A Comparison between Microscopic and Molecular Methods for Identification of Ostreopsis Species in Marine Samples

An assessment of O. ovata and O. cf. siamensis presence in some seawater samples and on macro algae was carried out in the Mediterranean Sea. The identification of taxa investigated was performed using traditional microscopic techniques and molecular tools, to evaluate the distribution area of these species too. Ostreopsis includes epiphytic/benthonic microalgae known for their production of toxic compounds that can cause biopoisoning. Microscopic analysis reveal that the presence of Ostreopsis spp. and O. ovata in macroalgal samples is greater than in water ones. In a greater number of samples, through molecular analysis the presence of investigated species has been detected, in comparison to the previous results of microscopic analysis. They also allowed identifying Ostreopsis spp and O. ovata species even in those samples in which microscopic analysis hasn’t detected any cells, probably because it’s beneath the detection limit of method. However for environmental monitoring the microscopic analysis have proved useful to detect the presence with high-precision of these species in a marine environment and to monitor their proliferation in time while molecular approach could be expensive, difficult to apply and inaccurate first of all because of the impossibility to distinguish live cells from dead cells.