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 effect of salt concentration on the survival and growth rate of Escherichia coli isolated from Lagos Lagoon surface water was investigated. This was necessitated to ascertain the suitability of using E. coli as feacal pollution indicator in this water body which experiences fluctuation in salinity values. The salinity during the study ranged from 25.13 and 35.69‰. All the five E. coli isolated during the entire study period, grew luxuriantly in 0 to 4% salt concentrations with increase in optical density values of 78 -93% and high (0.005 -0.45) growth rates within 300 minutes of incubation. The growth of these isolates at 6% salt concentration was also good with 22 -77% optical density increase and growth rate range of 0.25 -0.37. However, minimal or no growth was noted at 8 to 12% salt concentrations with corresponding low increase in optical density and negligible or even negative growth rate. Although the effect of salt concentrations on the five isolates tested were comparable, the isolate (Ec2) which was isolated during the least salinity period, showed the least growth rate in all salt concentrations. These findings suggest that salinity at point of isolation can influence salt tolerance, but further affirms the use of E. coli as pollution indicator for Lagos Lagoon since they exhibited considerable halo-tolerance and survived salt concentrations up to 6%.