2010年两个航次獐子岛海域浮游纤毛虫丰度和生物量

Abundance and biomass of planktonic ciliates in the sea area around Zhangzi Island,Northern Yellow Sea in July and August 2010

2010年7、8月在北黄海獐子岛海域进行了浮游纤毛虫丰度和生物量的调查。7月浮游纤毛虫的平均丰度为(5107±4451)个/L,平均生物量为(10.17±9.06)μg C/L。8月浮游纤毛虫的平均丰度为(7894±7212)个/L,平均生物量为(15.24±18.49)μg C/L。7月表层浮游纤毛虫丰度和生物量均呈现近岸多、远岸少的趋势。8月Y1-3、Y2-5两个站表层纤毛虫丰度较高,Y2-5、Y1-1两个站表层纤毛虫生物量较高。7月STA断面浮游纤毛虫丰度呈现表层或次表层高、底层低的特点。8月STA、Y1断面纤毛虫丰度在表层或次表层高、底层低,而Y2断面纤毛虫垂直分布较一致。7月纤毛虫水体丰度及生物量在近岸较远岸高,8月纤毛虫水体丰度及生物量在离岛较近的Y2-5、Y1-1两站较高。7、8月航次中分别鉴定出砂壳纤毛虫17和21种,其中拟铃虫属(Tintinnopsis)种数最多,Tintinnopsis corniger Hada,1964为中国海区的新记录种。7、8月砂壳纤毛虫丰度占纤毛虫总丰度的平均比例分别为(19.0±21.6)%和(13.0±16.1)%;7、8月砂壳纤毛虫生物量占纤毛虫总生物量的平均比例分别为(58.2±33.0)%和(42.6±33.2)%。7、8月两个航次中小型无壳纤毛虫在无壳纤毛虫丰度中均占绝对优势。

We investigated the abundance and biomass of planktonic ciliates in the sea around Zhangzi Island,Northern Yellow Sea,in July and August 2010.Ciliates were sampled from surface,middle and bottom depths at nineteen sample stations along three transects（Transect STA,Y1 and Y2）.A 1-L water sample was collected at each depth with a 2.5-L Niskin water sampler and fixed in 1% acid Lugol′s iodine solution.The bottles were stored in the dark for up to two months until analyzed.The fixed water samples were left to settle for at least 48 h in plastic bottles and the supernatant was siphoned out until a 150 mL sample was left.The concentrated sample was examined and counted following the Utermhl method.A subsample of 16 mL of the concentrated sample was settled in Utermhl sedimentation chambers and counted using an Olympus IX51 inverted microscope at 100× or 400×.The classification of tintinnids was based on taxonomic literature.The dimensions of the ciliates were measured and the cell volume of each species was estimated using appropriate geometric shapes.Non-loricate ciliates were divided into three size classes by cell volume： NCI（10^3 to 104 μm^3）,NCII（10^4 to 10^5 μm^3） and NCIII（105 μm^3）.The carbon-to-volume ratio used to calculate biomass was 0.19 pg C/μm^3.The plasma of tintinnids was assumed to occupy 30% of the lorica volume.Abundance and biomass of the ciliates cross-water column were calculated as the integral of the abundance and biomass from the bottom to the surface.The results showed that the average abundance of total ciliates in July and August was（5107±4451） ind/L and（7894±7212） ind/L,respectively.The average biomass of total ciliates was（10.17±9.06） μg C/L and（15.24±18.49） μg C/L.Surface ciliate abundance and biomass decreased from coastal to offshore waters in July.Surface ciliate abundance was higher at St.Y1-3 and St.Y2-5 while surface ciliate biomass was higher at St.Y2-5 and St.Y1-1.Ciliate abundance decreased from the surface or subsurface down to the bottom along Transect STA in July,Transect STA and Y1 in August,while it was vertically homogeneous along Transect Y2 in August.The average abundance and biomass of total ciliates cross-water column were higher in coastal waters than in offshore waters in July and were higher at St.Y2-5 and St.Y1-1 in August.A total of 17 and 21 tintinnid species were identified,in July and August respectively.Nearly 50% of species were in the genus Tintinnopsis,and we recorded the species Tintinnopsis corniger Hada,1964 for the first time in Chinese waters.Tintinnids occupied（19.0±21.6）% and（13.0±16.1）% of the total ciliate abundance and（58.2±33.0）% and（42.6±33.2）% of the total biomass in July and August,respectively.Small bio-volume ciliates dominated in total non-loricate ciliate abundance in both July and August.