A polyp from nothing: The extreme regeneration capacity of the Atlantic invasive sun corals Tubastraea coccinea and T. tagusensis (Anthozoa, Scleractinia)

The azooxanthellate sun corals Tubastraea coccinea and T. tagusensis have invaded and dramatically changed rocky reef habitats along the Brazilian coast. Management of invaded areas has brought discussions on its potential negative effects regarding species dispersal, including those related to fragmentation. Although fragmentation has been observed in unmanaged localities, here we experimentally tested the sun coral ability to regenerate from undifferentiated coral tissue to fully functional polyps in response to differences in food supply, temperature, and fragment size. In general, survival and successful regeneration were high and markedly similar for both species. However, while percent of tissue retraction/reorganization (a proxy of metabolic cost) responded to fragment size and temperature, mouth development was faster in fed fragments. Together, our findings indicate that sun coral fragments may regenerate at temperatures that lead to extensive bleaching in native scleractinians that harbor Symbiodinium. Although no doubts remain about the necessity and efficacy of the management of invasive Tubastraea spp., recovery of undifferentiated coral tissue to fully functional polyps may contribute to their invasion success and should be taken into account during management efforts.