Abstract
Strategies used to assess patterns of change in species richness and biomass of seagrass communities along siltation gradients located off the coast of Southeast Asia are detailed. These measurement programs were carried out in waters located off the coasts of the Philippines and Thailand. Substantial declines in seagrass species richness and community leaf biomass were found in regions where the silt and clay content of the sediment exceeded 15%. Multispecific meadows were the only regions where researchers found members of Syringodium isoetifolium and Cymodecea rotundata. Heavily silted sediments supported only one type of seagrass, namely Enhalus acoroides. A ranking of species sensitivities to siltation is proposed. These findings will assist in the development of limits on siltation loads to coastal waters in the region.