A recent journal article published in Tropics reports on a study of wood-boring isopod impacts on mangrove trees in a recovering forest in Batan Estuary, Aklan, Philippines. The research involved IESM Faculty Member Rene Rollon, together with IESM researchers Giannina Marie G. Albano, Green Ann A. Cruz, and Maia Patricia D. Garcia, in collaboration with scientists from partner institutions in the Philippines and Japan. The study assessed how infestation by the marine isopod Sphaeroma terebrans affects trunk condition in three mangrove species, Avicennia marina, Avicennia alba, and Sonneratia alba, using field measurements and non-destructive acoustic tomography.
Results showed that the density of isopod-bored holes on mangrove trunks was strongly related to tidal elevation, with higher hole densities occurring in trunk sections that experienced longer periods of tidal inundation and minimal air exposure. Across all three species, hole density declined with increasing height above mean lower low water level, indicating that prolonged exposure to air limits isopod colonization. Peak infestation was consistently observed in lower trunk sections that remained submerged for most of the year.
Analysis of internal trunk condition revealed clear species-specific differences in decay. Avicennia marina exhibited significantly greater trunk decay area and volume compared with A. alba and S. alba, particularly in the lower, frequently inundated sections of the trunk. While isopod activity was associated with the initiation of internal decay, the study found that hole density alone did not fully explain the extent of trunk deterioration, suggesting that host species characteristics and environmental factors also play important roles. These findings provide empirical evidence relevant to mangrove rehabilitation and monitoring efforts in Philippine estuaries.
Reference: Maquirang, J. R. H., Rollon, R. N., Suwa, R., Primavera-Tirol, Y., Albano, G. M. G., Cruz, G. A. A., Garcia, M. P. D., Basina, R. M., & Nadaoka, K. (2026). Impact of wood-boring isopod Sphaeroma terebrans on the trunks of different mangrove species at a recovering forest in Batan Estuary, Aklan, Philippines. Tropics, SIMM06. https://doi.org/10.3759/tropics.SIMM06
