Plankton Biodiversity Research Articles

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

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

Complementary roles of eDNA metabarcoding and microscopy in plankton monitoring across seven habitats

Abstract Plankton biodiversity in aquatic ecosystems is currently investigated by labor-intensive and time-consuming microscope identification. Environmental DNA (eDNA) metabarcoding is emerging as a highly effective and objective tool for assessing biodiversity. In this study, we compared the effectiveness of eDNA metabarcoding with conventional microscope identification for monitoring plankton biodiversity in seven habitats. The eDNA metabarcoding identified a rich diversity of 190 families, 410 genera and 871 species within the planktonic community across seven habitats. In contrast, traditional microscope identification only identified 51 families, 75 genera and 96 species. In addition, primer choice influenced the detected plankton community diversity, with the V4 primers performing poorly for detecting Cladocera and Euglenophyta taxa and the V9 primers revealing more eukaryotic plankton species. Despite primer-specific differences in species detection, there was substantial overlap between the species detected by eDNA metabarcoding strategies and microscope identification. These results suggest that eDNA metabarcoding can be used as a complementary method alongside microscope identification rather than replacing them entirely.

Plankton Resting Stages Distribution in Bottom Sediments along the Confinement Gradient of the Taranto Sea System (Ionian Sea, Southern Italy)

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.

The NEREA Augmented Observatory: an integrative approach to marine coastal ecology

The NEREA (Naples Ecological REsearch for Augmented observatories) initiative aims to establish an augmented observatory in the Gulf of Naples (GoN), designed to advance the understanding of marine ecosystems through a holistic approach. Inspired by the Tara Oceans expedition and building on the scientific legacy of the MareChiara Long-Term Ecological Research (LTER-MC) site, NEREA integrates traditional physical, chemical, and biological measurements with state-of-the-art methodologies such as metabarcoding and metagenomics. Here we present the first 10 months of NEREA data, collected from April 2019 to January 2020, encompassing physico-chemical parameters, plankton biodiversity (e.g., microscopy and flow cytometry), prokaryotic and eukaryotic metabarcoding, a prokaryotic gene catalogue, and a collection of 3818 prokaryotic Metagenome-Assembled Genomes (MAGs). NEREA’s efforts produce a significant volume of multifaceted data, which enhances our understanding of marine ecosystems and promotes the development of scientific hypotheses and ideas.

Spatiotemporal Dynamics of Plankton Communities in the Chongqing Section of the National Nature Reserve for Rare and Endemic Fishes in the Upper Yangtze River

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.

Pollution level and ecological risk assessment of triazine herbicides in Laizhou Bay and derivation of seawater quality criteria

Triazine herbicides are widely used in agriculture and have become common pollutants in marine environments. However, the spatiotemporal distribution characteristics and water quality criteria (WQC) of triazine herbicides are still unclear. This study found that triazine herbicides had a high detection rate of 100 % in surface seawater of Laizhou Bay, China, with average concentrations of 217.61, 225.13, 21.97, and 1296.72 ng/L in March, May, August, and October, respectively. Moreover, estuaries were important sources, and especially the Yellow River estuary exhibited the highest concentrations of 16,115.86 ng/L in October. The 10 triazine herbicides were detected in the sediments of Laizhou Bay, with a concentration ranging from 0.14−1.68 μg/kg. Atrazine and prometryn accounted for 33.41 %−59.10 % and 28.93 %−50.06 % of the total triazine herbicides in the seawater, and prometryn had the highest proportion (63.50 %) in the sediments. Correlation analysis revealed that triazine herbicides led to the loss of plankton biodiversity, which further decreased the dissolved oxygen. In addition, this study collected 45 acute toxicity data and 22 chronic toxicity data of atrazine, 16 acute toxicity data of prometryn, and supplemented with toxicity experiments of prometryn on marine organisms. Based on the toxicity database, the WQCs of atrazine and prometryn were derived using species sensitivity distribution. The overall risk probability of atrazine and prometryn were both less than 1.75 % in the Laizhou Bay, indicating an acceptable risk. This study not only clarified the pollution status and ecological risk of triazine herbicides, but also provided scientific basis for their environmental management standards.

Analysis of Water Quality and Plankton Biodiversity in Conservation Area of PT PHE Raja Tempira

Analysis of Water Quality and Plankton Biodiversity in Conservation Area of PT PHE Raja Tempira

Using bioluminescence as a tool for studying diversity in marine zooplankton and dinoflagellates: an initial assessment.

Bioluminescence is light chemically produced by an organism. It is widespread across all major marine phyla and has evolved multiple times, resulting in a high diversity of spectral properties and first flash kinetic parameters (FFKP). The bioluminescence of a system is often a good proxy for planktonic biomass. The species-specific parameters of bioluminescent displays can be measured to identify species in situ and describe planktonic biodiversity. Most bioluminescent organisms will flash when mechanically stimulated i.e., when subjected to supra-threshold levels of shear stress. Here we compare first flash kinetic parameters such as flash duration, peak intensity, rise time, decay time, first-flash mechanically stimulated light and e-folding time obtained with the commercially available Underwater Bioluminescence Assessment Tool (UBAT). We provide descriptions of the first flash kinetic parameters of several species of dinoflagellates Pyrocystis fusiformis, Pyrocystis noctiluca, Pyrodinium bahamense, Lingulodinium polyedra, Alexandrium monilatum and two zooplankton (the ctenophore Mnemiopsis leidyi and the larvacean Oikopleura sp.). FFKPs are then compared and discussed using non-parametric analyses of variance (ANOVAs), hierarchical clustering and a linear discriminant analysis to assess the ability to use bioluminescence signatures for identification. Once the first flash kinetic parameters of a bioluminescent species have been described, it is possible to detect its presence using emissions collected by in situ bathyphotometers. Assessing abundance and diversity of bioluminescent species may therefore be possible.

Microcrustacean community structure is shaped by seasonality in a Brazilian semiarid reservoir

ABSTRACT Reservoirs are ecologically important ecosystems. In the Brazilian semiarid region, these ecosystems are impacted by environmental changes resulting from the rainfall regime. Furthermore, the reservoirs boast a rich planktonic biodiversity, which is directly influenced by the ecological dynamics of each reservoir. Our aim was to analyse the impact of rapid changes between the dry and rainy seasons on the limnological variables in a Brazilian semiarid reservoir. Furthermore, we analysed the impact of this phenomenon on the microcrustacean community in the reservoir. We observed that the reservoir is significantly impacted by the region’s rainfall regime. During the rainy season, the reservoir volume increases, resulting in higher pH and dissolved oxygen levels, and lower water temperature, electrical conductivity and total dissolved solids levels. The transition from the dry to the rainy season influenced the microcrustacean community. Our findings indicate that the transition from the dry to the rainy seasons in Brazilian semiarid region results in limnological changes in the reservoirs of this region. Furthermore, these changes also result in alterations to the microcrustacean community structure in these reservoirs.

Effects of waterway regulation structures on the planktonic community in the upper Yangtze River

To investigate the effects of the waterway regulation structures on the hydraulic characteristics, water physicochemical factors, and the planktonic community in the upper Yangtze River, this study was conducted in August and September of 2022 on two ecological dikes in the Chongqing section of the upper Yangtze River: the longitudinal dike and the spur dike. High-throughput sequencing technology was used to explore the differences in planktonic community structures upstream and downstream of the waterway regulation structures during the dry season, as well as their main influencing factors. The results showed that the dissolved oxygen increased significantly, and the turbidity and flow rate decreased significantly in downstream of dikes. The spur dike exhibited more pronounced changes in water quality and hydrodynamic factors compared to the longitudinal dike. The diversity index of phytoplankton, zooplankton, and fungi in the downstream of dikes were higher than those in the upstream, and the bacterial diversity index was higher than those of eukaryotes at each sampling site. The impact of the spur dike on the planktonic biodiversity index was greater than that of the longitudinal dike, as it alters flow velocity, turbidity, and dissolved oxygen. The major phyla of phytoplankton, zooplankton, and bacteria, including Cryptophyta (70.37–80.57 %), Mollusca (7.56–37.50 %), and Proteobacteria (48.53–55.92 %), had a higher relative abundance in upstream of dike, and their relative abundance in spur dike was higher than that in longitudinal dike. In contrast, the relative abundance of the major phylum of fungi, Ascomycota (37.15–56.85 %), showed an opposite trend in both dike-to-dike comparison and dike upstream-to-downstream comparison to the above three plankton. The analysis of the neutral community model indicated that the predominance of stochastic assembly processes in the planktonic community was higher in the longitudinal dike compared to the spur dike, and longitudinal dike demonstrated higher rates of planktonic migration and speciation compared to the spur dike. Flow rate, dissolved oxygen, and turbidity were the significance influencing factors on the planktonic community structure in the aquatic environment around dike. Differences in dike-related environmental factors result in greater interactions among prokaryotes in the spur dike, while eukaryotes exhibited a more complex network of relationships in the longitudinal dike. These findings can provide a theoretical basis for the protection of biodiversity and the construction of ecological waterways in the waterway regulation engineering area.

Potential seamount effect on the distribution of the hydrographic features and community structure of pelagic ciliates at the Caroline seamount (tropical western Pacific) in late (2017) and early summer (2019)

Seamounts are ubiquitous features in the world ocean with potential for increasing plankton biodiversity and abundance, and providing important habitats for aquatic predators. Although ecological importance of seamount is well known, the mechanisms for supporting seamount-associated microzooplankton (e.g., pelagic ciliates) communities remains to be substantiated. In this study, pelagic ciliate community structure variations and their relationship with environmental variables were investigated in the Caroline seamount in late (2017) and early summer (2019). Above the seamount in 2019, ciliates exhibited higher abundance and biomass than off the seamount, which supported the classic hypothesis of seamount effect. Aloricate ciliate small size-fraction (10–20 μm) was dominant in bathypelagic (>1000 m) zone. Although relative abundance of small size-fraction was similar in both 2017 and 2019, the absolute abundance in 2019 seamount-effect stations were obviously higher than that in 2017. All abundant tintinnids were classified into surface- and DCM (deep Chl a maximum layer)-peak groups. Among them, four abundant tintinnids (Acanthostomella conicoides, Eutintinnus hasleae, Salpingella curta and S. minutissima) had higher abundance at DCM and might uplifted to shallower waters by upwelling at 2019 seamount-effect stations. The multivariate biota-environment analysis showed that environmental variables have significant impacts on the ciliate community structures in 2017 and 2019. Higher Chl a and nutrient concentrations, and sustained upwelling might be two potential mechanisms for microzooplankton seamount effect. Our study constitutes a rather solid foundation for quantitative and functional study of microzooplankton populations over oligotrophic tropical seamounts.

Spiny lobster feeding grounds: an eDNA metabarcoding assessment reveals a high level of plankton biodiversity in Tawang Bay, Indonesia

ABSTRACT Plankton has been considered an important live diet for various marine species including spiny lobster larvae. Thus, studying the diversity and abundance of plankton taxa in the natural settlement habitat of spiny lobster larvae might reveal alternative live diets for the larvae. The study was conducted in Tawang Bay, an important habitat for spiny lobsters in East Java, Indonesia. Plankton samples were collected using a plankton net and analysed using eDNA metabarcoding and high-throughput sequencing. Of the collected samples, 26 phyla, 40 classes, 54 orders, 75 families, 85 genera, and 97 species were identified. Further analysis indicated that the diversity index was considered moderate as the value was 2.16, while the uniformity and dominance indices were 0.22 and 0.24, respectively, which indicates that there is no dominant plankton species in Tawang Bay. Among the identified taxa, at least 18 species including Acartia bispinosa, Oithona simplex, Oithona sp., Pseudodiaptomus euryhalinus, Calocalanus pavo, and Calocalanus minutus are potential live diets for larvae of aquaculture species including lobster and therefore should be further studied.

A Case Study of Physico-Chemical and Biological Parameters of Plankton Biodiversity and Fish Abundance in a Fresh Water Lake of Karimnagar District, Telangana State, India

A Case Study of Physico-Chemical and Biological Parameters of Plankton Biodiversity and Fish Abundance in a Fresh Water Lake of Karimnagar District, Telangana State, India

Ecological Implications in a Human-Impacted Lake-A Case Study of Cyanobacterial Blooms in a Recreationally Used Water Body.

This study was aimed primarily at describing the planktonic assemblages with special attention to invasive and toxin-producing cyanobacterial species in the context of ecological and health threats. The second aim was to analyze the aspect of recreational pressure, which may enhance the cyanobacterial blooms, and, as a consequence, the negative changes and loss of planktonic biodiversity. This study was carried out in recreationally used Lake Sztynorckie throughout the whole growing season of 2020 and included an assessment of the abundance and biomass of phytoplankton (cyanobacteria and algae) in relation to environmental variables. The total biomass was in the range of 28-70 mg L-1, which is typical for strong blooms. The dominant filamentous cyanobacteria were Pseudanabaena limnetica, Limnothrix redekei, Planktolyngbya limnetica, and Planktothrix agarhii, and three invasive nostocalean species Sphaerospermopsis aphanizomenoides, Cuspidothrix issatschenkoi, and Raphidiopsis raciborskii. They can pose a serious threat not only to the ecosystem but also to humans because of the possibility of cyanobacteria producing cyanotoxins, such as microcystins, saxitoxins, anatoxin-a, and cylindrospermopsins, having hepatotoxic, cytotoxic, neurotoxic, and dermatoxic effects. The water quality was assessed as water bodies had bad ecological status (based on phytoplankton), were highly meso-eutrophic (based on zooplankton), and had very low trophic efficiency and low biodiversity.

From metabarcoding time series to plankton food webs: The hidden role of trophic hierarchy in providing ecological resilience

AbstractThe advent of metabarcoding (metaB) in aquatic ecology has provided a huge amount of information on plankton biodiversity worldwide. However, the large datasets obtained with that approach are still partially explored, especially for what concerns the study of trophic interactions and food webs. In this study, we analysed a metaB time series from the Long‐Term Ecological Research station MareChiara (LTER‐MC) in the Gulf of Naples, Mediterranean Sea, Italy, to describe the link between plankton diversity and food‐web structure. We derived co‐occurrence networks from metaB time series, identified putative trophic interactions among co‐occurrences based on biological information (body size and trophic habit) available for planktonic organisms detected by metaB, and converted co‐occurrence networks into conceptual models of food webs. The latter showed structural properties resembling ecological processes, because network modularity (the presence of semi‐independent sub‐networks) paralleled trophic hierarchy (the dimensional difference between predator and prey). We also analysed the role of planktonic organisms in maintaining network modularity. The largest predators occupied distinct modules, suggesting niche partitioning, whereas the smallest preys worked as fundamental connectors between larger predators (and different modules). Overall, the presence of trophic hierarchy and modularity shown herein supports the view of the high ecological resilience of plankton, pursued via food‐web rewiring, to environmental shifts.

An analysis of interannual data on phytoplankton and zooplankton associations in fluctuating soda lakes

Aquatic ecosystems in arid regions are important and unique habitats for aquatic wildlife and support species biodiversity. Endorheic soda lakes in Central Asia are subject to great fluctuations in its size depending on climatic conditions. Here we present research results covering the last 20 years, including the period from the maximum filling of the Torey lakes (Transbaikalia, Russia) to their aridification and the initial phase of their refilling. Barun-Torey and Zun-Torey lakes are the largest soda lakes in the arid zone with a large water surface area. A unique feature of lakes is the unstable hydrological regime. The reason for the water level change is the periodic filling and drying of lakes due to cyclic climatic changes in humidity and temperature. We aim to determine the response of the plankton communities to environmental change in the Torey lakes over this period. We analysed the interannual variations in phytoplankton and zooplankton species richness, structure and density. We conducted our studies during various phases of the hydrological cycle, including three periods for Zun-Torey Lake (high (1999 and 2003), intermediate (2007, 2011) and low (2014 and 2016) lake levels) and two periods for Barun-Torey (high water level (1999 and 2003) and the initial filling phase (2014, 2016, 2018, 2020, 2021)). Barun-Torey Lake dried up completely in summer 2009 and since 2013 the initial refilling has been observed. Zun-Torey Lake dried up in fall 2017. Changes in water level and water chemistry determined plankton biodiversity transformation. Fluctuations of plankton communities were different for each lake and conformed the phases of the hydrological cycle. We identified four stage changes in plankton associations during the aridification of Zun-Torey Lake, and three stage changes in plankton associations as the water level fell and through the initial refilling phase for Barun-Torey Lake.

Plankton Planet: A frugal, cooperative measure of aquatic life at the planetary scale

In every liter of seawater there are between 10 and 100 billion life forms, mostly invisible, called marine plankton or marine microbiome, which form the largest and most dynamic ecosystem on our planet, at the heart of global ecological and economic processes. While physical and chemical parameters of planktonic ecosystems are fairly well measured and modeled at the planetary scale, biological data are still scarce due to the extreme cost and relative inflexibility of the classical vessels and instruments used to explore marine biodiversity. Here we introduce ‘Plankton Planet’, an initiative whose goal is to engage the curiosity and creativity of researchers, makers, and mariners to (i) co-develop a new generation of cost-effective (frugal) universal scientific instrumentation to measure the genetic and morphological diversity of marine microbiomes in context, (ii) organize their systematic deployment through coastal or open ocean communities of sea-users/farers, to generate uniform plankton data across global and long-term spatio-temporal scales, and (iii) setup tools to flow the data without embargo into public and explorable databases. As proof-of-concept, we show how 20 crews of sailors were able to sample plankton biomass from the world surface ocean in a single year, generating the first seatizen-based, planetary dataset of marine plankton biodiversity based on DNA barcodes. The quality of this dataset is comparable to that generated by Tara Oceans and is not biased by the multiplication of samplers. The data unveil significant genetic novelty and can be used to explore the taxonomic and ecological diversity of plankton at both regional and global scales. This pilot project paves the way for construction of a miniaturized, modular, evolvable, affordable and open-source citizen field-platform that will allow systematic assessment of the eco/morpho/genetic variation of aquatic ecosystems and microbiomes across the dimensions of the Earth system.

Modelling approaches for capturing plankton diversity (MODIV), their societal applications and data needs

Ecosystem models need to capture biodiversity, because it is a fundamental determinant of food web dynamics and consequently of the cycling of energy and matter in ecosystems. In oceanic food webs, the plankton compartment encompasses by far most of the biomass and diversity. Therefore, capturing plankton diversity is paramount for marine ecosystem modelling. In recent years, many models have been developed, each representing different aspects of plankton diversity, but a systematic comparison remains lacking. Here we present established modelling approaches to study plankton ecology and diversity, discussing the limitations and strengths of each approach. We emphasize their different spatial and temporal resolutions and consider the potential of these approaches as tools to address societal challenges. Finally, we make suggestions as to how better integration of field and experimental data with modelling could advance understanding of both plankton biodiversity specifically and more broadly the response of marine ecosystems to environmental change, including climate change.

Phytoplankton, with emphasis on potentially toxic cyanobacteria, from Amor Island, Alter do Chão (Santarém, Pará, Brazil)

Amor Island (Alter do Chão, Santarém, Pará, Brazil) is considered a region of great natural beauty and a national and international tourist attraction. The aim of this study was to determine the composition and density of the phytoplankton of the Amor Island, with emphasis on heterocytous cyanobacteria. Water samples for phytoplankton were collected and analyzed at seven points in October 2021. Filaments of heterocytous cyanobacteria were cultured and analyzed, measuring the cells of the first 30 trichomes. The abundance, diversity and evenness of phytoplankton species were calculated and balneability of beach in relation to algal blooms was evaluated. 106 generic and infrageneric taxa were identified, highlighting the Chlorophyta. Phytoplankton density was higher at Verde Lake (145.6 ± 22.0 org.L-1), diversity and evenness were higher at point 03 (Lake Verde) with 3.0 bits.cell-1 and 0.47, respectively. The most abundant species were: Aphanothece minutissima, Ankistrodesmus sp., Aphanothece sp., Aphanizomenon sp., Mougeotia sp., Merismopedia sp. and Quadrigula sp. The average density of cyanobacteria was higher in the Tapajós River (517.0 cell.mL-1). No algal and cyanobacterial blooms were identified, indicating water appropriate for bathing. Through morphological and morphometric description, the cultivated species were identified as Aphanizomenon gracile and Cylindrospermopsis/Raphidiopsis raciborskii, cited among the cyanobacteria with the highest occurrence of toxic blooms in the world. The region deserves phytoplankton monitoring studies, due to reports of cyanobacterial blooms, and greater knowledge of its planktonic biodiversity, since it is a threatened region.

The Marine Biodiversity Observation Network Plankton Workshops: Plankton Ecosystem Function, Biodiversity, and Forecasting—Research Requirements and Applications

The Marine Biodiversity Observation Network Plankton Workshops: Plankton Ecosystem Function, Biodiversity, and Forecasting—Research Requirements and Applications