Osmotic adjustment of four mangrove species growing on Iriomote Island, Japan

A study on Iriomote Island, part of Japan's UNESCO World Heritage Sites, reveals that mangrove species exhibit distinct diurnal variations in osmotic adjustment but lack significant differences in leaf internal solute concentrations across their distribution ranges. Researchers analyzed four mangrove species (Osbukia, Heritiera, Bruguiera, and Ceriops) at the Hira River estuary, comparing daytime and nighttime soluble sugar levels and ion ratios. While no strong correlation was found between Na+:K+ ratios and sugar concentrations, daytime increases in total soluble sugars were observed in Osbukia and Heritiera. Strong correlations existed between solute concentrations and river water salinity, pH, and dissolved oxygen, though Na+:K+ ratios showed no such relationship. This suggests that osmotic adjustment in these mangroves is influenced by environmental factors but varies diurnally rather than spatially.

IWANAGA, F., YAMAMOTO, F., MAIMAITI, A., YOSHIDA, Y., MORI, N., TANIGUCHI, S., & YAMANAKA, N. (2013). Osmotic adjustment of four mangrove species growing on Iriomote Island, Japan. Journal of the Japanese Society of Revegetation Technology, 39(1), 21–26. https://doi.org/10.7211/jjsrt.39.21