Assessment of the Trophic Status of the Lagoon-bay of Tiagba in Côte d’Ivoire

The phenomenon of eutrophication was investigated on a period of two years (August 2007 -July 2009) in the lagoon-bay of Tiagba. Throughout this investigation, the bay showed a basic character, a very low salinity (1.82 ± 0.5) mg/L and a weak conductivity (3.34 ± 0.68) mS/cm. The hydrosystem and the growth of anthropogenic activities on its hillsides particularly favored the high rate of phosphorus (0.36 ± 0.22) mg/L and nitrogen (0.46 ± 0.12) mg/L. Consequently, a high chlorophyll-a (43.34 ± 19.33) ^g/L, a low transparency (0.66 ± 0.07) m and a high suspended matters rate (28.87 ± 7.56) mg/L were observed. The trophic status determination, based on three conventional classifications showed that the lagoon bay of Tiagba was in hypereutrophication state. From The monthly observation of hydrochemistry it can be noted a constant hydro eutrophic characteristics of the bay