自然的要因によるアマモ場の消滅 - 氾濫河川からの浮泥供給による消滅事例の解析 -

概要

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The objective of this study is to clarify principal factors causing a deterioration of eelgrass meadows (Zostera marina L.) by the coast of Iwakuni Japan, after the typhoon attack on 24 September 1999. We investigated effects of fine sediment deposition on the deterioration of eelgrass meadows.Aerial photographs showed significant losses to the vegetative cover of eelgrass meadows near the estuary after the typhoon. Large amounts of sediments settled over the bottom after the typhoon. Sites near the estuary had higher deposits of suspended sediments on the eelgrass leaves. The deposition resulted in a 50% decrease in light intensity. The shading reduced the daily periods of irradiance-saturated photosynthesis required for eelgrass growth to less than 1/2. Comparison of diatom communities in the sediments indicated that the sediments originated from terrestrial sources, i. e. flooding rivers.These results suggest shading by fine sediments, supplied from flooding rivers, caused the deterioration of eelgrass meadows.
社団法人　日本水環境学会の論文
2001-03-10