Abstract
To investigate environmental factors affecting the species composition of benthic diatoms, surveys of the surface sediment and overlying water were conducted at three intertidal flats in Tokyo Bay: Marine Park, Edogawa, and Kasai. Species were identified by light microscopy and classified into two growth form types: gliding and adhesive. In total, 67 taxa were identified. Seasonal variations of dominant growth forms differed between the intertidal flats; dominant species were Catenula adhaerens, Cocconeis sp. 1, and Fallacia sp. (adhesive type) on the Marine Park; Fallacia forcipata (gliding type) on the Edogawa; and Amphora copulata, A. laevissima (adhesive type), Gyrosigma fasciola, and Navicula cf. mollis (gliding type) on the Kasai. Cluster analysis based on the similarity of major species differentiated the three sites, while the Kasai cluster was further subdivided by season. Redundancy analysis revealed that (1) the correlative environmental factors differed between growth forms and only the gliding type was positively related to mud content, and (2) diatom species composition on the Kasai was related to salinity. These results indicate that tide and wave disturbance and also salinity strongly affect benthic diatom species composition in Tokyo Bay.
