Disturbance influences the invasion of a seagrass into an existing meadow

Future impacts from climate change and human activities may increase the likelihood of invasions of native marine species into existing habitats as a result of range shifts. To provide an understanding of the invasion of a native seagrass species (Syringodium isoetifolium) into a tropical multi-species meadow, detailed field assessments were conducted over a six year period. After establishing in a discrete patch, the extent and standing crop of S. isoetifolium increased 800 and 7000 fold, respectively, between 1988 and 2003 (∼300–260,000 m2 and <1 kg DW to 7596 ± 555 kg DW). The expansion of S. isoetifolium was confined to subtidal areas and appears primarily from clonal growth. The observed expansion of this species into a new locality was found to be clearly influenced by cumulative impacts and chronic small-scale physical disturbances. This study has immediate relevance to managing impacts which influence the spread of invasive species.