北印度洋—南海表层水体中浮游动物胶体虫(放射虫)的物种多样性、生物地理及其季节变化

Biodiversity,biogeography and seasonal variation of zooplankton Collodarians(Radiolaria)in surface waters from the northern Indian Ocean to the South China Sea

具有共生体的浮游动物胶体虫在寡营养海域的有机碳循环和硅循环过程中发挥着重要的作用,但对于胶体虫的研究较为薄弱。文章利用走航式采样和虎红染色方法,首次揭示了北印度洋—马六甲海峡—南海跨多个海域表层水中胶体虫的物种多样性、生物地理及其季节变化。研究海区胶体虫的物种数非常丰富,春季17种、冬季高达27种;北印度洋—马六甲海峡的多样性在春季普遍低于南海、但在冬季则高于南海,表明北印度洋—南海生物多样性的区域地理分布受东亚季风影响显著。胶体虫群落结构的变化也存在生物地理上的差异、且受东亚季风影响显著,如胶球虫科(Collosphaeridae)在春冬季均具绝对优势、球虫科(Sphaerozoidae)只在冬季显著增加;春季和冬季的优势种组成也有不同,表明表层水体中胶体虫的群落组成受季节变化影响显著,东亚季风影响下表层水混合增强,导致属种组成发生显著变化,进而表现出季节变化是控制研究海区胶体虫群落结构的主因。胶体虫的丰度则与区域环境密切相关,如马六甲海峡至巽他陆架春、冬季均较低,南海次之,北印度洋春、冬季都相对较高,反映出其对特定海洋环境的适应性,推测大尺度下区域的影响要高于季风变化的控制。可见,胶体虫的物种多样性和绝对丰度能够反映出不同的生态环境信号,为今后利用胶体虫替代指标进行古海洋和古环境重建研究提供重要的观测数据和基础参考。

Zooplankton collodarians with symbiontes play important roles in the organic carbon cycle and silicon cycle in the oligotrophic waters.However,studies on the collodiarian geographic distribution were few.In this study,the biodiversity,biogeography and seasonal variation of collodarians in the surface water of the northern Indian Ocean(NIO),the Malacca Strait(MLS)and the South China Sea(SCS)are revealed for the first time by using the ship-board plankton net to collect samples and using the Rose Bengal stains to distinguish between“living”and“dead”specimens.Totally,the 17 species of collodarians occurred in spring,with 27 species in winter.The collodarian diversity in NIO and MLS is generally less than that in SCS in spring,while in the winter,the former is higher than the latter,indicating that the regional biodiversity from NIO to the SCS is considerably affected by the East Asian monsoon.Moreover,the changes of collodarian community structure have biogeographic differences under the influence of East Asian monsoon.For example,the family Collosphaeridae is obviously dominant both in spring and winter,while the family Sphaerozoidae is dominant only in winter;the composition of dominant species is also different between the spring and the winter,suggesting the collodairian community in surface water is significantly affected by the seasonal changes.Under the influence of East Asian monsoon,the mixing of surface water enhanced,resulting in obvious changes in the compostion of collodarian species,which indicates that seasonal changes are the main factor that controls the community structure of collodarians in the study sea area.The abundance of collodarians is closely related to the regional environment.For instance,the collodarian abundance is very low in spring and winter from MLS to the Sunda Shelf,followed by SCS,and is high in NIO,reflecting their adaptability to specific marine environment.It is assumed that the influence of habitat on a large scale is higher than the control of monsoon change.Therefore,the biodiversity and abundance of collodarians can reflect the different ecological environmental signals,which further provides important observation data and a basic reference for the reconstruction of palaeooceanography and palaeoenvironment by using the collodarian substitution indexes in the future.