南黄海梭形纽鳃樽昼夜垂直移动的初步研究

本文对2006年12月、2007年5月和6月在南黄海两个连续站S1-4和S3-3采集的梭形纽鳃樽的昼夜垂直移动进行了研究。结果表明, 在不同季节不同海域该种昼夜垂直移动行为略有差异。在S1-4站位, 12月份梭形纽鳃樽复体从未到达底层(50—70m), 在0—50m的水层中表现出不规则的昼夜垂直移动。从中午(12:00)到傍晚(18:00)主要分布在表层, 之后移动到较深的水层(10—30m), 而单体由于数量较少而未进行昼夜垂直移动分析; 5、6月份, 该种单体和复体都出现了明显的反向昼夜垂直移动, 即白天迁移到表层, 夜间向底层迁移, 5月份尤为明显。在S3-3站位, 12月份和5月份梭形纽鳃樽的单体和复体几乎在整个水层都有分布。12月份梭形纽鳃樽复体在夜间有向下移动的趋势, 在06:00时到达最底层, 白天主要分布在20m以上的水层中。5月份梭形纽鳃樽单体和复体昼夜垂直移动不明显, 但主要分布在10—20m的水层中。

DIEL VERTICAL MIGRATION OF SALPA FUSIFORMIS CUVIER IN THE SOUTHERN YELLOW SEA

Diel vertical migration (DVM) of Salpa fusiformis was studied at stations S1-4 (71m deep) and S3-3 (38m deep) in the southern Yellow Sea. Samples were collected in December 2006, May and June 2007. Results shows that the DVM varied in season and region. At station S1-4, in December, the aggregate form exhibited irregular DVM in the upper 50m. They concentrated in the surface layer from noon to sunset, and then migrated to deeper layer (10-30m), but never reached deep layer (50-70m). The solitary form in this month was too scarce to analyze. In May and June, both aggregate and solitary forms showed significant reversed DVM. They migrated upward to the surface water during daytime and downward to the bottom at night. At station S3-3, the aggregate form in December migrated downward at night and reached the bottom at 06:00. They dominated in the upper 20m during daytime. In May, the DVM was not significant for both forms and mainly distributed in shallow layer of 10-20m.