Petit-saut hydroelectric scheme: vegetal associations of stagnant waters in French Guyana

Abstract

Hydroelectric plant of Petit Saut is under construction on the river Sinnamary in French Guyana. The future reservoir will flood a 300 km area of virgin forest. Under tropical climate as in Brazil or Surinam, the reservoirs are often overgrown with macrophyte vegetation during several years from the start of flooding operations. In order to assess the risks of vegetal proliferations in the future reservoir of Petit Saut, rnacrophyte lists have been made out with special attention to some prolific pecies (Eichhornia crassipes, Salvinia auriculata, Pistia stratiotes, Oxycariurn cubense, etc.) in all types of aquatic environments (marshes, ditches, canals, ricefields, etc) by using phytosociological method (abundance/dorninance indice). A correspondence analysis of data have permitted to show the relationships between specific vegetal communities and typical water environments. The spatial distribution of the macrophyte communities in these various environments according to their limnological features constitute a starting point for devising the mean to limit their proliferations.