The purpose of this study is to develop an integrated platform to predict and evaluate coastal benthic
ecology-geoenvironmental dynamics based on a new cross-disciplinary research field called Ecological
Geotechnics, and to apply the developed integrated platform to fields such as tidal flat and sandy beach. The
principal findings and conclusions obtained through integrated studies of field observations/surveys, laboratory
experiments, and numerical analyses are as follows.
1) We developed an ecohabitat chart showing a complex interrelationship of the linkage between the habitat
geophysical environments and diverse biological activities of diverse macroinfauna inhabiting tidal flats and
sandy beaches. The ecohabitat chart showed that there is a close relationship between species diversity and
geoenvironmental dynamics. Such species diversity-geoenvironmental dynamics relationship was found to be
consistent in nature with the field evidence from two habitat restoration projects. 2) The distributions of
amphipod and isopod species inhabiting the surficial sediments of sandy beach were associated with common
geoenvironment for each species in all sandy beaches, despite different tidal range and its variations. The
tide-induced variations in suction was responsible for the cross-shore distribution changes of those benthic
species studied. 3) The variations in the developed suction consistently and quantitatively accounted for the
changes in benthic species distribution, associated with the event-induced morphological changes in sandy
beaches and tidal flat. 4) The developed integrated platform consistently predicted the distribution changes of
diverse benthic species, associated with storm- and typhoon-induced morphological changes in tidal flats and
sandy beaches, and demonstrated its effectiveness in a comprehensive manner.
These findings are expected to facilitate the prediction and evaluation of benthic species responses to
geoenvironmental changes in coastal ecosystems, for conservation, restoration and management of tidal flats and
sandy beaches.

Key Words: Tidal flat, sandy beach, biological diversity, suction, geoenvironmental dynamics, benthic
species distributions, restored habitat