Field Monitoring of Seaweed Bed Construction Using Coal-fly-ash Porous Concrete Panels on Coast of Noto Peninsula, Japan

Abstract

We conducted a pilot-scale experiment for seaweed bed construction using concrete substrata with newly developed fly-ash （ FA ） porous concrete panels or conventional concrete panels from November 23, 2013 to October 14, 2017 in a coastal area of Noto Peninsula, Japan. The FA porous concrete panel was manufactured by replacing 20-40 ％ of the cement with coal fly ash produced in a coal power plant. The total number of Ecklonia kurome sporophytes grown on two substrata after four years was 14 ． The erosion of central lamina began in the third year and the maturing of over 50 ％ of E. kurome sporophytes was observed in the fourth year. A greater number of E. kurome sporophytes tended to grow on FA porous concrete panels than on normal concrete panels; the maximum density of E. kurome sporophytes attached to FA porous concrete panels was 24 individuals per square meter. The final number of E. kurome sporophytes largely differed among the sides of each substratum, which seemed to be strongly affected by waves. No grazing marks of herbivorous fishes and benthic animals were observed during the four years of growth monitoring. These results suggest that E. kurome bed construction using FA porous concrete panels in the coastal area of Noto Peninsula would be possible.