INVESTIGADORES
PIZARRO Haydee Norma
artículos
Título:
Littoral epilithon of lentic water bodies at Hope Bay, Antarctic Peninsula: biomass variables in relation to environmental conditions.
Autor/es:
PIZARRO, H; L. ALLENDE; S.M. BONAVENTURA
Revista:
HYDROBIOLOGIA
Editorial:
Springer
Referencias:
Año: 2004 vol. 529 p. 237 - 250
ISSN:
0018-8158
Resumen:
Abstract
We studied the structural characteristics of the littoral epilithon in nine lentic water bodies at Hope Bay,
Antarctic Peninsula, during summer 2002. At each site we measured the main physical and chemical
variables and took epilithic samples for the analysis of dry weigh, ash, ash-free dry weight and chlo-
rophyll a concentration. Distance from the sea of each water body was also considered. One site was
selected for sampling lakes and ponds, except for Boeckella lake, where two sampling sites (A and B)
were selected due to the heterogeneity of its littoral zone. Three stones for chlorophyll a analysis and
another three to estimate dry weight, ash and ash-free dry weight, were taken randomly about 1m away
from the shore-line of each sampling site. Measurements of physical and chemical characteristics were
obtained similarly. Water samples for chemical analysis were taken sub-superficially. Lakatoss system of
classification and the Autotrophic Index were used to make functional inferences about the epilithic
communities. Two PCA analyses were made to classify the water bodies according to environmental
features and epilithic variables. In the latter, major patterns in data of epilithon were subsequently
interpreted based on environmental data using external validation. Pingu¨ i pond, located in the middle of
the penguin rookery, was considered as a passive sample in both PCA analyses due to its extreme
characteristics. Limnological features of the studied water bodies were similar to those of other Maritime
Antarctic lakes. According to the Lakatoss index, 60% of the sampled lakes had high epilithic mass and
a same proportion showed an inorganic type of epilithon The fact that 40% of the water bodies were
autotrophic confirmed the importance of benthos as primary producer. According to environmental
features, the well-defined groups of lakes emerged from the PCA were mainly determined by distance
from the sea, pH, conductivity and salinity, and corresponded to the principal hydrological basins found
in the region. Based on the results of the second PCA, littoral epilithon was affected by nitrate con-
centration and conductivity. In this ordination, water bodies from the same hydrological basin were
separated probably as a result of a very complex inter-play of factors with a site-specific response to
particular microhabitat characteristics.