INVESTIGADORES
GABELLONE Nestor Adrian
artículos
Título:
Phytoplankton structural changes in a saline lowland river (Salado River, Buenos Aires, Argentina) related to the El- Niño and La-Niña periods
Autor/es:
SOLARI LÍA CRISTINA; GABELLONE, N A; CLAPS, MARÍA CRISTINA; CASCO, MARÍA ADELA; QUAINI, KARINA; NESCHUK, NANCY CAROLINA
Revista:
Ecology and Evolution
Editorial:
John Wiley & Sons, Inc.
Referencias:
Año: 2014 vol. 4 p. 918 - 932
ISSN:
1852-2181
Resumen:
We analyzed lower-Salado-River phytoplankton for 10 years (1995?2005). Significant changes occurred in chlorophyte abundance (main alga in abundance, species richness) during a La-Niña event (1998?1999); which period we focussed on, including the basin (mainstream and tributaries), to identify possible indicators of a relationship between climatic phenomena and chlorophyte performance. We compared physicochemical and biologic parameters between two ENSO (El-Niño?La-Niña?Southern-Oscillation) periods: El-Niño (March, 1997?January, 1998) and La Niña, (May, 1998?May, 1999). The ENSO also affected phytoplankton in major South-American rivers, (e. g., Paraná), but not as markedly as in the Salado. Chlorophyte density increased during the La Niña. No pronounced changes in phytoplankton structure occurred during the sampling period. Under normal or extreme hydrologic conditions, mobile (Chlamydomonas spp.)and nonmobile (Monoraphidium spp.) chlorophytes codominated through a high surface-to-volume ratio resulting from small-sized cells?an advantageous feature in lotic water bodies. These species belonged to Reynolds´s functional groups X1 and X2, those typical of nutrient-enriched environments. Comparative analyses between the El Niño and the La Niña periods indicated significant differences in physicochemical (K+, dissolved polyphenols, particulate reactive phosphorus, alkalinity, pH) and biologic (species diversity and richness, phytoplankton and chlorophyte total densities) parameters between the two periods at all basin sites. During the La-Niña condition species richness was greater owing to interconnected shallow lakes and drainage-channel inputs, while the species diversity was lower because of Monoraphidium minutum and Chlamydomonas grovei codominance. Detailed analysis of the basin´s chlorophyte species revealed that changes in species density and dominance were regional; but different subbasins exhibited peculiarities in the density, richness, and species types present.