A case of fish mortality caused by Prymnesium parvum in inland waters in Yucatan, Mexico

A case of massive fish mortality is reported in an aquatic body in the municipality of Izamal in Yucatan, Mexico. The fish analyzed exhibited signs of hemorrhage and suffocation. Analysis of the phytoplankton samples revealed the presence of a flagellated microalga with characteristics consistent with Prymnesium parvum, particularly due to the presence of the haptonema. The average densities of the microalgae were approximately 16 × 10⁶ cells L⁻¹. The documentation of this species in the Yucatán Peninsula and the observed effects represent an emerging risk for the aquatic ecosystems of the region. This risk is linked to the extensive connectivity between aquatic systems in the region, combined with the significant dispersion capability of the species, which is magnified by the increasing eutrophication conditions in these bodies of water.