It is often reported seaweed grow and fishes gather around concrete port structures. Typical example was found at the mild slope type revetment of Kansai International Airport. The authors considered that these situations are better from the ecological viewpoint and techniques for accommodation of more organisms should be studied.
　Concrete blocks having various wall properties (uneven surfaces, ferrous sulfate coated surface etc.) were set on port structures. Changes of species and quantity of marine organisms (sessile animals, mobile animals and seaweed) which appeared on the concrete block surface were studied. In case of uneven surface (depth of unevenness is 5 cm) and ferrous sulfate coated surface, more seaweed and animals were found for the duration of about half a year after the set of concrete blocks. Quantity and number of species of both seaweed and animals were almost constant since 1.5 years after the set of concrete blocks.