Syringodium isoetifolium

This seagrass is sensitive to light deprivation and a lowering of salinity in its environment. In a major flooding event in Queensland, half the seagrasses were lost in a shallow study area in Moreton Bay, the Syringodium isoetifolium disappearing almost completely while Zostera muelleri and other seagrass species survived, relatively unaffected.^[4] Another Australian study examined the likelihood of Syringodium isoetifolium becoming invasive if its range changed as a result of climate change. In this experiment, a small patch of Syringodium isoetifolium was established in a tropical subtidal area, and the area covered by the plant increased in size by 800% in a fifteen-year period, mostly through clonal growth.^[5]

Marine fouling causes much economic loss from organisms growing on the hulls of ships, pipelines and other submerged structures. Seagrasses have developed defence mechanisms against such epibionts, and few fouling organisms grow on them. A methanolic extract of Syringodium isoetifolium was assessed as a natural antifouling agent.^[6] It was found to inhibit growth of microalgae and biofilm bacteria, as well as the limpet Patella vulgata and the brown mussel Perna perna, all of which cause marine fouling.^[6] The extract was non-toxic to brine shrimps and showed promise as an agent to replace the toxic chemicals that have been used historically. The secondary metabolites involved seem to be fatty acids in the range C16 to C24.^[6]