Seasonal Variations Of Dinophysis Species And Their Toxins In Qatari Waters, Arabian Gulf

Abstract

The results of investigations from several cruises carried out in Qatari waters between 2017 and 2018 were reported. The species composition, distribution and toxicity of Dinophysis community were examined. A total number of five taxa were recorded with dominancy of Dinophysis caudata followed by Dinophysis miles. Of these, two taxa are the first reports from Qatari waters: Dinophysis mitra and D. acuminata. The cell count revealed that the number of cells rose up from October 2017 toward the end of April 2018. Thirty-two freeze-dried samples were analyzed for Diarrhetic Shellfish Poison (DSP), confirming the presence of Pectenotoxin (PTXs) and Okadaic acid (OA), where toxin concentrations ranged from 0.0080 Ng/mg to 0.52 Ng/mg, respectfully. A number of physical and chemical parameters were measured. The salinity of water collected ranged between 42.00 ‰ and 38.97 ‰. Throughout the area investigated the temperature ranged from in excess of 34 °C in summer to 20 °C in winter. Nutrient concentrations recorded were relatively low, except in samples collected from industrial effusion. The statistical analysis on the physical parameters, nutrients, and cell counts and species number showed a significant difference between seasons and stations at P < 0.05.