Response of eolian ecosystems to minor climatic changes

MARCOMINI, S.; MAIDANA, N. I.

JOURNAL OF COASTAL RESEARCH

COASTAL EDUCATION & RESEARCH FOUNDATION

Año: 2006 p. 204 - 208

0749-0208

The coastal dunefield of northern Buenos Aires has been affected by two main factors: rainfall changes and urbanization. It was determine a trend to humid conditions since 1960. The changes detected on the dune fielddescribed were: (1) increase on the vegetation cover and deflation processes over active landforms; (2) decrease in dune migration rates; (3) increase on the beach erosion; (4) degradation of the dune landforms. After one of the largest flood occurred in July 2001 in the eastern Buenos Aires, the intertidal lows of the active dunes began to be permanent flooded by an increase of the water table. This fact induced changes on the dune ecosystem to adapt to new conditions. After this event the lakes began to be colonized by algae and fungi probably transported by winds. Diatoms (Rhopalodia, Nitschia, Navicula, Cymbella and Neidium); chlorophytes (Chlamydomonas, Cosmarium, Bulbochaete, Oedogonium and Chaetosferidium spp); euglenophytes (Euglena). Cianobacteria (Nostoc spp) and filamentous fungi growed between submerged macrophytes. In the bottom of the lakes appeared diatoms (Cymbella, Rhopalodia, Surirella, Amphora and Nitzschia spp.), dinofagellates and ostracods. On the lakes margins some species of vascular plants Spartina ciliata, Convolvulaceae (Dichondra sp, Panicum racemosum colonized the margins while the lakes got dry. Large bioturbation was also detected on the margins caused by holes made by toads (Bufo arenarum) and tubes of worms with complex trellis patterns. Buried subsuperfitial numerous spiders (Licosidae trochosa) were also found on the subaqueous margin of the lakes.