Alternative states drive the patterns in the bacterioplankton composition in shallow Pampean lakes (Argentina)

LLAMAES, MARIA EUGENIA; DEL GIORGIO, PAUL; ZAGARESE, HORACIO; FERRARO, MARCELA; IZAGUIRRE, IRINA

Environmental Microbiology Reports

Blackwell

Año: 2013

1758-2229

We assessed the influence of environmental factors in shaping the free-living bacterial community struc- ture in a set of shallow lakes characterized by contrasting stable state patterns (clear-vegetated, inorganic-turbid and phytoplankton-turbid). Six tem- perate shallow lakes from the Pampa Plain (Argen- tina) were sampled over an annual cycle, and two fingerprinting techniques were applied: a 16S rDNA analysis was performed using DGGE profiles, and a 16S–23S internally transcribed spacer region analy- sis was conducted by means of ARISA profiles. Our results show that the steady state that characterized the different shallow lakes played a major role in structuring the community: the composition of free- living bacteria differed significantly between clear- vegetated, inorganic-turbid and phytoplankton-turbid shallow lakes. The state of the system was more important in determining these patterns than season- ality, geographical location or degree of hydrological connectivity. Moreover, this strong environmental control was particularly evident in the pattern observed in one of the lakes, which shifted from a clear to a turbid state over the course of the study. This lake showed a directional selection of species from a typical clear-like to a turbid-like community. The combined DGGE/ARISA approach revealed not only broad patterns among different alternative steady states, but also more subtle differences within different regimes.