Nutritional and environmental regulation of growth and toxicity in Dinophysis
Tuesday, September 18, 2012
Redfield Auditorium - 12:00 Noon
Dr. Mengmeng "Jessie" Jessie Tong
Woods Hole Oceanographic Institution
Several species within the dinoflagellate genus Dinophysis are responsible for the diarrhetic shellfish poisoning (DSP) syndrome. Toxins from these organisms accumulate in shellfish and threaten public health and fisheries resources in many parts of the world. The toxic Dinophysis spp. are mixotrophic species which require both light and prey for cell growth and toxin production. A unique three-link food chain, cryptophyte-Myrionecta-Dinophysis was discovered that made feasible to investigate longstanding questions on nutritional requirements of Dinophysis species. Our results showed that temperature (4-10°C), light (0 and 65 μmol photons m-2 s-1) and growth stage had a positive relationship with the growth rate and toxin production of D. acuminata. No significant differences were seen in the growth rates or cellular toxin quotaof D. acuminata where the dinoflagellate was grown on food prey and culture medium consisting of three different nutrient levels, ranging in N: P ratio between 7~81. A matrix experiment on three cryptophytes, two ciliates and one Dinophysis was conducted for examine how food type affect. Together these data suggest that food quantity and type, not food quality, appears to be a more important factor affecting D. acuminata growth and biomass, which in return, affect the total toxin production of Dinophysis.