Feeding of Sagitta setosa in the Black Sea

Gut dissection of fixed individuals from samples collected during Cruise 6 of R/V Vityaz-2 in April-May 1984 was used to study feeding of Sagitta setosa in the layers of daytime plankton accumulation at the lower boundary of the oxycline. The principal food was copepodite stage V of Calanus and females of Calanus and Pseudocalanus. Analysis of daytime and night data with reference to length of migratory alterations of Sagitta populations and gut passage time indicates that they feed actively in the layers of day¬time plankton accumulations. Total food consumption during time spent in the subsurface layers ranged from 0.025-0.097 cal/indiv. in 12 h, equivalent to 37-143% of their metabolic energy expenditure. Over the course of 12 h Sagitta population consumes 0.3-5% and 0.5-6% of population of stage V copepodites and females of Calanus and Pseudocalanus females, respectively.本研究以1984年4—5月“维特亚兹-2号”（R/V Vityaz-2）第6次巡航采集的样本中固定标本的肠道解剖结果为实验材料，针对氧跃层下界处的日间浮游生物聚集层，研究住囊箭虫（Sagitta setosa）的摄食习性。该物种的主要食物为哲水蚤属（Calanus）的第五桡足幼体期（copepodite stage V）个体，以及哲水蚤属与拟哲水蚤属（Pseudocalanus）的雌体个体。结合箭虫种群的迁移变化时长与肠道排空时间，对日间、夜间的观测数据进行分析后发现，该物种会在日间浮游生物聚集层主动摄食。在次表层停留的12小时内，单一个体的总食物摄入量为0.025~0.097卡/个体，相当于其自身代谢能量消耗的37%~143%。在12小时的观测周期内，箭虫种群分别会摄食哲水蚤第五桡足幼体种群的0.3%~5%，以及哲水蚤雌体与拟哲水蚤雌体种群的0.5%~6%。