Laboratory of Aquatic Photobiology and Plankton Ecology, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
FEMS Microbiol Ecol. 2010 Sep;73(3):458-67. doi: 10.1111/j.1574-6941.2010.00904.x. Epub 2010 May 25.
The existence of bacterioneuston in aquatic ecosystems is well established, but little is known about its composition and dynamics, particularly in lakes. The bacterioneuston underlies extreme conditions at the air-water boundary, which may influence its dynamics in a different way compared with the bacterioplankton. In this study, we assessed quantitative changes in major bacterial groups of the surface microlayer (SML) (upper 900 microm) and the underlying water (ULW) (0.2-0.5 m depth) of an alpine lake during two consecutive ice-free seasons. Analysis of the bacterial community composition was done using catalyzed reporter deposition FISH with oligonucleotide probes. In addition, several physicochemical parameters were measured to characterize these two water layers. Dissolved organic carbon was consistently enriched in the SML and the dissolved organic matter pool presented clear signals of photodegradation and photobleaching. The water temperature was generally colder in the SML than in the subsurface. The bacterial community of the SML and the ULW was dominated by Betaproteobacteria and Actinobacteria. The bacterial community composition was associated with different combinations of physicochemical factors in these two layers, but temporal changes showed similar trends in both layers over the two seasons. Our results identify the SML of alpine lakes as a microhabitat where specific bacterial members such as of Betaproteobacteria seem to be efficient colonizers.
水生生态系统中存在细菌浮层这一现象已得到证实，但人们对其组成和动态，特别是在湖泊中的组成和动态知之甚少。细菌浮层存在于空气-水边界的极端条件下，这可能会以与浮游细菌不同的方式影响其动态。在这项研究中，我们评估了高山湖泊在两个连续无冰季节中，表水层（上 900 微米）和底层水（0.2-0.5 米深度）中主要细菌群的定量变化。使用寡核苷酸探针的催化报告沉积荧光原位杂交（CARD-FISH）分析了细菌群落组成。此外，还测量了几个物理化学参数来描述这两个水层。溶解有机碳在表水层中一直富集，而溶解有机质库则呈现出明显的光降解和光漂白信号。表水层的水温通常比底层水更冷。表水层和底层水的细菌群落主要由β变形菌门和放线菌门组成。这两个水层的细菌群落组成与不同的物理化学因素组合有关，但在两个季节中，两个水层的时间变化都表现出相似的趋势。我们的研究结果表明，高山湖泊的表水层是一个微生境，其中某些特定的细菌成员，如β变形菌门似乎是有效的定植者。
