Rapid assessment of coral cover from environmental DNA in Hawai'i

Abstract

AbstractCoral reefs support the most diverse assemblages of marine life on Earth, yet are declining due to local and global stressors. Rapid and widespread monitoring is essential for tracking ecosystem responses, but assessment of coral communities traditionally relies on time‐consuming visual estimates of coral cover, the percentage of substrate occupied by living corals. The analysis of environmental DNA (eDNA) offers fast and efficient insights into the abundance and distribution of species, yet it remains untested to monitor coral biomass. Here, we demonstrate that visual estimates are highly correlated with the abundance of coral eDNA on reefs in Hawai'i measured with a relatively simple, rapid, but replicated PCR‐based metabarcoding approach. Target sequence length was also tested by amplifying short (~120 base‐pairs) and long (~400 base‐pairs) fragments from the same region of two mitochondrial DNA genes, 16S ribosomal DNA, and cytochrome oxidase‐1 using primers designed to preferentially amplify Hawaiian coral genera. Careful primer selection and target sequence lengths play an important role in determination of coral abundance from eDNA biomass. Given its broad applicability and ease of use, eDNA metabarcoding can provide complementary analytical support for biomonitoring programs and management initiatives tracking changes in coral cover caused by climate change and other disturbances on coral reefs.