Grant: Research Tools and Instruments

Micro- and macroalgae are central components in the functioning of aquatic ecosystems providing primary production and critical habitat. Shifts in algal abundance or diversity, particularly due to increasing climate stress, could have cascading impacts through marine food webs. Unfortunately, our understanding of the physiological responses of algae to environmental stress is generally limited to studies of macroscopic seaweeds or phytoplankton cells in bulk solution, and we know little about the physiology of individual microscopic phototrophs, including the photosynthetic propagules and microscopic life stages that are critical to seaweed reproductive cycles. Funding requested in this application is to acquire a Microscope Imaging-PAM (Pulse Amplitude Modulation) fluorometer, which will uniquely allow researchers to investigate the stress physiology of microscopic photosynthetic organisms, from single cells (e.g., unicellular algae, spores) and microscopic life stages of seaweeds (e.g., gametophytes, germlings) to microorganisms (e.g., flatworms) that have eaten algae and retained chloroplasts that may or may not still be functional (kleptoplasty'). PAM fluorometers measure light acquisition and chlorophyll fluorescence as proxies for physiological stress in phototrophs; conventional PAM fluorometers use fibre-optic probes to deliver light and detect fluorescence in macroscopic seaweeds or phytoplankton cells in solution. These conventional methods are insufficient to detect fluorescence signals from individual cells or single microorganisms. The proposed Microscope Imaging-PAM combines traditional fluorometry with microscopy and highly sensitive CCD cameras and image analysis to capture real-time images of chlorophyll fluorescence in microscopic phototrophs. This innovative instrument records photosynthetic parameters and images simultaneously, uniquely allowing users to differentiate the health of individual cells and chloroplasts within tissues and to link stress with changes in microorganism behaviour. This novel equipment will be essential to studies of seaweed life-cycles in response to environmental stress, informing seaweed aquaculture initiatives as well as climate change policy to preserve habitat-forming macroalgae, and will also create an exciting new research direction for the physiological study of kleptoplastids within host microorganisms. The Microscope Imaging-PAM has wide applications and versatility that will significantly broaden the scope of physiological experiments on microscopic phototrophs and will enhance the training of HQP studying stress photophysiology.