title: LIPID CLASS, CAROTENOID, AND TOXIN DYNAMICS OF KARENIA BREVIS (DINOPHYCEAE) DURING DIEL VERTICAL MIGRATION(1).
abstract: The internal lipid, carotenoid, and toxin concentrations of Karenia brevis (C. C. Davis) Gert Hansen and Moestrup are influenced by its ability to use ambient light and nutrients for growth and reproduction. This study investigated changes in K. brevis toxicity, lipid class, and carotenoid concentrations in low-light, nitrate-replete (250 μmol quanta · m(-2)  · s(-1) , 80 μM NO3 ); high-light, nitrate-replete (960 μmol quanta · m(-2)  · s(-1) , 80 μM NO3 ); and high-light, nitrate-reduced (960 μmol quanta · m(-2)  · s(-1) , <5 μM NO3 ) mesocosms. Reverse-phase HPLC quantified the epoxidation state (EPS) of the xanthophyll-cycle pigments diadinoxanthin and diatoxanthin, and a Chromarod Iatroscan thin layer chromatography/flame ionization detection (TLC/FID) system quantified changes in lipid class concentrations. EPS did not exceed 0.20 in the low-light mesocosm, but increased to 0.65 in the high-light mesocosms. Triacylglycerol and monogalactosyldiacylglycerol (MGDG) were the largest lipid classes consisting of 9.3% to 48.7% and 37.3% to 69.7% of total lipid, respectively. Both lipid classes also experienced the greatest concentration changes in high-light experiments. K. brevis increased EPS and toxin concentrations while decreasing its lipid concentrations under high light. K. brevis may mobilize its toxins into the surrounding environment by reducing lipid concentrations, such as sterols, limiting competition, or toxins are released because lipids are decreased in high light, reducing any protective mechanism against their own toxins.
authors.affiliation: U.S. EPA National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32563, USADepartment of Marine, Earth, & Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27695-8208, USA.
authors.forename: Blake A
authors.initials: BA
authors.lastname: Schaeffer
authors.affiliation: U.S. EPA National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32563, USADepartment of Marine, Earth, & Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27695-8208, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kamykowski
authors.affiliation: U.S. EPA National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32563, USADepartment of Marine, Earth, & Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27695-8208, USA.
authors.forename: Laurie
authors.initials: L
authors.lastname: McKay
authors.affiliation: U.S. EPA National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32563, USADepartment of Marine, Earth, & Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27695-8208, USA.
authors.forename: Geoff
authors.initials: G
authors.lastname: Sinclair
authors.affiliation: U.S. EPA National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32563, USADepartment of Marine, Earth, & Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27695-8208, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Milligan
keywords: behavior; brevetoxins; dinoflagellate; epoxidation state; lipids