Adaptation mechanisms and ecological consequences of seaweed invasions: a review case of agarophyte Gracilaria vermiculophylla

To prioritize management, conservation and restoration from seaweed invasions, it is important for policy-makers to elucidate the ecological mechanisms during the three phases of invasion: introduction, establishment, and diffusion. In this review, we synthesize the current knowledge of the invasion mechanisms and ecological impacts of Gracilaria vermiculophylla, a red agarophyte native to Asia Northwest Pacific, which now has become a rapid and successful coastal invader in the Atlantic and Eastern Pacific Oceans. Eco-physiological and chemical studies have revealed that some ecological traits, including survival in dark condition (e.g. the ballast water), tolerance to grazing and extreme salinities and temperatures, insensitive to UVR and light intensity and nutrient levels, adaptation to a wide diversity of habitats, and chemical defense to potential predators, may provide G. vermiculophylla an unmatched advantage during its global invasion. The rapid growth, flexible reproduction through fragmentation, efficient recruitment on hard substratum, seeding success on various vectors, and interaction with local community organisms may also contribute to its rapid increase in abundance and effects on the invaded coastal ecosystems. G. vermiculophylla showed both negative and positive impacts to the marine ecosystems through changing interspecific competition, increasing habitat diversity, altering the community complex, and transforming biogeochemical cycles and estuarine food webs. Future surveys such as marine exotic genomics, transcriptome sequencing and epigenetic variation between native and invasive entities may provide insightful promise on molecular mechanisms of seaweed invasion.