Is predation of juvenile crown-of-thorns seastars (Acanthaster cf. solaris) by peppermint shrimp (Lysmata vittata) dependent on age, size, or diet?

Ten predation experiments were carried out examine whether predation of juvenile CoTS by peppermint shrimp (L. vittata) is affected by the age, size, or diet of juvenile CoTS.

Over a span of 9.5 months, ten experiments were carried out with juvenile CoTS ranging from 1 to 9 months of age and 0.34 mm and 21.37 mm in diameter. Juvenile CoTS were reared and fed a diet of either CCA throughout the experiments or corals (introduced at 4 months, and only offered from around 5 months ). Shrimps assessed for health status, measured with callipers to the nearest millimetre (from rostrum to tail) and left to acclimatize unfed in 250 ml jars for two–three days as suggested for invertebrate gut content analysis experiments, (5–16 per experimental run, depending on availability).

On the fourth day, a single juvenile CoTS was measured (maximum diameter, with callipers) and introduced into each jar. The jars were monitored daily for the following three days. The condition of the juvenile CoTs was scored as:

None – if there was not change in appearance

Partial predations – if they were alive but had missing limbs or injuries

Lethal predation – if they had been fully consumed by the predator.

Data analysis examined the effects of CoTS size and age on the incidence of partial and lethal predation.

本研究开展了10次捕食实验，旨在探究薄荷虾（peppermint shrimp，L. vittata）对幼年长棘海星（CoTS，Crown-of-Thorns Sea Star）的捕食行为是否受幼年CoTS的年龄、体型与饮食的影响。

实验周期共计9.5个月，所用幼年CoTS的日龄范围为1至9个月，体直径介于0.34 mm至21.37 mm之间。幼年CoTS分为两组饲养：一组全程以壳状珊瑚藻（CCA，Crustose Coralline Algae）为食，另一组则在实验第4个月引入珊瑚饵料，且仅在约第5个月起开始投喂。实验所用薄荷虾需先进行健康状态评估，使用游标卡尺（callipers）测量其从吻突至尾端的体长，精确至毫米级别；随后将其置于250 mL广口瓶中禁食驯化2至3天，该操作参考无脊椎动物肠道内容物分析实验的标准流程，每次实验投放5至16只虾，具体数量依可获取量而定。

实验第4天，先使用游标卡尺测量单只幼年CoTS的最大体直径，随后将其放入每个广口瓶中。接下来的3天内每日对广口瓶进行监测。幼年CoTS的存活状态分为以下三类：
- 无变化：外观无任何异常
- 部分捕食：个体仍存活，但存在肢体缺损或损伤
- 致死捕食：个体已被捕食者完全取食

数据分析环节旨在探究CoTS的体型与日龄对部分捕食与致死捕食发生率的影响。