Abstract Radiolarians are planktonic protozoon that play an important role in marine ecosystem and paleoenvironmental construction. The South China Sea (SCS) and Malacca Strait (MLS), strongly influenced by the East Asian monsoon, are the key gateway between the Pacific and Indian Oceans. However, few studies of radiolarians in the water column are performed during winter and spring in the SCS and MLS due to the adverse sea conditions. In this study the use of a ship-board plankton net rendered it possible to obtain shallow water samples (~5 m depth) along transects from the northern SCS to MLS during the spring of 2017 and winter of 2017–2018. The results show that partitioning among Spumellaria, Nassellaria and Collodaria radiolarians differed spatially and seasonally. The high partition of Collodaria and low partition of Nassellaria are potential indicators of the strongly stratified waters with low nutrients for paleoceanographic studies in the slope and basin SCS. The radiolarian assemblages in the MLS are quite different from those in the SCS, that is, the two communities are largely independent, suggesting that advective transport between the MLS and SCS is rare. There are obvious seasonal variations in species diversity and abundance in both the MLS and SCS, generally with higher biodiversity and maximum abundances in winter. The results of Q-mode cluster analysis showed that radiolarian assemblages during winter were grouped together in the slope and basin SCS, and their distributions had moved to the southwest relative to those in spring. The results demonstrate the East Asian monsoon has a significant controlling effect on radiolarian diversity and geographic distribution in the studied areas. We also established five candidates for weakly stratified waters with high nutrients: Archiperidium hexacantha, Acanthodesmia vinculatus, Peromelissa phalacra, Dictyocoryne muelleri, and Tetrapyle octacantha. Thus, this study increases the knowledge of radiolarian geographic distribution in the tropics as a whole, as well as revealing the sensitive response of radiolarians to the regional environments, a fact which may prove useful for reconstructing the paleoceanographic changes.

中文翻译：

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2017年春季与2017-2018年冬季南海和马六甲海峡放射虫生物地理对比

摘要 放射虫是浮游原生动物，在海洋生态系统和古环境建设中发挥着重要作用。南海 (SCS) 和马六甲海峡 (MLS) 受东亚季风的强烈影响，是太平洋和印度洋之间的重要门户。然而，由于恶劣的海况，在 SCS 和 MLS 的冬季和春季对水体中的放射虫进行的研究很少。在这项研究中，使用船载浮游生物网可以在 2017 年春季和 2017-2018 年冬季沿从南海北部到 MLS 的横断面获取浅水样本（~5 m 深）。结果表明，Spumellaria、Nassellaria 和 Collodaria 放射虫之间的划分在空间和季节上都不同。Collodaria 的高分配和 Nassellaria 的低分配是在斜坡和盆地 SCS 中进行古海洋学研究的强分层低营养水的潜在指标。MLS 中的放射虫组合与 SCS 中的那些有很大不同，即两个群落在很大程度上是独立的，这表明 MLS 和 SCS 之间的平流运输很少见。MLS和SCS的物种多样性和丰度存在明显的季节性变化，通常生物多样性较高，冬季丰度最大。Q-mode聚类分析结果表明，冬季的放射虫组合在斜坡和盆地SCS中聚集在一起，并且它们的分布相对于春季向西南方向移动。结果表明，东亚季风对研究区的放射虫多样性和地理分布具有显着的控制作用。我们还为具有高营养成分的弱分层水域建立了五个候选者：Archiperidium hexacantha、Acanthodesmia vinculatus、Peromelissa phalacra、Dictyocoryne muelleri 和 Tetrapyle八角树。因此，这项研究增加了对整个热带地区放射虫地理分布的认识，并揭示了放射虫对区域环境的敏感反应，这一事实可能有助于重建古海洋学变化。Acanthodesmia vinculatus、Peromelissa phalacra、Dictyocoryne muelleri 和 Tetrapyle八角树。因此，这项研究增加了对整个热带地区放射虫地理分布的认识，并揭示了放射虫对区域环境的敏感反应，这一事实可能有助于重建古海洋学变化。Acanthodesmia vinculatus、Peromelissa phalacra、Dictyocoryne muelleri 和 Tetrapyle八角树。因此，这项研究增加了对整个热带地区放射虫地理分布的认识，并揭示了放射虫对区域环境的敏感反应，这一事实可能有助于重建古海洋学变化。