Observation of a high abundance aggregation of the deep-sea urchin Chaetodiadema pallidum A. Agassiz and H.L. Clark, 1907 on the Northwestern Hawaiian Island Mokumanamana

AUV images of deep-sea megafauna on the seamount Mokumanamana in the Northwestern Hawaiian Islands revealed a large aggregation of the diadematoid urchin Chaetodiadema pallidum. This species had not been previously recorded on this seamount, but was known from other locations in the Hawaiian Archipelago. A total of 11,360 individuals were counted by eye from 1,369 seafloor images along the 200, 250, and 300 m depth contours on the west side of Mokumanamana. To estimate the full population size, Inverse Distance Weighting and Empirical Bayesian Kriging interpolation calculated a total population size of between 139,552 and 144,063 individuals. These estimates are 1-2 orders of magnitude greater than any previous estimates of urchin aggregation abundances. Little biological data exists for this species; thus, it is difficult to know if this is a spawning aggregation, a feeding front, a type of \"schooling\" behavior, or some combination thereof, but a food source did seem to be present in the form of mesophotic green algal detritus.

对西北夏威夷群岛莫库马纳马纳海山的深海大型生物自主水下航行器（Autonomous Underwater Vehicle，AUV）影像开展分析，结果显示该区域存在大量冠海胆类（diadematoid）海胆——苍白刺海胆（Chaetodiadema pallidum）的聚群。该物种此前未在该海山被记录，但在夏威夷群岛的其他区域已有分布报道。研究人员通过目视计数莫库马纳马纳海山西侧沿200米、250米及300米等深线采集的1369张海底影像，共统计得到11360个个体。为估算总种群规模，研究人员采用反距离加权（Inverse Distance Weighting）与经验贝叶斯克里金（Empirical Bayesian Kriging）插值法进行测算，得出总种群规模介于139552至144063个个体之间。该估算结果比此前所有海胆聚群丰度的估算值高出1至2个数量级。目前关于该物种的生物学数据极为匮乏，因此难以确定此次聚群属于产卵聚群、摄食锋面、某种"集群"行为，还是上述类型的组合，但现场似乎存在以中光带绿藻碎屑形式存在的食物来源。