Spatiotemporal variation of harmful phytoplankton in recreational beaches in Campeche, southeastern Gulf of Mexico

Abstract

The coastal waters of 6 recreational beaches on the coast of Campeche in the Gulf of Mexico were monitored from March to October 2019. Temperature, salinity, and pH ranges varied depending on the season and were likely influenced by the local hydrography and shallow depth of the study area. The harmful taxa identified in this study included 3 diatom, 5 dinoflagellate, and 2 cyanobacteria species, with abundances ranging from 102 to 105 cell·L–1. Within the phytoplankton community, phytoflagellates (nanophytoplankton <20 µm) exhibited a peak abundance of 1.6 × 106 cell·L–1 at Boca del Río in Champotón. Microphytoplankton (>20 µm), including diatoms, dinoflagellates, and cyanobacteria, were a secondary component with densities ranging from 103 to 106 cell·L–1. The dinoflagellate Pyrodinium bahamense, identified as toxic to humans on the Campeche coast, showed a maximum abundance of 2.0 × 105 cell·L–1 in May at Boca del Río. The toxic diatom Pseudo-nitzschia exhibited a peak abundance of 105 cell·L–1 at Payucan in May. The cyanobacteria genera Anabaena and Trichodesmium exhibited abundances ranging from 102 to 104 cell·L–1. Potentially harmful phytoplankton and cyanobacteria were present in all seasons and months, indicating that continual monitoring is needed to assess beach quality to ensure the safety of recreational beaches.