Protozoan Bacterivory in the Ice and the Water Column of a Cold Temperate Lagoon
Protozoan Bacterivory in the Ice and the Water Column of a Cold Temperate Lagoon
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冷温带泻湖冰和水柱中的原生动物细菌
DOI：
10.1007/s002489900134
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发表时间：
1999
影响因子：
3.6
通讯作者：
S. Juniper
中科院分区：
文献类型：
--
作者：
T. Sime;S. Demers;S. Juniper
1992年2 - 3月，在日本寒温带泻湖（Saroma-Ko lagoon，北海道，44°N, 144°E）的冰-盐水和水柱群落中，研究了冰群落发育的冬末阶段（2 - 3月）细菌丰度和含菌原生生物的丰度和活性。冰盐水和浮游生物样品的细菌丰度平均分别为6和1 × 105 cells ml - 1，在采样期间总体呈下降趋势。通过直接观察短期（<1 h）摄入荧光标记细菌（FLB）在其食物液泡中的情况，鉴定出的嗜菌原生生物主要以鞭毛虫为主，主要是冷冻共体型和黄体样细胞以及Gymnodinium属的小鞭毛虫。嗜菌纤毛虫主要有：prostomatid Urotricha sp.， scuticociates Uronema和Cyclidium， choreotrichs Lohmaniella oviformis和strobidium，以及hypotrrich Euplotes sp.。在冰盐水中，鞭毛虫和纤毛虫的原生生物丰度分别为4 × 103和8.1个细胞ml - 1，在浮游生物中分别为0.3 × 103和1.2个细胞ml - 1。与细菌相反，原生生物的丰度在整个采样期间普遍增加，表明捕食者-猎物相互作用。根据FLB在24 h内的消失率测量，原生细菌平均占总细菌存量的36%（冰）和24%（浮游生物），并表现出与原生生物丰度相同的季节格局。计算出的特定清除率（范围为2-67 nl原生动物−1 h−1）和摄食率（<1 - 26颗粒原生动物−1 h−1）可能是最小估计，放牧影响有时可能更高。“嗜菌原生生物”对非细菌食品依赖的适应症也被提供。虽然细菌流失的其他来源可能很重要，但这项研究为原生动物组合作为细菌食草动物的潜力提供了证据，这些细菌食草动物存在于海冰-盐水生物群和北半球海冰南缘的水柱中。
A bstractBacterial abundance and bacterivorous protist abundance and activity were examined in ice-brine and water column communities of a cold temperate Japanese lagoon (Saroma-Ko Lagoon, Hokkaido, 44°N, 144°E), during the late winter phase of ice community development (February–March 1992). Bacterial abundance averaged 6 and 1 × 105 cells ml−1 in the ice-brine and plankton samples, respectively, and generally decreased during the sampling period. Bacterivorous protists, identified based on direct observation of short-term (<1 h) ingested fluorescently labeled bacteria (FLB) in their food vacuoles, were largely dominated by flagellates, mainly cryothecomonad-type and chrysomonad-like cells and small dinoflagellates of the genus Gymnodinium. Bacterivorous ciliates included mainly the prostomatid Urotricha sp., the scuticociliates Uronema and Cyclidium, the choreotrichs Lohmaniella oviformis and Strobilidium, and the hypotrich Euplotes sp. Protist abundance averaged 4 × 103 and 8.1 cells ml−1 in the ice-brine and 0.3 × 103 and 1.2 cells ml−1 in the plankton, for flagellates and ciliates, respectively. In contrast to bacteria, the abundance of protists generally increased throughout the sampling period, indicating predator–prey interactions. Protistan bacterivory, measured from the rate of FLB disappearance over 24 h, averaged 36% (ice) and 24% (plankton) of bacterial standing stock and exhibited the same seasonal pattern as for protist abundance. The calculated specific clearance (range, 2–67 nl protozoa−1 h−1) and ingestion (<1–26 particles protozoa−1 h−1) rates were likely to be minimal estimates and grazing impact may have been higher on occasion. Indications for the dependence of ``bacterivorous protists'' on nonbacterial food items were also provided. Although alternative sources of bacterial loss are likely to be of importance, this study provides evidence for the potential of protozoan assemblages as bacterial grazers in both sea ice-brine biota and water column at the southern limit of sea ice in the northern hemisphere.