模拟海底水流和光照条件下光棘球海胆行为特征及其聚礁效果的初步研究

为观察光棘球海胆Strongylocentrotus nudus在饱食、饥饿和饥饿再投喂状态下的行为特征,及其对水泥、PVC两种材质模型礁的聚集特性,在实验室中模拟光棘球海胆栖息海域底层的昼夜水流速度和光照强度进行试验。结果表明:当光照强度达到560 lx、水流速度达到20 cm/s(9:00)时,均匀分布的光棘球海胆有90%向模型礁附近区域移动;当光照强度和水流速度下降时,光棘球海胆向模型礁附近区域外移动;运动趋势明显的光棘球海胆在饱食、饥饿和饥饿再投喂3种状态下的平均移动速度分别为0.039、0.041、0.052 cm/s,3种状态下光棘球海胆顺、逆水流运动次数的比值依次为饥饿状态(1.63)饱食状态(1.18)饥饿再投喂状态(0.73),饥饿再投喂状态下光棘球海胆的活跃程度高于饱食和饥饿状态;鱼礁材质也影响光棘球海胆的聚集行为,光棘球海胆在饱食、饥饿和饥饿再投喂状态下对水泥模型礁的平均聚集率分别为25%、17%、24%,对PVC模型礁的平均聚集率分别为16%、7%、12%,光棘球海胆对两种模型礁的聚集效果均为饱食状态饥饿再投喂状态饥饿状态。研究表明,光棘球海胆在饱食和饥饿再投喂状态下对两种模型礁的聚集效果较好,而水泥材质的模型礁比PVC材质的模型礁聚集效果更好。

Behavior and aggregation of sea urchin Strongylocentrotus nudus to reefs under the simulated water current and illumination at seafloor

Behavior and aggregation of satiated, fasted and refed sea urchin Strongylocentrotus nudus were investi-gated in reefs prepared by two types of PVC under simulated water current and illumination at seafloor. The results showed that 90% of sea urchin evenly distributed was found to move near to the reef zone at light intensity of 560 lx, and flow velocity of 20 cm/s(9:00), while they moved outoff the reefs at the declining light intensity and water velocity. The sea urchin had movement speed of 0. 052 cm/s, 0. 039 cm/s and 0. 041 cm/s when they were satia-ted, fasted and refed, respectively, with the movement frequency ratio of along water to against water in the three states was described as:fasted (1. 63)>satiation(1. 18)>refed after fasted(0. 73), indicating that refeeding after fasted led to higher activity than at satiation and fast. Also, the reef material influenced the aggregation behavior of sea urchin. An average aggregation rate of 25%, 17% and 24% to the cement reefs was observed in the sea urchin which was satiated, fasted and refed, respectively, and there was average aggregation rate of 16%, 7% and 12%to the PVC reefs in the sea urchin which was satiated, fasted and refed, respectively, showing the descendant order of aggregation rate as satiation>feeding after fast>fast. The findings indicate that better aggregation rate was found in the satiated and refed sea urchin, and that there was better aggregation rate in the cement reefs than that in the PVC reefs.