Development of transplantation method for the restoration of surfgrass, Phyllospadix japonicus, in an exposed rocky shore using an artificial underwater structure

Abstract

The surfgrass Phyllospadix japonicus is an abundant seagrass on the exposed rocky shores of the Korean peninsula. Many surfgrass meadows on the coasts of Korea have been adversely affected by anthropogenic activities and natural phenomena such as “rock whitening,” which is caused by overgrowths of crustose coralline algae. Few attempts have been made to develop transplanting techniques for surfgrass, owing to the difficulty of transplant survival on exposed rocky shores. We developed a new Phyllospadix Transplant System (PTS), which was an artificial underwater structure constructed of a 4:5:1 ratio of cement, sand, and water. In January 2005, we transplanted P. japonicus shoots using the newly developed PTS. P. japonicus shoots were tied together at the lower part of the sheaths to iron screws, which were placed in a hollow part of the PTS, with latex elastic. To evaluate the feasibility of this transplantation technique, we compared vegetative and reproductive shoot densities, growth, and morphological characteristics in transplants to those of shoots in nearby natural beds over a 2-year period. Transplant density increased gradually without significant initial shoot loss. Approximately 6 months after transplantation, leaf growth of transplants was similar to that of naturally growing shoots. The shoot heights and sheath lengths of transplants were similar to those of naturally growing shoots at 10–15 months post-planting. Approximately 50 mm of rhizome elongation was detected in P. japonicus transplants over the 2-year period. Since P. japonicus transplants attached to the PTS successfully established at the test area, the transplantation of surfgrass using the PTS may be an effective approach to restoring the habitat of P. japonicus.