Dynamique de structuration spatio-temporelle des populations de familles de macroinvertébrés dans un continuum lac de barrage-effluent-fleuve issu de périmètre irrigué. Bassin de la Volta (Burkina Faso)

Abstract

Objective: A monthly sampling of benthic macroinvertebrates was done at the hydro-agricultural of dam Boura in the basin of the Volta (Burkina) during the period of February to July 2012 in order to describe the structuring of insect succession along with changes occurring in habitats of this irrigation system.
Methodology and results: The samples of insects were collected from 6 stations placed on the shoreline (Station I), the adjoining zone to the coastline (Station II), the sewage channal (stations III, IV that is located at midsection of the irrigated area and the Station V far away from this area) and the Mouhoun stream (Station VI); the sampling method used conventional method the European Union named " Directive Cadre sur l’Eau (DCE) " advised for the sampling of the benthics macroinvertebrates. The survey revealed a community composed in majority of insects (more of 75%) and sparsely distributed. On one hand at the shoreline and the coastal- adjoining zone in the lake of dam, 23 families of macroinvertebrates were sampled; they mostly belong to the shoreline except for 10 families identified in the adjoining zone to the coastline. These two zones of the dam shelter the same malacological fauna consisting of the families of Unionidae, Lymneidas, Ampullariidae, Planorbidae, Valvatidae and Bulinidae. The survey revealed otherwise that the difference between the biological diversity indices of Shannon of these two zones was more pronounced during the month of July, period of rain in the basin., concerning the dam-sewage channal-river continuum, a total of 35 families were sampled: 27 from dam water and stations near the irrigated zones; and 32 been collected from the station of the sewage channel far from the irrigated perimeter and from the stream. The identification of individuals belonging to the family of the Baetidae and the Ephemerellidae (order of the Ephemeroptera) in the river water highlights a possible reconstruction of biodiversity in the river because both two families are indicator fertile water.
Conclusion and application of results: it is concluded of this survey that the agricultural hydro amenities have an influence on the spatio-temporal structuring of the macroinvertebrates. The results of this survey can be used otherwise to keep biodiversity and the restoration of these ecosystems continually impacted.

Keywords: macroinvertebrates; succession; continuum; hydro-agricultural dams; irrigation; river; Mouhoun; Volta basin.