 Corresponding author: Davies Ibienebo Chris Department of Fisheries, University of Port Harcourt, P.M.B. 5323, Rivers State, Port Harcourt, Nigeria. Copyright © 2022 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Phytoplankton community of the Isaka-Bundu waterway in Rivers State, Nigeria; A polluted tidal mangrove wetland Davies Ibienebo Chris 1, * and Evelyn Godwin Amaewhule 2 1 Department of Fisheries, University of Port Harcourt, P.M.B. 5323, Rivers State, Port Harcourt, Nigeria. 2 Department of Animal and Environmental Biology, University of Port Harcourt, P.M.B. 5323, Rivers State, Port Harcourt, Nigeria. Magna Scientia Advanced Research and Reviews, 2022, 05(02), 054–064 Publication history: Received on 25 June 2022; revised on 10 August 2022; accepted on 12 August 2022 Article DOI: https://doi.org/10.30574/msarr.2022.5.2.0053 Abstract This study aimed to investigate the composition, abundance, distribution, and diversity of the phytoplankton community of the Isaka-Bundu waterway in Rivers state, which is a polluted tidal mangrove wetland. Phytoplankton was collected bimonthly from July to December 2021 at high tide from four stations according to APHA methods. The species diversity was calculated using standard indices. The total composition of 334 individual phytoplankton was identified in the 3 stations and control. The total composition of 220 species from 5 Phylum was recorded. This observed decrease in the species diversity and richness could also be attributed to changes in environmental variables due to pollution resulting from industrial effluent discharge into the river which has adversely affected the aquatic biota. Based on these activities, there is an urgent need to carry out a regular study on the phytoplankton community that supports its fisheries in this aquatic environment. The results of this study indicate the characteristic species and compositions of phytoplankton in the Isaka-Bundu waterway in Rivers state. The species abundance and distribution are a confirmation while the composition, and diversity gave an insight into the adverse effect of these cumulative activities. The result showed that the Isaka-Bundu waterway had been extremely polluted. Keywords: Artisanal refinery; Isaka-Bundu; Pollution; Mangrove wetland; Phytoplankton 1. Introduction The aquatic environment is exposed to different kinds of effluent discharged from industries, sewage treatment plants, and drainages from urban and agricultural areas [1]. Discharges from municipal and industrial sources of sewage and the drainage of agricultural and urban areas are all disposed of in aquatic environments [2]. In addition to causing damage to aquatic life, these pollutants can also cause an imbalance in the composition of plankton [3]. Due to anthropogenic activities like those described above, there is a risk of an imbalance in the population and distribution of plankton, and consequently, damage to the resources that depend on them for their existence [4]. The composition of plankton has a direct impact on the trophic levels of plankton feeders, such as commercial fish [5]. However, phytoplankton and zooplankton communities are microorganisms that live at the first and second lower trophic levels, and the health of the aquatic ecosystem depends on the plankton colonies as plankton play an essential role as part of the food chain [6]; [7], Since phytoplankton are primary producers for the aquatic food web, they can use the sun's energy to transform air into sugars, and thus provide food for zooplankton and other aquatic creatures such as fishes that are also eaten by other animals and mammals [8]; [9]. Discharges such as these, particularly from industries, contain heavy inorganic metals [10].