A lost world? Archaic crinoid-dominated assemblages on an Antarctic seamount
A lost world? Archaic crinoid-dominated assemblages on an Antarctic seamount
复制标题
DOI：
10.1016/j.dsr2.2010.09.006
复制
发表时间：
2011-01-01
影响因子：
3
通讯作者：
Rickard, Graham J.
中科院分区：
文献类型：
--
作者：
Bowden, David A.;Schiaparelli, Stefano;Rickard, Graham J.
2008年2月，新西兰IPY-CAML研究航行（TAN0802）期间，对罗斯海北部的Admiralty（南纬67度，东经171度）和Scott岛（南纬67度22分，东经179度55分）海山进行了相机和物理采样设备的勘探。在金钟海山西北端和东南端，在580-600米深的孤立的小丘上，发现了一个以有柄的海鲷和腕足类为主的引人注目的组合。这些地点的海床上散落着海百合小骨，海百合茎基部在裸露的岩石上很明显，表明这些组合已经持续了相当长的时间。海百合的分布地点仅限于孤立的小丘，而主海山侧翼的大片区域则被密集的悬浮物食性蛇蛉虫覆盖。这些组合在结构上更类似于古新世和晚始新世化石地层中保存的组合，而不是南极现存的任何组合。通过与斯科特岛海底山的动物组合对比，发现有柄海百合的丰度与棘球纲、小行星和石蟹捕食者的丰度呈强烈的负相关，小行星和棘球纲都以海百合为食。这些观察结果与流行的假设是一致的，即在古新世广泛存在的以海蚕和蛇虫为主的群落被移动捕食者的辐射所取代，而南大洋孤立栖息地的条件可能充当了避难所，使古老的底栖生物群落得以持续存在。(C) 2010 Elsevier Ltd.版权所有。
The previously unsurveyed Admiralty (67 degrees S, 171 degrees E) and Scott Island (67 degrees 22'S, 179 degrees 55'E) seamounts to the north of the Ross Sea were explored using cameras and physical sampling gear during the New Zealand IPY-CAML research voyage (TAN0802) in February 2008. A striking assemblage dominated by stalked crinoids and brachiopods was found at 580-600 m depths on isolated knolls at the northwest and southeast extremities of Admiralty Seamount. The seabed at these sites was littered with crinoid ossicles, and crinoid stalk bases were conspicuous on exposed rocks, suggesting that these assemblages have persisted for a considerable period of time. The crinoid sites were limited to the isolated knolls but large areas of the flanks of the main seamount were covered by dense populations of suspension-feeding ophiuroids. These assemblages are more similar in structure to those preserved in fossil strata from the Palaeocene and late Eocene than to any extant assemblages yet described from the Antarctic. In comparisons with faunal assemblages on Scott Island seamount, the abundance of stalked crinoids was strongly inversely correlated with the abundance of echinoid, asteroid, and lithodid crab predators and both asteroids and echinoids were photographed feeding on crinoids. These observations are consistent with the prevailing hypotheses that crinoid- and ophiuroid-dominated assemblages, which were widespread in the Palaeocene, were displaced by the radiation of mobile predators, and that conditions in isolated habitats in the Southern Ocean may have acted as refugia, allowing the persistence of archaic benthic assemblages. (C) 2010 Elsevier Ltd. All rights reserved.