There are many papers on red tide occurrences and eutrophication. Here, we use these data to examine the relationship between dam construction and red tide occurrence in Kesennuma Bay, Dokai Bay and the small bays of ...There are many papers on red tide occurrences and eutrophication. Here, we use these data to examine the relationship between dam construction and red tide occurrence in Kesennuma Bay, Dokai Bay and the small bays of the Seto Inland Sea, Japan. Here, for the first time, differences in mechanisms of red tide occurrences in these small bays are demonstrated. Mud overflowing from dams likely induces red tides in these areas as the mud flows out from the mouth of the rivers, is carried along the coast by the longshore current, and then enters and is deposited into small bays. Red tide is considered to be induced by the accumulation of mud and siltation. From data on the locations and year of red tide occurrences in the Gulf of Mexico, the same mechanism as for the occurrence of red tide in small bays of Japanwas found to be applicable.展开更多
The defoliation of Cryptomeria japonica is observed in shrine forests around Hikone, Japan. Here, moisture content, soil pH, exchangeable Mg, Ca and Al of soil in shrine forests of C. japonica were examined in order t...The defoliation of Cryptomeria japonica is observed in shrine forests around Hikone, Japan. Here, moisture content, soil pH, exchangeable Mg, Ca and Al of soil in shrine forests of C. japonica were examined in order to assess the relationship between these factors and defoliation. There was no relationship between soil pH, exchangeable Mg and Ca in soil and the degree of defoliation in shrine forests. Exchangeable Al in the soil of shrine forests increased with decreasing soil pH below pH 5.0, but there was no relationship between exchangeable Al and degree of defoliation in shrine forests. Soil moisture content differed between severely defoliated forests and forests with no defoliation. Soil moisture is thought to play a large role in inducing defoliation of C. japonica. Based on results from previous studies, the declining forests in the basin of the Kuzuryu River in Fukui Prefecture and in the basin of the Koito River in Chiba Prefecture reported by Yambe (1973) were considered to have been caused by the construction of dams. On these rivers, dams were constructed several years before the forest decline researched by Yambe. Dam construction is thought to have caused the low moisture content in the basins.展开更多
文摘There are many papers on red tide occurrences and eutrophication. Here, we use these data to examine the relationship between dam construction and red tide occurrence in Kesennuma Bay, Dokai Bay and the small bays of the Seto Inland Sea, Japan. Here, for the first time, differences in mechanisms of red tide occurrences in these small bays are demonstrated. Mud overflowing from dams likely induces red tides in these areas as the mud flows out from the mouth of the rivers, is carried along the coast by the longshore current, and then enters and is deposited into small bays. Red tide is considered to be induced by the accumulation of mud and siltation. From data on the locations and year of red tide occurrences in the Gulf of Mexico, the same mechanism as for the occurrence of red tide in small bays of Japanwas found to be applicable.
文摘The defoliation of Cryptomeria japonica is observed in shrine forests around Hikone, Japan. Here, moisture content, soil pH, exchangeable Mg, Ca and Al of soil in shrine forests of C. japonica were examined in order to assess the relationship between these factors and defoliation. There was no relationship between soil pH, exchangeable Mg and Ca in soil and the degree of defoliation in shrine forests. Exchangeable Al in the soil of shrine forests increased with decreasing soil pH below pH 5.0, but there was no relationship between exchangeable Al and degree of defoliation in shrine forests. Soil moisture content differed between severely defoliated forests and forests with no defoliation. Soil moisture is thought to play a large role in inducing defoliation of C. japonica. Based on results from previous studies, the declining forests in the basin of the Kuzuryu River in Fukui Prefecture and in the basin of the Koito River in Chiba Prefecture reported by Yambe (1973) were considered to have been caused by the construction of dams. On these rivers, dams were constructed several years before the forest decline researched by Yambe. Dam construction is thought to have caused the low moisture content in the basins.
