南海北部陆坡金鼻眶灯鱼秋季摄食节律

中层鱼是深海食物网的重要组成部分,其摄食节律的研究对探讨以中层鱼为核心的能量流动与物质循环具有重要意义。本研究利用2014年10月南海北部陆坡海域拖网调查数据,对中层鱼优势种金鼻眶灯鱼(Diaphus chrysorhynchus)秋季的摄食节律进行了研究。结果表明:(1)金鼻眶灯鱼取样体长范围为28~110 mm,集中于50~59 mm体长组,各时间段摄食等级与体长间均不存在正相关;(2)金鼻眶灯鱼在18:00左右上浮摄食,次日05:30左右达到摄食高峰,为连续摄食,5个取样时间段平均摄食等级范围为1.50~2.57,呈增长趋势;(3)差异性分析表明,金鼻眶灯鱼傍晚与夜间或清晨间摄食等级差异性显著,表现在18:30~19:30时间段与01:00~02:00、04:45~05:50或06:30~07:30三个时间段间(P=0.041;P=0.000;P=0.007),另03:30~04:30与04:45~05:50时间段间摄食等级也存在极显著差异(P=0.005);(4)金鼻眶灯鱼各时间段摄食等级频率呈波浪形变化,4级频率在06:30~07:30时间段达到最高峰;0级频率在黄昏18:30~19:30时最高,01:00~02:00降为0,03:30~04:30上升到黄昏时的一半,此后连续下降。总体而言,金鼻眶灯鱼傍晚至次日清晨连续摄食,连续排遗,摄食集中于清晨。综上所述,金鼻眶灯鱼是一种昼夜垂直迁移、夜间连续摄食与排遗的浮游动物食性鱼类,其在南海陆坡水域能量流与物质流中起着承上启下的作用。

Feeding rhythm of Diaphus chrysorhynchus on the north slope of the South China Sea

Mesopelagic fishes are a key component of oceanic ecosystems. Feeding rhythm is important for the study of energy flow and material cycles in food webs that include mesopelagic fish. In this study, we examined the feeding rhythm of Diaphus chrysorhynchus based on trawl-survey data from October 2014, on the north slope of the South China Sea, and analyzing their feeding intensity. (1) The lengths of D. chrysorhynchus sampled ranged from 28 mm to 110 mm, concentrated in the range of 50 to 59 mm. There was no significant relationship between body length and feeding intensity (P=0.054, n=228). (2) D. chrysorhynchus started feeding at about 18:00 every day (rising together with zooplankton), finished feeding at about 05:30 the next morning (sinking with the zooplankton), and fed continuously during that period. The average feeding intensity of D. chrysorhynchus, among five sampling times, ranged from 1.50 to 2.57, showing an increasing trend. (3) There was a significant difference in the feeding intensity of D. chrysorhynchus between evening, and night or early morning, reflected in the comparison of three periods, namely 18:30-19:30 and 01:00-02:00, 04:45-05:50, and 06:30-07:30 (P=0.041, P=0.000, and P=0.007 respectively). In addition, there was a highly significant difference (P=0.005) in the feeding intensity of D. chrysorhynchus between 03:30-04:30 and 04:45-05:50. (4) The percentage of feeding intensities of D. chrysorhynchus among 5 periods showed a wave trend, the fourth feeding-intensity percentage had the highest value at 06:30-07:30, the zero feeding intensity percentage had the highest value at 18:30-19:30, and was half of this value at 03:30-04:30, and then decreased continuously until 06:30-07:30. In general, D. chrysorhynchus showed continuous feeding and egestion from evening to the next morning, while feeding was concentrated during the morning. In conclusion, D. chrysorhynchus, a mesopelagic fish species, fed on zooplankton from evening to the next morning, with habits of diel vertical migration and egestion from 01:00 till a certain time the next day. D. chrysorhynchus plays an important role in material and energy flow on the continental slope of the South China Sea.