ABSTRACT: Small mobile crustaceans are abundant on seaweeds. Many of these crustaceans rapidly abandon their host if it is detached from the seafloor and floats towards the surface, but the trigger for this ‘bailout’ behaviour is unknown. We tested 2 potential cues, i.e. rapid change in light and rapid change in water pressure, using >1 mm epifauna on the brown seaweed Carpophyllum plumosum as a model system. Bailout occurred in response to reduced water pressure, but not to changing light, as (1) bailout occurred at similar rates in light and dark, (2) bailout occurred on the seafloor when water pressure was reduced within a transparent chamber by the equivalent of ~0.5 m depth or more, and (3) little bailout occurred when water pressure was held constant within the chamber while seaweeds were raised to the surface. Increase in pressure (simulating sinking) did not induce bailout. The rate of bailout increased with increasing magnitude of pressure reduction but was not influenced greatly by the rate of change of pressure within the range tested (up to an equivalent of 0.4 m depth s^-1). The use of pressure rather than light as a cue for bailout is consistent with the need for seaweed-associated crustaceans to rapidly abandon a detached host and relocate to suitable habitat during both day and night.

中文翻译：

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降低海藻相关甲壳类动物的水压提示“救援”

摘要：小型移动甲壳类动物在海藻中含量很高。如果这些甲壳类动物从海底脱离并漂浮到水面，许多甲壳类动物会迅速放弃它们的宿主，但是这种“紧急救援”行为的诱因尚不清楚。我们在棕色海藻Carpophyllum plumosum上使用> 1 mm的表生动物，测试了2个潜在线索，即光照快速变化和水压快速变化作为模型系统。救援响应于降低的水压而发生，而不是改变光照，因为（1）救援在明暗情况下以相似的速率发生，（2）当透明舱室内的水压降低了等效值时，海底发生了救援。深度约为0.5 m或更大，并且（3）当室内的水压保持恒定，而海藻则升到水面时，几乎没有救援。压力增加（模拟沉没）并未引起救援。救助率随压力降低幅度的增加而增加，但不受测试范围内压力变化率的最大影响（最大深度为0.4 m s ^-1））。使用压力而不是光作为救助的线索与海藻相关的甲壳类动物在白天和黑夜中迅速抛弃一个独立的寄主并迁移到合适的栖息地的需求是一致的。