Diversity and Population Dynamics of Microbial Groups in Pelagic Column of Iko River, Eastern Obolo L.G.A, Akwa Ibom State, Nigeria

The diversity and population dynamics of microbial groups in pelagic column of Iko River Estuary, Nigeria were investigated using standard microbiological and analytical procedures. The results revealed that the densities of culturable microbes in the estuary were influenced by tidal regimes. Heterotrophic bacteria were the most abundant in the pelagic column with 26.39% and 29.01% occurrences during the low and high tides respectively. The study revealed variations in the loads of heterotrophic and autotrophic bacteria in the pelagic column of the estuarine ecosystem during the low and high tides respectively. The values recorded showed that the Protists community was dominated by heterotrophic bacteria during the low and high tides with the later harboring a much higher total heterotrophic count of 2.25 x105±0.023 cfu/ml as against 1.95 x105±0.260 cfu/ml obtained during the low tide. Geographic Information System (GIS) models of microbial communities revealed marked variation which ranged between tidal influences and locations. A high fecal coliform concentration in the North-East of the estuarine environment is a pointer to the unsanitary status of the estuarine environment. The mean temperature of the epilimnion revealed characteristic mesophilic temperature ranges with narrow spatial variations. The findings revealed that tidal bars and flats in shallow mesotidal estuary are subject to the action of tidal currents and waves. These complex events give rise to large variations in microbial communities in pelagic column which may be harnessed for effective environmental monitoring.