Revolutions in rearing barnacles: rotating flow and substratum for culturing larvae and adults

Barnacles that live attached to dynamic surfaces, particularly species that are epizoic with marine megafauna, draw benefit from their mobile homes through assistance with passive feeding and escape from predators. A moveable substratum may also offer positive cues for their settling larvae. In this study, we tested a technique for rearing in the laboratory, from larval stage to adult, a barnacle that associates with sea turtles, Chelonibia testudinaria. A dual-stage culturing system was devised, coupling circular tanks with rotating substrata to generate effects of flow and motion. A round-bottomed culturing vessel with gentle cyclical flow was used to raise larvae and then induce them to settle on revolving PVC pipes. The colonized pipes were then transferred to a separate tank for grow-out with continued rotation. Though settlement rates were low, the system proved valuable in obtaining the even distribution of a satisfactory number of juveniles across the pipes and in growing them in the laboratory for up to 2 yrs. This technique opens a variety of avenues of study for taxa that prefer or require a dynamic substratum.