Restoration of the temperate canopy-forming brown algae Ecklonia cava and Sargassum macrocarpum using epoxy-based transplantation technique for natural rocky reefs
摘要
Ecklonia cava and Sargassum macrocarpum are foundational canopy-forming species that provide various ecosystem services in temperate coastal regions of the northwestern Pacific. However, their habitats are increasingly threatened by anthropogenic activities and climate change, highlighting the urgent need for restoration. In this study, we developed and tested a novel restoration technique for transplanting juvenile (less than 1-year-old) individuals of both species onto subtidal rocky reefs at a depth of 5 m. The method involved attaching holdfasts to small epoxy panels using instant adhesive, then securing them to the reef using screws. This approach promoted natural attachment through holdfast development. Morphological traits of transplanted individuals were monitored monthly. After one year, approximately 58% of individuals survived, and the longest blade lengths were recorded in August (43 cm for E. cava and 54 cm for S. macrocarpum), similar to those observed in natural populations. Although survival was negatively affected by herbivory and physical disturbances such as typhoons, the development of holdfasts contributed to high survival rates, demonstrating the effectiveness of the method. Based on morphological development, the optimal transplantation period appears to be October to November. Overall, this holdfast-based reef attachment method is considered more effective than traditional rope-based transplantation techniques.