Palynological Analysis of Late Holocene Sediments and its Paleoenvironmental Interpretations from Lagos Coastal Environment, Southwestern Nigeria

Adekanmbi, O.H ; Ajikah, L.B. ; Onuminya, T.O. ; Ogundipe, O.T. (2019-08)

Staff publications


Background and Objective: Information from the distribution of palynomorphs is used to infer past vegetation changes and paleo-climatic settings, characteristic of a particular environment. This palynological studies aimed to assess the distribution of palynomorphs and reconstruct the past vegetation and make inferences on the paleoclimate of a late Holocene core. Materials and Methods: Sediments samples were collected at intervals of 3 cm to a depth of 51 cm using a universal peat corer and subjected to standard palynological procedures. Prepared slides were studied with both light and scanning electron microscope. Photomicrograph of some recovered palynomorphs was imaged using Zeiss merlin scanning electron microscope. Lithological analysis and standard accelerated mass spectrometry (AMS) was also carried out to provide a calibrated accurate ratio of 14C and 13C dates. Results: Five palynoecological groups were recognized to include mangrove, freshwater swamp, riverine/lowland rainforest and fern spores suggestive of a humid climate. Absolute ages from radiocarbon dating showed the study sediments were deposited around the last 111.8±0.4 BP indicating the late Holocene. Lithology, pH and salinity analysis revealed a miscellany of sedimentary depositional environment in which the recovered palynomorphs were preserved. Conclusion: Significantly the study revealed the disappearance of mangrove vegetation notably Rhizophora sp. and Acrosticum aureum, while open vegetation dominated recovery indicating an increase in human influence on the study area.