King tides are extra high tides that occur when the earth, moon, and sun align during a full or new moon. These king tides can cause coastal flooding, impacting coastal ecosystems in ways similar to how rising sea levels might. Researchers funded by the Pacific Islands CASC are using environmental DNA (eDNA) to study how fish communities in Hawaiʻi’s Heʻeia estuary are affected by seasonal extreme tides to better understand these impacts.  

eDNA, or genetic material left behind in the environment by organisms from their skin, scales, fur, poop, mucus, or scales, allows scientists to track species without directly handling or observing them. By extracting and analyzing the genetic material captured in air, water, or soil samples, scientists can monitor fish diversity and ecosystem changes in a lower impact and more efficient manner.  

The idea for the eDNA Toolkit emerged from conversations with stewardship practitioners during restoration activities -- discussions which emphasized the need for accessible and efficient ways to monitor species and ecosystem changes. In response, the researchers and local fishpond organizations worked together to co-create a practical toolkit that offers clear guidelines for collecting and analyzing eDNA samples without needing advanced training. Several conservation groups are already using the non-invasive method to monitor native and endemic goby species (ʻoʻopu), which are good indicators of stream health. The project team is currently continuing to share the toolkit and gather feedback to improve its usefulness. 

Researchers hope the eDNA Toolkit will help local communities and organizations monitor fish diversity, manage resources, and prepare for the long-term effects of climate change.  

This work was funded by the Pacific Islands Climate Adaptation Science Center Project: "Effect of Extreme Tidal Events on Future Sea-Level Rise Scenarios for Heʻeia Fish Communities Undergoing Ahupuaʻa Restoration"