We analyzed 9,933 larvae from 383 samples in the Gulf of Aqaba collected during 2010-2011 stratified over sites, depth and seasons and analyzed their metagenome using NGS technology.. Reef fish larvae Eilat

The global deterioration of coral reefs is fueling considerable reef monitoring and conservation efforts worldwide. A major focus of these efforts is the larval pool of reef fish, which is crucial to population replenishment and dispersal in the coral reef. However, species-level community-wide monitoring of reef fish larvae was so far impractical due to the high morphological identity between larvae of different species. Here we used barcode-based, amplification-free, high throughput metagenomics to study larval ecology in the Gulf of Aqaba, a habitat that includes >1.5% of all world fish species. We analyzed 9,933 larvae from 383 samples collected during 2010-2011 stratified over sites, depth and seasons. Metagenomic DNA extracted from pooled larvae was matched to a database of genomic barcodes compiled for 77% of adult reef fish in the region. This yielded species-level, quantitative reconstruction of the larval community, allowing species abundance estimation. We documented spatio-temporal preferences of larvae of multiple species, and found significant correlations between the abundance of adults and their larvae, suggesting that larval supply plays a major role in determining local adult densities. We also documented larval flux of species whose adults were never sighted in the region, suggesting recruitment barriers as the major cause for adult absence. Our data also suggest larvae as a dispersal mode for Lessepsian migration of Indo-Pacific species into the Mediterranean. Our method, which facilitates quantitative ecological inferences at high taxonomic resolution, is applicable to any larval community and could assist in coral-reef conservation as well as fishery management efforts