中国科学院海洋研究所机构知识库

动物的集群行为可以获得较高生存收益，直接影响动物的生长、繁殖等。刺参Apostichopus japonicus具有重要经济和生态价值，在刺参增养殖过程中，查明刺参群体运动行为特征对于刺参资源追踪、保护与可持续增殖具有重要意义。本研究以刺参群体行为生态学为方向，利用视频记录和分析，重点探究群体内刺参个体的集群意愿和运动特征，以及食物资源、栖息地环境和捕食者压力等因素对刺参群体特征的影响。主要结果及内容如下：

1. 种内同伴与食物资源对刺参群体运动行为特征的影响

本文在实验室条件下研究了种内同伴对刺参运动行为影响以及食物资源对刺参运动行为影响。通过缩时摄影技术以及专业行为学软件分析发现，刺参运动行为显著受到种内同伴影响。在食物资源充足且周围没有种内同伴条件下，刺参运动随机度R值较低，运动方向更加随机，以更多时间内停留在食物资源充足区域内进行摄食。在食物资源匮乏且周围没有种内同伴条件下，刺参运动随机度R值较高，运动更具有方向性，以更快发现食物；当周围有种内同伴存在时，刺参运动随机度R值升高且在更短时间内离开观察区（P<0.05）。而当食物资源充足且周围有种内同伴条件下，其运动随机度R值较低，由此可见食物资源能显著缓解种内竞争压力。在所有处理中，刺参口部和中心点运动速度都没有显著差异（P>0.05）。上述结果显示食物资源缺乏时种内竞争能影响刺参运动行为，进一步可能影响刺参的野外分布；当食物资源充足时能显著缓解种内竞争压力，为刺参资源调查与评估提供了理论支撑。

2. 栖息地分布与种内竞争对刺参群体分布特征的影响

动物集群可以获得较高的生存收益。野外调查发现刺参A. japonicus多集中分布于食物资源充足、环境适宜的生境斑块内，但栖息地分布与种内个体间竞争如何影响刺参的集群行为特征尚未有研究报道。本文通过缩时摄像机拍摄及视频分析，研究了刺参集群分布特征，结果发现：刺参在礁石栖息地的栖息时间显著高于在缸壁处的栖息时间（P < 0.05），刺参对栖息地有明显偏好性；刺参在运动时并未聚集在同一栖息地，而离散分布在多处栖息地中（P < 0.05）；当密度增大到15头/缸（11.31 头/平方米, d=1.3m）时，刺参在栖息地内的平均聚集率和平均聚集时间会显著下降（P < 0.05），种内竞争加剧。综上所述，刺参的集群特征受种内竞争和栖息地分布的影响较大，刺参多呈斑块状分布，在密度过高时种内竞争压力上升，刺参个体间相互远离以减少竞争。本研究查明了实验室条件下栖息地环境对刺参群体分布的影响，可为野外刺参增养殖与资源持续利用提供理论参考。

3. 捕食者压力对刺参集群行为特征的影响

关于捕食者捕食刺参研究较少，有研究发现捕食者海星Asterias amurensis对刺参有强烈捕食意愿。本文通过分析捕食者海星A. amurensis对刺参聚集规模与集群特征影响，来探究捕食者压力对刺参集群行为特征影响。研究发现，刺参集群规模与单头刺参没有显著差异。加入捕食者海星后，在密度3头/缸与5头/缸（长度×宽度×高度：0.8×0.6×0.5m）处理组中，刺参平均聚集规模、平均拥挤度、斑块指数均没有发生显著变化（P>0.05），刺参集群规模未发生改变。综上所述，刺参集群规模未因捕食者压力影响而发生改变，刺参并未形成集群防御机制来抵抗捕食者天敌。

Animals can benefit from aggregation behavior, which could directly affect growth and reproduction of animals. There are great economic and ecological value in aquaculture of sea cucumber Apostichopus japonicus. Research on aggregation of sea cucumber could help figure out animal tracking, protection and sustainable multiplication. Based on video recording and software analysis, we studied animal motor behavior and aggregation, effects of food resources, habitats and predators on different features of sea cucumber group. The main results and contents are as follows:

1. Effects of intraspecific members and food resources on motor behavior of sea cucumber

We describe movement of sea cucumber A. japonicus in laboratory conditions using time-lapse video and behavior analysis software with reference to wild density. Experiments reveal that intraspecific members significantly affect movement behavior of A. japonicas. Animals moved more randomly when provided food in the absence of intraspecific members, which could ensure that animals can spent more time feeding. Individuals moved more directly in the presence of others to escape from arena (P<0.05). Food can eliminate intra-specific competition, as single individual in groups move more randomly when provided with food. There are no significant difference between mouth and body velocity in all treatment (P>0.05). These results indicate that intraspecific competition affects movement of A. japonicus, which may potentially determine exploitation of animals, but food resources can eliminate intraspecific competition, and thus may be important causal agents in the wild distribution of A. japonicas.

2. Effects of habitat distribution and intraspecific competition on aggregation features of sea cucumber

Animals can obtain ecological benefit while aggregating in groups. Sea cucumber A. japonicus showed high preference for habitat with adequate food resources in the field. However, there was little research explicating how habitats and intraspecific members affected the aggregation of A. japonicus. We investigated the aggregation behavior of A. japonicus based on time-lapse video camera in the Lab. The results showed that: sea cucumbers showed strong preference for the habitat rather than the wall of the tank with animals spending more time at habitat (P < 0.05); the sea cucumbers distributed in 2 or 3 habitats separately versus animals aggregated in 1 habitat (P < 0.05); as the density reached to 15 individuals every tank (11.31 ind/m², d=1.3m), the mean attractive rate and mean attractive time significantly decreased (P < 0.05) which indicated that there was intraspecific competition among animals. In conclusion, aggregation of sea cucumbers is significantly affected by intraspecific competition and habitat, and sea cucumbers distributed in different patches. Sea cucumbers would escape from the central area to reduce the competition when the density was high. This study identified the effect of habitat distribution and intraspecific competition on the aggregation of sea cucumbers in the Lab and provided a theoretical reference for the cultivation and sustainable use of resources of sea cucumber in the wild.

3. Effects of predator on aggregation behavior of sea cucumber

There are few studies focusing on predation on sea cucumber. It had been found that predator starfish Asterias amurensis had strong predation selectivity on sea cucumber. In this research, we studied the aggregation size and aggregation characteristics of sea cucumber under the pressure of predator A. amurensis. It was found that the average aggregation size, mean crowding and index of patchiness of sea cucumber group were not significantly different from single individual. The average aggregation size, mean crowding and index of patchiness of sea cucumber group at density 3 and 5 showed no significant difference under the pressure of predation of sea star (P>0.05), which indicated that aggregation of sea cucumber was not significantly affected by predators. In summary, the population size of sea cucumber was not changed under the pressure of predator. The sea cucumber had formed no aggregation defense mechanism against predator.