Particulate matter dynamics and phytoplankton seasonality in a reservoir embayment ecosystem

Phytoplankton losses from the water column and the relationships among seasonal change, algal community structure, and the fate of particle-associated materials were investigated in the Walker Branch embayment of Melton Hill Reservoir, Anderson county Tennessee, Sinking and ascent rates of phytoplankton were measured using settling columns, and in situ particle removal by sinking was estimated using the naturally-occurring radionuclides Beryllium-7 and Lead-210. Changes in autochthonous phytoplankton assemblage composition, concentration and production reflected the seasonal aspects of suspended particle flux. Beryllium-7 removal rates corresponded with those of the predominant form of particulate matter, and differed greatly from removal rates of Lead-210. The rapid association of particle-reactive materials with the predominant form of particulate matter following input events suggests that the seasonality of particulate matter is a central factor in the sorption, residence time and ultimate fate of particle-associated materials within aquatic ecosystems.