ABSTRACT: Shielding skirts are widely used as a non-invasive preventive measure against salmon lice Lepeophtheirus salmonis infestations on Atlantic salmon Salmo salar in sea-cages. Low levels of dissolved oxygen (DO) are reported from some sites, but not others. This disparity is usually explained by local variations in current flow and hydrography. The aim of the present study was to investigate these local variations through vertical mapping of DO and hydrography at 2 hydrographically different sites equipped with shielding skirts. The 2 sites chosen, Fornes and Soløya, are in northern Norway and are equipped with a permeable and a non-permeable skirt, respectively. Over a period of 3 d, current speed and direction were recorded outside the cage, while DO and hydrography were measured both inside and outside the cage, above and below the skirt. At Fornes, the DO inside the cage varied throughout the study period, while DO outside remained stable. The variation in DO inside the cage co-occurred with variations in strength and depth of a present pycnocline that broke down during the study period. At Soløya, DO levels were high throughout the study, and there was no gradient in salinity, temperature or density, indicating good vertical mixing. These data illustrate how the interaction between skirts and local conditions can influence the temporal and spatial variations of DO inside shielded cages and highlight the importance of studying local current conditions and hydrography when applying shielding skirts.

中文翻译：

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在两个水文位置不同的地方，用虱子屏蔽裙撑在鲑鱼海鱼笼中溶解氧的动力学

摘要：屏蔽裙被广泛用作对鲑鱼虱子在大西洋鲑鱼Salmo salar上的鲑鱼Lepeophtheirus鲑鱼侵扰的一种非侵入性预防措施在海笼中。据报道有些地方有低水平的溶解氧（DO），但其他地方没有。通常通过电流和水文学的局部变化来解释这种差异。本研究的目的是通过DO和水文学在2个装备有屏蔽裙的不同水文地点的垂直映射研究这些局部变化。所选择的两个地点，Fornes和Soløya，位于挪威北部，分别配备了可渗透和不可渗透的裙板。在3 d的时间内，记录了笼子外部的当前速度和方向，同时测量了笼子内部和外部，裙边上方和下方的DO和水文学。在福恩斯大学，在研究期间，笼子内部的溶解氧变化，而外部的溶解氧保持稳定。笼子内部的溶解氧变化与目前在研究期间发生分解的比考克林的强度和深度同时发生。在索勒亚，整个研究过程中的溶解氧水平都很高，盐度，温度或密度没有梯度，表明垂直混合良好。这些数据说明了裙边和局部条件之间的相互作用如何影响屏蔽笼内溶解氧的时空变化，并突出了应用屏蔽裙边时研究局部当前条件和水文学的重要性。