Ship-hull mediated introduction risk of Colaconema formosanum: barnacle-associated dispersal and ecophysiological potential for coastal establishment
摘要
Human-mediated biological introductions, particularly via ship hull fouling in international maritime transport, present a significant threat to coastal marine ecosystems. Barnacles, despite antifouling measures, often colonize vessel surfaces and may facilitate the cryptic dispersal of epizoic macroalgae. In this study, we isolated and cultured a filamentous red alga from barnacles attached to a commercial vessel hull to clarify its taxonomic identity and assess its ecophysiological traits. Molecular phylogenetic analyses based on rbcL and COI-5P gene regions identified the alga as Colaconema formosanum, a subtropical species previously reported as an endophyte in Taiwan. Laboratory experiments revealed that C. formosanum exhibits optimal growth and photosynthetic performance at 25 °C and under high light intensity (100 μmol photons m⁻2 s⁻1), while maintaining active growth across a wide range of temperature (10–30 °C) and light conditions (20–100 μmol photons m⁻2 s⁻1). These physiological traits suggest strong potential for C. formosanum to establish viable populations along the Korean coastline, especially under warming sea surface temperatures. The role of barnacle fouling in facilitating the covert spread of this alga highlights the need for targeted biosecurity and hull management strategies. Our findings underscore the risk posed by shipping activities in facilitating the potential introduction and invasiveness of subtropical seaweeds in temperate regions.