Integrated effects of Ulva prolifera bloom and decay on nutrients inventory and cycling in marginal sea of China. (February 2021)

• Record Type: Journal Article
• Authors: Zhang, Pengyan; Xin, Yu; Zhong, Xiaosong; Yan, Zhenwei; Jin, Yuemei; Yan, Maojun; Liu, Tao
• Is Part Of: Chemosphere. Volume 264(2021)Part 1
• Publication Date: 2021-02
• Subjects: Dissolved organic nitrogen -- Nitrogen isotope -- Tangential flow filtration -- Ulva prolifera -- Dissolved inorganic nitrogen -- Decay; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.128389
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Ulva prolifera blooms occur annually in the Yellow Sea. Most studies focus on how U. prolifera blooming is influenced by nitrogen chemical forms and concentrations, while little concern goes to how U. prolifera bloom-decay cycle would impact local seawater nutrients structure. Therefore, we use 15 N-labeled NO3 tracers and transcriptome analysis to determine N uptake, metabolism, and interconversion during U. prolifera growth and decay, so that we can quantify the conversions rate and fluxes of different nitrogen chemical forms. U. prolifera absorbes 17.37 μmol g −1 ·d −1 NO3 –N during growth. NO3 –N predominates (73.75–92.15%) in the dissolved inorganic nitrogen (DIN) in U. prolifera . During decay, NH4 –N accountes for 60.87–92.13% of the in-cell DIN. The decomposing U. prolifera releases considerable amounts of NH4 –N and dissolved organic nitrogen (DON) (63.8–98.2% < 1 kDa fraction and 1.8–36.2% is > 1 kDa fraction) into the ambient environment. The high DON release rate (59.57 μmol g −1 d −1 ) indicates active DON biosynthesis in U. prolifera . The isotope 15 NO3 –N tracer showes that 73.6% of the 15 NO3 –N is transformed to DON. The <1 kDa and the >1 kDa fractions account for 67.46–90.86% and 9.14–32.54% of the DON, respectively. The high efficiency of U. prolifera in utilizing NO3 –N is explained by the responsive nitrate/nitrite transporter in cell membrane, and the DON biosynthesized capability is attributed to the up-regulated glutamine synthetase. Our study highlights the unique role of U. prolifera as a "Nitrogen-Pump" in converting nitrogen chemical forms during its bloom-decay cycle and quantifies its impacts on local N -nutrients inventory. Highlights: Ulva prolifera efficiently absorbs NO3 –N and converts into organic nitrogen. Most of the dissolved organic nitrogen excreted by Ulva Prolifera is < 1 KDa. The 15 N-labeled culture assays picture nitrogen metabolisms in Ulva Prolifera . The up-regulated NRT and GS is associated with rapid NO3 –N uptake and DON release. The bloom-decay cycle of Ulva Prolifera greatly impacts local N -nutrients inventory.