Phytoplankton of the Chaco-Pampean Plain

YOLANDA ZALOCAR DE DOMITROVIC; DEVERCELLI, MELINA; FORASTIER MARINA E.

FUNDAMENTAL AND APPLIED LIMNOLOGY

E SCHWEIZERBARTSCHE VERLAGS

Lugar: Stuttgart; Año: 2014 vol. 65 p. 81 - 98

1863-9135

Abstract: This article summarizes the characteristics of phytoplankton of the Chaco-Pampean Plainbetween the Pilcomayo River (25º15?S; 57º45?W) and the Lower Salado River (31º39?S; 60º45?W)towards the Paraguay-Paraná system. This subtropical area has a climate gradient from east (wet) towest (arid). Rivers and streams have a seasonal regime, with fl oods in autumn and dry periods at theend of winter. These hydrological fl uctuations appear to be the driving forces of the phytoplanktoncommunity. During low waters (fl ow reduction and increase in salinity), diversity is reduced anddensity of euryhaline species is increased. The highest algal development in this area was observedduring the extraordinary low water period of La Niña. In occasions of environmental stability and hightemperatures, water blooms of Anabaenopsis arnoldii, A. nadsonii and Nodularia harveyana have beenrecorded.The lenitic environments of the western region (arid) show marked fl uctuations in extension and depthand may dry during periods of scarce precipitations. Phytoplankton density is low and represented bysmall Chlorococcales and Euglenophyceae. Water blooms of Dolichospermum spp. and Cylindrospermopsisraciborskii are frequent. Shallow lakes and wetlands of the eastern region (wet), which havepresence of macrophytes and high organic matter, are dominated by Cryptophyceae, Chlorococcalesand a wide variety of species of Euglenophyceae and diatoms. The Ramsar Site called ?HumedalesChaco? has the greatest diversity of species in this region