As climate change accelerates, the need for fast and accurate ways to monitor threatened ecosystems is becoming increasingly urgent. Coral reefs, in particular, have suffered major declines in both cover and diversity. Environmental DNA (eDNA) metabarcoding — analysing DNA from seawater — offers a powerful new tool to complement traditional reef monitoring.
In this study, researchers combined conventional coral survey data with eDNA collected from seawater around the highly diverse Rowley Shoals in Western Australia. Using two coral-targeted ITS2 assays and a customised reference database that included tissue sequences from 70 locally collected coral specimens, they were able to identify 37 coral genera and 40 species from just 56 one-litre water samples.
The results showed substantial overlap between eDNA detections and visual surveys. Importantly, taxonomic resolution improved dramatically when the analysis was “spiked” with high-quality local reference sequences, demonstrating that curated databases greatly enhance species-level identification in eDNA metabarcoding.
This study highlights the strong potential of eDNA for monitoring coral biodiversity and underscores the value of building local reference datasets to support accurate taxonomic assignments.
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