Changes in intra-lagoon connectivity of black-lipped pearl oyster populations in less than a decade in a pearl farming semi-closed atoll Bouchet, N. Teaniniuraitemoana, V. Reisser, C. Lo-Yat, A. Trophime, T. /Andréfouët, Serge Pinctada margaritifera Genomics Connectivity Aquaculture Lagoon Pearl Farming The genetic connectivity between different pearl oyster (Pinctada margaritifera) populations from the pearlfarming Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia) was reassessed 8 years after an initial study performed in 2017. The 2017 genomic analysis revealed the presence of two spatially-structured genetic clusters, including a wild population from the north part of the Ahe lagoon, which was the only source of all spats. Specimens from wild (n = 170), farmed (n = 136) and spat (n = 433) populations were collected in 2024-2025 to primarily re-assess the origin (farmed or wild, or both) of the spats. In stark contrast with the 2017 results, the genomic analysis based on 14,886 SNPs common to all samples revealed low genetic diversity, high inbreeding rates, and the existence of two genetic clusters each without clear spatial distribution, suggesting intra- and inter-population genetic homogenization at lagoon scale. The 2024-2025 data suggest that both wild and farmed populations can contribute to the spat production. The observed population homogenization is explained by the ban of inter-island transfers since 2019 which was endorsed by pearl farmers, leading to a farming oyster production in closed-circuit within the lagoon. The comparison between all samples suggests that the current 2024-2025 populations are related to the north wild population present in 2017. In the light of the current decrease of wild oyster stocks and spat production in Ahe and elsewhere, the consequences of these findings are discussed in terms of restocking and long-term monitoring of wild oyster populations in both exploited and pristine lagoons. 2026 text https://www.documentation.ird.fr/hor/fdi:010097093 fdi:010097093 Bouchet N., Teaniniuraitemoana V., Reisser C., Lo-Yat A., Trophime T., Andréfouët Serge. Changes in intra-lagoon connectivity of black-lipped pearl oyster populations in less than a decade in a pearl farming semi-closed atoll. 2026, 230, 119826 [13 p.] EN POLYNESIE FRANCAISE TUAMOTU GAMBIER