This study evaluated the influence of environmental factors and four revetment methods, concrete lining, dry masonry, wet masonry and natural mud-wall, on benthic invertebrate communities (BIC) in the Hukara Irrigation Canal, Shizuoka Prefecture, Japan, in October 1993, and in April and September 1994. The species composition of the BIC was influenced by two environmental factors; the cover degree on the revetments and the size of gravel on the canal beds, which were regulated by the revetment construction methods. The long revetment section of the concrete lining may have an effect to decrease the diversity of the BIC and the density of benthic individuals, because of a high velocity of the water flow, lack of gravel and poor vegetation cover. From the results, the followings are recommended in construction for increasing the diversity of the BIC; to shorten the distance of the same revetment method, to use natural materials rich in porosity, and to cover the revetment with natural vegetation.

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A breeding bird community in a mixed forest (28ha) in a suburb of Morioka City, Iwate Prefecture, northern Honshu, Japan, was investigated for 27 years between 1970 and 1996 by the territory mapping method. No significant difference was found in breeding pair density during the period, while a slight decrease was found in the number of breeding species. Composition of the bird community changed significantly during the period. Among the residents, Parus group densities increased mainly with the improvement of nest box instalation techniques. Picidae group densities increased in response to an increase of dead trees. Corvus group densities increased in accordance with an increase of human visitors in the study area. Mid-sized, short-distant migrants (Streptopelia orientalis, Hypsipetes amautotis, etc.) notably decreased due to an invasion of Accipiter gentilis and an increase in nest attacks by crows. Small sized species (Zosterops japonica and Carduelis sinica) increased without known reasons. Among the summer visitors, although most species decreased in accordance with the other areas of Japan, densities of Ficedura narcissina and Cettia squameiceps increased. A decrease in overwintering habitat in South-East Asia due to logging or other developmental actions may be a cause of the general decrease in the summer visitors.

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From 1991 through 1995, 2219 nesting loggerhead turtle (Caretta caretta) were marked with plastic and metal tags and were released on 16 nesting beaches between the Ryukyu Archipelago and Shizuoka of Japan. Of them, 55 turtles were recovered until August of 1995, except for the individuals that remigrated to the released beaches. Thirty-four turtles (62%) were found from the coastal waters of Japan and 18 turtles (33%) were obtained from the East China Sea. The remaining two and one turtles were found from the Philippine and the Vietnamese coastal waters, respectively. They are the first records for the loggerhead turtle to be distributed in these areas. Seasons that turtles were recaptured were different between the coastal waters of Japan and the East and South China Sea. In the coastal waters of Japan, a few cases of recapture were reported during the winter. However, in the East and South China Sea, turtles were found almost throughout the year. Therefore, females that nested on the Japanese coast from the late May to the early August are considered to migrate to a wide area of the eastern Pacific, mostly to the East China Sea, after staying in the coastal waters of Japan until about October of the same year. Many of the recapture records were obtained by trawling vessels in the East China Sea and by set nets operating in the Japanese coastal waters. We discussed on their conservation.

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In the spring of 1993, we observed 25 redds of Sakhalin taimen (Hucho perryi) in a tributary of the Sarufutsu River, northern Hokkaido. The distribution of the redds was almost identical during three consecutive spawning seasons in the study stream. Spawning habitat was evaluated by measuring eight variables at randomly selected pools and by comparing them between pools with and without redds. The area occupied by overhanging vegetation was uniformly large regardless of the presence of the redds, but was larger at pools with no redds. In contrast, the area occupied by woody debris and an undercut bank was larger at pools with redds than pools without redds.

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