Phytoplankton diversity in coral reefs of Guanahacabibes National Park, Cuba

Coral reefs are highly complex and biodiverse ecosystems that are fundamental to ecological balance and socioeconomic development. Assessing and monitoring the communities that comprise them is essential to preserving their stability and ensuring their long-term conservation. Guanahacabibes National Park is home to one of the best-preserved and most diverse reefs on the Cuban platform and in the Caribbean. Studies have been conducted on multiple species in the area, but there is a knowledge gap regarding phytoplankton. Changes in the composition of the phytoplankton community allow for the rapid detection of deteriorating environmental conditions in the ecosystem. This research aims to obtain an inventory of the diversity and composition of the phytoplankton community in the waters of the Guanahacabibes National Park reefs. In August 2022 and 2023, five reefs in the contemplative diving area were sampled. Seven phyla, seven classes,27 orders, 31 families, and 32 genera were identified. Heterokontophyta had the greatest contribution to specific richness, with the highest number of organisms recorded in the Cabezo de Marcel and Acuario reefs. The genera Navicula, Thalassiosira, Gymnodinium, Oxytoxum and Aphanocapsa predominated, as did the species Nitzschia longissima and Scrippsiella acuminata. The waters of the reefs in the contemplative diving area of Guanahacabibes National Park present favorable environmental conditions, characterized by low phytoplankton richness and concentration. However, the presence of potentially harmful organisms highlights the importance of implementing continuous monitoring in this marine area.