Biogeography of bacterioplankton assemblages in a latitudinal gradient of lakes from Patagonia to Antarctica

SCHIAFFINO, M. R.; UNREIN, F.; GASOL, J. M.; MASSANA, R.; BALAGUÉ, V.; IZAGUIRRE, I.

San Juan

Congreso; 2011 ASLO Aquatic Sciences Meeting; 2011

American Society of Limnology and Oceanography

Bacterioplankton structure was analyzed in 45 freshwater environments (lakes, shallow lakes, ponds) across a >2,100 km transect, from Argentinean Patagonia (45°S) to Maritime Antarctica (63°S) in a gradient of increased latitude and climate severity. Bacterioplankton community composition (BCC) was assessed by a fingerprinting method (denaturing gradient gel electrophoresis-DGGE) followed by band sequencing, whereas the bacterial abundance was estimated by epifluorescence microscopy. Both lake area and latitude had a significant effect on BCC and operational taxonomic unit (OTU) richness. Lake trophic state and latitude showed a significant influence on bacterioplankton abundance. OTU richness and total bacterioplankton abundance declined significantly with increased latitude, and lake area was positively correlated with OTU richness. Of 76 different OTUs identified, 45 were shared between Patagonian and Antarctic water bodies, 28 were present only in Patagonian lakes and 3 were exclusive of the Antarctic lakes. Among the sequences, 54% were similar to others reported from cold habitats elsewhere on the planet. Our results indicate there are both environmental and spatial factors controlling bacterioplankton community structure and support the hypotheses of biogeographic patterns of bacterial assemblages.