Asterocarpa humilis and Corella eumyota are two ascidians native from the southern hemisphere identified on UK shores in recent years. They are atypical species that although being solitary brood their larvae. Little is known regarding their reproductive behaviour in their introduced range and how their reproductive and larval traits facilitate the populations’ establishment. Here, three experiments were conducted to assess their reproductive seasonality, fecundity and larval ecology; additionally comparisons were made with another solitary brooding species, Dendrodoa grossularia, three typical solitary broadcast-spawning species, Ciona intestinalis, Molgula socialis and Ascidiella aspersa, and three colonial brooding species, Botrylloides violaceus, Botryllus schlosseri and Diplosoma listerianum. A. humilis brooded larvae throughout the year. A. humilis and C. eumyota released larvae for the entire duration of the experiment (February to July).Throughout the season, the average fecundity for
C. eumyota was 398.22 offspring.g-1, and 221.96 offspring.g-1 for A. humilis. They
displayed high fecundities more similar to broadcast-spawning species than brooding species. Larval dispersal and settlement behaviours were linked to the species’ reproductive strategy. Solitary brooders, including A. humilis and C. eumyota, showed short dispersal distances and preferences for shaded and sheltered substrates, this behaviour potentially reduces post-settlement mortality and promotes population build- up. The ability of C. eumyota and A. humilis to reproduce over a long period of the year, added to their high fecundity and larval behaviour promoting aggregation, allows for a facilitated process of population build-up. This study demonstrates that
C.eumyota and A. humilis are efficient invaders whose reproductive traits enable their success.In collaboration with
The Marine Biological Association of the U
