Karenia brevis is a harmful algal bloom (HAB)-forming dinoflagellate that causes Florida red tides, resulting in fish kills, neurotoxic shellfish poisoning, and respiratory irritation. The negative impacts of K. brevis blooms create demand for effective mitigation strategies, including clay flocculation and chemical control using the naturally derived flavonoids luteolin and curcumin. Cell death is the aim of most mitigation strategies, however, by targeting physiological processes such as photosynthesis, it is possible to disrupt bloom development while conserving resources and minimizing impacts on the environment. Experiments were conducted on four strains of K. brevis (New Pass, Wilson Low Toxin, Wilson, and Manasota) to examine the photophysiological responses during exposure to modified clay (0.1 g/L), curcumin (3 mg/L), and luteolin (3 mg/L). Using Pulse-Amplitude-Modulation (PAM) fluorometry, the quantum yield of Photosystem II (PSII), relative maximum electron transport rate, and absorption cross-section of PSII were measured as the photophysiological parameters. The curcumin was the most effective compound at reducing photophysiological parameters and cell counts in all tested strains. Clay was the second most effective compound at reducing yield and relative electron transport rate. Luteolin exhibited the least effect on cell photophysiology. Inter-strain differences were observed. Notably, the Wilson strain was most impacted by luteolin, and Wilson treated with curcumin showed recovery by 24 hours while other strains did not.

Primary Presenter: Miah Manning, Rutgers University (miahmanning1040@gmail.com)

Authors:

Miah Manning, Rutgers University  (miahmanning1040@gmail.com)

Vince Lovko, Mote Marine Laboratory  (vlovko@mote.org)

Sumit Chakraborty, Mote Marine Laboratory  (schakraborty@mote.org)