鱼类视觉胁迫与利它素对大型溞生长繁殖的影响

Effects of fish visual stress and kairomone on the growth and reproduction of Daphnia magna

使用长江中下游地区常见的麦穗鱼及大型溞作为研究对象,在避免直接摄食的情况下将麦穗鱼与大型溞在同一容器中培养,设计视觉胁迫与利它素影响的交叉实验,对照组为无视觉胁迫无利它素组、实验组分别是无视觉胁迫有利它素组、有视觉胁迫有利它素组、有视觉胁迫无利它素组,研究其对大型溞生长、体型和繁殖的影响。结果发现:无利它素组的大型溞体长增长更快;无利它素影响的大型溞壳刺生长较快,在视觉胁迫有无的实验组中表现出不同的反应,无利它素影响有视觉胁迫处理组的壳刺长度较无视觉胁迫更长;无利它素组繁殖量的均值与有利它素组相比较,高出了2.89倍,并且有利它素有视觉胁迫组的死亡速率最快。虽然生物操纵技术使枝角类的捕食者减少,但是水体中残留的鱼类利它素对水生态系统中的枝角类依旧存在抑制作用。研究表明麦穗鱼对枝角类不仅有直接摄食的压力,还可通过视觉胁迫与利它素对枝角类体型、生长和繁殖产生间接的影响。

There are various reasons for the miniaturization of zooplankton in subtropical areas and the current view of many scholars is inclined to the predation pressure of fish. In this experiment, Pseudorasbora parva and Daphnia magna that are common in the middle and lower reaches of the Yangtze River were chosen as the research object. The two species were cultured in the same container but P. parva couldn’t prey directly on D. magna. On such a premise, a cross-over experiment was designed to study the effects of visual stress and kairomone on the growth, body size and reproduction of D. magna. The study was divided into four groups, namely, the non-visual stress kairomone group, the visual stress kairomone group, the non-visual stress non-kairomone group, and the visual stress non-kairomone group. Results indicated that: the body length of D. magna increased more rapidly in the absence of kairomone;The spine length of D. magna increased more rapidly in the absence of kairomone, and the spines were longer under visual stress;The average reproduction of D. magna was 2.89 times higher in the absence of kairomone, and the visual stress kairomone group had the fastest death rate. Although biological manipulation has reduced the number of cladoceran predators, the residual fish kairomone in water remains to inhibit the cladoceran in aquatic ecosystems. The results showed that fish not only have direct feeding pressure on cladoceran, but also have indirect effects on cladoceran body size, growth and reproduction through visual stress and kairomone.