Nutrient sources, phytoplankton blooms, and hypoxia along the Chinese coast in the East China Sea: Insight from 2014.

Phytoplankton blooms are common along the Chinese coast in the East China Sea, driven by various nutrient sources including river discharge, bottom water regeneration, and Kuroshio subsurface water intrusion. A notable 2014 summer bloom off the Zhejiang coast, exhibiting a Chl a concentration of 20.1 µg L-1, was significantly influenced by Changjiang River discharge, and high nutrient concentrations are often observed in the region's surface water. During blooms, primary production peaks at 1686.3 mg C m-3 d-1, indicating substantial CO2 absorption, with surface water fCO2 declining to 299.5 µatm, closely linked to plankton activities. Hypoxia often coincides with these frequent bloom occurrences, implicating marine-derived organic matter decomposition as a pivotal factor. Elevated particulate organic carbon concentrations further support this assumption, alongside increased nutrient levels, fCO2, and low pH in hypoxic waters. These findings underscore the intricate interplay between phytoplankton, nutrient cycling, and hypoxia formation, essential for effective coastal ecosystem management.

Hypoxia in autumn of the East China Sea.

Hypoxia (O2 ≤ 2 mg L-1) can severely threaten the survival of marine life and alter the biogeochemical cycles of coastal ecosystems. Its impacts are dependent on its duration. In the present study, hypoxia was observed in autumn at the end of October 2011. It may be one of the latest recorded annual hypoxic events in the East China Sea (ECS). In the hypoxic regions, a large amount of nutrients and dissolved inorganic carbon were observed to regenerate. Also, acidification (low pH) was observed. On the other hand, hypoxic dissipation may be due to the destratification caused by the upwelling of the hypoxic regions in the ECS. These results suggest that hypoxia may occur for longer periods of time than expected and, accordingly, the effects of hypoxia on the ECS ecosystems should be reconsidered and further evaluated.

Clinical characteristics and treatment response of Hodgkin's lymphoma in Taiwan.

BACKGROUND/PURPOSE: Hodgkin's lymphoma (HL) is particularly rare in Asia, including Taiwan. The report concerning its clinical features and treatment outcomes in Asians is limited. An exploration of the characteristics of HL in this area is of importance for future studies. METHODS: In this study, 133 patients with HL diagnosed between January 1985 and December 2004 at National Taiwan University Hospital were analyzed retrospectively. RESULTS: The age distribution revealed a young-adult peak at the age around 20 years. The nodular sclerosis type (NS-HL) was the most common histopathologic subtype (45%), followed by mixed cellularity (29%), lymphocyte predominant (13%), and lymphocyte depleted subtype (2%). The incidence of NS-HL was, however, lower compared with that in the West (around 70%). The male to female ratio was approximately 1:2 in patients with NS-HL, in contrast to the male predominance in patients with other subtypes. Induction therapy led to complete remission (CR) in 87% of patients. At a median follow-up of 78 months, the 10-year overall survival (OS) was 79% in all HL patients and was 90% in those who achieved first CR. In multivariate analysis, the achievement of CR was the only independent factor associated with good OS. CONCLUSION: The treatment response of HL in Taiwan is good and comparable to that in Western countries. The epidemiologic differences between Taiwan and the West mandate further studies.

The dynamics of a dominant dinoflagellate, Noctiluca scintillans, in the subtropical coastal waters of the Matsu archipelago.

Bioluminescent seas caused by blooms of the dinoflagellate Noctiluca scintillans are a famous scenic attraction in the Matsu archipelago near the Chinese coast in the northern part of the Taiwan Strait. The relationship between the abundance of N. scintillans and various environmental factors was examined in the subtropical coastal waters of these islands from April to December, 2016. N. scintillans disappeared after June 20th, when the sea water temperature exceeded 27°C. A strong inverse correlation between N. scintillans and diatoms in PCA analysis indicated that diatoms suffer high grazing pressure from N. scintillans. N. scintillans appeared most abundantly during the flood season, when diatoms are most abundant. Strong inverse correlations between N. scintillans and the wind speed and wind direction in PCA further point to the effect of wind on the accumulation of cells.

Contrasting the relative importance of species sorting and dispersal limitation in shaping marine bacterial versus protist communities.

A central challenge in microbial ecology is to understand the underlying mechanisms driving community assembly, particularly in the continuum of species sorting and dispersal limitation. However, little is known about the relative importance of species sorting and dispersal limitation in shaping marine microbial communities; especially, how they are related to organism types/traits and water depth. Here, we used variation partitioning and null model analysis to compare mechanisms driving bacterial and protist metacommunity dynamics at the basin scale in the East China Sea, based on MiSeq paired-end sequencing of 16S ribosomal DNA (rDNA) and 18S rDNA, respectively, in surface, deep chlorophyll maximum and bottom layers. Our analyses indicated that protist communities were governed more strongly by species sorting relative to dispersal limitation than were bacterial communities; this pattern was consistent across the three-depth layers, albeit to different degrees. Furthermore, we detected that bacteria exhibited wider habitat niche breadths than protists, whereas, passive dispersal abilities were not appreciably different between them. Our findings support the 'size-plasticity' hypothesis: smaller organisms (bacteria) are less environment filtered than larger organisms (protists), as smaller organisms are more likely to be plastic in metabolic abilities and have greater environmental tolerance.

Elevated particulate organic carbon export flux induced by internal waves in the oligotrophic northern South China Sea.

To understand the biogeochemical response to internal waves in the deep basin of the northern South China Sea (NSCS), particulate organic carbon (POC) export fluxes were quantified for the first time during the passage of large internal waves using drifting sediment traps attached with hydrographic sensors. Results revealed large variations in temperature, nitrate and chlorophyll a (Chl a) concentrations during and after internal waves, suggesting that cold nutrient-replete waters may be brought to the euphotic zone in the dissipation zone during and after the passage of internal wave packets, resulted in phytoplankton flourished. Most importantly, POC export fluxes (110.9 ± 10.7 mg C m-2 d-1) were significantly enhanced after internal waves compared to non-internal wave area (32.6-73.0 mg C m-2 d-1) in the NSCS. Such elevated POC fluxes may be induced by downward flourished biogenic particles, particle aggregation or converged particles from mixed layer triggered by internal waves.

Sinking fluxes of 210Pb and 210Po in the deep basin of the northern South China Sea.

Vertical fluxes of total mass (Fmass), particulate organic carbon (FPOC), particulate inorganic carbon (FPIC), 210Pb (FPb-210), and 210Po (FPo-210) were determined by sediment traps deployed at two depths, 2000 m and 3500 m, at SEATS (South East Asian Time-series Study, 116°00°E, 18°00°N) in the northern South China Sea during June 2008-June 2009. The Fmass ranges from 12.2 to 55.1 mg m-2 d-1 and from 89.3 to 250.8 mg m-2 d-1, at 2000 m and 3500 m, respectively, and shows seasonal and inter-annul variation. The temporal variation of FPOC, FPIC, and FPb-210 were in phase with the Fmass, which was coupled with the seasonal cycles of primary production in the euphotic layer. The FPb-210 ranges from 5 to 48 dpm m-2d-1 and from 38 to 105 dpm m-2d-1, at 2000 m and 3500 m, respectively. Contrasting with 210Pb, the FPo-210 shows poor correlation with Fmass. The FPo-210 ranges from 3 to 146 dpm m-2d-1 and from 50 to 309 dpm m-2d-1, at 2000 m and 3500 m, respectively. Episodic events of the settling of biological particles from the surface layer and the regeneration processes the deep layer control the 210Po removal in the water column of the South China Sea. Strong correlations of the flux and source ratio of 210Pb, (F/P)Pb-210, and the particulate carbon fluxes were found, which give relationships of FPOC (µg cm-2y-1) = 26.8 + 371.0 (F/P)Pb-210 and FPIC (µg cm-2y-1) = -1.4 + 533.1 (F/P)Pb-210.