Krill play a crucial role in the transfer of energy in the marine food web, connecting primary producers and the upper trophic levels in the Terra Nova Bay polynya (TNBP), which is part of the Ross Sea marine protected area. Despite the substantial ecological importance of krill, there are few studies on their distribution and abundance in the TNBP. An acoustic survey was conducted on 7–14 January 2019 in the TNBP, Ross Sea, using a Simrad EK60 echosounder (38 and 120 kHz) aboard the icebreaker RV Araon. The most commonly used range of the difference of the mean volume backscattering strength (MVBS) (2–16 dB) was applied to distinguish krill. The acoustic data (120 kHz) were extracted to examine the krill distribution characteristics. The study area was divided into low-value areas and high-value areas based on the third quartile of the nautical area scattering coefficient. The results showed that the krill aggregations were distributed in three layers at depths of 0–30 m, 70–110 m, and 270–300 m. The interpolated environmental parameters associated with the backscattering strength were compared. High-value areas of krill coincided with relatively low temperature, low salinity, and high chlorophyll, although very weak correlations were found. The primary goal of this study was to understand the vertical and horizontal distributions of krill acoustic biomass and to relate the observed patterns to the dominant environmental conditions.

中文翻译：

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南极Terra Nova Bay Polynya磷虾散射层的声学探测

磷虾在海洋食物网中的能量转移中发挥着至关重要的作用，将初级生产者和 Terra Nova Bay polynya (TNBP) 的上层营养层联系起来，TNBP 是罗斯海海洋保护区的一部分。尽管磷虾具有重要的生态重要性，但关于它们在 TNBP 中的分布和丰度的研究很少。2019 年 1 月 7 日至 14 日，使用破冰船 RV Araon 上的 Simrad EK60 回声测深仪（38 和 120 kHz）在罗斯海 TNBP 进行了声学调查。最常用的平均体积反向散射强度 (MVBS) (2-16 dB) 差值范围用于区分磷虾。提取声学数据 (120 kHz) 以检查磷虾分布特征。根据海区散射系数的四分位数将研究区划分为低值区和高值区。结果表明，磷虾聚集体分布在0-30 m、70-110 m和270-300 m深度的三层。比较了与反向散射强度相关的内插环境参数。磷虾的高价值区域与相对较低的温度、低盐度和高叶绿素相吻合，但发现相关性非常弱。本研究的主要目标是了解磷虾声学生物量的垂直和水平分布，并将观察到的模式与主要环境条件联系起来。和 270–300 m。比较了与反向散射强度相关的内插环境参数。磷虾的高价值区域与相对较低的温度、低盐度和高叶绿素相吻合，但发现相关性非常弱。本研究的主要目标是了解磷虾声学生物量的垂直和水平分布，并将观察到的模式与主要环境条件联系起来。和 270–300 m。比较了与反向散射强度相关的内插环境参数。磷虾的高价值区域与相对较低的温度、低盐度和高叶绿素相吻合，但发现相关性非常弱。本研究的主要目标是了解磷虾声学生物量的垂直和水平分布，并将观察到的模式与主要环境条件联系起来。