Résumé
In West Africa lagoons, structures made of brush, palms or bamboos (called Acadja) are installed in shallow zones creating a particular biotope in order to induce the development of periphytic material attracting or supporting the requirements of phytophagous fishes. First stages of bamboo colonization by bacterial and algal communities (biomasses and productions) were followed during 48 days in an experimental structure at the Layo aquaculture station (Ebrie lagoon, Cote-d'Ivoire). Water samples were collected near the structure to characterize the hydrobiological environment (turbidity, conductivity, nutrients, bacterial and phytoplanctonic biomass). Samplings of periphytic material were collected at different levels (5, 30 and 50 cm) on bamboos (average length of 90 cm). Bacterial microflora are the first microorganisms colonizing the bamboo with abundances close to 5* 10(7) bacteries cm(-2), maximal biomass observed after 35 days of colonization and maxima of tritiated thymidine incorporation values noted after 20 days. After bacterial colonization, adnate diatoms, bentho-pelagic and filamentous species rapidly appeared with a temporal evolution following a logistic type pattern. The final composition of algal communities seemed to be reached after 3 weeks of colonization although the algal biomass raised to 190 mg of chlorophyll after 48 days. Variations of primary production followed the same pattern than those of biomass with progressive increase of values with time and depth. Simultaneous development of bacterial and algal activities during the colonization suggests a trophic linkage between the two periphytic communities growing on bamboos.