Changes in Vegetation in Relation to Human Activities in Atlas Cove, Lagos, Nigeria

Abstract

In the conservation and management of our environment, information on vegetation change and pollution monitoring as a result of human activities is still highly important. This necessitated a palaeoenvironmental investigation through drilled sediments of a 51 cm core in Atlas Cove on the Commodore Channel in Lagos State, in order to ascertain possible changes in the past ecological conditions of the study area over time. Eighteen sediment samples were collected at intervals of 3 cm between the depth of 0.00 cm and 51.00 cm and subjected to palynological, lithological, pH, salinity, and heavy metal analyses. The palynological study revealed a diversified and sparse array of palynomorphs. Pollen of Asystasia gangetica, Alstonia congensis, Rauvolfia vomitoria, Cyperus sp., Kyllinga erecta, Rhizophora racemosa, Acrostichum aureum, Polypodiaceae, Paspalum sp., Pteris sp., Alchornea cordifolia, and Elchornia crassipes were found to be dominant. The pH and salinity values of the sediment samples also varied considerably at different depths. A considerable number of lithological types were recognized, which varied in grain-size, grain sorting and grain-texture. The concentrations of Fe, Cu, As, Pb, Zn, Cr, Se, Ni, Mn, Co, Cd, and Al vary greatly. When the results were compared to the soil guideline value for commercial areas using the CLEA-Contaminated Land Exposure Assessment, they were found to be below the limit for commercial areas, indicating that environmental contamination is negligible. This study's findings will be used to develop realistic conservation and management plans for this biologically unique ecosystem in the future.