Phytoplankton, microscopic organisms (microalgae) that form the base of aquatic food webs, generate approximately half of the world’s oxygen through photosynthesis. As a result, they profoundly influence elemental cycling, aquatic productivity, food webs, and climate at both local and global scales. Furthermore, phytoplankton divides rapidly (hours/days), making them ideal sentinels of change and both evolutionary and environmental processes. We have implemented a series of field surveys as well as field and laboratory experiments that help us better understand the mechanisms by which phytoplankton, especially harmful algal bloom (HAB) forming species, respond to anthropogenic stressors. BUEE students will participate in field and laboratory studies that help us better understand the linkages between these processes and water quality as well as their impacts on nutrient cycling and food web processes in urban coastal ecosystems.