Red tide produced by the dinoflagellate Peridinium quinquecorne in Veracruz, México (oct-nov. 2002): morphology of the causative agent.

Abstract

In late October, 2002, a red tide was observed along the shore of the Port of Veracruz. Water samples were collected with bottle and fixed with lugols solution. Twelve days later a second set of samples was collected. In addition water temperature, dissolved oxygen and salinity measurements were taken from four stations. Species were identified with a Light microscope, and cells were counted using an inverted microscope, following the Utermöhl method. The species responsible, the armored dinoflagellate Peridinium quinquecorne Abé 1927, was studied in detail with scanning electron microscope, which showed a high morphological variation, mainly in both shape and size of the cell . The highest cell density reached to 2.5 x 106 cells l-1. The second samples set showed a notable decrease in the cell density of P. quinquecorne, which dropped to 4 975 cells l-1; other species occurring with lower densities were Dinophysis caudata and Pseudonitzschia spp., and surface temperature, salinity and dissolved oxygen were 26.3° C, 34 psu and 6.5 mg·l-1, respectively. Strong winds and cloudy sky were also recorded. No fish killings, odors or irritation were reported. This is the first report of a red tide caused by P. quinquecorne in Veracruz. As in other parts of the world no harmful effects were observed.