In most organisms, including humans, estimating rates of mortality and the causes of death is critical to understanding their ecology. Unfortunately, for phytoplankton (the microscopic photosynthetic organisms at the base of food chains in lakes and oceans) we do not know why and how they die. This lack of knowledge is a problem because phytoplankton death may be a critical factor in understanding harmful algal blooms, and responses to pollution or changing climate. The investigators will adapt cell biology techniques commonly used in medicine (including microscopy and flow cytometry - a specialized technique for rapidly measuring living cells), to study death in phytoplankton in the laboratory and in freshwater ponds and lakes. They will determine the key environmental factors (e.g. temperature, light or availability of nutrients) that trigger death in phytoplankton, and when and how phytoplankton die in nature. This information will be used to develop a mathematical model of how individual phytoplankton cells grow, divide and die, depending on environmental conditions. The techniques and the model will improve the ability to monitor aquatic ecosystems to detect environmental threats, predict the effects of environmental change and inform management decisions. The research will promote training of undergraduates, integrating them into interdisciplinary research experiences through programs in biology and mathematics at University of Wisconsin-Milwaukee (UWM) and environmental science and engineering at Northeastern University (NEU). Participation of under-represented groups will be facilitated through UWM?s McNair scholars program and NEU's Opportunities for Undergraduate Research on the Charles River program. A portable flow cytometer will enhance infrastructure for research and education, and enrich undergraduate limnology classes at UWM by introducing a new technology. Broad dissemination of results and improvement of public understanding of science will be facilitated through a series of public seminars, and continuing development of web-based educational materials.