Abstract

With the new data on bathymetry, currentology, in this ecosystem and the abiotic variables studied from February to May 2007, a review of the Manche-à-Eau’s biological zonation recently stated from the fish assemblage is proposed. The water volume turnover at each tide (14,8%) twice a day combined with an active and various hydrodynamism contribute to vivify the lagoon and provide information for a better interpretation of the Well-Being Index values and the populational parameters gradients of the fish assemblage. During the studied period, no gradient is observed with the abiotic variables. The water characteristics are homogeneous everywhere in the lagoon, in the water column and whatever the period studied (temperature: 30,02°C; salinity: 36,16 ‰; pH: 8,29; turbidity: 6,10 mg/L; conductivity: 5,51S/m; dissolved oxygen: 7,18mg/L; dissolved solids: 32,78g/Ll; osmolarity: 1021,7milliosmoles). A revised biological zonation of the Manche-à-Eau lagoon is proposed. According to the quality observed, it is made of three zones, instead four, from II to IV: the zone II is more spread at South and narrow along the island, the zone III occupies the geater part of the ecosystem and the zone IV centered on the two main depressions at South and West, on the shallows and its North-West border and the end of the sector enclaved at South-West.

PDF Preview