Saccostrea and Crassostrea (Bivalvia: Ostreidae) in Colombia and evidence of community shifts in the central Caribbean coast

Abstract

Abstract Members of the Ostreidae are ecologically and economically important bivalves that form dense reef structures and function as ecosystem engineers. Despite their relevance, knowledge of this family in the Colombian Caribbean remains limited, with species delimitation hindered by high morphological variability and long-standing taxonomic uncertainties, particularly between Crassostrea rhizophorae and C. virginica. This study updates our understanding of the diversity and distribution of Ostreidae in the central Colombian Caribbean, including the detection of a non-native oyster species. Field surveys were conducted in the Puerto Velero marina (PVm) and the Mallorquín Coastal Lagoon (MCL), two environmentally contrasting systems influenced by the Magdalena River plume and intense anthropogenic pressures. Specimens from artificial substrates at PVm and mangroves and concrete debris at MCL were identified using morphology and DNA barcoding. Results provide the first record of C. virginica in MCL, refining its regional taxonomic status. More notably, we report the first occurrence of the Indo-Pacific oyster Saccostrea lineage F in Colombia, with specimens from both PVm and MCL, suggesting introduction via maritime traffic. Ecological shifts in MCL, including the decline of native Crassostrea and the emergence of opportunistic or introduced bivalves, highlight ongoing biotic reorganization. These findings highlight the need for integrative taxonomy and long-term monitoring to better assess invasion risks and support coastal ecosystem conservation.