Thursday June 23, 5:40pm CEST
James M. FIORENDINO1, Daniel L. ROELKE2, Lisa CAMPBELL1
Portion Control: Modelling the Effect of Prey Size on Dinophysis Blooms in the Gulf of Mexico
1Department of Oceanography, Texas A&M University, College Station, TX 77843, USA
2Department of Marine Biology, Texas A&M University at Galveston, Galveston, TX, 77553, USA
Increasingly common blooms of toxic Dinophysis species represent a threat to human health and shellfish fisheries in the United States. The dependence of mixotrophic kleptoplastidic Dinophysis species on specific prey, the marine ciliate Mesodinium rubrum, further complicates predicting and mitigating the impacts of Dinophysis blooms. A decade of high temporal resolution monitoring of the phytoplankton community along the Texas, United States coast with Imaging FlowCytobots (IFCB) has revealed seasonal Dinophysis ovum blooms of varying intensity that occur between January and April in the Gulf of Mexico. Previous analysis of IFCB field data revealed a weak time-lagged relationship between D. ovum and Mesodinium abundance. Recent laboratory culturing experiments have indicated temperature and prey biomass are important factors influencing Dinophysis biomass and growth rates. Utilizing data from laboratory culturing experiments and the Texas Observatory for Algal Succession Timeseries, we developed a model of Dinophysis and prey population dynamics in the Gulf of Mexico. The model results indicated prey biomass, rather than abundance alone, was a more reliable predictor of D. ovum bloom onset and intensity. We also found temperature played an important role in the onset of D. ovum blooms, specifically overlap of D. ovum and its prey. The influence of future warming on D. ovum bloom dynamics in the Gulf of Mexico will determine whether increases in D. ovum bloom frequency or intensity are likely to occur.