A checklist of dead fishes (Actinopterygii and Elasmobranchii) associated with the algal bloom event of the summer of 2022 on the Yucatan coasts, southern Gulf of Mexico

Harmful algal blooms (HABs) are natural phenomena that occur when colonies of microalgae grow out of control and produce toxic or harmful effects on the surrounding fauna. In August 2022, an HAB, dominated by the diatom, Cylindrotheca closterium (Ehrenberg) Reimann et J.C. Lewin, 1964, occurred on the Yucatan coast, southern Gulf of Mexico. In the presently reported study, two photo transects were established along the coastline, one at the onset of the bloom, at Telchac port, and the other at the final phase of the event, at Chixchulub port. The affected fish species were documented photographically and a taxonomic list, with their abundance, density, and biomass is presented, as well as a summary of the affected ecosystems according to the affinity of these species. A total of 54 species were recorded; 48 in Telchac and 21 in Chicxulub, with 15 species occurring at both sites. The affected species have a greater affinity to reef systems, beaches, and estuaries, in that order, between 3 m and 113 m depth. In the International Union for the Conservation of Nature (IUCN) nomenclature, the majority of the species are in the “least concern” category, however, species were also recorded in the “near threatened”, “vulnerable”, and “endangered” categories. Therefore, it is extremely important to monitor these events and report the affected species, since the increase in the frequency of these phenomena due to local and global factors can have significant repercussions on species endemic to the coastal zone

New report and range extension of smallmouth flounder, Etropus microstomus (Actinopterygii: Carangiformes: Cyclopsettidae), in the Gulf of Mexico

The smallmouth flounder, Etropus microstomus (Gill, 1864), is a species of benthic habits, associated with soft sandy bottoms, and distributed from Canada to the New Orleans coasts, and with specific reports in Corpus Christi, TX, USA. No records have been available from the Mexican coast, however. In the presently reported study, the first finding of this species, in three proximate localities, is described from the Mexican coast. This record constitutes a considerable expansion range in the Gulf of Mexico. Ten specimens were identified through traditional taxonomic characters, together with a CO1 genetic sequence. The presence of this species in the Mexican coastal zone may be due to the dissemination of ichthyoplankton in the ballast water of commercial ships or to the ocean currents along the coasts of the Gulf of Mexico