We studied vertical distribution and diel vertical migration (DVM) behaviour of mesopelagic acoustic scattering layers in relation to environmental conditions in the Norwegian Sea, the Iceland Sea, the Irminger Sea, and the Labrador Sea. Distinct mesopelagic scattering layers were found in all basins, but the daytime depth of the layers varied between basins. The results suggested that daytime vertical distribution across the four basins are strongly influenced by optical conditions. DVM occurred in all basins, and since daytime vertical distribution was influenced by optical conditions, it affected the amplitude of vertical connectivity. We used the proportion of the acoustic backscatter that migrated vertically into the epipelagic zone as a proxy for active vertical flux to the mesopelagic. The proportion of micronekton backscatter participating in the vertical migrations varied between the basins, with the highest and lowest vertical connectivity in the Norwegian Sea and the Iceland Sea respectively. We conclude that a more than 8-fold reduction in backscatter flux in the Iceland Sea was primarily attributable to optical conditions there, as high nighttime light levels appeared to exclude the micronekton from the epipelagic zone.

我们研究了中海声散射层的垂直分布和diel垂直迁移（DVM）行为与挪威海，冰岛海，艾明格海和拉布拉多海中的环境条件的关系。在所有盆地中都发现了不同的近中生散射层，但是白天的深度在各个盆地之间有所不同。结果表明，四个盆地的白天垂直分布受到光学条件的强烈影响。DVM发生在所有盆地，并且由于白天的垂直分布受到光学条件的影响，因此它影响了垂直连通性的幅度。我们使用垂直向上游带迁移的声向后向散射的比例，作为向中古陆系有效垂直通量的代表。在各个盆地之间，微神经元反向散射参与垂直迁移的比例各不相同，在挪威海和冰岛海中垂直连通性最高和最低。我们得出的结论是，冰岛海的反向散射通量减少了8倍以上，这主要归因于那里的光学条件，因为夜间高光照水平似乎将微核排除在了上层带。