THE INFLUENCE OF HYDRODYNAMIC REGIME ON INFAUNAL ASSEMBLAGES INHABITING CARBONATE SEDIMENTS ON CENTRAL PACIFIC SEAMOUNTS
THE INFLUENCE OF HYDRODYNAMIC REGIME ON INFAUNAL ASSEMBLAGES INHABITING CARBONATE SEDIMENTS ON CENTRAL PACIFIC SEAMOUNTS
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DOI：
10.1016/0198-0149(89)90117-9
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发表时间：
1989-12-01
期刊：
影响因子：
--
通讯作者：
THOMAS, CL
中科院分区：
文献类型：
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作者：
LEVIN, LA;THOMAS, CL
我们对中太平洋深海海山的以下假设进行了调查：（1）在海流增强的区域，底栖动物和微生物丰度升高;（2）底栖动物的生活方式反映了水动力条件的变化;（3）在高能状态下，生物扰动更加强烈。我们的研究是在三个地点进行的：地平线盖奥特沉积物盖（1840米），其特点是强大的底流和波纹有孔虫砂，地平线盖奥特（1480米）和麦哲伦隆起（3150米），其沉积物是无波纹和更细的粒度的中央峰会的西北周边。与我们的第一个假设相反，高能量地平线周边沉积物表现出比山顶地点更低的生物活性，如反映在更低的有机氮（0.011%对0.015-0.017%）、更高的C/N比（19对11）、更低的细菌计数（1.21对2.03-2.15 × 10 - 3）、更高的pH值（1.21对2.03-2.15 × 10 - 3）和更低的pH值（1.21对2.03）。108 ml-1）和较低的大型底栖动物丰度（255 vs 388-829 m-2）。沉积物有机碳值（0.14-0.19%）和小型底栖动物丰度（2866-5150 m-2）之间没有显着差异的三个网站。底栖动物的生活习性各不相同的网站，但沉积物混合没有。大型动物被发现更深的波纹周边沉积物比帽沉积物。在高能地平线周边的多毛类动物中，无柄和表面进食模式占主导地位，而运动和地下进食在安静，细粒的制度中更为常见。在所有三个地点，在100年的时间尺度上都发生了显著的沉积物混合，这可能是盖区大型底栖生物扰动和周边地点物理沉积物不稳定的结果。过量的210 Pb表现出中等程度的高库存（38-59 dpm cm-2）和深度渗透（> 15 cm）。估计的混合系数（Db）范围从0.6至3.0厘米2 y-1在三个网站。我们的研究结果表明，与不同海山的类似状况相比，水动力差异可能导致单个海山的沉积物和动物群特征出现更大的变化。将地平线盖奥特和麦哲伦隆起的数据与东太平洋海山的可比数据进行比较，发现中部太平洋海山沉积物的有机碳含量、微生物丰度、大型动物密度和地下存款馈线代表性都低于东太平洋海山沉积物。
We investigated the following hypotheses for deep seamounts in the central Pacific Ocean: (1) infaunal and microbial abundances are elevated in regions of current intensification, (2) infaunal lifestyles reflect variation in hydrodynamic conditions and (3) bioturbation is more intense in high-energy regimes. Our studies were carried out at three sites: the northwest perimeter of the Horizon Guyot sediment cap (1840 m), which is characterized by strong bottom currents and rippled foraminiferan sands, and the central summits of Horizon Guyot (1480 m) and Magellan Rise (3150 m), whose sediments are unrippled and finer grained. Contrary to our first hypothesis, the high-energy, Horizon perimeter sediments exhibited lower biological activity than the summit sites, as reflected in lower organic nitrogen (0.011% vs 0.015-0.017%), higher C/N ratios (19 vs 11), lower bacterial counts (1.21 vs 2.03-2.15 .times. 108 ml-1) and lower macrofaunal abundances (255 vs 388-829 m-2). Sediment organic carbon values (0.14-0.19%) and meiofaunal abundances (2866-5150 m-2) did not differ significantly among the three sites. Infaunal life habits varied among sites but sediment mixing did not. Macrofauna were found deeper in rippled perimeter sediments than in the cap sediments. Sessility and surface-feeding modes dominated among polychaetes at the higher-energy Horizon perimeter, while motility and subsurface feeding were more common in the quieter, finer-grained regimes. Significant sediment mixing takes place on 100-year time scales at all three sites, probably a result of large, infaunal bioturbants at the cap sites and physical sediment instability at the perimeter sites. Excess 210Pb exhibited moderately high inventories (38-59 dpm cm-2) and deep penetration (> 15 cm). Estimated mixing coefficients (Db) ranged from 0.6 to 3.0 cm2 y-1 at the three sites. Our findings indicate that hydrodynamic differences can lead to greater variation in sediment and faunal characteristics on a single seamount than are found in similar regimes on different seamounts. Comparison of the Horizon Guyot and Magellan Rise data to comparable data from eastern Pacific seamounts, reveals lower organic carbon content, microbial abundance, macrofaunal densities, and subsurface deposit feeder representation, in central than eastern Pacific seamount sediments.