Seasonal Survey of Phytoplankton as Biondicators of Water Quality in the Streams of Kagoro Forest, Kaduna State-Northern Nigeria

The Kagoro Forest like many tropical forests is under heavy pressure for economic resources due to increasing human population, poverty and climatic change. The Physico-chemical characteristics of water and Phytoplankton from the three streams flowing in Kagoro Forest were sampled using methods described by APHA (1998) during two visits, once in the wet season and the other in the dry season. Seven sampling points were selected to reflect the overall health status of the streams. Physicochemical characteristics such as Total Hardness, Alkalinity, Dissolved Oxygen, Electrical Conductivity, pH and PO4-P did not vary significantly between seasons (p<0.05) whereas NO3-N varied significantly between seasons (p<0.05). The concentration of PO4-P and NO3-N observed where higher than the WHO recommended levels for natural unpolluted waters. Species belonging to the Bacillariophyceae, Chlorophyceae, Cyanophyeeae and Euglenophyceae were observed during the study. Species with very high abundance > (100cells/L) observed during the study period include Synedra ulna, Navicula sp. Melosira numuloides, Oscillatoria sp and Cymbella cistula. The number of Taxa, number of individuals, Shanon-weinner diversity index, and simpson's index observed in the dry season were generally higher than the values observed in the wet season, respectively. The higher abundance of Euglena sp and Oscillatoia sp during the dry season may is an indication of higher organic pollution in the dry season as they are indicators of organic pollution.