Nanoflagellates (mixotrophs, heterotrophs and autotrophs) in the oligotrophic eastern Mediterranean: standing stocks, bacterivory and relationships with bacterial production
Nanoflagellates (mixotrophs, heterotrophs and autotrophs) in the oligotrophic eastern Mediterranean: standing stocks, bacterivory and relationships with bacterial production
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DOI：
10.3354/meps181297
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发表时间：
1999-01-01
影响因子：
2.5
通讯作者：
Dolan, JR
中科院分区：
文献类型：
--
作者：
Christaki, U;Van Wambeke, F;Dolan, JR
1997年早春（南部盆地）和夏末（北部和南部盆地）在MATER项目（质量转移和生态系统响应）的框架内，对寡营养爱琴海（东地中海）纳米鞭毛虫的垂直分布（0至100 m）和丰度进行了检查。根据叶绿体的拥有和荧光标记微细胞（FLM）的消耗，鉴定了纳米鞭毛虫的不同营养类型（混合营养型、异养型和光养型）。将细菌产量（亮氨酸法）与根据 FLM 消耗估计的细菌产量进行比较。我们发现，相对于异养纳米鞭毛虫，混合营养纳米鞭毛虫作为食菌动物发挥的作用较小，并且总食菌细菌产量大致平衡。在早春，水柱凉爽（14.2℃）且混合良好时，鞭毛虫浓度最低，光养鞭毛虫是优势群体，浓度随深度变化不大。混合营养生物、异养生物和自养生物的平均浓度分别为0.07、0.34和0.64 x 10(3)细胞ml(-1)。 0至100 m层的细菌产量平均约为0.74 μg C l(-1) d(-1)。据估计，FLM 摄入的纳米鞭毛虫细菌占细菌产量的 40%，而混合营养型纳米鞭毛虫则占细菌产量的 5%。夏末，纳米鞭毛虫总浓度较高。混合营养生物、异养生物和自养生物的平均浓度在南部盆地分别为0.09、1.14和0.66×10(3)细胞ml(-1)，在北部盆地分别为0.09、1.1和0.98×10(3)细胞ml(-1)。九月，两个盆地的细菌产量大致平衡了估计的纳米鞭毛虫消耗量。与 3 月份的估计类似，混合营养型纳米鞭毛虫约占纳米鞭毛虫细菌的 5%。在三月份的一项营养富集实验中，含磷的处理导致细菌产量增加和可识别的混合营养菌减少。
The vertical distribution (0 to 100 m) and abundance of nanoflagellates were examined in the oligotrophic Aegean Sea (east Mediterranean) in early spring (south basin) and late summer (north and south basins) of 1997 in the framework of the MATER project (Mass Transfer and Ecosystem Response). Different trophic types of nanoflagellates (mixotrophic, heterotrophic, and phototrophic) were identified based on the possession of chloroplasts and the consumption of Fluorescently Labelled Minicells (FLM). Bacterial production (leucine method) was compared with bacterivory estimated from FLM consumption. We found that mixotrophic nanoflagellates played a small role as bacterivores relative to heterotrophic nanoflagellates and total bacterivory roughly balanced bacterial production. In early spring with cool (14.2 degrees C) well-mixed water columns, flagellate concentrations were lowest, phototrophic flagellates were the dominant group and concentrations varied little with depth. Average concentrations of mixotrophs, heterotrophs and autotrophs were 0.07, 0.34, and 0.64 x 10(3) cells ml(-1) respectively. Bacterial production in the 0 to 100 m layer averaged about 0.74 mu g C l(-1) d(-1). Estimated nanoflagellate bacterivory from FLM ingestion accounted for 40% of bacterial production with mixotrophic nanoflagellates consuming 5% of bacterial production. In late summer, total nanoflagellate concentrations were higher. Average concentrations of mixotrophs, heterotrophs and autotrophs were 0.09, 1.14, and 0.66 x 10(3) cells ml(-1), respectively in the southern basin and 0.09, 1.1, and 0.98 x 10(3) cells ml(-1), respectively, in the northern basin. In September, bacterial production for both basins roughly balanced estimated nanoflagellate consumption. Similar to the March estimates, mixotrophic nanoflagellates accounted for about 5% of nanoflagellate bacterivory. In a nutrient enrichment experiment in March, treatments including phosphorus resulted in increased bacterial production and reductions in identifiable mixotrophs.