Distribution of planktic foraminifera at the ice margin in the Arctic (Fram Strait)
Distribution of planktic foraminifera at the ice margin in the Arctic (Fram Strait)
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DOI：
10.1016/s0377-8398(96)00014-x
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发表时间：
1997-02-01
影响因子：
1.9
通讯作者：
Wefer, G
中科院分区：
文献类型：
--
作者：
Carstens, J;Hebbeln, D;Wefer, G
在弗拉姆海峡（北欧海北方）沿着北纬78度和80度的两个东西向断面，在水柱上部200米的五个平行深度间隔，以网拖（>63 μ m）收集浮游有孔虫。在无冰区，获得了水柱上部200 m处的绝对丰度，高达500个个体/m（3）。沿着冰缘的绝对丰度高达1250 ind/m3，而在冰覆盖区发现的绝对丰度不超过50 ind/m3。令人惊讶的是，这些丰度的强烈变化并不伴随着无冰区和冰覆盖区之间动物组合的显著变化。厚皮新球四边形虫Neogloboquadrina pachyderma是大多数样品中的优势种，占总区系组合的60%。Globigerina quinqueloba贡献了38%，所有其他物种加起来只占总动物群的2%。所采集有孔虫的绝对丰度和相对丰度均强烈依赖于所使用的网目尺寸。使用较小的网格尺寸提供了一个更广泛的物种谱，这是特别感兴趣的古海洋学重建在北欧海域，其中化石组合>150亩米往往只包括一个物种。在弗拉姆海峡的特定水文条件下，与温暖的大西洋沃茨下面寒冷的极地表面沃茨，导致一个相当不典型的深度分布的南极有孔虫。所有物种似乎都喜欢温带大西洋沃茨（50米至200米）。因此，物种组成以及地球化学示踪剂不反映表层海洋条件，这再次具有潜在的有趣的古海洋重建的影响。
Planktic foraminifera were collected in net tows (>63 mu m) along two east-west transects at 78 degrees and 80 degrees N in the Fram Strait (northern Nordic Seas) at five concurrent depth intervals in the upper 200 m of the water column. In the ice-free zone, absolute abundances in the upper 200 m of the water column up to 500 individuals/m(3) were obtained. Along the ice margin the absolute abundances reached up to 1250 ind/m(3), while in the ice-covered areas not more than 50 ind/m(3) have been found. Surprisingly, these strong variations in abundance are not accompanied by significant changes in faunal assemblages between the ice-free and the ice-covered regions. Neogloboquadrina pachyderma is the dominant species in most samples, making up to 60% of the total faunal assemblage. Globigerina quinqueloba contributes 38%, and all other species combined make up only 2% of the total fauna. Both, absolute and relative abundances of the collected foraminifera are strongly dependent an the mesh size used. Using smaller mesh sizes provides a wider species spectrum, which is of special interest for paleoceanographic reconstructions in the Nordic Seas, where fossil assemblages >150 mu m often consist of only one species. The specific hydrographic conditions in the Fram Strait, with warm Atlantic waters underlying cold Polar surface waters, result in a rather atypical depth distribution of the planktic foraminifera. All species seem to prefer the temperate Atlantic waters (between 50 m and 200 m). Thus, the species composition as well as geochemical tracers do not reflect the surface ocean conditions, which again has potentially interesting implications for paleoceanographic reconstructions.