Distribution Analysis of Enhalus Acroides Vegetation, Using Hydraulic Model, in the Northwest Sea Area of Iriomote Island, Okinawa, Japan

A study reveals that the distribution of Enhalus acroides, a tropical seagrass species listed as endangered (Vulnerable) by Japan's Environment Ministry, is significantly influenced by specific physical conditions. Dense and tall stands of this seagrass are found in waters up to 0.76 meters deep, characterized by average significant wave heights of 25–32 cm during high winter waves, bottom current speeds of 11–19 cm/s, and residual tidal currents of 0.1–0.3 cm/s at spring tides. Researchers used a hydraulic model to simulate wave conditions in the northwest sea area of Iriomote Island, Okinawa, Japan, and validated these findings against observed seagrass distribution patterns. The study demonstrates that physical environmental factors play a critical role in shaping the seagrass's habitat, providing insights into its conservation in this UNESCO World Heritage Site.

NAKASE, K., MURAKAMI, T., UKAI, A., MIZUTANI, A., SHIMOKAWA, S., & KOHNO, H. (2015). DISTRIBUTION ANALYSIS OF ENHALUS ACROIDES VEGETATION, USING HYDRAULIC MODEL, IN THE NORTHWEST SEA AREA OF IRIOMOTE ISLAND, OKINAWA, JAPAN. Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 71(2), I. https://doi.org/10.2208/jscejoe.71.i_957