Sequential resuspension of protists by accelerating tidal flow: Implications for community structure in the benthic boundary layer
Sequential resuspension of protists by accelerating tidal flow: Implications for community structure in the benthic boundary layer
复制标题
通过加速潮汐流顺序重新悬浮原生生物：对底栖边界层群落结构的影响
DOI：
10.4319/lo.2002.47.4.1152
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发表时间：
2002
影响因子：
4.5
通讯作者：
Oladipo M. Ashiru
中科院分区：
文献类型：
--
作者：
J. Shimeta;C. Amos;S. Beaulieu;Oladipo M. Ashiru
我们用现场水槽和潮汐加速过程中的海底边界层取样，测量了潮下海岸的原生生物和细菌的再悬浮阈值。异养纳米鞭毛虫、寡毛纤毛虫、远端硅藻和细菌在弱水流(摩擦速度u*crit=0.2 5-0.80 cm S-1)中重新悬浮，可能与表层绒毛状沉积物有关。Hypotrich纤毛虫、盾壳纤毛虫、硅藻、横纹夜蛾和侧耳藻。再悬浮在中等流量(u*crit=0.82-1.3 cm S-1)中，然后是有色纳米鞭毛虫和两种菱形藻的硅藻。强气流(u*Crit>；=1.5 cm S-1)。次毛藻和鳞毛藻的再悬浮与沉积物侵蚀阈值无关，而大多数硅藻再悬浮在大量沉积物中。不同的阈值可能是由于细胞大小、比重、行为或与颗粒的关联。当潮流加速到u*=1.3cm·S-1时，再悬浮使水底以上5 cm处的细胞浓度增加2-16倍，不同的类群之间存在差异。群落结构也发生了相应的变化，纤毛虫群落中的寡毛、短毛和鞭毛虫的比例从75%增加到96%，上述硅藻分类群的比例从37%增加到63%。顺序再悬浮表明，在再悬浮事件中进入水体的物种组合取决于最大床面剪应力，从而随春潮循环以及大气强迫和局部水文变化而变化。水流引起的群落结构波动可能会影响底栖边界层和沉积物中微生物食物网的动态。
We measured resuspension thresholds of protists and bacteria at a subtidal coastal site with in situ flumes and by sampling the benthic boundary layer during tidal accelerations. Heterotrophic nanoflagellates, oligotrich ciliates, the diatom Navicula distans, and bacteria resuspended in weak flow (friction velocity u*crit = 0.25–0.80 cm s-1), likely associated with a surficial fluff layer of sediment. Hypotrich ciliates, scuticociliates, and the diatoms N. transitans and Pleurosigma sp. resuspended in moderate flow (u*crit = 0.82–1.3 cm s-1), followed by pigmented nanoflagellates and diatoms of two Nitzschia spp. in strong flow (u*crit >= 1.5 cm s-1). Hypotrichs and scuticociliates resuspended independent of sediment erosion thresholds, whereas most diatoms resuspended with bulk sediment. Differing thresholds may be due to cell size, specific gravity, behavior, or association with particles. As tidal currents accelerated to u* = 1.3 cm s-1, resuspension caused cell concentrations at 5 cm above bottom to increase by 2–16 times, varying among taxa. Community structure shifted accordingly, with total oligotrichs, hypotrichs, and scuticociliates changing from 75% to 96% of the ciliate community and the total diatom taxa listed above changing from 37% to 63% of the pennate cells. Sequential resuspension suggests that the species assemblage entering the water column during a resuspension event depends on the maximal bed shear stress, thus varying with the springneap cycle as well as atmospheric forcing and local hydrography. Flow‐induced fluctuations of community structure may influence microbial food‐web dynamics in the benthic boundary layer and sediment.