Distribution and Growth Condition of Enhalus Acoroides in Iriomote Island

Enhalus acoroides, a tropical seagrass with a northern distribution limit around the Yaeyama Islands, is listed as Endangered (II) by Japan's Ministry of the Environment. While localized declines have been documented in Iriomote Island, its broader distribution and growth conditions remain unclear. A study mapping its presence across the northwestern coast of Iriomote Island revealed that dense stands occupy only 14% of suitable shoreline, typically in sheltered bays where wave exposure is minimal compared to offshore areas (D.L. ±0.0–-0.5 m). This suggests that while the species persists in low-energy environments, its population is fragmented and vulnerable to further decline.

TAKEYAMA, K., KOHNO, H., KURAMOCHI, T., IWASAKI, A., MURAKAMI, T., KIMURA, K., UKAI, A., & NAKASE, K. (2014). DISTRIBUTION AND GROWTH CONDITION OF ENHALUS ACOROIDES IN IRIOMOTE ISLAND. Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 70(2), I. https://doi.org/10.2208/jscejoe.70.i_1068