Annual variation in Calanus sinicus abundance and population structure in the northern boundary area of the Yellow Sea Cold Water Mass

• Published in: Chinese journal of oceanology and limnology Vol. 31; no. 6; pp. 1284 - 1294
• Main Author: 尹洁慧 张光涛 赵增霞 王世伟 万艾勇
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.11.2013; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Abundance; Annual variations; Aquatic crustaceans; autumn; Biology; Calanus; Calanus sinicus; Cohorts; cold; Cold water; Cold water masses; Dominant species; Earth and Environmental Science; Earth Sciences; Low temperature; Marine; Marine ecology; Oceanography; Plankton; Population number; Population structure; recruitment; Sex; Sex ratio; Spatial variations; spring; Summer; Survival; temperature profiles; Thermal stratification; Vertical profiles; Water masses; Water temperature; 中华哲水蚤; 丰度; 人口结构; 周年变化; 垂直结构; 种群结构; 边界; 黄海冷水团; Yellow Sea; INW, Huanghai Sea; over-summer strategy; boundary area; Yellow Sea Cold Water Mass (YSCWM); thermal stratification
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-013-3004-3

The Yellow Sea Cold Water Mass （YSCWM） was suggested as an over-summering site of the dominant copepod species Calanus sinicus in coastal Chinese seas. Population abundance and structure were investigated by monthly sampling along three transects across the northern boundary of the YSCWM during 2009-2010. Results show that thermal stratification existed from June to October and that the vertical thermal difference increased with depth. Generally, total abundance was lowest in October and highest in June, and the female/male sex ratio was highest in February and lowest in August. Evident spatial differences in abundance were observed during the existence of the YSCWM. In June, total abundance averaged 158.8 ind/m~ at well-stratified stations, and 532.1 ind/m3 at other stations. Similarly, high abundances of 322.0 and 324.4 ind/m3 were recorded from July to August inside the YSCWM, while the abundance decreased from 50.4 to 1.9 ind/m3 outside the water mass. C. sinicus distribution tended to even out over the study area in September when the YSCWM disappeared. We believe that the YSCWM may retard population recruitment in spring and preserve abundant cohorts in summer. The summer population was transported to neritic waters in autumn. In addition to low temperatures, stable vertical structure was also an essential condition for preservation of the summer population. C. sinicus can survive the summer in marginal areas in high abundance, but the population structure is completely different in terms of C5 proportion and sex ratio.