INVESTIGADORES
BOLTOVSKOY Demetrio
artículos
Título:
Latitudinal patterns and interannual variations of spring phytoplankton in relation to hydrographic conditions of the southwestern Atlantic Ocean (34°?62°S)
Autor/es:
OLGUÍN SALINAS HF; BRANDINI F; BOLTOVSKOY DEMETRIO
Revista:
HELGOLAND MARINE RESEARCH
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2015
ISSN:
1438-387X
Resumen:
In the present study, the distribution and abundance
of microphytoplankton were assessed in the southwestern
Atlantic Ocean from subtropical to polar waters
(34?62S) in two austral springs with contrasting hydrographic
conditions. Vertical profiles of open-ocean (ca.
54W) samples (C 18 L filtered water) were performed in
20 stations (0?100 m) in 1994 and in 17 stations (0?50 m)
in 1995. The latitudinal patterns of microphytoplankton
groups, chlorophyll a, and diatom and silicoflagellate species
were analyzed and compared with our previous study
carried out in spring 1993 (30?61S). In the three springs,
197 diatom species, 173 of which showed mean relative
density lower than 1 %, were identified. A consistent diatom
biogeographic pattern emerged in the three consecutive
springs, defining the Transitional (corresponding to
the Brazil?Malvinas Current Confluence), Subantarctic and
Antarctic Zones; and the Subantarctic and Polar Fronts, as
their boundaries. This zonation reflects persistent features
of this hydrographically heterogeneous region. The Polar
Front was a weaker biogeographic boundary for diatom
species than the Subantarctic Front. Interannual changes in
diatoms (mainly in species richness, dominant species and
degree of dominance of species with different ecological
affinities) were detected. The Transitional Zone, which is
one of the most hydrographically variable regions of the
world ocean, showed the highest changes in the diatom
assemblage, reflecting a colder spring in 1995 and a warmer
spring in 1994 than normal (1993). These changes agreed
with differences reported for 1993?1995 in large-scale hydrographic
conditions, including a widespread diversity
decrease in 1995 due to a weaker influence of subtropical
waters.