Seokwoo Hong1, Junsu Kim1, Young Wook Ko2, Kwon Mo Yang1, Daniela Macias1, Jeong Ha Kim1
1Department of Biological Sciences, Sungkyunkwan University, Suwon, Republic of Korea, 2Division of Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
Correspondence: Jeong Ha Kim, jhkbio@skku.edu
Subtidals in the east coast of Korea represent typical urchin barrens with low macroalgal abundance. We investigated the relative effects of grazer control and transplantation on algal forest restoration in subtidal barren rocks in Jangho, east coast of Korea. We set three experimental treatments: no urchins (NU), NU plus no herbivorous gastropods (NH), NH plus Ecklonia bicyclis transplant (NHT) in an additive manipulative design. Six months after the initiation of the experiment, seaweed abundance increased in all experimental treatments. The highest peak was found in the spring season of the 1st year. Year-to-year variations became smaller throughout the survey period due to transitions in algal assemblage from fast-growing annuals to perennials. The comparison of NU and control site indicated that urchin removal had an exclusive effect on algal recovery while additional removal of herbivorous gastropods had no effect on quantitative recovery. The community assemblages of the three treatments became more distinct in the subsequent years, showing diverse dominance in NU, red algal dominance in NH, and dominance of E. bicyclis and understory groups in NHT. Subsequent demographic studies of E. bicyclis showed a continuous increase in population size and number of recruits. Furthermore, dispersal of E. bicyclis to surrounding habitats was observed, confirming the successful population establishment from transplantation. Our research provides evidence that 1) urchin removal from barrens can lead to rapid restoration of seaweed forests in subtidal habitats and 2) successful establishment of kelp population functions as a spore source, promoting phase shift from barren to algal forest.