Marine phytoplankton live in a dynamic and variable environment. Changes in salinity, temperature and nutrients are major factors that control the growth and distribution of phytoplankton populations. Salinity can vary significantly in coastal waters, so many coastal phytoplankton species have evolved mechanisms to quickly regulate their internal water concentration, a process known as osmoregulation. In response to decreases in salinity, the dinoflagellate, Karenia brevis, responsible for producing toxic red tides in the Gulf of Mexico, produces a rapid >10-fold increase in ladder frame polyethers (LFPs), which include the potent neurotoxins called brevetoxin. The functional role of LFPs in K. brevis is unknown; however, the production of such large quantities suggests that there must be a critical cellular role. An interdisciplinary approach combining physiological experiments, cell imaging, next generation sequencing, and metabolomic profiling will be used to explore the relationship between gene transcription and physiological/metabolic responses. To determine if LFP production is a common mechanism for osmoregulation in dinoflagellates, similar experiments will be conducted with additional species of dinoflagellates also known to produce LFPs. Changes in LFP production in response to low salinity may explain how K. brevis and other toxin-producing dinoflagellates can thrive in coastal ecosystems. The project's outcome will provide an explanation for toxin production in 'red tide' dinoflagellates and reveal how toxic dinoflagellates, with slow growth rates now, may compete successfully in coastal environments under future conditions.
The project's broader impacts include training and education of a post-doctoral researcher, three graduate students, and undergraduate students using state-of-the-art techniques to address questions in evolution and ecology. Results will also be utilized in a graduate Molecular Ecology course taught at TAMU providing students with hands-on experience with actual experimental data for training in this rapidly emerging field.