Abstract
In this study, we observed spatial distributions of planktonic, benthic, and epiphytic microalgal biomass in the seagrass meadows of an estuary（Lake Furen, Japan）. Among planktonic microalgae, phytoplankton was particularly abundant in mesohaline water. On the other hand, suspended microphytobenthos was found to be decreased with increasing salinity and significantly increased with depth. Benthic and epiphytic microalgal biomass were 6．6－143- and7．9－20-times higher than planktonic microalgal biomass in the water column（32－200mg C m－2）, respectively. The sum of planktonic, benthic, and epiphytic microalgal primary production was ca.5，000mg C m－2 d－1 and considered to support fishery production. We therefore concluded that benthic microalgae mainly raised microalgal production throughout the lake, and that planktonic and epiphytic microalgae in particular contributed to microalgal production in oligo- to mesohaline and polyhaline water, respectively.
