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Study on the effects of aquatic vegetation on foraging behaviour of planktivores in lakes

湖泊水生植被对浮游动物觅食行为的影响研究

基本信息

批准号：
10450179
负责人：
ASAEDA Takashi
金额：
$ 8.51万
依托单位：
Saitama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

In littoral zones of lakes, macrophytes have considerable structural variation and that provides protection to prey communities by hindering predator foraging. The swimming and feeding behaviour of a planktivore (Pseudorasbora parva) with their prey (Daphnia pulex) were studied in a series of laboratory experiments with varying densities of simulated submerged vegetation. Prey availability was varied from 0.5, 1, 2, 5, 10 and 25 prey.lィイD1-1ィエD1. As the stem density gradually increased, the predator's foraging efficiency decreased considerably relative to feeding in open water. Moreover, a good relation in feeding rate and swimming speed existed with the average stem distance to fish body length ratio. Abrupt reduction in feeding and swimming was recorded when fish body length ratio was near 0.7, which is approximately equal to one stride length of a fish.In fish, hunger increases the motivation to feed and also efficiency of feeding. After 36 hours of food deprivation, the feeding and swimming behaviour of Pseudorasbora parva was studied under different prey densities. The initial feeding rates showed marked variations in relation to prey availability. Under high densities the initial feeding rate of fish was higher and subsequently decreased faster, when compared to those feeding under low prey densities. At high prey densities, two factors are involved : that of high prey encounter rates and also the attainment of food satiation at a faster rate. Across all prey densities, the feeding rates of fish reached a plateau after satiation. The swimming speed was noted as being directly related to the level of satiation. After satiation, the fish fed at a steady rate irrespective of prey density. However, the swimming speed of fish varied significantly in relation to prey density. It was found that the maximum feeding rates depend upon and show a marked variation with average prey distance.

在湖泊的沿岸的地带，水生植物具有相当大的结构变化，并通过阻碍捕食者觅食来保护猎物群落。在不同密度的模拟沉水植被条件下，研究了麦穗鱼（Pseudorasbora parva）及其猎物蚤状蚤（Daphnia pulex）的游泳和摄食行为。猎物的可利用性从0.5、1、2、5、10和25个猎物变化。随着密度的逐渐增加，捕食者的觅食效率相对于在开放水域中觅食显著降低。此外，摄食率和游动速度与平均茎距/体长比有很好的相关性。当鱼的体长比接近0.7（约等于一个鱼的步幅）时，摄食和游泳的活动突然减少，饥饿增加了鱼的摄食动机和摄食效率。对麦穗鱼进行了36 h的饥饿处理，研究了不同饵料密度下麦穗鱼的摄食和游泳行为。初始摄食率表现出显着的变化，猎物的可用性。在高密度下的鱼的初始摄食率较高，随后下降速度更快，相比，低猎物密度下的饲料。在高猎物密度，涉及两个因素：即高猎物的遭遇率，也达到了食物饱以更快的速度。在所有的猎物密度，鱼的摄食率达到一个平台后饱食。游泳速度被认为是直接相关的饱足水平。饱食后，鱼饲料在一个稳定的速度，无论猎物密度。然而，鱼的游泳速度变化显着的猎物密度。结果发现，最大摄食率依赖于平均猎物距离，并显示出显着的变化。