Research Article Nutrient and Phytoplankton Dynamics along the Ocean Road Sewage Discharge Channel, Dar es Salaam, Tanzania Mariam I. Hamisi 1 and Florence A. Mamboya 2 1 College of Natural and Mathematical Sciences, University of Dodoma, P.O. Box 259, Dodoma, Tanzania 2 Dar es Salaam Institute of Technology, Department of Science and Laboratory Technology, P.O. Box 2958, Dar es Salaam, Tanzania Correspondence should be addressed to Mariam I. Hamisi; mhamis2005@yahoo.co.uk Received 6 February 2014; Revised 21 April 2014; Accepted 22 April 2014; Published 4 June 2014 Academic Editor: Winn-Jung Huang Copyright © 2014 M. I. Hamisi and F. A. Mamboya. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Ocean Road shoreline is situated close to Dar es Salaam largest fsh market and is subjected to sewage discharge. In this study, temporal and spatial variations of physicochemical parameters and phytoplankton were studied in fve stations along the Ocean Road Coast. Phytoplankton composition, temperature, dissolved oxygen (DO), salinity, water clarity, pH, and dissolved inorganic nutrients (DIN) including nitrite, nitrate, and phosphate were measured. Results revealed that DIN were signifcantly higher in the station close to the discharge point than other stations ( < 0.0001). Tere were no signifcant temporal variations in DIN except nitrate that was signifcantly higher during Northeast Monsoon than Southeast Monsoon ( < 0.001). Other environmental parameters showed no signifcant diferences except clarity, conductivity, and DO. Occurrence of potential harmful species such as Trichodesmium, Microcystis, and Pseudo-nitzschia was observed. Te phytoplankton biomass (chlorophyll a) ranged from 3.2 to 56.5 mg m −3 and 18 to 113 mg m −3 for Mjimwema (MJ) and Ocean Road (OR) stations, respectively. Tere was signifcant diference ( = 0.0033) in chlorophyll a among the stations being higher in OR II. Te phytoplankton biomass was positively correlated with nutrient concentration in all stations except OR I. Tis study suggests an alarming level of DIN at OR that may alter phytoplankton biomass, abundance, and composition. 1. Introduction Aquatic ecosystems around the world mostly have been heavily impacted by waste discharges from human activities, including point sources of urban, residential and industrial pollution, and nonpoint sources of agricultural pollution which alters the nutrient contents of the coastal waters. Traditionally, pathways of nutrient infux to the coastal water bodies were considered mainly surface river runof and waste water discharges [1, 2]. Increase in anthropogenic inputs has led to severe eutrophication problems, inducing an enhancement of phytoplankton primary production in many coastal areas [3, 4]. In addition to increasing primary production, nutrients dynamics have inevitable efects on the taxonomic composition of phytoplankton communities [4]. It is known that there is a large diference between coastal ecosystems in the magnitude and character of responses of phytoplankton biomass or primary production to anthro- pogenic inputs (e.g., [5, 6]). It is also known that seasonal succession of phytoplankton can be controlled by a com- bination of physical, chemical, and biological variables [7]. However, Reynolds [5] reported that nutrient is the major factor afecting the dynamics of phytoplankton. For instance, excessive nutrients loading can result in proliferation of the harmful phytoplankton species, the phenomena known as harmful algal blooms [6, 8]. Harmful algal blooms can cause fsh mortality and seafood poisoning; toxins are hazardous to aquatic ecosystem as they may accumulate into aquatic organisms and transfer, in a food chain, from low trophic levels to higher trophic levels. In addition, phytoplankton bloom can limit light pen- etration [9–11] hence limiting photosynthesis of the benthic Hindawi Publishing Corporation Journal of Ecosystems Volume 2014, Article ID 271456, 8 pages http://dx.doi.org/10.1155/2014/271456