Foraminíferos bentónicos como indicadores ambientales en dos entornos arrecifales de Colombia: la isla de Providencia y la bahía de Cartagena

Reef settings play key ecosystemic functions in the Caribbean realm, but the unrestrained exploitation of their natural resources and other anthropogenic effects threaten their preservation. Here, we explore the use of the foraminiferal assemblages as bioindicators in two Colombian Caribbean localities with different levels of environmental stress. The material studied was collected from the reef zones in Old Providence Island (San Andrés Archipelago) and Varadero (Cartagena Bay), where typical reef lagoon foraminiferal assemblages are found. The main taxa comprised the symbiont-bearing genera Archaias, Asterigerina, Amphistegina, and Heterostegina, the porcelaneous forms Quinqueloculina,Triloculina, and Spiroloculina, and the rotaliids Rotorbinella, Cymbaloporetta, and Eponides. The stress-tolerant taxa Ammonia, Clavulina, and Cribroelphidium were also identified in variable abundances. The detailed analysis of the faunistic composition in Old Providence and Varadero indicated significant differences in the abundances of some taxa, likely related to specific stress conditions in both localities. These stress conditions were particularly evident in Varadero, where the FORAM (Foraminifers in Reef Assessment and Monitoring) index (FI) estimations suggest moderate to highly stressed reef settings, similar to those found in preliminary surveys in this área and probably influenced by the higher anthropogenic impact at the Cartagena Bay. In contrast, the foraminiferal assemblages and the FI estimations of Old Providence suggest low to moderate stress conditions, as previously reported in other insular bodies of the archipelago.