Epiphytic Diatoms Growing on Nypa Fructican of Okpoka Creek, Niger Delta, Nigeria and Their Relationship to Water Quality

摘要

Okpoka Creek of the Upper Bonny Estuary in the Niger Delta is a sink receiving organic anthropogenic effluents from Trans-Amadi Industrial Layout and the waterfront communities. The study investigated resultant impact on the abiotic and biotic factors hrough the assessment of the physico-chemical properties of surface waters and epiphytic diatoms. Surface water and epiphyton samples were collected monthly from May 2004 - April 2006 at low and high tides from ten stations according to APHA methods. These were analysed for temperature, transparency, turbidity, dissolved oxygen (DO), biological oxygen demand (BOD), pH and nutrients. Epiphytic diatoms were identified microscopically. Species diversity was calculated using standard indices. Data analyses were done using analysis of variance, Duncan multiple range and descriptive statistics. Water temperature 28.6±0.06°C, turbidity 3.6±0.32 NTU and transparency 0.7±0.01m showed insignificant spatial variations (p>0.05). Water chemical parameters were: salinity, 14.4±4.67%; DO, 5.0±0.10 mg Lˉ1 and BOD, 3.3±0.09 mg Lˉ1. Phosphate and ammonia exceeded FEPA and USEPA acceptable levels for natural water bodies. Pollution-indicator epiphytic diatom genera recorded were Navicula, Nitzschia and Synedra. The high nutrients status favours the high abundance and distribution of epiphytic diatoms. The observed implicative genera indicate organic pollution from anthropogenic sources. Discharges of untreated domestic and industrial effluents should be discouraged.