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MEPS prepress abstract   -  DOI:

Mechanism for the marked increase of Ulva prolifera in the south Yellow Sea: Light intensity, nitrogen, phosphorus, or co-limitations?

Changyou Wang*, Chen Chen, Rongguo Su, Zhuhua Luo, Longjiang Mao, Yuanzhi Zhang

*Corresponding author:

ABSTRACT: An understanding of regulating factors and early warning of Ulva prolifera biomass increase may reduce harm or prevent bloom disasters in the Yellow Sea. The minimal nutrient concentration ([Min_NP]) and light limiting depth (Zlim) for the growth of floating U. prolifera were also studied. Bioavailable dissolved nitrogen (BDN) concentrations in most parts of the study area were almost higher than the minimal N concentrations for the growth of floating thalli ([Min_N]f), indicating no N limitation for the growth of floating thalli. However, the minimal N concentrations required for germlings development into thalli ([Min_N]g) was higher than BDN in the majority of the area above 35°N. This indicated that germlings floating out of Subei Shoal couldn’t grow into thalli because of N limitation. The minimal P concentrations for germlings development ([Min_P]g) was even higher than total dissolved P above 35°N. This suggested that P limitation occurred for germlings floating out of Subei Shoal. The Zlim for the floating thalli was less than 0.1 m in most parts of Subei Shoal, which explained why the rapid growth of floating thalli only occurred when they floated out from the Subei Shoal. A grid pattern with Mp per day was designed to predict the possible accumulated multiple increase in biomass (AcMp) when U. prolifera drifted northward differently. The predicted AcMp in 2017, 2010 and 2009 were close to the ratio of the coverage area from remote sensing data. Such a grid pattern facilitates quick decisions in disaster prevention and reduction.