Skip to main content

ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Marine Biogeochemistry
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1437405

Salinity Threshold for Phosphorus Limitation in an Estuary-Coast Continuum

Provisionally accepted
Shujie Cai Shujie Cai 1Weiran Liu Weiran Liu 2Zhuyin Tong Zhuyin Tong 1Lizhen Lin Lizhen Lin 1Linjian OU Linjian OU 3Wupeng Xiao Wupeng Xiao 1*Bangqin Huang Bangqin Huang 1*
  • 1 Xiamen University, Xiamen, China
  • 2 System Research Institute of ECO-ETCH & ECO-EL, Ltd.MCC Group, Beijing, China
  • 3 Research Center for Harmful Algae and Marine Biology, Jinan University, Guangzhou, China

The final, formatted version of the article will be published soon.

    River-derived nutrient imbalances can induce phosphorus (P) limitation in coastal plankton, but the salinity thresholds that govern this phenomenon have received little attention. Here, we provide a first insight into threshold responses in P-limitation along the salinity gradient in coastal ecosystems. Our seasonal sampling in the northern South China Sea showed a clear nonlinear decrease in alkaline phosphatase activity (APA) with increasing salinity. A pivotal finding was the identification of a salinity threshold at 32.83, presenting an early-warning indicator for P-limitation detection. Using a mixed-effects model, we further revealed that the robust positive correlation between phytoplankton biomass and APA gradually weakened as salinity increased toward this threshold. This implies a shift in phytoplankton's P-limitation at this salinity threshold and the contribution of heterotrophic bacteria in APA within high-salinity seawater.These insights highlight the importance of refining monitoring strategies with salinity and APA dynamics as early-warning indicators for nutrient limitation in coastal ecosystems.

    Keywords: Pearl River plume, Phytoplankton, phosphorus limitation, coastal ecosystem, Threshold model

    Received: 23 May 2024; Accepted: 12 Aug 2024.

    Copyright: © 2024 Cai, Liu, Tong, Lin, OU, Xiao and Huang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Wupeng Xiao, Xiamen University, Xiamen, China
    Bangqin Huang, Xiamen University, Xiamen, China

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.