Seamount effects on the diel vertical migration and spatial structure of micronekton
Seamount effects on the diel vertical migration and spatial structure of micronekton
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DOI：
10.1016/j.pocean.2019.03.008
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发表时间：
2019-07-01
影响因子：
4.1
通讯作者：
Silva, Monica A.
中科院分区：
文献类型：
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作者：
Cascao, Irma;Domokos, Reka;Silva, Monica A.
我们研究的昼夜垂直迁移（DVM）的行为和垂直空间结构的声音散射层（SL）在两个海山（秃鹰和Gigante）在亚速尔群岛和周围的开放水域。在2009年至2011年的春季、夏季和秋季进行的9次巡航中，昼夜记录了主动声学数据。SL是具有两个主要层的永久特征，浅散射层（SSL）和深散射层（DSL）。在海山高原，固体激光器白天聚集在海底附近，晚上则聚集在稍浅的沃茨。高原上的后向散射强度在白天和晚上之间变化不大，并且始终高于斜坡以上或开放水域的SSL。在斜坡和开放水域发现的DSL在黄昏时向表面迁移，并在黎明时返回到白天的深度，但在深开放水域，强烈的DSL持续了一夜。变异函数表明，SSLs和DSLs的分布并不均匀，但海山高原，斜坡和开放水域，昼夜期间的空间异质性的变化量。综上所述，这些研究结果表明：（1）Condor和Gigante海山拥有一个常驻微浮游生物群落，（2）夜间高原上有垂直迁移生物涌入，（3）海山地形影响DSL的DVM行为。物理过程，如泰勒帽效应，沿着地形阻塞和迁移生物的横向平流，可能在微浮游生物从开放水域向海山高原迁移中发挥作用。这些发现对于了解海山群落的生态以及海山生境在海洋生态系统中的功能至关重要。
We examined the diel vertical migration (DVM) behavior and vertical spatial structure of sound-scattering layers (SLs) at two seamounts (Condor and Gigante) in the Azores and in surrounding open-waters. Active acoustic data were recorded day and night during nine cruises conducted in spring, summer and autumn between 2009 and 2011. SLs were permanent features with two main layers, shallow scattering layers (SSLs) and deep scattering layers (DSLs). Over seamount plateaus, SSLs aggregated close to the seafloor during the day and in slightly shallower waters at night. Backscatter intensity on plateaus varied little between day and night and was consistently higher than in SSLs above slopes or in open-waters. DSLs found over slopes and open-waters migrated towards the surface at dusk and returned to their daylight depths at dawn but an intense DSL persisted overnight in deep open-waters. Variograms showed that SSLs and DSLs were not uniformly distributed but amount of spatial heterogeneity varied between seamount plateaus, slopes and open-waters, and day-night periods. Taken together, these findings suggest that (1) Condor and Gigante Seamounts host a resident micronekton community, (2) there is an influx of vertically migrating organisms over the plateaus at night, and (3) seamount topography affects the DVM behavior of the DSL. Physical processes, such as Taylor cap effect, along with topographic blockage and lateral advection of migrating organisms, may play a role in transporting micronekton from open-waters to seamount plateaus. These findings are critical to understanding the ecology of seamount communities and the function of seamount habitats in oceanic ecosystems.