Biogeochemistry

, Volume 17, Issue 2, pp 85–121

Nutrient dynamics in the floodplain ponds of the Paraná River (Argentina) dominated by the water hyacinth Eichhornia crassipes.

  • Richard Carignan
  • Juan José Neiff
Article

DOI: 10.1007/BF00002642

Cite this article as:
Carignan, R. & Neiff, J.J. Biogeochemistry (1992) 17: 85. doi:10.1007/BF00002642

Abstract

Some aspects of nutrient status and dynamics prevailing during low and high water conditions in the fringing floodplain ponds of the Paraná River dominated by the floating macrophyte Eichhornia crassipes are described. During summertime low water conditions, low DIN:DRP ratios (0.16–1.0) and low DIN (0.5–4.8 μmol.liter−1) in the root-zone of the floating meadows suggest that macrophyte growth is limited by nitrogen. DRP concentrations appear to be controlled more by abiotic sorption-dissolution than by biological reactions. Preflood nutrient fluxes from the sediments, as estimated from porewater profiles, show that a minimum of 1.19 and 0.38 mmol.m−2.d−1 of DIN and DRP were regenerated from the sediments, respectively. Heterotrophic N2 fixation is primarily associated with decaying litter (0.4 to 3.2 μmolN2.g−1.d−1). Nutrient recycling from sediments and meadow-litter, and heterotrophic N2 fixation (1.4 mmolN.m−2.d−1) appear sufficient to sustain high floating macrophyte productivity for long periods of time, without invoking large inputs from the river. The high water and early isolation periods are characterized by a very dynamic behavior of DIN, reflecting marked imbalances between N supply and demand by the biota. After hydrologic isolation of the ponds, DIN rapidly decreases to undetectable levels and stays low for the following 3 weeks, presumably as a result of high demand by phytoplankton and sediment bacteria. DIN increases again to high values 3–8 weeks after the flood, following the re-establishment of NH4+ fluxes from the sediments. Compared to DIN, DRP concentrations remain relatively high and change little during and after the flood. Because of their small amplitude and short duration, floods do not appear to stimulate floating macrophyte production in the Paraná.

Key words

nitrogen fixationphosphorusinternal loadingwater hyacinthfloodplainParanáflood-pulse hypothesis

Copyright information

© Kluwer Academic Publishers 1992

Authors and Affiliations

  • Richard Carignan
    • 1
  • Juan José Neiff
    • 2
  1. 1.Université du QuébecINRS-EauSte-Foy (Qc)Canada
  2. 2.Centro de Ecología Aplicada del LitoralConsejo Nacional de Investigaciones Científicas y TécnicasCorrientesArgentina