Evaluation of Epiphytic Algae Assemblage and Nutrient Status as Bioindicator of Organic Pollution in Alice Creek, Rivers State, Nigeria

Abstract

Alice Creek is a tributary of the Sombreiro River in the Akuku-Toru Local Government Area of Rivers State. It serves diverse purposes to the people of the area and others who depend on its aquatic resources, thereby exposing the river to influxes of pollutants that are of natural and human sources. The epiphyton assemblage and nutrient status were studied to determine organic pollution in this creek. Samples of epiphyton and surface water were collected monthly between February and May 2020 from three (3) sampling stations established along the creek course according to standard methods. Epiphytic algae samples were identified microscopically. Species diversity was calculated using standard indices. Surface water samples were analyzed for ammonia and phosphate by APHA methods. Data were analyzed using the Statistical Package for Social Sciences (SPSS) Version 23 for analysis of variance. A total of 50 individuals, 26 genera, and 35 species of epiphyton from six taxonomic groups, namely: Chlorophyta (10 species), Cyanophyta (9 species), Euglenophyta (6 species), Dinophyta (6 species), Bacillariophyta (3 species), and Xanthophyta (1 species) were recorded from the Alice Creek. Ammonia concentrations (mg/L) ranged between 5.59±0.91 (Station 2), 4.86±0.40 (May) and 6.24±0.86 (Station 3), 7.27±0.18 (February). Phosphate concentrations (mg/L) ranged from 0.31±0.56 (Station 2), 0.30±0.02 (May) to 0.40±0.11 (Station 1), 0.40±0.14 (March). Temporal variations of ammonia and phosphate were significant (p<0.05). The presence of Navicula (diatom), Microcystis, Oscillatoria, nabaenopsis, Anabaena, (bluegreen), high ammonia and phosphate indicated organic pollution in Alice Creek. The study recommends a coordinated environmental management plan to conserve aquatic resources of the Creek.