There are two types of movement pattern in the Brachionidae (rotifers), swimming and attachment, although the factors that induce a shift between them have not been adequately clarified. This study investigated the effects of five external factors—food limitation, temperature, salinity, predator, and un-ionized ammonia—on movement in females of the euryhaline rotifer Brachionus plicatilis sensu stricto. Rotifers under periodic starvation showed increased swimming frequency (percentage of swimming rotifers) to about 50% on feeding compared to controls under continuous feeding (21%). Starved rotifers were further exposed to the following conditions for 2 days: a range of water temperature (15–25 °C), salinity (17–34 practical salinity units), a predator (or other rotifers)-conditioned medium, and un-ionized ammonia (NH3-N; 5–20 mg/l). Neither temperature nor predator conditioning significantly affected rotifer swimming frequency. However, rotifers transferred to a higher salinity or to a rotifer-conditioned medium ceased to exhibit swimming. All the tested ammonia levels caused vigorous swimming of rotifers during the initial experimental period. The results indicate that swimming in female rotifers can be classified as (1) an escape behavior induced by environmental stress, and (2) a response to higher viability under certain favorable environmental conditions.

中文翻译：

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调节海洋轮虫褶皱臂轮虫运动的外部因素

腕轮科（轮虫）有两种运动模式，游泳和附着，但导致它们之间转变的因素尚未得到充分阐明。这项研究调查了五种外部因素——食物限制、温度、盐度、捕食者和非离子氨——对广盐性轮虫 Brachionus plicatilis sensu stricto 雌性运动的影响。与连续喂养下的对照 (21%) 相比，周期性饥饿下的轮虫在喂养时表现出增加的游泳频率（游泳轮虫的百分比）至约 50%。饥饿的轮虫进一步暴露在以下条件下 2 天：水温范围（15-25°C）、盐度（17-34 实际盐度单位）、捕食者（或其他轮虫）条件培养基和非离子氨（NH3-N；5–20 mg/l）。温度和捕食者条件反射都不会显着影响轮虫的游泳频率。然而，转移到更高盐度或轮虫条件培养基的轮虫不再表现出游泳。在最初的实验期间，所有测试的氨水平都会引起轮虫的剧烈游动。结果表明，在雌性轮虫中游泳可以归类为（1）由环境压力引起的逃逸行为，以及（2）在某些有利的环境条件下对更高生存力的反应。