INVESTIGADORES
IZAGUIRRE Irina
artículos
Título:
Nanoplankton diversity in Maritime Antarctic lakes: characterization and molecular fingerprinting comparison
Autor/es:
UNREIN, F., I. IZAGUIRRE, R. MASSANA, V. BALAGUÉ Y J. GASOL
Revista:
AQUATIC MICROBIAL ECOLOGY
Editorial:
Inter- Research Science Center
Referencias:
Año: 2005 vol. 18 p. 269 - 282
ISSN:
0948-3055
Resumen:
The composition of planktonic eukaryotes in the size fraction 320 µm of 10 maritime
Antarctic lakes was studied by denaturing gradient gel electrophoresis (DGGE). Microscopic observations
were also carried out to compare the results obtained by this molecular fingerprinting technique
with morphological data. Six lakes from Hope Bay (Antarctic Peninsula) and 4 from the Potter
Peninsula (King George Island) were sampled during the austral summer of 2003. These lakes were
of different trophic status and covered a wide range of limnological features. Previous studies of the
planktonic communities of these lakes revealed high nanoflagellate abundance and biomass, but
their taxonomic identification was usually uncertain due to their similarity in size and shape. Here,
the application of DGGE allowed both a comparison of the structure of the nanoplanktonic communities
and an identification of the dominant populations through sequencing of the most prominent
DGGE bands. The most important organisms in these lakes were the Chrysophyceae, represented in
the DGGE gel by 5 different band positions and identified by microscopy in 5 different morphotypes,
including uniflagellated and biflagellated naked organisms: 1 sequence belonged to the Chrysosphaerales,
2 closely related bands (likely 2 species from the same genus) belonged probably to the
Ochromonadales (unicellular biflagellates), while the other 2 bands could not be assigned to any
defined chrysophyte group. Sequences related to Chlorophyceae, Bacillariophyceae and probably
Cercozoa were also retrieved. A Dictyochophyceae belonging to the order Pedinellales is reported for
the first time in freshwater Antarctic ecosystems. Microscopic observations suggest that this phytoplanktonic
organism most likely corresponds to Pseudopedinella. Most of the lakes shared several
common sequences, such as 2 chrysophyte bands, which suggests the existence of well-adapted
nanoplanktonic species dispersed throughout the Antarctic lakes. However, some sequences
appeared exclusively in specific lakes, which seems to be related to the trophic status of the water
bodies and probably also to the local conditions of the maritime Antarctic regions sampled.Pseudopedinella. Most of the lakes shared several
common sequences, such as 2 chrysophyte bands, which suggests the existence of well-adapted
nanoplanktonic species dispersed throughout the Antarctic lakes. However, some sequences
appeared exclusively in specific lakes, which seems to be related to the trophic status of the water
bodies and probably also to the local conditions of the maritime Antarctic regions sampled.