Microplastic pollution and regulating factors in the surface sediment of the Xuande Atolls in the South China Sea.

Microplastics are widely present in the marine environment, but their pollution and potential risk assessment in the seabed sediments have not been well addressed in remote sea areas. In this study, microplastics in 50 surface sediment samples from the Xuande Atolls at the Xisha of the South China Sea were studied. There were 20 samples with detectable microplastics of 5-20 items kg.

Role of diatom-derived oxylipins in organic phosphorus recycling during coastal diatom blooms in the northern South China Sea.

Diatom-bacteria interactions and the associated bloom dynamics have not been fully understood in the coastal oceans. Here, we focus on the polyunsaturated aldehydes (PUAs) produced by diatoms in the post-bloom phase and look into their roles in microbial phosphorus (P) recycling outside of a P-limited estuary. The phytoplankton community in the bloom was dominated by PUAs-producing diatoms (Skeletonema costatum, Thalassiosira spp.

Microplastic contamination in coral reef fishes and its potential risks in the remote Xisha areas of the South China Sea.

Microplastics are recognized as a newly emerging threat to marine organisms as they can be ingested and accumulated through multiple trophic levels. However, microplastic contamination and its potential risk assessment in coral reef fishes have been less addressed, particularly in remote ocean regions. In this study, microplastics in 167 samples of coral reef fish (a total of eighteen species) from the Xisha areas of the South China Sea were studied.

Transparent exopolymer particle dynamics along a shelf-to-sea gradient and impacts on the regional carbon cycle.

Transparent exopolymer particles (TEPs) have drawn extensive attention in recent decades due to their crucial role in the biogeochemical and ecological processes of the ocean. However, TEP distribution and fluxes are relatively less addressed in the shelf-seas, where its variability can be affected by not only biology but also complex physical dynamics. Here, we present a comprehensive study of TEP from the coast to the basin (12 sampling sites) of the northern South China Sea (NSCS).

Biogeochemical controls of surface ocean phosphate.

Surface ocean phosphate is commonly below the standard analytical detection limits, leading to an incomplete picture of the global variation and biogeochemical role of phosphate. A global compilation of phosphate measured using high-sensitivity methods revealed several previously unrecognized low-phosphate areas and clear regional differences. Both observational climatologies and Earth system models (ESMs) systematically overestimated surface phosphate.

Macroecological patterns of the phytoplankton production of polyunsaturated aldehydes.

The polyunsaturated aldehydes (PUAs) are bioactive metabolites commonly released by phytoplankton species. Based primarily on laboratory experiments, PUAs have been implicated in deleterious effects on herbivores and competing phytoplankton species or in the regulation of the rates of bacterial organic matter remineralization; however, the role of the PUAs at an ecosystem level is still under discussion. Using data of PUA production in natural phytoplankton assemblages over a wide range of conditions, we analyzed macroecological patterns aiming for a comprehensive environmental contextualization that will further our understanding of the control and ecologic role played by these compounds.

Intercomparison and coupling of magnesium-induced co-precipitation and long-path liquid-waveguide capillary cell techniques for trace analysis of phosphate in seawater.

Currently, two common techniques for nanomolar-level phosphate measurements in seawater are magnesium-induced co-precipitation (MAGIC) and long-path liquid-waveguide capillary cell (LWCC) spectrophotometry. These techniques have been applied in the open ocean, and our understanding of phosphate distributions in oligotrophic subtropical gyres is based on those data. However, intercomparison of these methods has not previously been performed at nanomolar levels.

Eddy/wind interactions stimulate extraordinary mid-ocean plankton blooms.

Episodic eddy-driven upwelling may supply a significant fraction of the nutrients required to sustain primary productivity of the subtropical ocean. New observations in the northwest Atlantic reveal that, although plankton blooms occur in both cyclones and mode-water eddies, the biological responses differ. Mode-water eddies can generate extraordinary diatom biomass and primary production at depth, relative to the time series near Bermuda.