Biological and physical influences on marine snowfall at the equator
Biological and physical influences on marine snowfall at the equator
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DOI：
10.1038/ngeo3042
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发表时间：
2017-11-01
影响因子：
18.3
通讯作者：
Stemmann, L.
中科院分区：
文献类型：
--
作者：
Kiko, R.;Biastoch, A.;Stemmann, L.
赤道大西洋和太平洋的高初级生产力是热带海洋生物地球化学的主要特征之一，并使大量颗粒物质流向深海。然而，生物过程和赤道洋流动力学是如何影响颗粒大小分布和通量的，人们知之甚少。在这里，我们使用高分辨率的尺寸分辨率粒子成像和声学多普勒海流剖面仪数据来评估赤道海洋中的这些影响。我们发现，大西洋和太平洋赤道300至600米深处的粒子丰度和通量都有所增加，这是浮游动物和Nekton在每日循环中垂直迁徙的深度范围。我们将这种颗粒物的最大值归因于这些生物产生的粪便颗粒。在1000-4000米深度，我们发现赤道带(S 1度-北纬1度)的颗粒有机碳通量是赤道外地区的3倍。在3000m处，通量主要由直径小于0.53 mm的小颗粒组成。小颗粒的优势似乎是由于该区域主动和被动颗粒输出的增加，以及北纬2度和南纬2度的向东深急流对颗粒的聚焦造成的。因此，我们认为浮游动物的运动和洋流调节了颗粒碳从表面向深海的转移。
High primary productivity in the equatorial Atlantic and Pacific oceans is one of the key features of tropical ocean biogeochemistry and fuels a substantial flux of particulate matter towards the abyssal ocean. How biological processes and equatorial current dynamics shape the particle size distribution and flux, however, is poorly understood. Here we use high-resolution size-resolved particle imaging and Acoustic Doppler Current Profiler data to assess these influences in equatorial oceans. We find an increase in particle abundance and flux at depths of 300 to 600 m at the Atlantic and Pacific equator, a depth range to which zooplankton and nekton migrate vertically in a daily cycle. We attribute this particle maximum to faecal pellet production by these organisms. At depths of 1,000 to 4,000 m, we find that the particulate organic carbon flux is up to three times greater in the equatorial belt (1 degrees S-1 degrees N) than in off-equatorial regions. At 3,000 m, the flux is dominated by small particles less than 0.53 mm in diameter. The dominance of small particles seems to be caused by enhanced active and passive particle export in this region, as well as by the focusing of particles by deep eastward jets found at 2 degrees N and 2 degrees S. We thus suggest that zooplankton movements and ocean currents modulate the transfer of particulate carbon from the surface to the deep ocean.