PICRC Collaborates on Environmental DNA Study Exploring Coral Communities in Palau

Coral reefs are globally recognized for the extraordinary biodiversity they support. In Palau, reefs are among the most pristine and well-developed in the world and constitute an essential resource for local communities.

In the face of climate change, which can trigger mass coral mortality events, it is critical to design appropriate conservation measures to preserve these valuable ecosystems. Achieving this requires continued research efforts to deepen our understanding of reef systems and translate scientific knowledge into effective, locally adapted management and protection strategies.

To better understand the composition of coral communities across Palau and the factors shaping them, researchers from the Okinawa Institute of Science and Technology, the Incorporated Foundation Okinawa Environment Science Center, the Palau International Coral Reef Center (PICRC), and The Nature Conservancy (Micronesia and Polynesia Program) conducted a collaborative study recently published in the peer-reviewed journal Frontiers in Marine Science.

By analyzing fragments of DNA present in seawater—known as environmental DNA (eDNA)—from 10 reef sites across Palau, researchers were able to identify 60 of the 69 genera of scleractinian corals (also known as hard or reef-building corals) recorded in the country. To do so, they applied a technique called metabarcoding, which amplifies and sequences DNA fragments in order to determine the genera or species to which they belong. To complement these molecular analyses, two experienced coral reef specialists conducted in-water surveys, snorkeling at each site to record coral community types and dominant coral genera.

The results revealed that coral community structure is shaped by local geological features—such as lagoons, reef slopes, and moats—rather than by geographic orientation (for example, north versus south). Dominant coral genera, including Acropora and Porites, varied among sites, forming three distinct community profiles that highlight the diversity and complexity of Palau’s reefs. Additionally, certain coral genera were found exclusively in specific locations, including the western outer reefs.

Beyond further demonstrating the strong potential of eDNA as a tool for reef research, this study provides new insights into how coral communities in Palau may have developed and which factors influence their structure and diversity. These findings can help inform the design of more effective conservation measures tailored to local reef characteristics.

The full study, “Environmental DNA metabarcoding reveals geologic, not geographic, drivers of coral community structure in Palau,” is available open access at https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2025.1669587/full