Hisatugo Karina F, Mansano Adrislaine S, Seleghim Mirna H R
Departamento de Ecologia e Biologia Evolutiva Universidade Federal de São Carlos São CarlosSP Brazil.
Braz J Microbiol. 2014 May 19;45(1):143-51. doi: 10.1590/s1517-83822014000100020. eCollection 2014.
In aquatic ecosystems, bacteria are controlled by several organisms in the food chain, such as protozoa, that use them as food source. This study aimed to quantify the ingestion and clearance rates of bacteria by ciliates and heterotrophic nanoflagellates (HNF) in a subtropical freshwater reservoir (Monjolinho reservoir - São Carlos - Brazil) during one year period, in order to verify their importance as consumers and controllers of bacteria in two seasons, a dry/cold and a rainy/warm one. For this purpose, in situ bacterivory experiments were carried out bimonthly using fluorescently labeled bacteria with 5-(4,6 diclorotriazin-2yl) aminofluorescein (DTAF). Although ciliates have shown the highest individual ingestion and clearance rates, bacterivory was dominated by HNF, who showed higher population ingestion rates (mean of 9,140 bacteria h(-1) mL(-1)) when compared to ciliates (mean of 492 bacteria h(-1) mL(-1)). The greater predation impact on bacterial communities was caused mainly by the small HNF (< 5 μm) population, especially in the rainy season, probably due to the abundances of these organisms, the precipitation, trophic index state and water temperature that were higher in this period. Thus, the protozoan densities together with environmental variables were extremely relevant in determining the seasonal pattern of bacterivory in Monjolinho reservoir.
在水生生态系统中，细菌受到食物链中多种生物的控制，比如以细菌为食源的原生动物。本研究旨在量化亚热带淡水水库（巴西圣保罗州圣卡洛斯市的蒙若利尼奥水库）中纤毛虫和异养型纳米鞭毛虫（HNF）在一年时间内对细菌的摄食和清除率，以验证它们在旱/冷和雨/暖两个季节作为细菌消费者和控制者的重要性。为此，每隔两个月使用5-（4,6-二氯三嗪-2-基）氨基荧光素（DTAF）标记的荧光细菌进行原位食细菌实验。尽管纤毛虫的个体摄食和清除率最高，但食细菌作用主要由HNF主导，与纤毛虫（平均492个细菌·小时⁻¹·毫升⁻¹）相比，HNF的群体摄食率更高（平均9140个细菌·小时⁻¹·毫升⁻¹）。对细菌群落的更大捕食影响主要由小型HNF（<5微米）群体造成，尤其是在雨季，这可能是由于该时期这些生物的丰度、降水量、营养指数状态和水温较高。因此，原生动物密度与环境变量对于确定蒙若利尼奥水库食细菌作用的季节模式极为重要。
