Abstract: The spatial distribution of eggs of Stolephorus commersonnii and its relationship with water mass were studied based on ecological survey data of four cruises in the Pearl River Estuary in August of 2013, 2017, 2019, and 2020. The adaptability of the S. commersonnii eggs to salinity was analyzed using Gaussian model. According to K-means cluster analysis of water temperature and salinity, the survey region could be divided into three water masses: runoff water, brackish mixed water, and high-salinity water. The eggs of S. commersonnii were distributed in the regions of brackish mixed water and high-salinity water, but almost not in runoff water. The relationship between egg abundance and sea surface salinity (SSS) was consistent with the Gaussian model in August 2020. The optimal SSS was 16.28, ranging from 11.76 to 20.80, while the tolerance range was from 7.24 to 25.32. The eggs of S. commersonnii were mainly distributed in the middle of the Pearl River Estuary, including south of Neilingding Island, waters around Qingzhou, Guishan and Lantau islands. In the northern part of the Pearl River Estuary, the distribution of S. commersonnii eggs varied with the fluctuation of runoff input. There were almost no eggs in 30 m deep shelf area towards southeast.

Key words: K-means cluster, water mass, salinity, Gaussian model.