Communautés, biomasses et productions algales au sein d'un récif artificiel (acadja) en milieu lagunaire tropical = Algal communities, biomasses and production in an artificial reef (Acadja) built in a brackish tropical lagoon
Guiral, D.; Arfi, R.; Da, K.P.; Konan-Brou, A.A. (1993). Communautés, biomasses et productions algales au sein d'un récif artificiel (acadja) en milieu lagunaire tropical = Algal communities, biomasses and production in an artificial reef (Acadja) built in a brackish tropical lagoon. Rev. Hydrobiol. Trop. 26(3): 219-228
In: Revue d'Hydrobiologie Tropicale. Editions ORSTOM: Bondy. ISSN 0240-8783, more
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| Authors | | Top |
- Guiral, D.
- Arfi, R.
- Da, K.P.
- Konan-Brou, A.A.
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| Abstract |
In an extensive aquaculture structure established in an oligohaline and turbid area of the Ébrie Lagoon (Côte d'Ivoire), biomass production, energetic yields and specific composition of the phytoplanktonic and periphytic communities are compared. The structure, called acadja corresponds to an artificial reef of bamboo stuck into the sediment. The periphytic and phytoplanktonic biomasses within the acadja were 4 times higher than that of lagoon water and 73 % of this biomass corresponded to the fixed community. The total autotrophic production of acadja estimated at 9.9 g C.m-².j-¹ was 4.5 times higher than that of lagoon water, of which 80 % are produced by the periphytic population. This high productiuity of acadja is linked to: -an important spatial concentration of the periphyton which is not exposed to the hydrodynamic effects and is little affected by sedimentation processes; -a productiuity per biomass unit and a photosynthetic efficiency significantly higher for fixed communities than for pelagic communities. The periphyton included 3 groups of filamentous algae dominated by a Chlorophyceae (Rhizoclonium riparium) and some Cyanobacteria of the genus Lyngbia for the more productive surface layers and a Rhodophyceae (Audouinella daviesii) for deeper layers. These filamentous algae were in turn colonized by epiphytic Diatoms forming a diversified (37 species) sub-community dominated by the genera Melosira and Nitzschia. Considering the high photosynthetic yield of the fixed communities (5.2 % for periphyton against 0.8 % for phytoplankton), acadja allows a noticeable increase in the natural productivity of the lagoon environment. In acadja, phytophagous fish farming would constitute a possible use of the surplus autotrophic production. |
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