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Living at the border: A community and single‐cell assessment of lake bacterioneuston activity
Author(s) -
Hörtnagl Paul,
Pérez Mariá Teresa,
Sommaruga Ruben
Publication year - 2010
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2010.55.3.1134
Subject(s) - betaproteobacteria , actinobacteria , composition (language) , bacteria , environmental chemistry , deposition (geology) , altitude (triangle) , habitat , ecology , biology , chemistry , environmental science , sediment , paleontology , linguistics , philosophy , genetics , geometry , 16s ribosomal rna , mathematics
We assessed the physicochemical properties of the surface microlayer (SML: first 900 µm) and its underlying water (ULW: 0.2–0.5‐m depth) and compared the composition and activity of their bacterial communities in six lakes located across an altitude gradient. Activity was assessed at both the community level, by measuring leucine bulk incorporation, and at the single‐cell level, by using microautoradiography. Catalyzed reporter deposition fluorescence in situ hybridization was used to quantitatively assess the structure of the bacterial assemblage. Dissolved organic matter at the SML was significantly enriched in small‐size molecules as compared to the ULW. Bacterial abundance in the SML ranged from 3.2 × 10 5 cells mL −1 to 3.2 × 10 6 cells mL −1 and was enriched in four out of six lakes when compared to the ULW. The SML and ULW showed lake‐specific differences in bacterial community composition, although in most cases, both layers were dominated by Betaproteobacteria. This group also contributed the most to total activity in both layers in all lakes, followed by Actinobacteria. Despite large differences in environmental conditions among lakes, the fraction of active neustonic bacteria was very similar in most of them. Both bulk and single‐cell activities are not necessarily lower in the SML than in the ULW, and well‐adapted bacteria exist in the extreme conditions found in this habitat.