Fisheries Farming Laboratory, Fisheries Experimental Station, Wakayama Research Center of Agriculture, Forestry and Fisheries, Tanabe, Wakayama 646-0058, Japan
Concentrations of carbon (C), nitrogen (N) and phosphorus (P) in leaf, leaf sheath and rhizome of Zostera japonica that had grown at intertidal sampling points in Tanabe Bay, the Pacific Coast of central Japan, annual net production and annual C, N and P accumulations were investigated. The concentrations of C, N and P changed between 270 and 369 mg g−1, 11.1 and 30.4 mg g−1 and 1.74 and 3.82 mg g−1, respectively. Annual net productions of communities in Takinai and Uchinoura are calculated as 392.9 and 351.8 g·m−2·year−1, respectively. Maximum production rate of aboveground biomass is 2.68 g·m−2·day−1 and maximum C, N and P accumulation rates of aboveground biomass are calculated as 756.9, 66.2 and 8.02 mg·m−2·day−1, respectively. C:N:P in biomass of Z. japonica in Takinai and Uchinoura calculated from the annual accumulations are 295:13:1 and 282:16:1, respectively. N and P concentrations of aboveground biomass increased and C concentration of rhizome decreased from January to May when increases of biomass and leaf elongation occurred. Production rate and C, N and P accumulation rates of aboveground biomass rose during the same period.