2004 Fiscal Year Final Research Report Summary
Assessment of the effects of damming and channelization on freshwater fish habitats
| Project/Area Number |
15510037
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental impact assessment/Environmental policy
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| Research Institution | National Institute for Environmental Studies |
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Principal Investigator |
FUKUSHIMA Michio National Institute for Environmental Studies, Biodiversity Conservation Research Project, Researcher, 生物多様性研究プロジェクト, 主任研究員 (10291048)
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| Co-Investigator(Kenkyū-buntansha) |
KANEKO Masami Rakuno Gakuen University, Faculty of Environment Systems, Assistant professor, 環境システム学部・地域環境学科, 助教授 (00347767)
YABUKI Tetsuo Rakuno Gakuen University, Faculty of Environment Systems, Professor, 環境システム学部・地域環境学科, 教授 (50275484)
KAMEYAMA Satoshi National Institute for Environmental Studies, Watershed Environments and Management Research Project, Researcher, 流域圏環境管理研究プロジェクト, 主任研究員 (80332237)
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| Project Period (FY) |
2003 – 2004
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| Keywords | habitat fragmentation / freshwater fishes / dams / meanders / channelization / index of complexity / entropy / predictive habitat models |
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| Research Abstract |
I assessed using GIS the effects of habitat fragmentation caused by damming on species richness and individual species occurrence based on the databases of dams and fish surveys conducted during the past 50 years in Hokkaido. It was found that both fish species richness and the loss of the species richness due to damming are greater in reaches of streams and rivers with lower elevations in the island. Species that were most significantly impacted by damming belonged to the so-called diadromous species which migrate between freshwater and salt water, for instance salmon and many gobiids species. It was suggested that fish ways that are designed to facilitate fish and other aquatic creatures to pass around dams function effectively for fishes with sufficient swimming ability, such as salmon and trout, but function poorly for fishes without the ability, such as gobiids and other small benthic fishes.
In addition, I developed an index to measure the degree of habitat simplification due to channelization or channel straightening and applied this index to streams in Hokkaido. The index which is based on the concept of entropy was applied to and compared among the tributaries of the Kushiro River which were digitally traced from 1:50,000 topological maps published in four eras of 1920s, 1950s, 1970s, and 1990s. As a result, it became obvious that channel complexity has been reduced over periods, especially since 1970s, due to channelization.
Furthermore, I started developing infrastructure of various databases with geographical information that are available nationwide in order to expand the spatial scale of the study and to examine anthropogenic impacts on ecosystems in the whole nation. As a step toward this infrastructure development, I created GIS data of large dams in Japan and developed an algorithm to identify and visually grasp using GIS the watersheds and years fragmented by the dams. I also developed a fish database based on two national surveys conducted in Japan.
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