Patterns of behaviour of four shrimp species in a laboratory experiment

This study assessed the behaviour patterns of four shrimp species in a laboratory experiment that was repeated on 8 separate occasions throughout 1978. The experiment was set up in aquariums with sediment and eelgrass densities that reflected field conditions in Western Port Bay, Victoria. There were 1 to 3 replicate aquarium per run of the experiment. The shrimps species used in the experiment were the abundant species in eelgrass beds in Western Port Bay, Macrobrachium.intermedium, Pontophilus intermedius and Hippolyte caradina. Chlorotocella leptorhyncus. All shrimp species were present in each aquarium with a maximum of 4 individuals of each of the larger species (M.intermedium and P.intermedius), to avoid behavioral artifacts due to overcrowding. The behaviour activities and vertical distribution of each species relative to the substrate was assessed by making repeated observations on the instantaneous activity and location of individuals over a 4 day period. Observations were made in the night and day and were classified into 4 categories; inactive, grooming, feeding, or walking/swimming.

P.intermedius was always inactive during the day, and remained partially buried in surface sediments until night when it emerged to move up into the eelgrass. The relative time devoted to feeding was fairly constant between the other 3 species. Levels of inactivity and grooming behaviour were higher during daylight whereas feeding and walking/swimming was more common at night.

本研究针对1978年间重复开展8次的室内控制实验，分析了4种虾类的行为模式。实验在模拟澳大利亚维多利亚州西港湾野外生境的水族箱中搭建，其内沉积物与鳗草密度均匹配该区域的实际野外条件。每次实验运行设置1至3组平行水族箱。本次实验选用的4种受试虾类均为西港湾鳗草床的优势物种，分别为中间沼虾（Macrobrachium intermedium）、中间尖额虾（Pontophilus intermedius）、卡罗丁隐虾（Hippolyte caradina）与细吻绿虾（Chlorotocella leptorhyncus）。每个水族箱中均投放所有受试物种，其中体型较大的两个物种（M. intermedium与P. intermedius）的个体投放上限均为4只，以避免过度拥挤引发行为伪迹。

通过为期4天的重复观测，记录各物种个体的瞬时行为与栖息位置，以此分析其行为活动类型与相对底质的垂直分布特征。观测覆盖昼夜时段，行为类别被划分为4类：静止、体表清理、摄食以及行走/游泳。

中间尖额虾（Pontophilus intermedius）日间始终处于静止状态，部分掩埋于表层沉积物中，直至夜间才会活动并迁移至鳗草群落中。其余3个物种的摄食时间占比相对稳定。日间无活动与体表清理行为的占比更高，而夜间摄食与行走/游泳行为则更为常见。