2018 Volume 56 Issue 1-2 Pages 11-20
This study estimated the area of eelgrass beds in Matsukawa-ura Lagoon and investigated spatiotemporal changes of the area using satellite images obtained after the 2011 off the Pacific coast of Tohoku Earthquake. Furthermore, we examined the spatial distribution of mud contents in the lagoon after the earthquake. In April 2012, the eelgrass beds were observed in small area（0.013 km²）of the northern part of the lagoon. Almost all eelgrass was physically removed by devastating tsunami waves. In September 2014, the bed area had increased sharply to approximately 0.39 km². The spatial distribution also expanded from the northern to the central lagoon. In November 2015, the rate of increase was only approximately 10% compared with the previous year. No remarkable change was found in the spatial distribution. The mud content was 0-79%, the eelgrass bed was observed in the area where the mud contents were less than 30%. The eelgrass bed area in 2015 was roughly twice that in 2010. Eelgrass beds had expanded to the upper edge of the waterway after the earthquake. The subtidal zone, which is suitable for eelgrass growth, expanded because of ground subsidence.
