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

Zhengchao Wu; Qian P Li; Richard B Rivkin; Senjie Lin

doi:10.1016/j.scitotenv.2023.166518

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

Sci Total Environ. 2023 Dec 10:903:166518. doi: 10.1016/j.scitotenv.2023.166518. Epub 2023 Aug 30.

Authors

Zhengchao Wu¹, Qian P Li², Richard B Rivkin³, Senjie Lin⁴

Affiliations

¹ State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, Guangdong, China.
² State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, Guangdong, China. Electronic address: qianli@scsio.ac.cn.
³ Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
⁴ Department of Marine Sciences, University of Connecticut, Groton, CT 06340, USA.

PMID: 37657543
DOI: 10.1016/j.scitotenv.2023.166518

Abstract

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., and Pesudonitzschia delicates) with elevated concentrations of biogenic particulate PUAs. In addition, there were micromolar levels of particle-adsorbed PUAs hotspots with distinct compositions in and out of the bloom determined by a combining large-volume filtration and on-site derivation method. Field experiments were conducted to further assess the responses of particle-attached bacteria (PAB) to different PUAs amendments. We found no differences in the alkaline phosphatase (APase) activity and the abundance of PAB between inside and outside the bloom at a low PUAs dosage (<30 μM). However, for a high PUAs dosage (300 μM), APase activity and PAB growth were reduced significantly outside the bloom but no influences within the bloom. Our findings indicate that the hotspot-level oxylipins may play essential roles in bacterial P-remineralization in P-limited coastal areas. PAB can adapt to the high level of PUAs released by diatoms (or their resulting detritus) and potentially maintain a high rate of organic P recycling during the late stages of diatom blooms. Consequently, the interaction between oxylipin-rich diatoms and bacteria may affect phytoplankton blooms and carbon sequestration in the coastal oceans.

Keywords: Alkaline phosphatase; Coastal South China Sea; Diatom bloom; Oxylipins; Particle-attached bacteria; Phosphorus-limitation.