Norf Helge, Arndt Hartmut, Weitere Markus
Zoological Institute, Department of General Ecology and Limnology, University of Cologne, 50931, Cologne, Germany.
Microb Ecol. 2009 May;57(4):687-700. doi: 10.1007/s00248-008-9470-z. Epub 2008 Dec 9.
Four experiments covering different seasons were performed to test the impact of increased benthic and planktonic resource availability on the structure of biofilm-dwelling ciliate communities which were cultivated in river bypass systems. The growth of benthic bacteria was stimulated by the addition of dissolved organic carbon. The enrichment of the planktonic resource was achieved by supplementation with suspended bacteria. It was shown that both resource enrichments can differentially influence abundance and taxonomic structure of ciliate communities. Furthermore, both resources can influence different stages during biofilm colonization. Increased benthic bacterial growth mainly resulted in both an accumulation of primarily grazing-resistant bacterial filaments and in an increase in the number of vagile heterotrophic flagellates. This can stimulate nanophagous ciliates (feeding on flagellates) in addition to the direct stimulation of bacteriovorous ciliates. The effects of the planktonic bacteria enrichments were twofold: They could have been utilized either directly by suspension-feeding ciliates or indirectly through an enhanced growth of suspension-feeding attached heterotrophic flagellates, which were then in turn grazed upon by ciliates. The magnitude of responses of the total ciliate abundance to the two resource enrichments further depended on the background conditions, thereby showing temporarily variable limitations of these resources. Furthermore, the particular taxonomic groups stimulated by one resource type sometimes differed between the experiments, an observation which demonstrates that the response depends on different environmental factors and is not easily predictable based simply on resource type. Taken together, our results emphasize the need of a differentiated view on the effects of resources on complex biofilm-dwelling consumer communities with respect to both the origin of carbon source as well as the particular environmental conditions.
进行了四项覆盖不同季节的实验，以测试底栖和浮游资源可利用性增加对在河流旁路系统中培养的生物膜栖息纤毛虫群落结构的影响。通过添加溶解有机碳来刺激底栖细菌的生长。通过补充悬浮细菌来实现浮游资源的富集。结果表明，两种资源的富集均可不同程度地影响纤毛虫群落的丰度和分类结构。此外，两种资源均可影响生物膜定殖的不同阶段。底栖细菌生长的增加主要导致主要抗捕食细菌丝的积累以及游动异养鞭毛虫数量的增加。这除了直接刺激食细菌纤毛虫外，还可刺激纳米食性纤毛虫（以鞭毛虫为食）。浮游细菌富集的影响是双重的：它们既可以被悬浮取食的纤毛虫直接利用，也可以通过悬浮取食的附着异养鞭毛虫的生长增强而间接利用，而这些鞭毛虫随后又会被纤毛虫捕食。总纤毛虫丰度对两种资源富集的响应程度进一步取决于背景条件，从而表明这些资源存在暂时可变的限制。此外，在不同实验中，受一种资源类型刺激的特定分类群有时会有所不同，这一观察结果表明，响应取决于不同的环境因素，不能仅基于资源类型简单预测。综上所述，我们的结果强调，对于复杂的生物膜栖息消费者群落，需要从碳源来源以及特定环境条件两方面，对资源影响进行差异化看待。
