Effect of water velocity on Undaria pinnatifida and Saccharina japonica growth in a novel tank system designed for macroalgae cultivation

摘要

Abstract Kelps are economically valuable primary producers; therefore, many studies on breeding have attempted to increase kelp productivity and quality. However, most cultivation tests have been performed in the ocean, thereby limiting the development of new cultivars. To reduce the breeding duration period and confirm cultivar phenotypes, we developed a novel tank culture system, referred to as a circulation and floating culture system (CFCS), for cultivating macroalgae. In the CFCS, kelp can be cultivated under controlled environmental conditions. Water velocity in the CFCS can be regulated by changing the angle of a seawater inlet spout without changing the volume of seawater in the tank. Undaria pinnatifida and Saccharina japonica cultivated in the CFCS exhibited morphological features very similar to those of plants grown naturally in the ocean. The result suggests that the facility is useful for identifying water motion conditions suitable for increasing the production of any macroalgae species. Using this facility, both species were grown from juvenile sporophytes (20?mm) to maturity; for U. pinnatifida, the subsequent generation was successfully cultivated. Improved growth of U. pinnatifida was achieved in fast flows compared with slow flows, whereas S. japonica developed a wider shape and heavier biomass in slow flows compared with fast flows. We discuss the application and implication of the CFCS for breeding research and the physiological ecology of macroalgae.]]>