Coccolithophore distributions of the North and South Atlantic Ocean
Coccolithophore distributions of the North and South Atlantic Ocean
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DOI：
10.1016/j.dsr.2019.06.012
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发表时间：
2019-09-01
影响因子：
2.4
通讯作者：
Wyeth, Amy
中科院分区：
文献类型：
--
作者：
Balch, William M.;Bowler, Bruce C.;Wyeth, Amy
我们展示了北纬 50 度至南纬 50 度之间的 10 次大西洋经线横断面 (AMT) 巡航的平均颗石藻和相关生物地球化学结果，这些结果显示了这个庞大数据集中的许多独特观测结果。赤道水域的颗石藻浓度始终最低。最高浓度的颗石藻细胞和颗石石与温带、亚极地环境有关。分离的石珊瑚的浓度分散到大约 300 m 的深度，并且显示出较低的航行间方差。亚热带的颗石藻细胞浓度在南大西洋 < 200 m 深度和北大西洋 100 m 深度处保持最高，靠近 26.5 至 27 sigma-theta (sigma(theta)) 等重线，位于亚南极模式水 (SAMW) 内。颗石藻细胞的多样性和物种丰富度高于分离的颗石藻细胞，并且通常在表面群体中比在深层叶绿素最大值（DCM）中更高。在南纬 50 度的南大洋表层水域以及从南纬 50 度到赤道的 DCM 中，携带板石的颗石藻种类在伞状和花状颗石藻类群中占主导地位。 DCM 与 sigma(theta) 密切相关，类似于 27 kg m(-3)，与 SAMW 内的硝吖啶顶部重合。与叶绿素相比，颗石藻细胞和分离颗石藻的浓度与密度场的相关性要小得多。当综合POC：叶绿素比率最高时，观察到最高综合透光石珊瑚浓度。 PIC:POC 比率随着深度的增加而增加，并在硝垸顶部附近接近最大值。大方解石带水域（上部 300m）显示生物二氧化硅：颗粒无机碳比率 (BSi:PIC) > 1，而所有其他水域显示 BSi:PIC 比率 < 1。在低磷酸盐和硅酸盐浓度的水域中，在 SAMW 内部和上方观察到 PIC 和 BSi 的峰值。这项研究的结果表明，南大洋富含颗石藻的 SAMW 在形成后正在受到调节，因此当它在大西洋赤道地区上升时，水体不再有利于颗石藻的生长。
We present average coccolithophore and associated biogeochemical results from ten Atlantic Meridional Transect (AMT) cruises between 50 degrees N-50 degrees S, results that show a number of unique observations across this massive data set. Lowest concentrations of coccolithophores were consistently found in equatorial waters. Highest concentrations of coccolithophore cells and coccoliths were associated with temperate, sub-polar environments. Concentrations of detached coccoliths were dispersed to similar to 300m depth and show low inter-cruise variance. Coccolithophore cell concentrations in the subtropics remain highest at < 200m depth in the S. Atlantic and 100m in the N. Atlantic, near the 26.5 to 27 sigma-theta (sigma(theta)) isopycnal, within the Subantarctic Mode Water (SAMW). Diversity and species richness of coccolithophore cells was greater than for the detached coccoliths and generally greater in surface populations than in the deep chlorophyll maximum (DCM). Placolith-bearing coccolithophore species dominated over the umbelliform and floriform coccolithophore groups in surface waters of the Southern Ocean at 50 S, as well as the DCM from 50 S to the equator. The DCM was strongly associated with the sigma(theta), of similar to 27 kg m(-3), coincident with the top of the nitracline, within the SAMW. Concentrations of coccolithophore cells and detached coccoliths were much less related to the density field than chlorophyll was. Highest integrated euphotic coccolith concentrations were observed when the integrated POC:chlorophyll ratio was highest. PIC:POC ratios increased with depth and approached maximum values near the top of the nitracline. Great Calcite Belt waters (upper 300m) showed biogenic silica:particulate inorganic carbon ratios (BSi:PIC) > 1 while all other waters showed BSi:PIC ratios < 1. Peaks in PIC and BSi were observed within, and above the SAMW, in waters with low phosphate and silicate concentrations. The results of this study suggest that coccolithophore-rich SAMW in the Southern Ocean is being conditioned after its formation, such that by the time it upwells in the Atlantic equatorial region, the water is no longer conducive to coccolithophore growth.