PRIMARY PRODUCTIVITY

A measure of algal producitivity or rate of growth in a body of water, the primary productivity measures the mass of carbon used annually by algae per unit area of lake surface. This measure, also referred to as the Algal Growth Rate, is expressed as an index figure in grams of carbon per square meter per year, and indicates the state of Eutrophication of a body of water. Algal productivity is influenced by the quantities of nutrients that flow into, or fall onto, the lake each year and the number of days of sunshine. Another important factor is the mixing of the lake, which brings up to the surface where algae exist nutrients which have accumulated near the bottom of the lake.