Biogeochemical factors regulating photosynthetically dissolved organic carbon produced by phytoplankton in the Taiwan Strait.

The distribution and mechanisms of photosynthetically dissolved organic carbon (PDOC) released by marine phytoplankton are frequently neglected and inadequately understood because most studies on carbon sequestration capacity have focused on photosynthetic particulate organic carbon. In this study, percentage extracellular release (PER) and its environmental influencing factors were investigated for 10 cruises in the Taiwan Strait during 2006-2023. The results indicated that the PER increased horizontally from the nearshore to the off-shelf and vertically from the surface to the bottom within the euphotic zone.

Dynamics of benthic microeukaryotic communities in a mangrove wetland invaded by Spartina alterniflora: Effects of vegetation, seasonality, and sediment depth.

Benthic microeukaryotes are crucial mediators of biogeochemical cycles in coastal wetland ecosystems, yet their spatial and temporal variability remains poorly understood. This study delineates the diversity patterns of benthic microeukaryotes in a Spartina alterniflora-invaded mangrove ecosystem in Fujian, China. Using high-throughput sequencing of 18S rRNA gene transcripts, we identified the influences of vegetation, seasonality, and sediment depth on microeukaryotic communities.

From the Sunlit to the Aphotic Zone: Assembly Mechanisms and Co-Occurrence Patterns of Protistan-Bacterial Microbiotas in the Western Pacific Ocean.

We know little about the assembly processes and association patterns of microbial communities below the photic zone. In marine pelagic systems, there are insufficient observational data regarding why and how the microbial assemblies and associations vary from photic to aphotic zones. In this study, we investigated size-fractionated oceanic microbiotas, specifically free-living (FL; 0.

Water masses and their associated temperature and cross-domain biotic factors co-shape upwelling microbial communities.

Disentangling the drivers and mechanisms that shape microbial communities in a river-influenced coastal upwelling system requires considering a hydrologic dimension that can drive both deterministic and stochastic community assembly by generating hydrological heterogeneity and dispersal events. Additionally, ubiquitous and complex microbial interactions can play a significant role in community structuring. However, how the hydrology, biotic, and abiotic factors collectively shape microbial distribution in the hydrologically complicated river plume-upwelling coupling system remains unknown.

Elevated pCO changes community structure and function by affecting phytoplankton group-specific mortality.

The rise of atmospheric pCO has created a number of problems for marine ecosystem. In this study, we initially quantified the effects of elevated pCO on the group-specific mortality of phytoplankton in a natural community based on the results of mesocosm experiments. Diatoms dominated the phytoplankton community, and the concentration of chlorophyll a was significantly higher in the high-pCO treatment than the low-pCO treatment.

Contrasting Community Assembly Mechanisms Underlie Similar Biogeographic Patterns of Surface Microbiota in the Tropical North Pacific Ocean.

Marine microbiota are critical components of global biogeochemical cycles. However, the biogeographic patterns and ecological processes that structure them remain poorly understood, especially in the oligotrophic ocean. In this study, we used high-throughput sequencing of 16S and 18S rRNA genes to investigate the distribution patterns of bacterial and microeukaryotic communities and their assembly mechanisms in the surface waters of the tropical North Pacific Ocean.

Protistan-Bacterial Microbiota Exhibit Stronger Species Sorting and Greater Network Connectivity Offshore than Nearshore across a Coast-to-Basin Continuum.

Little is known regarding how community assembly and species association vary with habitat and depth. Here, we examined the assembly and association of protistan and bacterial communities across a coast-shelf-slope-basin gradient of the South China Sea using high-throughput sequencing of the V3 and V4 regions of the rRNA gene transcript. Our study revealed that homogenizing dispersal and drift exerted an influence on protistan communities comparable to that on bacterial communities.

Biogeographic Role of the Kuroshio Current Intrusion in the Microzooplankton Community in the Boundary Zone of the Northern South China Sea.

Kuroshio Current intrusion (KCI) has significant impacts on the oceanographic conditions and ecological processes of the Pacific-Asian marginal seas. Little is known to which extent and how, specifically, the microzooplankton community can be influenced through the intrusion. Here, we focused on ciliates that often dominated the microzooplankton community and investigated their communities using high-throughput sequencing of 18S rRNA gene transcripts in the northern South China Sea (NSCS), where the Kuroshio Current (KC) intrudes frequently.

Patterns of Relative and Quantitative Abundances of Marine Bacteria in Surface Waters of the Subtropical Northwest Pacific Ocean Estimated With High-Throughput Quantification Sequencing.

Bacteria play a pivotal role in shaping ecosystems and contributing to elemental cycling and energy flow in the oceans. However, few studies have focused on bacteria at a trans-basin scale, and studies across the subtropical Northwest Pacific Ocean (NWPO), one of the largest biomes on Earth, have been especially lacking. Although the recently developed high-throughput quantitative sequencing methodology can simultaneously provide information on relative abundance, quantitative abundance, and taxonomic affiliations, it has not been thoroughly evaluated.

Blackfordia virginica blooms shift the trophic structure to smaller size plankton in subtropical shallow waters.

The hydromedusa Blackfordia virginica is an invasive species that has disrupted coastal marine food webs throughout the world. Here, we report the response of plankton community to B. virginica blooms in a subtropical lagoon in China.

The legacy of trace metal deposition from historical anthropogenic river management: A regional driver of offshore sedimentary microbial diversity.

River management, both modern and historical, have dramatically modified offshore environments. While numerous studies have described the modern impacts, very few have evaluated the legacies remaining from hundreds of years ago. Herein, we show trace metal enrichment in the surface sediment of the abandoned Yellow River Delta, hypothesized to be associated with ancient river management.

Temporal and spatial variations of alkaline phosphatase activity related to phosphorus status of phytoplankton in the East China Sea.

Phosphorus (P) is a potential limiting nutrient for primary production in the East China Sea (ECS). Four cruises over four seasons were conducted during 2009-2011 to evaluate the dynamics of alkaline phosphatase (AP) activity (APA) and the P status of phytoplankton in the ECS. Sampling for bulk and single-cell APA assays was performed across the ECS, which included the Changjiang River diluted water (CDW), the mid-shelf surface water (MSW), and the Kuroshio surface water (KSW) masses.

Water mass-driven spatial effects and environmental heterogeneity shape microeukaryote biogeography in a subtropical, hydrographically complex ocean system - A case study of ciliates.

The relative importance of geographic distance and depth in shaping microeukaryote community composition on a regional scale remains unclear, especially how that composition is related to the movement of water masses. Here, we collected 156 water samples across the Taiwan Strait, which is characterized by complex topography and dynamic circulation, to investigate the composition of the ciliate community with high-throughput sequencing of the 18S rRNA gene transcript. Ciliate alpha diversity exhibited strong correlations with water chemistry, food abundance, and geographic distance; approximately 50% of the variance of the diversity could be explained by dissolved oxygen concentrations, chlorophyll a concentrations, bacterial abundance, and latitude.

Diversity Distribution and Assembly Mechanisms of Planktonic and Benthic Microeukaryote Communities in Intertidal Zones of Southeast Fujian, China.

The intertidal zone occupies the shore between the high and low tide marks and is subjected both to natural forces and anthropogenic activities. Compared with the coastal ecosystem, studies comparing diversity and community structure of intertidal planktonic and benthic microeukaryotes are limited. Therefore, the ecological processes mediating their assemblies remain poorly understood.

Integrated Space-Time Dataset Reveals High Diversity and Distinct Community Structure of Ciliates in Mesopelagic Waters of the Northern South China Sea.

Little is known about diversity distribution and community structure of ciliates in mesopelagic waters, especially how they are related to spatial and temporal changes. Here, an integrative approach, combining high-throughput cDNA sequencing and quantitative protargol stain, was used to analyze ciliate communities collected temporally along a transect from coastal to oceanic regions at depths ranging from the surface to 1000 m. The mesopelagic zone exhibited comparable alpha diversity to surface water which was consistent over temporal variation, with high diversity occurring at the interface with the euphotic zone.

Responses of marine phytoplankton communities to environmental changes: New insights from a niche classification scheme.

Predicting changes of phytoplankton communities in response to global warming is one of the challenges of ecological forecasting. One of the constraints is the paucity of general principles applicable to community ecology. Based on a synecological analysis of a decadal-scale database, we created a niche habitat classification scheme relating nine phytoplankton groups to fifteen statistically refined realized niches comprised of three niche dimensions: temperature, irradiance, and nitrate concentrations.

The impact of giant jellyfish Nemopilema nomurai blooms on plankton communities in a temperate marginal sea.

This study focused on the bloom-developing process of the giant jellyfish, Nemopilema nomurai, on phytoplankton and microzooplankton communities. Two repeated field observations on the jellyfish bloom were conducted in June 2012 and 2014 in the southern Yellow Sea where blooms of N. nomurai were frequently observed.

Contrasting patterns of genetic structure and phylogeography in the marine agarophytes Gelidiophycus divaricatus and G. freshwateri (Gelidiales, Rhodophyta) from East Asia.

The evolutionary and population demographic history of marine red algae in East Asia is poorly understood. Here, we reconstructed the phylogeographies of two upper intertidal species endemic to East Asia, Gelidiophycus divaricatus and G. freshwateri.

Protist diversity and community assembly in surface sediments of the South China Sea.

Protists are pivotal components of marine ecosystems in terms of their high diversity, but protist communities have been poorly explored in benthic environments. Here, we investigated protist diversity and community assembly in surface sediments in the South China Sea (SCS) at a basin scale. Pyrosequencing of 18S rDNA was performed for a total of six samples taken from the surface seafloor at water depths ranging from 79 to 2,939 m.

Picoeukaryotic Diversity And Activity in the Northwestern Pacific Ocean Based on rDNA and rRNA High-Throughput Sequencing.

Picoeukaryotes play an important role in the biogenic element cycle and energy flow in oligotrophic ecosystems. However, their biodiversity and activity are poorly studied in open ocean systems, such as the northwestern Pacific Ocean, which is characterized by a complex hydrological setting. Here, we investigated the diversity and activity of picoeukaryotes in the northwestern Pacific Ocean using high-throughput sequencing targeting the V9 region of 18S rDNA and rRNA.

Community dynamics of free-living and particle-attached bacteria following a reservoir Microcystis bloom.

The composition of microbial communities can vary at the microspatial scale between free-living (FL) and particle-attached (PA) niches. However, it remains unclear how FL and PA bacterial communities respond to cyanobacterial blooms across water depths. Here, we examined the community dynamics of the FL (0.

Pigmented microbial eukaryotes fuel the deep sea carbon pool in the tropical Western Pacific Ocean.

Phototrophic microbial eukaryotes dominate primary production over large oceanic regions. Due to their small sizes and slow sinking rates, it is assumed they contribute relatively little to the downward export of organic carbon via the biological pump. Therefore, the community structure of phototrophic cells in the deep ocean has long been overlooked and remains largely unknown.

Diel Patterns of Variable Fluorescence and Carbon Fixation of Picocyanobacteria -Dominated Phytoplankton in the South China Sea Basin.

The various photosynthetic apparatus and light utilization strategies of phytoplankton are among the critical factors that regulate the distribution of phytoplankton and primary productivity in the ocean. Active chlorophyll fluorescence has been a powerful technique for assessing the nutritional status of phytoplankton by studying the dynamics of photosynthesis. Further studies of the energetic stoichiometry between light absorption and carbon fixation have enhanced understanding of the ways phytoplankton adapt to their niches.

Distinct patterns and processes of abundant and rare eukaryotic plankton communities following a reservoir cyanobacterial bloom.

Plankton communities normally consist of few abundant and many rare species, yet little is known about the ecological role of rare planktonic eukaryotes. Here we used a 18S ribosomal DNA sequencing approach to investigate the dynamics of rare planktonic eukaryotes, and to explore the co-occurrence patterns of abundant and rare eukaryotic plankton in a subtropical reservoir following a cyanobacterial bloom event. Our results showed that the bloom event significantly altered the eukaryotic plankton community composition and rare plankton diversity without affecting the diversity of abundant plankton.