Adaptive development of tolerance to wave-induced dislodgement for cultured Laminaria japonica in response to water movement

Transplant experiment was conducted to investigate the developmental tolera nce to wave-induced dislodgement for Laminaria japonica in response to wate r movement. L. japonica plants cultured on long-line rope in a sheltered si te were moved to a moderately exposed site monthly from February to May. At tachment strength for plants from the sheltered site increased linearly wit h the plant weight but was much lower than that for transplants with the sa me plant weight. The ratio of attachment strength to plant weight in late J une showed a linear increase with the days of cultivation at the transplant site. Comparison of the frequency distribution of the root-mean-square wat er velocity at the transplant, site with that at the sheltered site suggest ed that there might exist the velocity threshold of developmental tolerance to dislodgement, probably from 15 to 20 cm/s in rms value.