Vol. 9 No. (1): 31 - 49 (0): Phytoplankton diversity as index of water quality in the Umuaja Watershed of Ethiope River, Delta state, Nigeria

Phytoplankton composition, abundance, diversity indices and water quality parameters
were monitored for twenty-four months to assess the health status of River Ethiope at
the source in the Umuja watershed following standard methods. The physicochemical
parameters indicated an oligotrophic system. The phytoplankton structure was
composed of Chlorophyta with 55 species constituting 34.16%, Bacillariophyta 48
species (29.81%), Cyanophyta 45 species (28.0 %), Euglenophyta 7 species (4.35 %),
Rhodophyta ( 2.48 %), Xanthophyta and Chrysophyta had 0.62 % each different from
numerical structure (Cyanophyta accounting for 45.0% of 711 individuals,
Bacillariophyta (41.63%), Chlorophyta (11.25%), Centrales (1.12%) and Euglenophyta
(0.98%)). The phytoplankton taxa were diverse and quantitatively low. The coefficient
factors and factor analysis of phytoplankton abundance indicated the influence of air
and water temperatures, total solids, TSS and TDS, nitrate, sulphate and phosphate (p<
0.05) on its composition and abundance. Low diversity indices (0.00 - 1.277) and the
abundance of organic loving and toxins producing organisms are signatories to
organically polluted water body. However, the presence of freshwater species despite
biological signs of pollution indicates the system’s resilience and possible recovery with
adequate sanitary awareness or sensitization.