Predicting Harmful Algal Blooms: A Case Study with Dinophysis ovum in the Gulf of Mexico

Abstract

Blooms of Dinophysis ovum and Mesodinium spp. have been observed in the Gulf of Mexico since 2007 using Imaging FlowCytobot technology. Bloom dynamics of these two organisms in conjunction with ancillary environmental data for a 5 year period were analyzed to identify the conditions necessary for bloom initiation or presence with the goal of predicting future blooms of Dinophysis. I determined that a narrow range of temperature and salinity may be necessary for bloom initiation of Dinophysis and Mesodinium in the Gulf of Mexico. Using time series analysis, I observed a positive time-lagged correlation between the two organisms in each year when both were present, which indicates that presence of Mesodinium can be used as a leading indicator for a Dinophysis bloom. Analysis of images over the time series also revealed a wide range in the size of Mesodinium cells, which suggests that species other than M. rubrum may be present in the Gulf of Mexico. Finally, based on the occurrence of a Dinophysis bloom preceded by low abundances of Mesodinium, I believe that Dinophysis is able to utilize ciliates other than M. rubrum as prey. My observations indicate that these factors can affect initiation, presence or abundance of Dinophysis and thus may help in the prediction of future blooms.