The Networked Aquatic Microbial Observing System (NAMOS) is an array of embedded networked sensors that has been developed to study plankton populations in marine and aquatic environments. The application of NAMOS in Lake Fulmor, adjacent to the James Mountain Reserve, California, has begun to yield valuable insights into plankton community structure and dynamics, including phytoplankton spatial and temporal distributions throughout the lake. Data collected during deployments of the system in May, July, and October, 2005 revealed decreases in water column temperature stratification, accompanied by overall increases in chlorophyll in the lake throughout the three deployments. Chlorophyll concentrations (indicative of phytoplankton biomass) exhibited strong diel variations at a depth of one meter, with highest concentrations during the evening and early morning (18:00-06:00) and much lower values during the day. These findings presumably indicate a strong vertical migratory behavior of the phytoplankton assemblage.