Distribution, productivity, life history and biodiversity of seagrass community along Sanriku Coast: A review

Abstract

The seagrass flora in Japan is characterized by the occurrence of several species of Zosteraceae that are considered to be endemic to the northwestern Pacific. In seagrass beds along Sanriku Coast, northeastern Honshu Island of Japan, the endemic Zostera spp. generally occur at subtidal soft bottom, usually forming multispecific seagrass beds with the cosmopolitan eelgrass Z. marina. This paper reviews some of the recent studies on ecology of the seagrass community conducted at Otsuchi Bay, Funakoshi Bay and Yamada Bay along Sanriku Coast of Iwate Prefecture. We specially focus on following subjects ; (1) spatial distribution of Z. caespitosa in Yamada Bay surveyed using eco-sounding techniques, (2) comparative studies on morphological and life history traits of Zostera spp., (3) quantitative estimation on shoot dynamics, growth and primary production of Z. caulescens, (4) ecology of epifaunal community on the aboveground parts of seagrasses, and (5) population genetic structure and gene flow among populations of Z. caespitosa analyzed using molecular data. The results of these studies showed that the seagrass community along Sanriku Coast is one of the most productive parts of the coastal ecosystem, and that various environmental and biological factors are involved in a complex manner to produce observed patterns of population structure and dynamics of the seagrass community.