The Role of Mycosporine-Like Amino Acids (MAAs) in Harmful Bloom-Forming Dinoflagellates: Effects of Ultraviolet Radiation, Vertical Mixing, and Nutrient AvailabilityEPA Grant Number: U915751
Title: The Role of Mycosporine-Like Amino Acids (MAAs) in Harmful Bloom-Forming Dinoflagellates: Effects of Ultraviolet Radiation, Vertical Mixing, and Nutrient Availability
Investigators: Frame, Elizabeth R.
Institution: University of California - San Diego
EPA Project Officer: Michaud, Jayne
Project Period: August 1, 2000 through August 1, 2003
Project Amount: $79,247
RFA: STAR Graduate Fellowships (2000) RFA Text | Recipients Lists
Research Category: Fellowship - Oceanography , Aquatic Ecosystems , Academic Fellowships
The objective of this research project is to determine how mycosporine-like amino acids (MAAs), a class of UV-absorbing compounds thought to have a photoprotective function, influence bloom formation in harmful dinoflagellate species.
To examine the effect of UVR and PAR on MAA production, the investigator will use a solar simulator with environmentally realistic ratios of UV and visible radiation. The UVR and/or PAR exposure can be varied using a combination of filters and screens and track MAA production. MAAs will be identified and quantified by HPLC. Measurements will also be made of photosynthetic energy conversion efficiency using pulse amplitude modulated (PAM) fluorometry. Cell concentration, cell size, protein content, and chlorophyll concentration will also be monitored. Insight into the importance of the role of MAAs can be inferred from allocation of nitrogen when it is scarce. To determine the effects of nutrient status on MAA production, cultures will be grown in nitrogen-replete and low-nitrogen media at UVR levels determined to be detrimental to cells in the experiments described above. Experiments with phosphate limitation will also be conducted to determine if the response is specific to nitrogen, or a general nutrient-stress response. The results of the lab experiments will be synthesized to examine the effects of vertical mixing on the effectiveness of MAA production for UV photoprotection in the environment. A simple model of UV-exposure history for a phytoplankton cell will be used to determine under what vertical mixing conditions production of MAAs would provide a cell with adequate UV-photoprotection.
This research is expected to improve our understanding of the role that MAAs play in allowing some species of dinoflagellates to out-compete other phytoplankton that are subject to the detrimental effects of harmful UVB radiation.