The South American seagrass Zostera chiliensis: endangered or invasive?

The seagrass Zostera chilensis was recently described following taxonomic separation of Heterozostera tasmanica into four new species. With only three known populations occurring along the coast of central Chile it is... [ view full abstract ]

The seagrass Zostera chilensis was recently described following taxonomic separation of Heterozostera tasmanica into four new species. With only three known populations occurring along the coast of central Chile it is classified as an endangered species under the IUCN redlist. Recent molecular work has revealed no distinction between Z. chiliensis and the Australian seagrass Z. nigricaulis, suggesting a recent introduction to Chile. Successful amplification of seagrass samples from Chile using species-specific microsatellite markers developed for Z. nigricaulis support the idea that Chilean populations are derived from Australia. Using a combination of molecular data, historical shipping records, fragment viability data and oceanic modeling, we explore the possibility of a trans-oceanic dispersal event spanning several thousands of kilometers, versus a human mediated introduction event via shipping. Levels of genotypic diversity and patterns of connectivity among the three isolated populations along the Chilean coast are also explored. The results from this study have important implications for understand how potentially rare (but important) trans-oceanic dispersal events can lead to establishment of new populations.