Algal assemblages across a wetland, from a shallow lake to the relictual oxbow lakes (Lower Paraná Rive, South America)

IZAGUIRRE, I.; O´FARRELL, I.; UNREIN, F.; SINISTRO, R.; DOS SANTOS AFONSO, M.; TELL, G.

HYDROBIOLOGIA

Kluwer Academic Publishers

Año: 2004 vol. 511 p. 25 - 36

0018-8158

This study deals with the variation in the algal assemblages across the transversal dimension of a wetland of the Lower Paraná River from October 1998 to September 1999. The relationship between the algal composition and the physico-chemical variables is analyzed by means of Canonical Correspondence Analysis. The abundant floatingmacrophytes generated a severe reduction in light penetration in the relictual oxbowlakes (ROLs), almost anoxic conditions and high values of P, N and K. Such characteristics accounted for their very particular algal flora dominated by Cyanobacteria and several diatoms, species probably mixotrophic regarding their capacity to grow in darkness and tolerate very low oxygen contents. In the shallow lake, the phytoplankton comprised many small autotrophic green algae, accompanied by many flagellates of the classes Cryptophyceae, Euglenophyceae and Dinophyceae. Our results indicate that the macrophyte cover was probably the stirring factor in the selection of algal species along the transitional zone comprising a floodplain shallow lake and several ROLs.