2021 Volume 77 Issue 2 Pages I_589-I_594
The purpose of this study is to determine the cause of Ecklonia kurome decline in the seagrass beds that have been formed and the seagrass bed's recovery. For that purpose, we observed by using a fixed-point camera and analyzed the DNA concentration of specific fish in seawater. In May 2019, there was a lot of Ecklonia kurome with only stems left in the seagrass bed, and there were traces of feeding damage, suggesting that the effects of feeding damage were large. There was no correlation between the proportion of Ecklonia kurome remaining only in the stem and the frequency of appearance of Siganus fuscescens, Acanthopagrus schlegelii and Stephanolepis cirrhifer, observed by the stationary cameras. When Ecklonia kurome declined, almost no Siganus fuscescens DNA was detected in the constructed area until May 2019. There is no direct evidence of feeding damage other than feeding damage marks that could be confirmed. In the artificial seaweed bed substratum, where seaweeds declined due to feeding damage, small seaweeds reappeared just after the creation. Ecklonia kurome also appeared in about 19 months, and the seaweed species just before the decline.
