Reponse des differents taxons meiofaunistiques a la contamination par un antibiotique (la Penicilline G) : etude microcosmique

Abstract

Microcosm experimentation : A microcosmic experimentation was conducted to determine the effect of antibiotic (Penicillin G) on communities meiofaunistiques collected at the sediment of Bizerte lagoon (Northern Tunisia). Five increasing doses of this emerging contaminant (D1: 3 mg, L super(-1), D2 : 30 mg. L super(-1) D3: 300 mg. L super(-1), D4: 600 mg. L super(-1) and D5: 700 mg. L super(-1)), were used. After 30 days of exposure a microcosmic experimentation was conducted. Meiofauna of Bizerte lagoon was affected by increasing doses of penicillin G added. Thus, the densities meiofaunistiques averages were very volatile. The microcosm witness showed an average value of 91,33 plus or minus 22.05 ind. mic super(-1). A rise in the average density of meiofauna was observed with lower doses of the contaminant. Thus, an average value of 161.33 plus or minus 10.96 ind. mic super(-1) was calculated for the first dose (3 mg. L super(-1)) and a value of 220 plus or minus 21.93 ind. mic-1 for the second dose (30 mg. L super(-1)).This latter value is the highest average density of experience. Beyond this dose fall meiofaunistiques average densities was noticed. Thus, values of 85 plus or minus 10.53 ind. mic-1, 54 plus or minus 9.35 ind. mic-1 and 20 plus or minus 1 ind. mic super(-1) were respectively observed in the microcosms treated by D3 doses (300 mg. L super(-1)), D4 (600 mg. L super(-1)) and D5 (700 mg. L super(-1)). Free-living nematodes, meiofaunistique dominant taxon of marine and lagoon sediments were responsible for the fluctuation of the density of total meiofauna. Meiofaunistique other groups (copepods, polychaetes, oligochaetes) were less decisive.