Abstract
This paper reported a two season study of diversity, spatial distribution, species composition of phytoplankton and physico-chemical characteristics of the Eastern Obolo River Estuary between June and November 2015 and December and May, 2016. Water conductivity (≥675) showed direct relationship with phytoplankton abundance, turbidity showed strong correlation with species density as well. Species were more evenly distributed across 3 stations at dry season and poorly distributed across 3 stations at wet season. Shannon-wiener index (H) showed differences within the stations and seasons. Simpson’s diversity index (D) recorded the lowest in station 2 for both seasons. A wide range of phytoplankton species distributed in 5109 individual species, 85 taxa, 16 orders, 8 classes and in 5 divisions during wet season while in dry season 6906 individual species, 84 taxa, 18 orders, 6 classes and 4 divisions were found. The abundance of phytoplankton in dry season occurred in the sequence Baccillariophyta (79%) > Cyanophyta (12%) > Chlorophyta (7%) Dinophyta (2%) while in wet season the sequence was thus; Bacillariophyta (60%) > Chlorophyta (22%) > Cyanophyta (15%) > Dinophyta (3%) > Euglenophyta (0%) respectively. Bacillariophyta were the most dominant both in abundance and species composition in both seasons. Key words: Chlorophyll-a, evenness, diversity, spatial distribution.
Highlights
The study of phytoplankton is quite crucial because it serves as a pathway through which the aquatic ecosystem is supported
Reactive silicate recorded a progressive increase into the wet season (≥0.4; ≤0.75) but Nitrate levels increased in dry season
Phytoplankton biomass was higher in stations with brackish water, it was higher in dry season due to relative stability of the estuarine water and higher light penetration
Summary
The study of phytoplankton is quite crucial because it serves as a pathway through which the aquatic ecosystem is supported. Phytoplanktons are primary producers of the open ocean. Phytoplankton serve as food to the zooplankton which in turn serve as food to all larval forms, this makes them form the basis of food chain in an aquatic environment. While phytoplankton constitutes starting point of energy transfer, they are highly sensitive to allochthonously imposed changes in the environment (Khattak et al, 2005; Eletta et al, 2005). The species composition, biomass, relative abundance, species richness, species evenness, spatial and temporal distribution of this aquatic biota is an expression of the environmental health or biological.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
