ABSTRACT：Recently, the bottom sounding is regularly done in the coastal area of various places. However, their data have not been used sufficiently to research the changes of beach profiles, such as beach erosions and depositions.

The changes of beach profiles at the east and the west side coast before and after constructing the east breakwater in the east ward of Tomakomai Port were analyzed by using the bottom sounding data. And some factors that influence on the changes of beach profiles were considered by the multiple egression analysis.

ABSTRACT：Distribution and composition of small plastic marine debris in the Seto Inland Sea was investigated at 219 beaches, 10 river sides and 24 sea surface between 2006 and 2008. The average densities of small plastic marine debris were 48,470 pieces per m² on the beaches, 243,473 pieces per km² on the sea surface and 37,954 pieces per m² on the riversides. Foamed plastic fragment was the highest density in this area. The densities were 45,833 pieces per m² (94.6%) on the beaches, 147,752 pieces per km² (60.7%) on the sea surface and 15,727 pieces per m² (41.5%) on the riversides. Major five items of small plastics were foamed plastic fragments, hard plastic fragments, tips of synthetic lawn, resin pellets and capsule of chemical fertilizers. They were recognized on the riversides above the brackish –water region.