| Title | Bacterial diversity and morphology in deep ultraoligotrophic Andean lakes: role of UVR on vertical distribution |
| Abstract | We investigated the community composition and the relative size and shape distribution of bacterial assemblages in deep transparent lakes, where bacteria may be affected by harmful ultraviolet radiation (UVR). Summer samples of the euphotic zones of nine ultraoligotrophic lakes located in different drainage basins between 40°27' and 42°49'S in the North Andean Patagonia were analyzed for relative diversity by denaturating gradient gel electrophoresis and the bacterial morphology (free-living cocci and rods vs. filamentous forms) in relation to environmental factors (UVR, photosynthetically active radiation, temperature, nutrients, nanoflagellates, and ciliate abundances). The overall bacterial community composition was similar in all lakes and over depth in each lake. In contrast, the relative proportion of filaments to total bacterial biovolume was higher in the upper layers, which have higher UVR intensities (305-340 nm). Lakes with lower Kd305 (diffuse extinction coefficient, 305 nm) showed a greater proportion of filaments. Filament mean length in the upper layers was also significantly greater than at deeper levels. There was a significant correlation between UVR and filament proportion, whereas neither nanopredator abundances (nanoflagellates and ciliates), nor predation pressure, nor resources (dissolved nutrients) could explain the high proportion of filamentation in the near-surface layers. We propose that UVR plays a decisive role stimulating bacterial filamentation, particularly in lakes with high UVR penetration. |
| Source | Limnology and oceanography 54(4), pp. 1098–1112 |
| Keywords | Bacterial diversityAndean lakesUV radiation |
| Journal | Limnology and oceanography |
| Editor | American Society of Limnology and Oceanography., [Waco, Tex., etc.], Stati Uniti d'America |
| Year | 2009 |
| Type | Articolo in rivista |
| DOI | 10.4319/lo.2009.54.4.1098 |
| Authors | Corno, G., B. Modenutti (1), C. Callieri, E. Balseiro (1), R. Bertoni & E. Caravati. |
| Text | 53138 2009 10.4319/lo.2009.54.4.1098 ISI Web of Science WOS 000268325100007 Bacterial diversity Andean lakes UV radiation Bacterial diversity and morphology in deep ultraoligotrophic Andean lakes role of UVR on vertical distribution Corno, G., B. Modenutti 1 , C. Callieri, E. Balseiro 1 , R. Bertoni E. Caravati. 1 Laboratorio de Limnolog1a, INIBIOMA, CONICET UNComahue, Bariloche, Argentina We investigated the community composition and the relative size and shape distribution of bacterial assemblages in deep transparent lakes, where bacteria may be affected by harmful ultraviolet radiation UVR . Summer samples of the euphotic zones of nine ultraoligotrophic lakes located in different drainage basins between 40°27 and 42°49 S in the North Andean Patagonia were analyzed for relative diversity by denaturating gradient gel electrophoresis and the bacterial morphology free living cocci and rods vs. filamentous forms in relation to environmental factors UVR, photosynthetically active radiation, temperature, nutrients, nanoflagellates, and ciliate abundances . The overall bacterial community composition was similar in all lakes and over depth in each lake. In contrast, the relative proportion of filaments to total bacterial biovolume was higher in the upper layers, which have higher UVR intensities 305 340 nm . Lakes with lower Kd305 diffuse extinction coefficient, 305 nm showed a greater proportion of filaments. Filament mean length in the upper layers was also significantly greater than at deeper levels. There was a significant correlation between UVR and filament proportion, whereas neither nanopredator abundances nanoflagellates and ciliates , nor predation pressure, nor resources dissolved nutrients could explain the high proportion of filamentation in the near surface layers. We propose that UVR plays a decisive role stimulating bacterial filamentation, particularly in lakes with high UVR penetration. 54 4 Articolo pubblicato Per la prima volta si e dimostrato in situ l effetto degli UV sulla filamentazione dei batteri in laghi ultraoligotrofi nord patagonici dove c e un forte impatto dell UV sulle comunita acquatiche. 2_Corno_et_al_2009_L_O.pdf Articolo in rivista American Society of Limnology and Oceanography. 0024 3590 Limnology and oceanography Limnology and oceanography Limnol. oceanogr. Limnology and oceanography. gianluca.corno CORNO GIANLUCA CARAVATI EMANUELE roberto.bertoni BERTONI ROBERTO cristiana.callieri CALLIERI CRISTIANA TA.P02.014.002 Impatto dei cambiamenti globali sugli ecosistemi acquatici |
