Effects of Physico-chemical Parameters on Phytoplankton of a Tidal Creek, Lagos, Nigeria

Abstract

Physico-chemical parameters have been observed to influence phytoplankton composition of coastal areas and water in Nigeria. In order to assess this, the phytoplankton composition of a tidal creek in Lagos was investigated in relation to the physico-chemical characteristics for twelve months (February 2010- January 2011). Six stations were created, phytoplankton samples were collected using 55µm mesh size plankton net and water samples were also collected for physico-chemical parameters analysis. Four major divisions, Bacillariophyta (78%), Chlorophyta (11%), Cyanophyta (10%) and Euglenophyta (0.07%) were documented. The phytoplankton abundance was influenced by parameters such as rainfall, phosphate-phosphorus, nitrate-nitrogen and salinity. The highest (5.7mg/L) and lowest values (0.01mg/L) of phosphate-phosphorus were recorded in May 2010 (station B) and in December 2010 (station F) respectively, while nitrate-nitrogen recorded its highest (17.3mg/L) and lowest values (0.02mg/L) in May 2010 (station B) and in November 2010 (station C) respectively. The pH ranged between 6.2 and 8.4. However, the salinity values recorded corresponded with rainfall pattern of the studied area. The highest (6.7) and lowest values (0.9) of species diversity (d) were recorded in July 2010 (station D) and June 2010 (station D) respectively. Shannon-weiner (H1) index recorded its highest (3.35) and lowest values (0.41) in July 2010 (station D) and in October 2010 (station C) respectively, while the highest (0.96) and the lowest values (0.2) of species evenness (j) where recorded in June 2010 (station D) and October 2010 (station C) respectively. Human induced stressors such as dredging, sand mining and poor sewage system might have affected the phytoplankton composition of the studied area.