9407279 Cohn This project is designed to better understand the mechanism and ecological role of cell movement in a ubiquitous and ecologically important group of algae known as diatoms. Diatoms are among the most abundant primary food sources in many aquatic food chains, and their ability to move within the sediment is believed to be important to their ecological success. These cells can generate movement despite being confined within a hardened glass-like cell wall that restricts any direct contact between the inner cell and the surface over which it moves. This project is designed to help determine the ecological functions of diatom movement and the factors which regulate this movement by: 1) using a computer-assisted video microscope system to quantitatively analyze the characteristics of diatom movement under a variety of environmental conditions; 2) performing comparative analysis of the movement of different diatom species displaying a variety of cell wall features and shapes; and 3) performing competition experiments to determine the relative abilities of different diatom species in a mixed population to undergo vertical movements and compete for limited resources (e.g., space, light or nutrients). These studies should help to determine a number of diatom properties including: the environmental cues and conditions which affect diatom movement; the ability of diatoms to survive or become acclimated over time changes in environmental conditions; and the type of movements undertaken by various species to try and compete for limited resources such as light and nutrients. ***
