Half a Century of Global Invasion: How Global Trends Can Inform the Spread and Phenology of the Non-Native Kelp, Undaria Pinnatifida, in California, United States.

This article focuses on the ecology, spread, and potential impacts of the non-native seaweed species Undaria pinnatifida along the California coast. Undaria, a kelp native to northeast Asia and listed by the IUCN as one of the world’s worst invasive alien species, has been documented globally in protected habitats such as bays and harbors, with some populations establishing in exposed rocky reef ecosystems. Using global literature and spatial analyses of sea surface temperature and habitat data, the study suggests that Undaria’s thermal tolerance and dispersal capacity could allow it to spread from harbors into adjacent natural kelp forest habitats in southern California, particularly around San Diego. Despite its widespread introduction and potential for ecological and economic impacts, there remains limited region-specific research on Undaria’s effects in California, highlighting the need for further study to inform management decisions.