Harmful blooms caused by dinoflagellates in the Pacific of Guatemala (2019–2022)

Abstract

Plankton studies in Guatemala are associated with the history of harmful algal blooms (HAB). An important event was observed in 1987, with 193 human poisonings due to shellfish consumption, of which 22 were lethal. The causative organism was Pyrodinium bahamense var. compressum. This species was reported again in November 2019 in the coastal Guatemalan Pacific. The species reached an abundance of 1 × 104 cells/L. In September 2020, the abundance of the Margalefidinium polykrikoides vegetative stage reached 1.24 × 106 cells/L, and its cysts 1.5 × 106 cells/L. Noctiluca scintillans proliferated (the first quantitatively estimated bloom of this species in Guatemala) in November 2020 and March 2021 (up to 1.2 × 106 cells/L). From January to December 2021, monthly monitoring was carried out in front of the Port of Quetzal at three sites (bottle and 25 μm mesh net samples). In April 2022, 11 cases of humans presenting symptoms of paralytic shellfish poisoning (PSP) were recorded in the western sector of the Guatemalan Pacific, in particular, in the municipality of Tiquisate in the department of Escuintla. From May 3 to 27, 2022, a HAB event caused the death of 4 and the poisoning of 34 humans in the departments near Mexico: Retalhuleu (Champerico), San Marcos (Tilapa) and Escuintla (Tiquisate, Buena Vista and Iztapa). The maximum saxitoxin (STX) concentration was determined in Retalhuleu (14,099 MU/100 g); until 7 July 2022, STX continued to be detected in Tilapa and Tiquisate (1,021 MU/100 g). The P. bahamense cells were observed in the stomach contents of the clam Tagelus sp. (Bivalvia: Solecurtidae).