Vertical distribution of the sound-scattering layer in the Amundsen Sea, Antarctica
Mid-trophic level at high-latitude coastal water in the Southern Ocean reside unique geographical condition with sea ice, coastal polynya, and ice shelf. To investigate the regional differences in their vertical distribution during summer, we examined acoustic backscatter data from scientific echo s...
| Published in: | Polar Science |
|---|---|
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2018
|
| Subjects: | |
| Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=14987 http://id.nii.ac.jp/1291/00014906/ |
| Summary: | Mid-trophic level at high-latitude coastal water in the Southern Ocean reside unique geographical condition with sea ice, coastal polynya, and ice shelf. To investigate the regional differences in their vertical distribution during summer, we examined acoustic backscatter data from scientific echo sounder, collected in the three representative regions in the Amundsen Sea: pack ice zone, coastal polynya zone, and ice shelf zone. The weighted mean depths (WMDs) representing zooplankton were calculated with the high resolution acoustic backscatter (1-m depth) to identify the vertical variability of the sound-scattering layer (SSL). WMDs were mainly distributed between 50 and 130 m exhibiting clear regional differences. The WMDs were detected in the shallow depth ranged between 48 and 84 m within the pack ice and coastal polynya, whereas they were observed at deeper depths around near ice shelf ranged between 117 and 126 m. WMDs varied with changing the stratification of water column structure representing strong linear relationship with the mixed layer depth (r = 0.69). This finding implies that understanding the essential forcing of zooplankton behavior will improve our ability to assess the coastal ecosystem in the Southern Ocean facing dramatic change. 南太洋の高緯度沿岸水域における中間栄養段階の生物である動物プランクトンの分布は、海氷域、沿岸ポリニア域、棚氷近接域によって独特の特徴を持つ。夏季の中間栄養段階の垂直分布の地域差を調べるために、アムンゼン海の3つの代表地域（海氷域、沿岸ポリニア域、棚氷近接域）で得られた計量魚探の音響後方散乱データを解析した。動物性プランクトンを表す加重平均深度（WMDs）は、高分解能音響後方散乱（1m深さ）を用いて計算し、音響散乱層（SSL）の垂直変動を特定した。 WMDsは主に50〜130mに分布し、明確な地域差を示した。 WMDsは、海氷域と沿岸ポリニアでは48〜84mの浅い深度で検出されたが、棚氷近接域では117〜126mの深いところで検出された。WMDsは水柱の成層構造と関連し変化しており、混合層の深さとの強い相関を示した（r = 0.69）。こうした知見は、動物プランクトン行動に及ぼす本質的な要因を理解することが、環境要因が大きく変化する南太洋の沿岸生態系の理解する能力を向上させると期待される。 |
|---|