INTERFERING PARAMETERS IN THEEUTROPHICATION OF THE SURFACE WATEROROS RESERVOIR, CEARA STATE, BRAZIL

The main goal aim of this work was study the parameters that influence in the spatial variation of the chlorophyll "a" in the surface water of the Oros reservoir, Ceara state, Brazil. It was studied the comparison of the water in that reservoir, too. Twelve water samples were taken in seven different sites in the reservoir. They were sampled every two months from April/2008 to April/ 2010. Total phosphorus, water temperature, water transparency and the chlorophyll "a" production were analyzed. To assessment the eutrophication between the sampled sites it was used the Hierarchical Cluster Analysis. Results showed that the eutrophication allowed observes that the water temperature, water transparence and total phosphorus are influential in the chlorophyll "a" production. The increasing of the water temperature increase the chlorophyll "a" concentration. Hierarchical Cluster Analysis showed that the sampled sites 1 and 2 are similar in relation to water eutrophication and it separates the water in two different groups. The group 1 was formed because of the both high sediment concentration and the low levels of chlorophyll "a" and the group 2 was formed because of the both high water temperature values and high chlorophyll "a" concentration.