Changes In Phytoplankton Community Research Articles

Pigment-based Phytoplankton Size Classes and Community Composition along the Western Antarctic Peninsula during the Turkish Antarctic Expedition of 2019

This study investigates the spatial variability of phytoplankton size classes (PSCs) and community composition along the western Antarctic Peninsula (WAP) during the Turkish Antarctic Expedition (TAE-III) in 2019. Using high-performance liquid chromatography (HPLC) pigment analysis, microscopy, and hydrographic data, we characterized phytoplankton communities across 11 stations during the Turkish Antarctic Expedition (TAE-III). The results revealed substantial regional differences, with nanophytoplankton contributing the most to the total phytoplankton biomass (23–78%), followed by microphytoplankton (3–53%) and picophytoplankton (1–69%). Prominent pigments, including chlorophyll-a, fucoxanthin, and 19-hexanoloxyfucoxanthin, indicated diatom and haptophyte dominance in specific areas. Variations in community composition were strongly influenced by sea surface temperature, salinity, and nutrient availability, driven by regional hydrographic conditions and ice melt dynamics. These findings enhance our understanding of phytoplankton adaptive strategies under changing environmental conditions and highlight their crucial role in the WAP`s polar marine ecosystem. This study provides baseline data essential for monitoring climate-driven changes in Antarctic phytoplankton communities.

Structural Characteristics of Phytoplankton Communities and Its Relationship with Environmental Factors in Different Habitats of Hedi Reservoir

To explore the characteristics of phytoplankton communities and their relationship with environmental factors in different habitats of Hedi Reservoir, the inflow rivers, estuaries, and reservoir area of Hedi Reservoir were investigated in February （recession period）, April （flood period）, July （flood period）, and December （recession period） of 2022. During the investigation, 231 species of phytoplankton that belong to seven phyla were identified, and the cell density of phytoplankton ranged from 2.94 × 106 - 8.04 × 108 cells·L-1. Phytoplankton cell density in flood periods were higher than that in recession periods, and that was higher in estuaries and the reservoir area than that in inflow rivers. Meanwhile, the cell density of phytoplankton in the estuarine and reservoir area was dominated by Cyanobacteria throughout the year, especially Raphidiopsis raciborskii, whereas the cell density of phytoplankton in inflow rivers was dominated by Cyanophyta, Chlorophyta, and Bacillariophyta. In the inflow river area, the dominant species of cyanobacteria were Microcystis aeruginosa, Limnothrix redekei, Pseudanabaena circinalis, and Merismopedia punctata； the dominant species of Chlorophyta were Chlorella vulgaris and Crucigenia tetrapedia； and the dominant species of Bacillariophyta were Chlorella vulgaris and Melosira granulate. The highest biodiversity （Shannon-Wiener Index, Pielou index, and Margalef index） were observed in the inflow river area of Hedi Reservoir. The correlation analysis （Pearson） indicated that the environmental factors that were significantly correlated to phytoplankton communities included water temperature, dissolved oxygen, pH, conductivity, nitrogen, and phosphorus concentration. The RDA analysis indicated that phytoplankton communities in the inflow river area were mainly affected by pH and total nitrogen concentration, which were majorly affected by water temperature and pH in the estuarine area and chiefly affected by turbidity and pH in the reservoir. The pH affected the changes in phytoplankton communities in all three different habitats, whereas the inflow river area was significantly affected by total nitrogen concentration, and the estuarine and reservoir were significantly affected by water temperature and turbidity, respectively.

Long-term changes in phytoplankton community, mainly cyanobacteria in Lake Kasumigaura, Japan

Long-term changes in phytoplankton community, mainly cyanobacteria in Lake Kasumigaura, Japan

Changes in Cyanobacterial Phytoplankton Communities in Lake-Water Mesocosms Treated with Either Glucose or Hydrogen Peroxide.

When cyanobacterial phytoplankton form harmful cyanobacterial blooms (HCBs), the toxins they produce threaten freshwater ecosystems. Hydrogen peroxide is often used to control HCBs, but it is broadly toxic and dangerous to handle. Previously, we demonstrated that glucose addition to lake water could suppress the abundance of cyanobacteria. In this study, glucose was compared to hydrogen peroxide for the treatment of cyanobacterial phytoplankton communities. The six-week study was conducted in the large mesocosms facility at Grand Valley State University's Annis Water Resources Institute in Michigan. To 1000 L of Muskegon Lake water, glucose was added at either 150 mg or 30 mg glucose/L. Hydrogen peroxide was added at 3 mg/L to two 1000 L mesocosms. And two mesocosms were left untreated as controls. Triplicate 100 mL samples were collected weekly from each mesocosm, which were then filtered and frozen at -80 °C for 16S rRNA amplicon sequencing. The 16S rRNA amplicon sequencing results revealed that hydrogen peroxide treatment quickly reduced the relative abundance of the cyanobacteria compared to the control mesocosms, but the cyanobacteria population returned over the course of the 6-week study. On the other hand, both glucose concentrations caused a rapid proliferation of multiple low abundance proteobacterial and bacteroidotal taxa resulting in notable increases in taxonomic richness over the duration of the study and reducing the relative abundance of cyanobacteria. Although hydrogen peroxide quickly suppressed the cyanobacteria, the population later returned to near starting levels. The glucose suppressed the cyanobacterial phytoplankton apparently by promoting competitive heterotrophic bacteria.

Phytoplankton community composition as a driver of annual autochthonous organic carbon dynamics in the northern coastal Baltic Sea

Phytoplankton are the major primary producers in the pelagic system. They greatly influence biogeochemical cycles but little is known about the importance of shifting phytoplankton community composition for carbon dynamics. This study investigates the impact of seasonal changes in coastal phytoplankton communities on pelagic carbon fluxes. A field sampling campaign, covering an annual cycle in primary production, was conducted to assess the seasonal changes of phytoplankton communities and relevant organic carbon parameters in the coastal Baltic Sea. The monitoring frequency ranged from 1 to 3 wk, adapted to match the seasonal phytoplankton blooms. In addition, sediment traps were deployed to determine the particulate carbon and nutrient export to the seafloor in every season. We found that the phytoplankton biomass during the spring bloom was as high as 550 µg C l-1 and was dominated by diatom species (88% of total phytoplankton biomass). In comparison, the more species-rich summer bloom reached a combined maximum biomass of 236 µg C l-1. However, the highest export flux of particulate organic carbon was found in the middle of August (561 mmol C m-2 d-1) and, not as expected, around the spring bloom in May (226 mmol C m-2 d-1), suggesting a high potential for carbon recycling within the pelagic food web rather than being exported to the seafloor or advected laterally. Our study emphasizes the importance of keystone species and diversity for carbon transport processes in marine coastal ecosystems and highlights complex relationships between phytoplankton biomass production, community composition and carbon dynamics.

Effect of the ten-year fishing ban on change of phytoplankton community structure: Insights from the Gan River.

The Yangtze River is one of the largest riverine ecosystems in the world and is a biodiversity hotspot. In recent years, this river ecosystem has undergone rapid habitat deterioration due to anthropogenic disturbances, leading to a decrease in freshwater biodiversity. Owing to these anthropogenic impacts, the Chinese government imposed a "Ten-year fishing ban" (TYFB) in the Yangtze River and its tributaries. Ecological changes associated with this decision have not been documented to evaluate the level of success. This study evaluates the success of the TYFB by analyzing the changes in phytoplankton communities and comparing them to periods before the TYFB was imposed. A total of 325 phytoplankton species belonging to 7 phyla and 103 genera dominated by Chlorophyceae and Bacillariophyceae were identified. Species diversity according to the Shannon-Wiener ranged between 1.19 and 3.00. The results indicated that phytoplankton diversity increased, while both density and biomass decreased after the TYFB. The health of the aquatic ecosystem appeared to have improved after the TYFB, as indicated by the phytoplankton-based index of biotic integrity. Significant seasonal and spatial differences were found among the number of species, density, and biomass of phytoplankton, where these differences were correlated with pH, water depth, chlorophyll-a, permanganate index, transparency, copper, ammonia nitrogen, and total phosphorus based on redundancy analysis. Results from this study indicate that the TYFB played an important role in the restoration of freshwater ecosystem in the Yangtze River and its tributaries.

Changes in near-shore phytoplankton community and distribution, southwestern Caspian Sea

Changes in near-shore phytoplankton community and distribution, southwestern Caspian Sea

Interannual succession of phytoplankton community in a canyon-shaped drinking water reservoir during the initial impoundment period: Taxonomic versus functional groups

During the initial impoundment period of a canyon-shaped reservoir, the water body fluctuated violently regarding water level, hydrological condition, and thermal stratification. These variations may alter the structure of phytoplankton community, resulting in algal blooms and seriously threatening the ecological security of the reservoir. It is of great significance to understand the continuous changes of phytoplankton in the initial impoundment period for the protection of reservoir water quality. Therefore, a two-year in-situ monitoring study was conducted on water quality and phytoplankton in a representative canyon-shaped reservoir named Sanhekou and the interannual changes of phytoplankton community and its response to environmental changes during the initial impoundment period were discussed at taxonomic versus functional classification levels. The results showed that the total nitrogen and permanganate index levels were relatively high in the first year due to rapid water storage and heavy rainfall input, and the more stable hydrological conditions in the second year promoted the increase of algae density and the transformation of community, and the proportion of cyanobacteria increased significantly. The succession order of phytoplankton in the first year of the initial impoundment period was Chlorophyta-Bacillariophyta-Chlorophyta, or J/F/X1-P/MP/W1-A/X1/MP, respectively. And the succession order in the second year was Cyanobacteria/Chlorophyta-Bacillariophyta-Chlorophyta, or LM/G/P-P/A/X1-X1/J/G. Water temperature, relative water column stability, mixing depth, and pH were crucial factors affecting phytoplankton community succession. This study revealed the interannual succession law and driving factors of phytoplankton in the initial impoundment period and provided an important reference for the operation management and ecological protection of canyon-shaped reservoirs.

Changes in size-dependent Chlorophyll a concentration and group-specific picophytoplankton abundance in short-term nutrient-addition experiments in the Equatorial Eastern Indian Ocean

To clarify the changes in phytoplankton community and influencing factors in short-term nutrient-addition experiments in the Equatorial Eastern Indian Ocean, we conducted three experiments (one in situ-like experiment, one on-deck experiment with deep seawater, and one on-deck experiment with surface seawater). Our findings indicate that when nutrients were added, there was a more significant increase in the chlorophyll a (chl a) concentrations of microphytoplankton (>20 μm) compared to those of nanophytoplankton (2-20 μm) and picophytoplankton (<2 μm). The chl a concentrations for phytoplankton <20 μm only exhibited significant increases in the on-board incubation of surface seawater collected at 1300 hr when grazing stress have likely been weak. In picophytoplankton, occasional increases in the abundances of Synechococcus were found, while the abundances of Prochlorococcus and eukaryotic picophytoplankton (Peuk) did not increase significantly. It results likely from the preference of grazing effect by herbivores and bottle effects. Additionally, the Prochlorococcus from 75 m was more adapted to weak light, thus its abundance sharply decreased when incubated under high light. We suggest that the nutrient effects have greater influence on microphytoplankton, but other factors, such as grazing and light, might contribute more to <20 μm phytoplankton. Furthermore, bottle effects should be considered when conducting incubation experiments.

Combined effect of warming, nutrients, and species pool size on the seasonal variability of phytoplankton composition: A modeling perspective

AbstractThe anticipated long‐term rise in temperature can have numerous effects on freshwater phytoplankton, however, there is a great deal of uncertainty about how biogeochemical processes modify community functioning under a warming climate. Previous works regarding a large shallow lake and a mesocosm study showed a positive relationship between the temporal variability of phytoplankton composition and mean temperature, which might be a sign of warming‐stimulated instability in ecosystem processes. To elucidate whether these observations are part of a more general phenomenon, we combined a numerical model describing the dependence of algal growth on temperature and nutrient concentration with a multispecies, multi‐nutrient model. We ran simulations representative of changes in phytoplankton communities with randomized initial species composition under different temperature scenarios (current annual temperature pattern increased with 1°C, 2°C, or 3°C), various levels of nitrogen and phosphorus supply and different degrees of temporal variability in those supplies. The model outputs showed that seasonal variability in composition can be enhanced by warming through the mechanistic links between nutrient availability, temperature, and species‐specific growth rates, but the rate of increase is also dependent on nutrient ratios and the size of the species pool. Moreover, temporal variability in nutrient loads also enhanced compositional variability, but the rate of increase also depended on the level of nutrient supply. The results of our study hint that the impact of climate change and eutrophication on phytoplankton dynamics can be more intricate than spatiotemporally limited field or experimental observations would suggest.

Phytoplankton optical fingerprint libraries for development of phytoplankton ocean color satellite products

Phytoplankton respond to physical and hydrographic forcing on time and space scales up to and including those relevant to climate change. Quantifying changes in phytoplankton communities over these scales is essential for predicting ocean food resources, occurrences of harmful algal blooms, and carbon and other elemental cycles, among other predictions. However, one of the best tools for quantifying phytoplankton communities across relevant time and space scales, ocean color sensors, is constrained by its own spectral capabilities and availability of adequately vetted and relevant optical models. To address this later shortcoming, greater than fifty strains of phytoplankton, from a range of taxonomic lineages, geographic locations, and time in culture, alone and in mixtures, were grown to exponential and/or stationary phase for determination of hyperspectral UV-VIS absorption coefficients, multi-angle and multi-spectral backscatter coefficients, volume scattering functions, particle size distributions, pigment content, and fluorescence. The aim of this publication is to share these measurements to expedite their utilization in the development of new optical models for the next generation of ocean color satellites.

Phytoplankton community changes in relation to nutrient fluxes along a quasi-stationary front

The main strait (Great Belt) connecting the North Sea and the Baltic Sea constitutes a quasi-stationary front and exposes phytoplankton to various degrees of water column mixing. Here, we examine phytoplankton community distributions (using the cell abundance of 4 readily identifiable diatoms) and estimate new production along the strait during early spring. Vertical turbulent mixing was ~10 times greater at stations in the strait compared to stations outside the strait. New production in the strait was on average ~50 mg C m-2 d-1, i.e. 8% of the average total primary production, and could explain the increase in chlorophyll observed along the strait. A non-metric multidimensional scaling analysis of phytoplankton community composition showed significant spatial groupings. However, variation of species abundances could not be explained by the general transport, where the abundance of the largest species decreased during the passage of the strait. A relatively small species (Guinardia delicatula) showed an increasing dominance in and above the subsurface chlorophyll maximum along the strait, and the bottom layer was also correspondingly dominated by a relatively small species (Skeletonema marinoi). This phytoplankton composition could be explained by photosynthetic traits associated with more efficient light usage of small cells together with increased nutrient supply in the strait.

Phytoplankton community structure during the melting phase of the land-fast ice in Prydz Bay, east Antarctica

Phytoplankton, the primary producers of all aquatic systems, form the base of the marine food web. Any change in the environmental settings of the given ecosystem will affect the phytoplankton community structure of the region. In the present work, water sampling was carried out from the poorly explored polar region, beneath the sea ice during the melting phase of land-fast ice near Indian Antarctic Research Station Bharati in Prydz Bay, East Antarctica. The water samples were analyzed for phytoplankton species diversity, nutrients, temperature, salinity, and Chlorophyll a (Chl a). Our observations indicate marked variations in phytoplankton biomass and community. A shift from diatom (Thalassiosira sp., Fragilariopsis sp.) to dinoflagellate (Protoperidinium sp.) community, along with the emergence of grazers was seen by the end of the observation period. The background environmental conditions also showed marked variations, as the concentration of nitrate at 0m depth reduced from 31.8 μM at Obs-1 to a non-detectable limit at Obs-3. Furthermore, at 0m depth, temperature increased from −1.32 °C at Obs-1 to −0.38 °C at Obs-3 while salinity decreased from 34.11 at Obs-1 to 33.68 at Obs-3, thus indicating the melting phase of sea ice from Obs-1 to Obs-3. These observations showed vertical stratification resulting from the basal melting of land-fast sea ice resulted in better availability of light, phytoplankton community change due to nutrient availability/utilization/limitation, followed by the presence of grazer community. This preliminary understanding will serve as a baseline dataset to design the targeted sampling/experiments in the future from the land-fast ice ecosystem.

The Seasonal Changes of Phytoplankton Community in Dongzhai Harbor Mangrove Reserve, Hainan, China

The Seasonal Changes of Phytoplankton Community in Dongzhai Harbor Mangrove Reserve, Hainan, China

Effects of Macrobrachium nipponense on Phytoplankton Communities and Water Environmental Factors in Macrobrachium rosenbergii Culture

Excessive feed input led to eutrophication and Cyanobacterial blooms in the culture of giant freshwater prawn (GFP, Macrobrachium rosenbergii). In order to improve the water quality and control the Cyanobacterial blooms, we tried the mixed culture of oriental river prawn (ORP, Macrobrachium nipponense), which can feed on plant and organic debris. In this study, the culture trial began on June 20th and ended on September 10th. The control group (CG) was GFPs monoculture, while the experimental group (EG) cultured GFPs and ORPs. Water samples were collected from the ponds for five times to compare the changes of water environmental factors and phytoplankton communities in CG and EG. Phosphate, nitrite, sulfide, and ammonia nitrogen in CG were significantly higher than those in EG at the end of culture (p < 0.05). In the middle stage of culture, the Margalef index, Pielou index, and Shannon–Wiener index of EG were significantly higher than those of CG (p < 0.05). The biomass and density of phytoplankton in EG were lower than those in CG, and the occurrence of Cyanobacterial blooms in EG was later. The results indicated that ORPs in the mixed culture model effectively transformed and stored part of the energy by consuming the residual bait, which reduced the degree of eutrophication and Cyanobacterial blooms.

Heterogeneous bacterial communities affected by phytoplankton community turnover and microcystins in plateau lakes of Southwestern China

Both phytoplankton and bacteria are fundamental organisms with key ecological functions in lake ecosystems. However, the mechanistic interactions through which phytoplankton community change and bacterial communities interact remain poorly understood. Here, the responses of bacterial communities to the community structure, resource-use efficiency (RUE), and community turnover of phytoplankton and microcystins (MCs) were investigated in Lake Dianchi, Lake Xingyun, and Lake Erhai of Southwestern China across two seasons (May and October 2020). Among phytoplankton, Cyanobacteria was the dominant species in all three lakes and attained greater dominance in October than in May due to variation in the RUE of nitrogen and phosphorus and environmental changes. The production of MCs, including MC_LR, MC_RR and MC_YR, was the result of the massive Cyanobacteria. Decreases in diversity and increases in heterogeneity were observed in the bacterial community structure. Nutrient levels, environmental factors and MCs (especially MC_YR) jointly affected the bacterial community in lakes, namely its diversity and community assembly. The cascading effects in lakes mediated by environmental conditions, phytoplankton community composition, RUE, community turnover, and MCs on bacterial communities were revealed in this study. These findings underscore the importance of relating phytoplankton community change and MCs to the bacterial community, which is fundamental for better understanding the lake ecosystem functioning and potential risks of MCs.

Effects of dissolved organic carbon gradient on epilimnetic zooplankton communities in lakes

Lake browning is expected to change aquatic ecosystems considerably. The changes that may occur in zooplankton communities with a high concentration of dissolved organic carbon (DOC) are little studied and not yet sufficiently understood. We studied zooplankton communities in Finland in 27 lakes with a wide DOC range. We explored how zooplankton diversity and biomass vary along a DOC gradient and how species belonging to different functional groups respond to varying DOC concentrations. The total biomass of zooplankton was not related to DOC concentration, but diversity decreased and the negative linear trend in diversity coincided with an increase in omnivorous zooplankton taxa, whereas several other herbivorous zooplankton taxa were displaced from the community along the gradient of DOC. The results of our study suggest that some well-adapted taxa, especially omnivorous taxa, can benefit from lake browning, but a larger number of taxa suffer from unfavourable conditions caused by high DOC concentration. DOC-induced changes in predation pressure and changes in phytoplankton community in terms of resource availability for zooplankton should be emphasized in future research to understand the effects of lake browning on zooplankton.

The response of Tampa Bay to a legacy mining nutrient release in the year following the event

IntroductionCultural eutrophication threatens numerous ecological and economical resources of Florida’s coastal ecosystems, such as beaches, mangroves, and seagrasses. In April 2021, an infrastructure failure at the retired Piney Point phosphorus mining retention reservoir garnered national attention, as 814 million liters of nutrient rich water were released into Tampa Bay, Florida over 10 days. The release of nitrogen and phosphorus-rich water into Tampa Bay – a region that had been known as a restoration success story since the 1990s – has highlighted the potential for unexpected challenges for coastal nutrient management.MethodsFor a year after the release, we sampled bi-weekly at four sites to monitor changes in nutrients, stable isotopes, and phytoplankton communities, complemented with continuous monitoring by multiparameter sondes. Our data complement the synthesis efforts of regional partners, the Tampa Bay and Sarasota Bay Estuary Programs, to better understand the effects of anthropogenic nutrients on estuarine health.ResultsPhytoplankton community structure indicated an initial diatom bloom that dissipated by the end of April 2021. In the summer, the bay was dominated by Karenia brevis, with conditions improving into the fall. To determine if there was a unique carbon (C) and nitrogen (N) signature of the discharge water, stable isotope values of carbon (δ13C) and nitrogen (δ15N) were analyzed in suspended particulate material (SPM). The δ15N values of the discharge SPM were −17.88‰ ± 0.76, which is exceptionally low and was unique relative to other nutrient sources in the region. In May and early June of 2021, all sites exhibited a decline in the δ15N values of SPM, suggesting that discharged N was incorporated into SPM after the event. The occurrence of very low δ15N values at the reference site, on the Gulf Coast outside of the Bay, indicates that some of the discharge was transported outside of Tampa Bay.DiscussionThis work illustrates the need for comprehensive nutrient management strategies to assess and manage the full range of consequences associated with anthropogenic nutrient inputs into coastal ecosystems. Ongoing and anticipated impacts of climate change – such as increasing tropical storm intensity, temperatures, rainfall, and sea level rise – will exacerbate this need.

Effects of climate, spatial and hydrological processes on shaping phytoplankton community structure and β-diversity in an estuary-ocean continuum (Amazon continental shelf, Brazil)

This study investigated the influence of the estuarine plume from the Maranhense Gulf on the phytoplankton community structure and β-diversity. To understand the effects of the regulation mechanisms on shaping phytoplankton community structure and β-diversity along an estuary-ocean continuum in the eastern sector of the Amazon shelf, this study considered spatiotemporal analyses of physical, chemical, and biological variables from May 2019 to June 2020. High temporal environmental heterogeneity was identified in Cumã Bay and significant spatial environmental variability in the estuary-ocean continuum. Based on the thermohaline properties, an estuarine plume was observed alongshore at a distance of approximately 60 km from the coastline. Both phytoplankton community structure and β-diversity varied in time and space. From 189 taxa, thirty-nine indicator species were selected based on their functional traits and indicator value. Skeletonema costatum was considered the best phytoplankton indicator of the estuarine water influence. Turnover was the main component responsible for boosting β-diversity at spatial and temporal scales. The present study was the first performed on an Amazon estuary-ocean continuum which applied diversity metrics (β-diversity) to generate new information about loss of taxon richness and provided important information about spatiotemporal changes in phytoplankton community and environmental heterogeneity.

Phytoplankton community changes in a coastal upwelling system during the last century

Phytoplankton community changes in a coastal upwelling system during the last century