This study investigates the impact of sand dredging activities on coastal ecosystem and community survival around Ibeshe area of the Lagos Lagoon, Nigeria. Surface water and bottom sediment samples were collected from locations partitioned into Dredged Area (DA) and Undredged Area (UA) in the lagoon for laboratory analyses. Questionnaires were administered to community dwellers and sand miners to further analyze perception of locals. Significant differences in water quality parameters and sediments properties from Dredged and Undredged areas, and highly significant relationship between sand dredging and unsustainable ecological practices in Ibeshe were observed. One way ANOVA test indicates that all water quality parameters measured with exception of turbidity and nitrate concentration were not significantly different (P > 0.05) between Dredged and Undredged area. With exception of moisture content other sediment parameters measured were not significantly different (P > 0.05) between Dredged and Undredged areas. The project also determined the impact of dredging activities on the fisheries and fishing business in the environment. Turbidity values revealed that fishes will be negatively affected due to dredging activities; moreover dwellers pay little or no attention to conservation of the area due to unawareness. Sand dredging operations negatively influence ecological resources and water composition of the area. This project is designed to randomly sample the opinion of sand mining operators and residents; and questionnaires were administered to obtain data. Strict regulation and enforcement will assist to control ecological destruction and solve problems facing the lagoon environment.

The nutrients (nitrate, nitrite, phosphate and silicate) of thirty-two stations in Ilaje, coastal waters and estuaries of Ondo state, Nigeria were studied in the month of August (during the wet season). The stations consist of two estuaries; Awoye (A1-A6), Abereke (AB1-AB7), anthropogenic impacted stations (I1-I12) and control stations (C1-C7). The aim of this study is to evaluate the eutrophication status of Ilaje coastal waters and estuaries in response to the stress caused by anthropogenic inputs from land use changes, agriculture, and industrial effluents. Our study reveal highest nitrate (3.20-6.98 mg/l) and phosphate (11.59-17.48mg/L) concentrations at the Abereke Estuaries. The significant correlation of nitrate with chlorophyll-a (p<0.01, r= +0.886) and the low N/P (<0.25) ratio suggest that nitrate is the primary limiting nutrient for phytoplankton production, and accounted for the high chlorophyll-a concentrations in the study area. The strong correlation of nitrite and silicate from the statistical bi-plots at the impacted stations, and the accompanied lowest dissolved oxygen (<5 mg/L) and acidic pH (<6) values suggest nitrite and silicate are sourced from anthropogenic effluents. The mean nitrite concentrations of 0.13mg/L at the impacted stations above the maximum permissible limit of nitrite (0.06 mg/L) for Tilapia production suggest an unfavorable environment for the Tilapia growth at the impacted stations. The chlorophyll-a concentrations scale further showed that the study area is characterized as bad eutrophication status (> 2.21 µg/L) an indication of the presence of heterogeneous phytoplankton community during the wet season. The study highlights the use of nutrients and chlorophyll-a scaling to determine the eutrophication status of coastal area.

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