Temporal and spatial phytoplankton biomass dynamics in southern Gulf of Lake Tana, Northwestern Ethiopia

Abstract

Southern Gulf of Lake Tana is southern part of Lake Tana in Northwestern Ethiopia. Water samples were obtained from eight sites of the gulf for six months during November to April 2010/11 twice a month to determine temporal and spatial variation in phytoplankton biomass of the gulf. Phytoplankton biomass data was estimated following total chlorophyll-a concentrations determination methods. There was no significant difference in sampling sites and interactions between sampling sites and months ( P >0.05). However, there is a significant difference in sampling months ( P <0.05). The absence of significant difference in sampling sites and the interactions might be due to the similarity in human or natural impacts, and phytoplankton growth and decline. But, the presence of significant difference among sampling months might be due to the difference in growth/decline periods of the phytoplankton. Southern Gulf of Lake Tana subparts are similarly impacted naturally or by humans who passed their time around the gulf. The Ethiopian government and concerned non-governmental organizations in general and local communities, in particular, have better cooperate their efforts for conservation and sustainable use of the gulf. Similarly, they have to play in awareness creation for stakeholders to reduce natural/human impacts to the lake gulf.