First record of the non-native ascidian Ascidiella aspersa in the Falkland Islands

Abstract Ascidiella aspersa is a solitary ascidian native to the North-east Atlantic that has been introduced to many regions around the globe. In 2023, individuals matching the description of A. aspersa were found on an artificial dock structure in Stanley Harbour, Falkland Islands, where there were no previous records of the species. Individuals were collected for morphological and genetic analyses, and previous surveys of the site were reanalysed to estimate the abundance of the population. The morphological examination and genetic analysis confirmed the individuals were A. aspersa. Analysis of the survey data suggested the species has been present since at least 2011 and forms a reasonably dense population on the more sheltered areas of the dock structure. Further survey work and population genetic investigations are required to better understand the likely origin of the population, and the abundance and extent of the species around the Falkland Islands.