1 for the small juveniles to 1.36 ± 0.05 for adults (mean ± se). Comparing the swimming speed results with the local currents obtained from drifting buoys analyzed in the area, adults would be able to swim strongly enough to overcome almost 70% of the currents, whereas the small juveniles would not reach 17%. This would allow larger individuals to select their habitat, while smaller individuals are left dependent on advection. Although experiments adding currents in aquaria would be necessary to confirm these theoretical results, the data obtained would be useful in improving the performance of bio‐mathematical models used to predict jellyfish blooms since, even though the sting of C. marsupialis is non‐fatal, it may produce systemic effects in sensitive swimmers. [ABSTRACT FROM AUTHOR]

The abundance distribution and species richness of encysted plankton have been investigated in the bottom sediments of the Taranto Marine System (southern Italy) for contributing to the understanding of plankton dynamics in a confined coastal area. This confined area is characterized by four contiguous basins with different degrees of confinement. The investigation was carried out in the fall season with the aim to intercept a period of rich cyst production from the plankton before overwintering. From the analysis of a total of 36 sediment samples, from 12 sample sites, the highest abundance of cysts and species richness were registered in the confined part of the system. A total of 103 cyst morphotypes have been recognized in the whole area, with highest abundances and taxa richness in the most confined stations. These results, suggesting a benthic-pelagic exchange of living matter, more intense in confined environments than in the open sea, highlight the necessity of (i) including the analysis of sediment cyst banks in studies of plankton dynamics, and (ii) to consider the role of confined areas, where the variability of environmental conditions favours a higher planktonic biodiversity in the sediments than in the water column. [ABSTRACT FROM AUTHOR]

Abstract 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 × 104 cells/L and the spatial variation ranged from 18.6707 × 104 to 247.5542 × 104 cells/L. The temporal variation of zooplankton abundance ranged from 18 to 42 ind/L and the spatial variation ranged from 19 to 62 ind/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.

Abstract Background 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. Results 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 18 S rDNA) metabarcoding of pelagic ciliates. We found a distinct vertical stratification of the entire ciliate communities, with a boundary at a depth of 200 m. Significant distance-decay patterns were found in the photic layers of 5 m to the deep chlorophyll maximum and in the 2,000 m, 3000 m and bottom layers, while no significant pattern occurred in the mesopelagic layers of 200 m – 1,000 m. Below 200 m, 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 200 m, 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 200 m. Conclusions 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 200 m transition layer improves our understanding of ocean ecosystems in the context of global warming. Graphical Abstract

Abstract Several experimental evidences and field data documented that zooplankton may alter its behavioral response in the presence of toxic phytoplankton, reducing its consumption to the point of starvation. This paper is devoted to the mathematical study of such interactions of toxic phytoplankton with grazer zooplankton. The non-toxic phytoplankton is assumed to adopt a density-dependent refuge strategy to avoid over-predation by zooplankton. Both groups of phytoplankton are assumed to suffer direct harm from anthropogenic toxicants, while zooplankton is affected indirectly by ingesting contaminated phytoplankton. We calibrate the proposed model with the field data from Talsari and Digha Mohana, India, and estimate some crucial model parameters consistent with the behavior of the observed data. Our results demonstrate that zooplankton grazing on toxic phytoplankton plays a key role in the emergence or mitigation of plankton blooms. We also highlight the system’s potential to exhibit multiple stable configurations under the same ecological conditions. The plankton system experiences significant regime shifts, which are explored through various bifurcation scenarios, such as transcritical and saddle-node bifurcations. These shifts are influenced by changes in refuge capacity, species growth rates, and environmental carrying capacity. Furthermore, we incorporate environmental variations due to seasonal periodic or almost periodic changes, allowing the refuge parameter to be time-dependent. We observe that the forced system exhibits double periodic solutions. Moreover, stronger seasonal variations in the refuge pattern lead to irregular chaotic blooms. In conclusion, the results offer valuable insights into the sustainability of biodiversity, potentially shedding light on the origin of diverse plankton bloom phenomena.

The forty-year-old Long-Term Ecological Research MareChiara (LTER-MC) program started on 26 January 1984, with fortnightly oceanographic sampling until 1991 and then, from 1995, with weekly sampling up to the present time. LTER-MC produced >150 publications that have been cited by thousands of other studies. In this scoping review, we analyzed this corpus using a semantic approach based on topic modeling, a machine-driven procedure to identify and map topics and their interactions. Understanding the causes behind the evolution of scientific topics, their emergence, splitting, hybridization, or merging within a scientific community is an important step in science policy in managing collaborative research and bringing it into the future. Across different topics, mainly represented by studies on Natural History, Biodiversity, Phenology, Life Cycles, and Community Ecology, the LTER-MC work expanded the knowledge on planktonic organisms, describing in detail their lifestyles and delineating their relationships with environmental conditions. In presenting these results, the potential strengths, weaknesses, opportunities, and threats connected to the overall scientific dimension of LTER-MC are discussed. Finally, the upcoming effort is envisioned in reinforcing internal collaboration to integrate basic and applied research around scientific investigations suitable for establishing a stronger interaction between science and policy, as indicated by the United Nations Decade of Ocean Science for Sustainable Development.

Plankton plays important roles in the marine ecosystems as important producers for primary production, major components in the global biogeochemical cycles, and the foundation of the marine food web. Despite their importance, long-term monitoring data about marine plankton are fairly limited, especially in the Asia-Pacific region. We fill this knowledge gap by providing a 29-year long-term monitoring data on the coastal areas of western Taiwan quarterly from 1993 to 2021. This long-term monitoring data can be used to set proper baseline for detecting human-induced impacts on the plankton, as well as modelling future scenarios under global changes. [ABSTRACT FROM AUTHOR]

In order to understand the community structure of plankton and environmental factors in the Chongqing section of the National Nature Reserve for Rare and Endemic Fishes (referred to as the "Reserve") along the upper Yangtze River, this study investigated phytoplankton and zooplankton in the water body from 2021 to 2022. The results revealed a diverse phytoplankton community with 243 species from 105 genera and 8 phyla, dominated by Bacillariophyta and Chlorophyta. Phytoplankton showed average densities of 1.7 × 106 cells/L and biomass of 2.6221 mg/L, following a seasonal pattern of summer > spring > winter. Zooplankton analysis identified 141 species from 77 genera and 4 phyla, with rotifers most abundant, followed by protozoa. Zooplankton displayed average densities of 0.17 × 104 ind./L and biomass of 0.3226 mg/L, also following a seasonal pattern of summer > spring > winter. Total phosphorus (TP) emerged as the primary environmental factor influencing plankton community structure, positively correlating with phytoplankton density and zooplankton biomass. Plankton biodiversity indices classified water quality in the Chongqing section of the "Reserve" as oligo-/mesotrophic. Overall, plankton diversity in this section is notably rich, with similar species composition between mainstems and tributaries but seasonal variations in community structure. While mainstem water quality generally meets standards, some tributaries exhibit varying degrees of pollution, underscoring the need for improved ecological management and protection measures. This is crucial for maintaining the sustainability of the ecosystem. [ABSTRACT FROM AUTHOR]

Cyanobacteria are globally occurring photosynthetic bacteria notable for their contribution to primary production and production of toxins which have detrimental ecosystem impacts. Furthermore, cyanobacteria can form mutualistic symbiotic relationships with a diverse set of eukaryotes, including land plants, aquatic plankton and fungi. Nevertheless, not all cyanobacteria are found in symbiotic associations suggesting symbiotic cyanobacteria have evolved specializations that facilitate host-interactions. Photosynthetic capabilities, nitrogen fixation, and the production of complex biochemicals are key functions provided by host-associated cyanobacterial symbionts. To explore if additional specializations are associated with such lifestyles in cyanobacteria, we have conducted comparative phylogenomics of molecular functions and of biosynthetic gene clusters (BGCs) in 984 cyanobacterial genomes. Cyanobacteria with host-associated and symbiotic lifestyles were concentrated in the family Nostocaceae, where eight monophyletic clades correspond to specific host taxa. In agreement with previous studies, symbionts are likely to provide fixed nitrogen to their eukaryotic partners, through multiple different nitrogen fixation pathways. Additionally, our analyses identified chitin metabolising pathways in cyanobacteria associated with specific host groups, while obligate symbionts had fewer BGCs. The conservation of molecular functions and BGCs between closely related symbiotic and free-living cyanobacteria suggests the potential for additional cyanobacteria to form symbiotic relationships than is currently known. [ABSTRACT FROM AUTHOR]

In recent years, fluorescence microscopy has revitalized the study of invertebrate comparative morphology. Here we explore the usefulness of combining confocal laser scanning microscopy (CLSM) and cuticular autofluorescence to examine the taxonomically challenging marine planktonic "y-larvae" (Pancrustacea: Facetotecta). To gauge the effectiveness of CLSM with autofluorescence in producing taxonomically useful images, we applied it to seven distinct y-naupliar species or morphospecies that had previously undergone scrutiny by other techniques. The specimens were part of a museum collection of glycerin-jelly slides of exuviae of last-stage y-nauplii, a key instar for studying the taxonomy of y-larvae. For Hansenocaris demodex, the level of detail obtained from a single specimen was comparable to that previously obtained by scanning electron microscopy (SEM). For Hansenocaris aquila, revisiting the original holotype specimen resulted in a dramatic increase in our understanding of the species' morphology, including taxonomically pivotal information about its spinose labrum and a digitally rotated lateral view. CLSM analyses of the other five specimens, which represented a broad spectrum of y-naupliar morphology, efficiently generated more such information. Novel observations were made concerning putative external rudiments of both the first and second maxillae in late nauplii as well as the extreme dorso-ventral flattening of some naupliar types. CLSM observation of museum slides of naupliar exuviae using cuticular autofluorescence thus shows great promise of becoming an excellent tool for studying the morphology and taxonomy of y-larvae, and we suggest that this technique might also profitably be applied to other forms of larval exuviae. [ABSTRACT FROM AUTHOR]

We evaluated the main environmental factors (abiotic and biotic) driving the phytoplankton community in a shallow tropical reservoir located in an environmentally protected area. Phytoplankton samples were collected from the surface and bottom of the reservoir. The phytoplankton samples were later identified at the species level, and the species were further assigned to morphology-based functional groups (MBFGs). Zooplankton were sampled through vertical haul, communities were identified to species level, and functional diversity was estimated based on community-weighted means (CWM). Phytoplankton MBFGs IV, V, and VI contributed the most to the biomass under high light availability coupled with low nutrient availability. Potentially toxic cyanobacteria from MBFG III were observed during thermal stratification. Hydraulic mixing plays a crucial role in reducing the phytoplankton biomass during the warmer/rainy season. Cyclopoid copepods accounted for more than 83% of the zooplankton biomass. There was a weak but significant effect of zooplankton functional diversity on phytoplankton functional diversity, mainly because of the dominance of small zooplankton. Altogether, our findings suggest that environmental filtering plays a greater role than zooplankton grazing in phytoplankton community structure in this shallow tropical reservoir. [ABSTRACT FROM AUTHOR]

The implementation of deep learning algorithms has brought new perspectives to plankton ecology. Emerging as an alternative approach to established methods, deep learning offers objective schemes to investigate plankton organisms in diverse environments. We provide an overview of deep‐learning‐based methods including detection and classification of phytoplankton and zooplankton images, foraging and swimming behavior analysis, and finally ecological modeling. Deep learning has the potential to speed up the analysis and reduce the human experimental bias, thus enabling data acquisition at relevant temporal and spatial scales with improved reproducibility. We also discuss shortcomings and show how deep learning architectures have evolved to mitigate imprecise readouts. Finally, we suggest opportunities where deep learning is particularly likely to catalyze plankton research. The examples are accompanied by detailed tutorials and code samples that allow readers to apply the methods described in this review to their own data. [ABSTRACT FROM AUTHOR]

The nature and extent of diversity in the plankton has fascinated scientists for over a century. Initially, the discovery of many new species in the remarkably uniform and unstructured pelagic environment appeared to challenge the concept of ecological niches. Later, it became obvious that only a fraction of plankton diversity had been formally described, because plankton assemblages are dominated by understudied eukaryotic lineages with small size that lack clearly distinguishable morphological features. The high diversity of the plankton has been confirmed by comprehensive metabarcoding surveys, but interpretation of the underlying molecular taxonomies is hindered by insufficient integration of genetic diversity with morphological taxonomy and ecological observations. Here we use planktonic foraminifera as a study model and reveal the full extent of their genetic diversity and investigate geographical and ecological patterns in their distribution. To this end, we assembled a global data set of ~7600 ribosomal DNA sequences obtained from morphologically characterised individual foraminifera, established a robust molecular taxonomic framework for the observed diversity, and used it to query a global metabarcoding data set covering ~1700 samples with ~2.48 billion reads. This allowed us to extract and assign 1 million reads, enabling characterisation of the structure of the genetic diversity of the group across ~1100 oceanic stations worldwide. Our sampling revealed the existence of, at most, 94 distinct molecular operational taxonomic units (MOTUs) at a level of divergence indicative of biological species. The genetic diversity only doubles the number of formally described species identified by morphological features. Furthermore, we observed that the allocation of genetic diversity to morphospecies is uneven. Only 16 morphospecies disguise evolutionarily significant genetic diversity, and the proportion of morphospecies that show genetic diversity increases poleward. Finally, we observe that MOTUs have a narrower geographic distribution than morphospecies and that in some cases the MOTUs belonging to the same morphospecies (cryptic species) have different environmental preferences. Overall, our analysis reveals that even in the light of global genetic sampling, planktonic foraminifera diversity is modest and finite. However, the extent and structure of the cryptic diversity reveals that genetic diversification is decoupled from morphological diversification, hinting at different mechanisms acting at different levels of divergence. [ABSTRACT FROM AUTHOR]

Lakes are particularly vulnerable to environmental changes and thus considered sentinels and integrators of processes that occur in the atmosphere and terrestrial environments. Individual up to ecosystemic metabolic pathways and nutrient cycling in lakes respond to both natural and human disturbances. Disentangling the effect of such different forces is a particular challenge for lake ecological studies. Here we present a conference paper based on previous studies carried out in Andean-Patagonian lakes under two important events: the Puyehue–Cordón Caulle eruption in 2011 and the glacial recession with a glacial lake outburst flood (GLOF) in 2009. We discuss how biological variables responded to these two natural events that produced the input of minerogenic inorganic particles into the lakes. We present the combination of observational and experimental research, including new molecular methods, that contributed to understanding the effects of these inorganic particles on aquatic ecosystems. Both events involved changes in the transparency of the lakes that affected phytoplankton parameters (biomass vertical distribution), bacteria composition and community structuring process. Finally, both events had very contrasting effects on zooplankton, in the same range of particle concentrations. Particles from glacial melting are beneficial for daphnids reducing the impact of ultraviolet radiation and increasing the quality of the food. In contrast, volcanic ashes are abrasive materials that have a deleterious effect for filtering zooplankton. [ABSTRACT FROM AUTHOR]

Despite the ubiquity of eddies at the Mid‐Atlantic Bight shelf‐break front, direct observations of frontal eddies at the shelf‐break front are historically sparse and their biological impact is mostly unknown. This study combines high resolution physical and biological snapshots of two frontal eddies with an idealized 3‐D regional model to investigate eddy formation, kinematics, upwelling patterns, and biological impacts. During May 2019, two eddies were observed in situ at the shelf‐break front. Each eddy showed evidence of nutrient and chlorophyll enhancement despite rotating in opposite directions and having different physical characteristics. Our results suggest that cyclonic eddies form as shelf waters are advected offshore and slope waters are advected shoreward, forming two filaments that spiral inward until sufficient water is entrained. Rising isohalines and upwelled slope water dye tracer within the model suggest that upwelling coincided with eddy formation and persisted for the duration of the eddy. In contrast, anticyclonic eddies form within troughs of the meandering shelf‐break front, with amplified frontal meanders creating recirculating flow. Upwelling of subsurface shelf water occurs in the form of detached cold pool waters during the formation of the anticyclonic eddies. The stability properties of each eddy type were estimated via the Burger number and suggest different ratios of baroclinic versus barotropic contributions to frontal eddy formation. Our observations and model results indicate that both eddy types may persist for more than a month and upwelling in both eddy types may have significant impacts on biological productivity of the shelf break. Plain Language Summary: The Middle Atlantic Bight shelf‐break front is a highly variable region that frequently forms frontal eddies. In situ observations of the physical and biological characteristics of these eddies are relatively scarce. We present observations of two eddies, each of which showed evidence of nutrient and chlorophyll enhancement despite having drastically different characteristics and different formation processes. Satellite data indicate that neither of the two types of eddies are rare, indicating a potential for frontal eddies to significantly influence biological communities near the front. Key Points: Two frontal eddies of opposite rotational directions were observed at the Middle Atlantic Bight shelf‐break frontNutrients, chlorophyll, diatom chains, and small copepods were enhanced in the eddiesModel simulation was consistent with upwelling within both features [ABSTRACT FROM AUTHOR]

Using scanning electron microscopy, 33 morphotypes of stomatocysts of Chrysophyceae are found in the plankton of the reservoirs, lakes, and rivers of the mountain–forest zone of the Southern Urals; 8 of them are noted in Russia for the first time, and 1 is described as new to science. The description of each morphotype is accompanied by a SEM micrography, geographical location, and environmental characteristics. Unornamented stomatocysts with a spherical form are predominant in abundance in plankton. Ornamented stomatocysts with a spherical form are predominant in diversity in plankton. The maximum diversity of stomatocysts is observed in spring and in autumn. The high diversity of stomatocysts indicates a significant diversity of golden algae in the Southern Ural region. [ABSTRACT FROM AUTHOR]

Background: Plankton is the essential ecological category that occupies the lower levels of aquatic trophic networks, representing a good indicator of environmental change. However, most studies deal with distribution of single species or taxa and do not take into account the complex of biological interactions of the real world that rule the ecological processes. Results: This study focused on analyzing Antarctic marine phytoplankton, mesozooplankton, and microzooplankton, examining their biological interactions and co-existences. Field data yielded 1053 biological interaction values, 762 coexistence values, and 15 zero values. Six phytoplankton assemblages and six copepod species were selected based on their abundance and ecological roles. Using 23 environmental descriptors, we modelled the distribution of taxa to accurately represent their occurrences. Sampling was conducted during the 2016–2017 Italian National Antarctic Programme (PNRA) 'P-ROSE' project in the East Ross Sea. Machine learning techniques were applied to the occurrence data to generate 48 predictive species distribution maps (SDMs), producing 3D maps for the entire Ross Sea area. These models quantitatively predicted the occurrences of each copepod and phytoplankton assemblage, providing crucial insights into potential variations in biotic and trophic interactions, with significant implications for the management and conservation of Antarctic marine resources. The Receiver Operating Characteristic (ROC) results indicated the highest model efficiency, for Cyanophyta (74%) among phytoplankton assemblages and Paralabidocera antarctica (83%) among copepod communities. The SDMs revealed distinct spatial heterogeneity in the Ross Sea area, with an average Relative Index of Occurrence values of 0.28 (min: 0; max: 0.65) for phytoplankton assemblages and 0.39 (min: 0; max: 0.71) for copepods. Conclusion: The results of this study are essential for a science-based management for one of the world's most pristine ecosystems and addressing potential climate-induced alterations in species interactions. Our study emphasizes the importance of considering biological interactions in planktonic studies, employing open access and machine learning for measurable and repeatable distribution modelling, and providing crucial ecological insights for informed conservation strategies in the face of environmental change. [ABSTRACT FROM AUTHOR]

Background: Streptococcus mutans has been implicated as a primary causative agent of dental caries and one of its important virulence properties is an ability to form biofilm on tooth surfaces. Thus, strategies to prevent and control S. mutans biofilms are requested. The present study aimed to examine the eradication of S. mutans planktonic and biofilm cells using riboflavin (Rib)-mediated antimicrobial photodynamic therapy (aPDT) enhanced by postbiotic mediators derived from Lactobacillus species. Materials and methods: Minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Rib and postbiotic mediators were determined. The antimicrobial and anti-biofilm effects of Rib-mediated aPDT (Rib plus blue light), Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus casei (LC) (aPDT+ LC), and Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus plantarum (LP) (aPDT+ LP) were evaluated. The anti-virulence potential of Rib-mediated aPDT, aPDT+ LC, and aPDT+ LP were assessed by measuring the expression of the gtfB gene using quantitative real-time polymerase chain reaction (qRT-PCR) at the highest concentrations of Rib, LC, and LP, at which the S. mutans had proliferation as the same as in the control (non-treated) group. Results: According to the results, the MIC doses of LC, LP, and Rib were 64 µg/mL, 128 µg/mL, and 128 µg/mL, respectively, while the MBC values of LC, LP, and Rib were 128 µg/mL, 256 µg/mL, and 256 µg/mL, respectively. Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC showed a significant reduction in Log10 CFU/mL of S. mutans compared to the control group (4.2, 4.9, and 5.2 Log10 CFU/mL, respectively; all P < 0.05). The most destruction of S. mutans biofilms was observed after treatment with aPDT+ LC followed by aPDT+ LP and Rib-mediated aPDT (77.5%, 73.3%, and 67.6%, respectively; all P < 0.05). The concentrations of 31.2 µg/mL, 62.5 µg/mL, and 62.5 µg/mL were considered as the highest concentrations of LC, LP, and Rib, respectively, at which S. mutans replicates as same as the control group and were used for gtfB gene expression assay using qRT-PCR during Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC treatments. Gene expression results revealed that aPDT+ LP and aPDT+ LC could decrease the gene expression level of gtfB by 6.3- and 5.7-fold, respectively (P < 0.05), while only 5.1-fold reduction was observed after Rib-mediated aPDT (P < 0.05). Conclusion: Our findings indicate that aPDT+ LP and aPDT+ LC hold promise for use as a treatment to combat S. mutans planktonic and biofilms growth as well as anti-virulence as a preventive strategy to inhibit biofilms development via reduction of gtfB gene expression. [ABSTRACT FROM AUTHOR]

Little is known about diatom parasitism in marine systems. Guinardia delicatula, a biomass‐dominant diatom on the Northeast US Shelf (NES), is regularly parasitized by the protistan nanoflagellate, Cryothecomonas aestivalis in this region. While G. delicatula is known to host other protistan parasites, direct observation of these interactions and their dynamics in nature remain elusive. Here, we integrate concurrent DNA meta‐barcoding and automated imaging‐in‐flow cytometry observations to characterize the dynamics of G. delicatula infection by a second parasite, Pirsonia (likely Pirsonia verrucosa). In contrast with C. aestivalis infections, Pirsonia infections are observed sporadically and typically only in a small fraction of the G. delicatula population on the NES. An exception was found in February 2020, when an anomalous co‐infection event was observed in G. delicatula featuring > 20% infection prevalence by Pirsonia and > 10% infection prevalence by C. aestivalis. Investigation of each parasite's infection dynamics' relationship with temperature and salinity suggested that C. aestivalis may consistently dominate G. delicatula infection dynamics due to its wider thermal tolerance range and more cosmopolitan distribution. Pirsonia only appeared capable of dominating G. delicatula infection at temperatures near or below 4°C, a known temperature threshold below which C. aestivalis infection is suppressed. Our results demonstrate the utility of integrating DNA meta‐barcoding and plankton imaging to observe the dynamics of diatom–parasite interactions in marine systems and shed light on the diversity of infection dynamics in diatom–parasite systems and the forcings governing competition among diatom parasites for a single host. [ABSTRACT FROM AUTHOR]

Five phylogenetic lineages were observed by present author in the eleven Tethyan Maastrichtian planktic foraminiferal species of the genus Plummerita. These lineages help to define the major faunal changes from the species throughout of three groups of the Plummerita. The first group (P. haggagae group) belongs to the four-chambered volition (4-ch) with axially pointed spine-like prolongation evolved to another species of five-chambered volition (5-ch) (P. hantkeninoides group), to another species of six-chambered volition (6-ch) (P. reicheli group). The five lineages are: (1) The Plummerita elkefensis (4-ch) to P. hantkeninoides (5-ch), (2) P. haggagae (4-ch) to P. costata (5-ch) to P. spainica (6-ch), (3) P. inflata (5-ch) to P. tunisica (6-ch) (4) P. kellerae (5-ch) to P. caribbeanica (6-ch), (5) P. premolisilvae (5-ch) to P. reicheli (6-ch). Unfortunately, most of these lineage are uncompleted from four to five to six-chamber volution, while only one of them is completed (no. 2). In spite of this uncompleted lineages situation, it seems that we must await further study to complete these lineages by another unknown taxa. [ABSTRACT FROM AUTHOR]

The North Sea region boasted one of the world's most important fisheries for many centuries. Climate directly and indirectly influences the development and survival of many important pelagic fish in the North Sea ecosystem. One indirect influence is the food availability in the form of phyto- and zooplankton abundance, which is strongly controlled by environmental factors. One of these environmental factors is local sea surface temperatures. A negative correlation between zooplankton abundance and sea surface temperature is well established for the epeiric sea on the European continental shelf. Continuous temporal observations of North Sea zooplankton production only exist since 1958. Therefore we developed a Historical Plankton Index (HPI) from 800 CE onwards to extend our record of temperature-driven zooplankton abundance in the North Sea over a multi-centennial time scale. For this we used the North Atlantic temperature reconstructions and associations between zooplankton abundance and contemporary sea surface temperatures established applying a General Additive Modelling (GAM) approach. We then examined the association between the HPI and historical landings from the Dutch commercial herring fishery in the 17th century to test the utility of our HPI. We examine the potential influence of food availability (in terms of zooplankton abundance) on the fishery, the evolution of which is often only considered in terms of human influences such as conflict, fishing gear and demand for fish as a commodity. We find that under certain conditions the HPI can explain 20% of the variability in Dutch herring landings. This highlights the importance of developing long-term and large-scale indices of natural marine ecosystem dynamics to understand the historical fortunes of the commercial fishing industry. The results are directly relevant to the United Nations' sustainable development goal 14 – life below water. [ABSTRACT FROM AUTHOR]

The taxonomic composition, abundance, diversity and spatial distribution of phytoplankton and zooplankton, as well as the prevailing hydrographic conditions, were examined in the Whin Estuary, which is considered one of the most pristine and productive coastal ecosystems of Ghana, which is located on the Gulf of Guinea. Hydrographic and plankton variables were determined along the gradient of the estuary between March and July 2022 across two seasons and tidal periods. A total of 50 genera of phytoplankton and 27 genera of zooplankton were recorded across the two seasons and sampling periods. Diatoms and copepods dominated the plankton communities across the estuary. Plankton genera such as Navicula, Nitzschia, Thalassiosira, Cyclops, Paracalanus and Temora were recorded across all the seasons and tidal periods, despite the varying hydrographic conditions. The environmental variables varied across the seasons, tidal periods and sampling stations in the estuary. For instance, temperature, DO, transparency, and chlorophyll a varied significantly (p < 0.05) across both the seasons and tidal periods. pH values were significantly (p < 0.05) lower in the rainy season compared to the dry season. There was a strong salinity gradient across the estuary, with the upper reaches dominated by freshwater organisms, such as cladocerans and cyanobacteria, and the lower reaches by marine organisms, primarily diatoms and copepods. In sum, the results reported here are important as they highlight the distribution of plankton communities in a tropical estuarine ecosystem and can serve as a reference for the management of tropical brackish ecosystems. [ABSTRACT FROM AUTHOR]

The Buenos Aires Lake Plateau, a unique semi-arid environment and priority area for waterbird conservation in Argentina, has recently shown reductions in lake sizes due to scarce rainfall. This study assessed the impact of contrasting hydrological conditions on the abiotic variables of lakes Chapu and Cervecero, as well as on the structure of plankton and how this affected the use of the lakes by waterbirds. We show that hydrological conditions shape the abiotic and biological features of these lakes. In 2015, both lakes were vegetated, but by 2016, their water level had dropped, causing decreased macrophyte coverage. In 2017, the lakes dried up completely, but were refilled the following year. The partial drought of 2015-2016 led to reduced concentrations of nutrients and food that support a high density and richness of birds, which are mostly aquatic and terrestrial feeders. After the extreme drought in 2017 and refilling phase in 2018, there was an improvement in the water quality of lake Chapu, as indicated by its increased clarity compared to that in 2015, while Cervecero remained turbid. Increased homogenization in plankton and waterbird species composition became evident in both lakes. There was a cyanobacteria bloom in Cervecero, while in Chapu Gammaproteobacteria were dominant. Both lakes supported few waterbirds, of which aquatic-terrestrial feeders and terrestrial herbivores were dominant. The abundance of the endemic and endangered hooded grebe (Podiceps gallardoi Rumboll 1974) declined with the cover of macrophytes, which these birds use when establishing their colonies. In sum, this study revealed changes in the conditions of lakes Chapu and Cervecero and their plankton communities in response to hydrological shifts, with implications for waterbird assemblages and, thus, biodiversity conservation. [ABSTRACT FROM AUTHOR]

Planktons are a fundamental piece of all ocean ecosystems yet, sampling plankton at the high resolution required to understand their dynamics remains a challenge. In-situ imaging tools offer an approach to sample plankton at fine scales. Advances in technology and methodology provide the ability to make in-situ imaging a common tool in plankton ecology. Despite the massive potential of in-situ imaging tools, there are no standard approaches for analyzing the associated data. Consequently, studies are inconsistent in analyzing in-situ imaging data, even for similar questions. This introduces challenges in comparing across studies and sampling devices. In this review, we briefly summarize the increasing use, potential and novel applications of in-situ imaging tools in plankton ecology. Then, we synthesize the common analyses used across these studies. Finally, we address the major statistical challenges associated with the unique sampling mechanisms of in-situ imaging tools and discuss the theoretical uncertainties, which arise from the low-sampling volumes of many in-situ imaging tools. To fully unlock the power of in-situ imaging tools in plankton ecological studies, researchers must carefully consider how to analyze their data. We provide recommendations for processing and analyzing data while also acknowledging a large need for developing new statistical tool. [ABSTRACT FROM AUTHOR]

Eco-engineering is an important tool for wetland restoration, but there are still large theoretical and application gaps in the knowledge of the effects of eco-engineering implementation on the interactions between environmental conditions and organisms during wetland restoration processes. In this study, we investigated water quality parameters and plankton communities in a national wetland park to clarify the mechanism of changes in plankton community structure and their ecological networks before and after the eco-engineering project. Undoubtedly, we found water quality was significantly improved with increased metazooplankton diversity after the implementation of eco-engineering. Ecological engineering reduced the effect of farmland drainage on the restored wetland and changed the phytoplankton community structure, which significantly reduced the relative abundance of Cyanobacteria and increased the relative abundance of Bacillariophyta. The structural equation modeling revealed that the total effect of metazooplankton on phytoplankton was significantly enhanced and associated with weakened relationships between phytoplankton and environmental variables after eco-engineering. In addition, the ecological network analysis also showed that the network connection between phytoplankton and metazooplankton was stronger after the eco-engineering implementation, leading to an enhanced biotic interactions in different trophic levels. These results indicate that the main approach to regulating primary producers in wetland ecosystems changed from "bottom-up" control to a combination of "bottom-up" and "top-down" control under the intervention of artificial recovery measures. Our findings shed new light on the effects of eco-engineering on the interactions between water quality and organisms and provide a scientific basis for the sustainable management of wetland ecosystems. [ABSTRACT FROM AUTHOR]

The present research article gives an account of the abundance and monthly variation of plankton diversity (i.e., phytoplankton and zooplankton) in Ashwani stream, Solan (H.P.). A total of 17 genera were recorded, out of which 11 belongs to Bacillariophyceae, 5 belongs to Chlorophyceae and 1 belongs to Cyanophyceae. Only single genera (Monostyla) of zooplankton were recorded. Study revealed that phytoplankton population was dominated by members of Bacillariophyceae followed by Chlorophyceae and Cyanophyceae. Relative abundance of plankton was higher during the December and January month (winter season) and lowest in April month. [ABSTRACT FROM AUTHOR]

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Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Trait-based models founded on biophysical principles are becoming popular in planktonic ecological modeling, and justifiably so. They allow for slim, efficient models with a significant reduction in parameters, well suited for modeling the past and future climate changes. In their simplest form, trait-based models describe the ecosystem in one set of parameters defined by first principles, rooted in physics, geometry, and evolution. The result is an emerging ecosystem defined by physical and chemical limitations at the cell level. At present, however, a significant part of these parameters is not fully constrained, which potentially introduces a considerable uncertainty to the model results. Here, we investigate how these parameters influence the ecosystem structure of one of the simplest trait-based models, the Nutrient-Unicellular-Multicellular (NUM) model. We describe the unicellular module of the NUM model and through an extensive parameter sensitivity analysis, we demonstrate that the model – with a large span in parameters – can capture the general features of the pico-, nano-, and micro planktonic ecosystem at the southern California Current. We show that it is possible to narrow the range of parameters to get a stable, acceptable, solution. Finally, we show that the model responds correctly to a change in oceanographic setting. Our analysis demonstrates that the unicellular module of the NUM model is accessible for the general non-expert without intimate knowledge of the parameter settings, and that the first-principal approach is well suited for modeling poorly resolved region and ecosystem evolution during current and deep time climate change. [ABSTRACT FROM AUTHOR]

In order to understand the structure of the plankton community, evaluate the water ecological environment quality, the physical and chemical properties of the water body and the status of the plankton community of 15 sampling sites in typical sections of upper Changjiang River in September 2021 were investigated, the composition of the plankton community structure was analyzed and the water quality status of the basin was evaluated. The result showed that 68 species of phytoplankton were detected in upper Changjiang River, belonging to 43 genera and 6 phyla. There were 15 species of zooplankton, including 12 species of Rotifera, 2 species of Cladocera and I species of Copepoda. Based on the physical and chemical parameters of water quality and plankton biological evaluation, the overall water quality of upper Changjiang River was in class II-III, which was in the state of medium pollution [ABSTRACT FROM AUTHOR]

Blooms of the harmful dinoflagellate Karenia brevis on the West Florida Shelf (WFS), Gulf of Mexico, are hypothesized to initiate in association with the colonial cyanobacterium Trichodesmium spp. and benefit from dissolved organic nitrogen (DON) release derived from N2-fixation by the cyanobacteria. Previous studies have detected DON release using direct experimental measurements, but there have been few studies that have followed nutrient release by in situ blooms of Trichodesmium and the associated plankton community. It was determined that long-term Trichodesmium spp. and Karenia brevis abundances on the WFS were related, following a 2-month lag. A separate Eulerian study of a Trichodesmium erythraeum bloom event was conducted over 9 days on the Great Barrier Reef. Concentrations of T. erythraeum increased over the course of the study, with coincident increases in dinoflagellate abundance and decreases in diatom abundance. Inside the bloom, concentrations of NH4+, PO43−, and DON increased significantly. The copepod grazer Macrosetella gracilis also increased in abundance as T. erythraeum numbers increased, contributing to nutrient release. Copepod grazing rates were measured, and N release rates estimated. Together, these studies show that Trichodesmium blooms have consequences for dinoflagellate abundance at both seasonal and ephemeral scales via direct and indirect N release. [ABSTRACT FROM AUTHOR]

Plankton parasites such as viruses, bacteria, fungi, and unicellular eukaryotes are associated symbionts colonizing algal groups in aquatic ecosystems. They occur within a network of microbe–microbe interactions in which they parasitize phytoplankton and seaweeds, i.e., primary producers generating organic carbon and forming the basis of marine food webs. These parasites use algae as a source of nutrients and reproduce at the expense of their host, causing infectious symptoms leading to disease and death. Plankton parasites can reduce the algal populations, and the infection of one specific species may, in turn, favor the development of another, influencing the seasonal succession of algal blooms in oceans, seas, and lakes. Many parasites have free-living stages that zooplankton graze upon, representing a significant trophic link in food webs. The biology and life cycle of plankton parasites are well investigated in marine and freshwater algal hosts. Still, the chemical signaling mediating these microbial interactions and the effect of co-occurring symbionts remain underexplored. This review focuses on the diversity of plankton parasites infecting algae, with a particular emphasis on unicellular eukaryotes. The ecological role of plankton parasites, the mechanisms regulating cellular infection and host resistance, and the interplay of alga-parasite interactions with coexisting microorganisms are discussed. [ABSTRACT FROM AUTHOR]