日本地球惑星科学連合2023年大会

講演情報

[J] 口頭発表

セッション記号 A (大気水圏科学) » A-CG 大気海洋・環境科学複合領域・一般

[A-CG45] 海洋表層-大気間の生物地球化学

2023年5月21日(日) 09:00 〜 10:30 102 (幕張メッセ国際会議場)

コンビーナ:亀山 宗彦(北海道大学)、岩本 洋子(広島大学大学院統合生命科学研究科)、野口 真希(国立研究開発法人海洋研究開発機構 地球表層システム研究センター)、小杉 如央(気象研究所)、座長:小杉 如央(気象研究所)、野口 真希(国立研究開発法人海洋研究開発機構 地球表層システム研究センター)

09:00 〜 09:15

[ACG45-01] Seasonal basin-scale variability of diatoms in surface waters of the North Pacific with their controlling environmental factors

*鈴木 光次1、Qiu Weichen1高尾 信太郎2中岡 慎一郎2 (1.北海道大学、2.国立環境研究所)

キーワード:植物プランクトン、珪藻類、北太平洋、海洋温暖化

Diatoms, considered one of the most ecologically and biogeochemically important phytoplankton, contribute around 20% of global primary productivity through photosynthesis and play a significant role in the exchange of carbon between the ocean and the atmosphere. However, the sizeable spatiotemporal variability of diatoms and their controlling environmental factors are still poorly understood. Here we show the seasonal basin-scale distribution patterns of diatoms in surface waters of the North Pacific between Japan and North America, as estimated from quantitative PCR (qPCR) assays targetting diatom-specific 18S rRNA gene fragments. These surface DNA samples have been collected by ship-of-opportunity observations using the M/V New Century 2 since September 2014. Diatom-specific 18S rRNA gene copies from spring to summer were significantly higher than those in fall or winter, indicating the occurrence of spring-summer diatom blooms. Meridional changes in the surface diatoms were somewhat unclear, as estimated with the 18S rRNA gene copies. Increases in seawater temperature and macronutrient concentrations (nitrate plus nitrite, phosphate, and silicate) in the subarctic region affected the diatom-specific 18S rRNA gene copies negatively and positively, respectively. Additionally, the sea surface height (SSH) anomaly estimated from satellite remote sensing was negatively correlated with the gene abundance in subarctic waters, indicating the influence of mesoscale eddies, which are frequently observed in the study area, on the diatom distribution. Our results suggest that surface diatoms in the subarctic region could be particularly vulnerable to ocean warming.