The study site is located in Koje Bay on the southern coast of Korea. Three species of Zostera (Z. japonica, Z. marina, and Z. caespitosa) are distributed sequentially along the gradient of water depth. Z. japonica primarily inhabits the intertidal zone, whereas Z. marina grows from the lower intertidal to shallow subtidal zones. Z. caespitosa is exclusively found in the shallow subtidal zone, typically co-occurring the lower distributional limit of Z. marina. Since 2008, seagrasses have gradually decreased in Koje Bay, with Z. japonica particularly experiencing a dramatic decline in the intertidal zone. In the study site, seagrasses in the intertidal zone suffer from repetitive and acute human-induced disturbances, such as clam harvesting activities and oyster cultivation. Rising water temperature and extreme climatic events, such as MHWs, are also potential threats to the subtidal seagrass species in Koje Bay.