Effective asexual reproduction of a widespread soft coral: comparative assessment of four different fragmentation...

Many coral reefs worldwide are experiencing declines in hard corals, resulting in other benthic organisms, e.g., soft corals, becoming more dominant. As such, more studies on the ecophysiology of soft corals are needed. Despite many methods for asexual reproduction of hard corals, effective methods for soft corals, i.e., without a hard skeleton, are scarce. This study, thus, assessed four fragmentation methods, the glue, rubber band, tunnel mesh, and plug mesh method for the pulsating soft coral Xenia umbellata that is widely distributed in the tropical Indo-Pacific.

Methods were comparatively assessed by determining the required time and labor for the fragmentation plus the health status of the fragmented corals by measuring their oxygen fluxes and pulsation rates, i.e., a special feature of this soft coral that can be used as a proxy for its health.

There were no significant health status differences between methods. This was indicated by similar gross photosynthesis (between 7.4 to 9.7 μg O₂ polyp^-1 h^-1) and pulsating rates (between 35 and 44 pulses min^-1) among methods. In terms of time/labor intensity and success rates, i.e., the percentage of fragments attached to the desired surface, the plug mesh method was the most efficient method with a significantly higher success rate (95 ± 5%), while the others had a success rate between 5 ± 5 and 45 ± 15%. The time needed for fragmentation, though not significant, was also the shortest (78 ± 11 s fragment^-1), while other methods required between 84 ± 14 and 126 ± 8 s frag^-1. The plug mesh method may thus be a valuable tool related to the reproduction of soft corals for use in subsequent experimental work.