Assessing Genomic Diversity and Clonality in Tape Seagrass in Guam and Surrounding Pacific Islands to Inform Climate Resilient Restoration

 
Seagrass meadows support island communities by sustaining fisheries and protecting shorelines. However, some species, such as tape grass, may lack the genetic variation needed to survive and adapt to warmer, saltier ocean waters. Researchers supported by this Pacific Islands CASC project will sequence the tape grass genome and assess genetic variation across Micronesia in relationship to different environmental conditions. Results will help management partners make decisions about seed-sourcing and transplanting to ensure seagrass populations can adapt to changing conditions and continue benefiting local communities.
 
Project Summary:
 
Seagrasses are marine flowering plants that form extensive underwater meadows, providing seafood, wave protection, recreation, cultural connections, and carbon storage. Yet, they face increasing threats from warmer, saltier waters and changing low-tide exposure. Whether seagrasses can survive these climate-driven changes depends in part on genetic variation – the differences in genes that may allow some plants to adapt more successfully. Tape grass is a large seagrass found in the Pacific and Indian Oceans that can grow over a meter tall and sequester large amounts of carbon. However, surveys of Guam’s seagrass beds have not found the female flowers or seeds needed for sexual reproduction, dispersal, and maintaining genetic variation. With only clonal reproduction, seagrass beds may lack resilience to changing conditions. Given declines in seagrass extent, seeds may need to be sourced from other locations to supplement populations, raising questions about where seeds should come from.
 
Scientists supported by this project will sequence the tape grass genome and survey genetic variation across Guam, Palau, and other Pacific Islands. The team will identify regions with high genetic variation, map patterns of dispersal and shared ancestry, and assess gene-environment relationships. Findings can help identify areas where seeds with certain genetics may be best suited for restoration under future conditions. Products will include a publicly available genome sequence, population genomic data, maps of genetic variation, and an online database of flowering and seed observations.

This project will help management partners across Micronesia decide whether to prioritize transplanting, and whether to source seeds from nearby islands or more distant ones. By uncovering the genetic variation and connectivity of tape grass populations across environments, scientists will provide actionable guidance for maintaining or increasing genetic variation within seagrass beds. This can help seagrasses adapt to climate change and continue supporting fisheries, protecting shorelines, and sustaining island communities.