流速对不同群体数量花鲈幼鱼游泳行为的影响

Effects of flow velocity on swimming behavior of Lateolabrax maculatus juvenile with different population sizes

  • 摘要: 为研究花鲈 (Lateolabrax maculatus) 对流速的行为适应特征,采用泳道流速仪测定了不同数量 (1、2、4、6、8尾) 花鲈幼鱼在多种流速 (0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5、5.0 BL·s−1,BL为体长) 下的游泳行为。结果显示,当流速达到4.5 BL·s−1时,各组群体运动速度 (Group movement speed, Gc) 均显著低于单尾鱼游泳速度 (p<0.05)。随着流速增加,反映鱼群凝聚力的个体间距离 (Inter-individual distance, IID) 在各组均呈现先降低后上升的趋势,并在流速达到3.5~4.5 BL·s−1时出现最低值,且最低值对应的流速随着群体数量的增加而增大。反映鱼群协调性的游泳速度同步性 (Swimming speed synchrony, Sv) 与IID呈现相反的变化趋势,且Sv峰值对应的流速也随着群体数量的增加而增大。当流速达到1.0 BL·s−1时,单尾鱼摆尾频率 (Tail beat frequency, TBF) 均显著高于相同流速下的其他各组 (p<0.05)。随着流速的增加,花鲈钻石型排布模式所占比例先下降后上升,方阵型模式所占比例则呈相反的变化趋势,但在各实验组中,不同流速下的花鲈均以钻石型排布模式为主。综上所述,随着流速的增加,花鲈群体的凝聚力和协调性均先升高后降低,群体数量的扩大有利于提高花鲈鱼群凝聚力和协调性,并且花鲈主要采用钻石型排布模式来降低游泳能量消耗。

     

    Abstract: To investigate the behavioral characteristics to flow velocity, we measured the swimming behaviors of juvenile Lateolabrax maculatus of different individuals (1, 2, 4, 6 and 8) at various flow velocities (0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 BL·s−1; BL: Body length) by using swimming ability test tank. When the flow velocity reached 4.5 BL·s−1, the group movement speed (Gc) of fish schooling was significantly lower than that of single fish (p<0.05). With an increase in the flow velocity, the inter-individual distance (IID) (Reflects the cohesion of fish swarm) first decreased and then increased in each group, and valley values were observed when the flow velocity reached 3.5–4.5 BL·s−1. Besides, the flow velocity corresponding to the above IID valley increased with the expansion of fish population. Besides, the trend of swimming speed synchrony (SV) (Reflects the coordination of fish population) was completely opposite with that of IID, and the flow velocity corresponding to the SV peak also increased with the fish schooling expansion. When the flow velocity reached 1.0 BL·s−1, the tail beat frequency (TBF) of single fish was significantly higher than that of other groups at the same flow velocity (p<0.05). With the increase of flow velocity, the proportion of diamond lattice displayed in fish schooling first decreased and then increased, which was opposite to the phalanx lattice pattern. However, the pattern of diamond lattice was always dominant in each group at different flow velocities. In conclusion, with the increase of flow velocity, the cohesion and coordination of L. maculatus schooling first increase and then decrease. The expansion of the fish population is conducive to improving its cohesion and coordination, and the fish mainly adopts a diamond lattice pattern to reduce swimming energy consumption.

     

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