台湾海峡浮游植物生物量和初级生产力的粒级结构及碳流途径

Size-fraction of phytoplankton biomass and productivity and photosynthetic carbon flow in Taiwan Strait

本文研究了 1 997年 8月、1 998年 2～ 3月、8月和 1 999年 8月台湾海峡浮游植物生物量和初级生产力的粒级组成、各粒级生物量和初级生产力变动 (包括年际变动 )及其影响因子 .结果表明 ,台湾海峡微型 (简称NANO)和微微型浮游植物 (简称PICO)占优势 ,贡献率分别达 3 4 %～ 48%、3 4 %～ 40 %,小型浮游植物 (简称MI CRO)仅占 1 2 %～ 2 7%.粒级组成和各粒级生物量存在着明显的季节和年际变化 ,如1 997年夏季三种粒级浮游植物生物量均明显低于其它年份 ,PICO和MICRO组份呈 1 998年夏季高于 1 997年和 1 999年夏季 ,而NANO组份则呈 1 998年夏季低于1 997年和 1 999年夏季 .PICO组份对初级生产力的贡献最大 ,达 45%～ 50 %,而NANO和MICRO组份对初级生产力的贡献相近 ,为 1 9%～ 3 2 %;PICO组份的同化系数明显高于NANO和MICRO组份 .初步分析了初级生产的碳流途径 ,表明台湾海峡初级生产的碳将有 2 5%经异养细菌的“二次”生产而进入微食物环 ,3 6%通过原生动物 (主要是异养鞭毛虫 )摄食“打包”作用后进入微食物环 ,即近 60 %的初级生产的碳经微食物环的两个起点分别进入微食物环 ,表明微型生物食物网在该海域生源有机碳转换过程中起重要作用 .

Size fraction of phytoplankton biomass and productivity, its annual variation and photosynthetic carbon flow in Taiwan Strait were investigated during the cruises in Aug., 1997, Feb.～Mar. and Aug., 1998, and Aug., 1999. Results showed that nanophytoplankton (NANO) and picophytoplankton (PICO) dominated the community, with contribution of 34%～48% and 34%～40%, respectively, microphytoplankton (MICRO) contributed only 12%～27%. Seasonal and annual variations occurred for size-structure and size-fractionated phytoplankton biomass, for examples, biomass of all three-size phytoplankton in Aug., 1997 was lower than that in Aug., 1998 and 1999; PICO and MICRO in Aug., 1998 was higher than that in Aug., 1997 and 1999, however, NANO in Aug., 1998 was lower than that in Aug.,1997 and 1999. PICO dominated the phytoplankton productivity with 45%～50%, NANO and MICRO made the similar contribution with 19%～32%. Assimilation coefficient of PICO was significantly higher than that of NANO and MICRO. Data also indicated that 25% of photosynthetic carbon (PC) were incorporated into microbial food web (MFW) via secondary production by heterobacteria, 36% of PC into MFW via gazing by heteroflagellate. Thus, approximately 60% of PC went into MFW via two paths of it (DOC and PICO), which indicated that MFW would play an important role in transformation of organic carbon in Taiwan Strait.