The temporal variability of planktonic ciliates was studied in an extreme oligotrophic environment with special focus on trophic modes and size classes. Abundance, biomass, size classes, mixotrophy vs. heterotrophy, and species composition of planktonic ciliates were investigated focusing on temporal (samples collected on a monthly basis during 2019) and vertical (7 depth layers in the euphotic zone, from surface to 120 m) distribution at a coastal station in the oligotrophic Eastern Mediterranean. Abundance was in general very low (20 to 1150 cells L^–1), except for September, which presented the highest abundance and biomass. Aloricate species dominated the ciliate community in all months and depths (% contribution from 77% in September to 99% in April). In general, oligotrichs presented maximum abundance at 2–10 m (except for June, July, and November: 100–120 m) whereas choreotrichs were more homogeneously distributed [and showed maxima at deep chlorophyll maximum (DCM)]. Small heterotrophs dominated the ciliate community at all depths and months, on average by 76% (they were 3 times more abundant than mixotrophs in terms of abundance and 2.5 times in terms of biomass). They were equally distributed both vertically and seasonally (and also in terms of size classes). In contrast, mixotrophs were found mainly at the surface layer to 20 m throughout the year, except for June and July (max at 100, 50 m). On average, 63% of integrated aloricate abundance was species <30 μm, of which 25% were mixotrophs. During the stratification period of May to November, the very small (<18 μm) and small (18–30 μm) mixotrophic species were distributed throughout the water column whereas the >50 μm mixotrophic species were found only above the DCM. In contrast, during the mixing period of December to May, mixotrophic ciliates were very few and were dominated by small and medium-sized species. It seems that mixotrophic and heterotrophic ciliates, on one hand, and the four size classes, on the other, are very distinct groups characterized by different distributions both vertically and seasonally. This may have important consequences for the structure and function of the microbial food web of which they are part, as well as for the carbon flow to the higher trophic levels of this oligotrophic environment in which ciliates are the main grazers.

在极端贫营养的环境中研究了浮游纤毛虫的时间变化，特别关注营养模式和大小类别。研究了浮游纤毛虫的丰度，生物量，大小类别，混养与异养和浮游纤毛的物种组成，重点是时间（在2019年期间每月收集的样本）和垂直（在富营养区的7个深度层，从表面到120 m）分布在贫营养东地中海沿岸的一个站。丰度通常很低（20 – 1150个细胞L ^–1），但9月除外，其丰度和生物量最高。在所有月份和深度中，带菌物种在纤毛虫群落中占主导地位（所占百分比从9月的77％增至4月的99％）。一般而言，低聚体在2–10 m处表现出最大丰度（6月，7月和11月除外：100–120 m），而拟南芥则分布更均匀[并且在深叶绿素最大值（DCM）处表现出最大值]。小型异养生物在所有深度和月份都占据着纤毛虫群落的平均水平，平均占76％（就丰度而言，它们比混养生物富集3倍，而生物量则高出其2.5倍）。它们在垂直和季节性（以及尺寸等级）上均等分布。相比之下，混合营养菌主要分布在全年表层至20 m处，除了六月和七月（最大值为100，50公尺）。平均而言，总的藻类丰富度中有63％是小于30μm的物种，其中有25％是混合营养菌。在5月至11月的分层期间，极小的（<18μm）和小的（18–30μm）的混合营养菌分布在整个水柱中，而> 50μm的混合营养菌仅在DCM上方发现。相比之下，在12月至5月的混合时期，混合营养纤毛虫很少，以中小型物种为主。似乎混合营养和异养纤毛虫，另一方面，四个大小类，是非常不同的类，其特征是垂直和季节上的不同分布。这可能会对微生物食物网的结构和功能产生重要影响，