Abstract
Community and morphological characteristics of Zostera marina were surveyed at 6 survey stations along the Ehime Prefectural coast in the season of luxuriant growth. The stations were located in different sea areas with different climatological and oceanographical conditions, that is, St. 1 (Ohmi-shima Is.), St. 2 (Asanami) and St.3 (Gogo-jima Is.) in Aki-nada (central Seto Inland Sea), St. 4 (Mitsukue) in Iyo-nada (western Seto Inland Sea), and St.5 (Yoshida), St.6 (Miura) in the Uwa Sea. The characteristics were quite different among the stations and among the different depths in each station, and mean shoot densities and biomass ranged 68- 869 shoots m-2 and 69. 7-171. 8 gDW m-2 respectively among the stations. In general, Z. marina communities were constituted by larger shoots in size with lower densities in the stations of Aki-nada, and by smaller shoots with higher densities in the stations of Iyo-nada and the Uwa Sea. Especially, shoot density in St. 6 was quite higher which is 869 shoots m-2 in mean (and 1,185 shoots m-2 in the densest place). The below-ground parts of the Z. marina communities in Iyo-nada and the Uwa Sea were more developed than those in Aki-nada, which was shown in their ratio of below-ground biomass to total biomass. The variation in morphological and community characteristics observed here was considered to reflect the phenotypic plasticity of Z. marina expressed under various physical conditions of the habitats, as well as genetic variations among local populations.
