<b>eDNA recovers fish composition turnover of the coral reefs of West Indian Ocean</b><b> islands</b>

The application of environmental DNA metabarcoding for monitoring marine biodiversity requires an understanding of the spatial scale of the eDNA signal, which is best tested in island systems. Here, we investigated the variation in Actinopterygii and Elasmobranchii species composition recovered from eDNA metabarcoding along a gradient of distance-to-reef in four of the five in total French Scattered Islands in the Western Indian Ocean.

We collected surface water samples at an increasing distance from reefs (0 m, 250 m, 500 m, 750 m). We used a metabarcoding protocol based on the ‘teleo’ primers to target marine reef fishes and classified taxa according to their habitat types (benthic or pelagic). We investigated the effect of distance-to-reef on <i>β</i> diversity variation using generalised linear mixed models and estimated species-specific distance-to-reef effects using a model-based approach for community data. eDNA metabarcoding analyses recovered distinct fish species composition across the four inventoried islands and variations along the distance-to-reef gradient.