Spatial, temporal, and storm runoff-related variations in phytoplankton community structure in a small, suburban reservoir

Phytoplankton abundance and community structure were determined routinely over an annual period and intensively during two storm-runoff events in a small suburban reservoir in northern Virginia, U.S.A. Traditional graphical techniques and a multivariate approach (Principal Components Analysis) were used to demonstrate a seasonal pattern of phytoplankton succession with greens and blue-greens dominant in summer, diatoms and chrysophytes in spring and fall, and cryptophytes in winter. Spatial variations were minor over horizontal and vertical dimensions during spring mixis, but depth variations were substantial during summer stratification. Storm runoff had little effect on phytoplankton composition during the stable summer period, but was associated with a substantial perturbation in community structure during the spring to summer transition.