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Abstract Detail


Adekanmbi, Helen [1], Ajikah, Linus [2], Ogundipe, Oluwatoyin [3].

Palynology and Paleovegetational Reconstruction of Lagos Coastal Environment, Southwestern Nigeria.

Quantitative analysis of fossil pollen grains and spores from various layers or horizons of sediments have been studied for the reconstruction of past vegetation and climate. The vegetation of Lagos coastal environment is frequently degraded and has recorded severe losses due anthropogenic activities, consequent of which many plant species are now extinct. A palynological analysis of sediments was carried out to assess the distribution of palynomorphs, reconstruct past vegetation and draw inferences on paleoclimate of the Lagos coastal environment. Ninety sediment samples were collected from five study locations of around the Lagos coastal area. Sample collection was done at an interval of 3 cm from depth 0.00 cm to 51.00 cm, using a universal peat corer and samples were subjected to standard palynological procedures. The prepared samples were studied with both light and scanning electron microscope. Photomicrographs of some recovered palynomorphs was taken using Zeiss merlin. Radiocarbon dating was carried out with a standard accelerated mass spectrometry (AMS) calibrated to provide an accurate ratio of 14C/13C dates. Palynomorphs recovered in these study locations include Elaeis guineensis, Alchornea cordifolia, Cyclosorus afer, Aspilia africana, Nymphaea sp., Cyperus sp., Symphonia globulifera, Rhizophora sp., Canthium sp. Poaceae, Arecaceae, Asteraceae, Euphorbiaceae, Polypodiaceae and Palmae. Other identified palynomorphs were spores of Pteris sp., Nephrolepis sp., Acrostichum sp., Ceratopteris sp., and a trilete fern; Botryoccocus brauni, Concentricytes sp., Pediastrum sp., microforaminiferal wall linings and fungal spores. Five phytoecological groups were recognized based on the botanical affinities of some recovered palynomorphs. These are mangrove swamp forest, freshwater swamp, rainforest, lowland rainforest and marine/freshwater swamp forest. Others groups are spores open forest and savanna vegetation. The preponderance of mangrove swamp forest, freshwater swamp forest, rainforest as well as lowland rainforest species is suggestive of a humid climate. However, there were periods of dry climate indicated by savanna and open forest vegetation sandwiched in-between. Absolute ages from the radiocarbon dating indicate that sediments were deposited around the last 760+/- 40 BP during the late Holocene. This study revealed the dominant palynomorphs deposited in the coastal area of Lagos and established a regional chronological evidence for a series of vegetation and paleoenvironmental changes in the late Holocene. Keywords: Palynomorphs, Vegetation, Paleoclimate, Late Holocene, Lagos coastal area

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1 - University Of Lagos, Akoka, Lagos, Department Of Botany, Block 3, Flat 7 Rabiatu Thompson Crescent Surulere, Lagos, 100001, Nigeria
2 - University of Lagos, Department of Botany, Akoka, Yaba,, Lagos, Lagos, 23401
3 - University of Lagos, Department of Botany, Akoka, Yaba, Lagos, 23401, Nigeria

Late Holocene

Presentation Type: Oral Paper
Session: 24, Late Mesozoic and Cenozoic Paleobotany
Location: 109/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 11:45 AM
Number: 24007
Abstract ID:821
Candidate for Awards:None

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