Growth and mortality rates of prokaryotes in the hypolimnion of a deep freshwater lake (Lake Biwa, Japan)
Growth and mortality rates of prokaryotes in the hypolimnion of a deep freshwater lake (Lake Biwa, Japan)
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深淡水湖（日本琵琶湖）下层原核生物的生长和死亡率
DOI：
10.1080/20442041.2017.1298222
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发表时间：
2017
期刊：
影响因子：
3.1
通讯作者：
Shin-ichi Nakano
中科院分区：
文献类型：
--
作者：
Hiroyuki Takasu;Shin-ichi Nakano
据报道，在低温带水域中存在微米级蓝藻(聚球藻属)，研究人员认为，聚球藻对低温带中的生态过程的贡献大于先前的假设；然而，聚球藻在食物网和/或低温带中物质循环中的生态作用仍不清楚。为了解决这个问题，我们评估了一个大型淡水湖(日本琵琶湖)在层化期间的原虫放牧和聚球藻病毒介导的死亡率。此外，我们还比较了聚球藻和异养细菌的死亡碳通量，以评估聚球藻在亚磁生态系统中的生态过程中的作用。我们的结果表明，聚球藻和异养菌的生物量主要是通过原生放牧来清除的。8月份聚球藻丰度最高，平均聚球藻：细菌碳生物量和日放牧损失率分别为10.8%和11.0%。因此，聚球藻生物量可能是亚磁微生物环中碳通量的一个重要的季节性组成部分。我们的结果首次提供了在亚磁生态系统中通过聚球虫和细菌的死亡来计算碳通量的数据。
The presence of pico-sized cyanobacteria (genusSynechococcus) in hypolimnetic waters has been reported, and investigators have suggested thatSynechococcuscontribute more to ecological processes in the hypolimnion than previously hypothesized; however, the ecological role ofSynechococcusin food webs and/or matter cycling in the hypolimnion remains unknown. To address this issue, we assessed protistan grazing and the virus-mediated mortality ofSynechococcusin the oxygenated hypolimnion of a large freshwater lake (Lake Biwa, Japan) during the stratification period. In addition, we compared the carbon flux through mortality ofSynechococcusto that of heterotrophic bacteria to evaluate the role ofSynechococcusin ecological processes within a hypolimnetic ecosystem. Our results suggest that the biomass ofSynechococcusand heterotrophic bacteria in the hypolimnion was removed primarily by protistan grazing. The abundance ofSynechococcuswas highest in August, when the averageSynechococcus:bacteria carbon biomass and daily grazing loss ratios were 10.8% and 11.0%, respectively. Thus, theSynechococcusbiomass is likely an important seasonal component of the carbon flux in the hypolimnetic microbial loop. Our results provide the first data on carbon flux through the mortality of bothSynechococcusand bacteria in a hypolimnetic ecosystem.