Palynology of Recent Bottom Sediments from Shallow Offshore Niger/Cross River Delta Nigeria: A Preliminary Study

摘要

To assess the distribution and transport media of palynomorphs in the shallow offshore eastern Niger/Cross River Delta, recent bottom sediments from three locations (distal ABC, middle DEF and proximal GH) in the area were palynologically investigated. Records of highest abundance and diversity values of palynomorphs in middle location DEF indicate that the Cross River brings about seventy percent of the palynomorphs into the eastern Niger Delta. Wind only brings Charred Poaceae cuticles and Podocarpus milanjianus as well as aiding Poaceae for their higher records in distal ABC than others. The most abundant plants represented in the sediment source areas of the sites today as revealed by the palynomorphs recovered are Poaceae, Elaeis guineensis , Acrostichum aureum , Pteris spp., Nephrolepis undulata , Cyclosorus afar and Stenochleana palustris ( Verrucatosporites spp.). Pollen of Rhizophora spp. and fresh water forest trees that are abundant in subsurface sediments have been reduced greatly and replaced by Poaceae and Elaeis guineensis pollen due to anthropogenic activities. Proximity to shore and shallow depth determine the abundance of pollen and spores, fungal elements and to an extent Concentricytes . Protoperidinium spp. and other dinoflagellates prefer the deeper ABC location with lowest temperature and high salinity. Microforaminiferal wall linings were however recovered mostly in the shallowest proximal site. Recovered diatoms show useful ecological trends. These results further confirm the usefulness of these palynomorphs and diatoms for paleoenvironmental and paleovegetational reconstruction. The degradation the Nigerian coastal ecosystems had undergone as well as presently undergoing due to anthropological activities is also revealed.