Fitoplancton en el humedal tropical Chaschoc en la cuenca baja del río Usumacinta

There are 3,256 species of phytoplankton reported in Mexico. In the southeast region, particularly in the basins of the Tonalá and Grijalva-Usumacinta rivers, between 155 and 300 species of phytoplankton have been reported. This number of species is considered low for a watershed with the largest water reservoir in Mexico; consequently, this study was focused to the phytoplankton species present in the tropical wetland Chaschoc, located in the basin of the Usumacinta River. Hence, phytoplankton was collected during the low flow of the flooding cycle in 2014 by oblique tows. A total of 129 morphospecies and 6 taxonomic groups were recorded: Cyanophyta (Cyanoprocaryota), Bacillariophyta, Chlorophyta, Cryptophyta, Euglenophyta (Euglenozoa) and Dinophyta (Dinoflagellata). Regarding the number of species, Chlorophyta was the best represented, while the group Cryptophyta was the less represented. In addition, 40 new records are reported for the Grijalva and Usumacinta basins, of which 13 are considered potentially toxic and 42 indicators of pollution and eutrophication. However, it is expected that the registration of species increases with samples in different seasons of the hydrological cycle and other wetlands associated with the Usumacinta River and its tributaries.