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A Study on Evaluation of Fishways of the Nagara Estuary Barrage based on Habitat and Upstream Migration for Japanese Mitten Crab

基于大闸蟹栖息地和上游洄游的长良河口拦河坝鱼道评价研究

基本信息

批准号：
15560450
负责人：
WADA Kiyoshi
金额：
$ 2.3万
依托单位：
Gifu National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Actual achievements of the four fishways of the Nagara estuary barrage for fishes were investigated based on the data of five-years monitoring on environmental changes. It should be noted that temporal concentration of upstream migration was observed both hourly and daily in the Seseragi (brook-type) fishway. The peak of the upstream migration of fishes corresponded to the neap tide period. Under natural condition, the range of salt water extends upstream farther as the tide advances. Settlement of the Japanese mitten crab (Eriocheir japonica) was investigated in the Seseragi-fishway. The megalopa larvae settled and metamorphosed to crab stage in the upper tidal zone in the fishway. The youngest crabs were nearly two millimeters in carapace width. Settlement of megalopa larvae occurred mainly in early summer (June) and early winter (December). The majority of larvae that settled in winter did not survive and metamorphose to the crab stage due to low water temperatures. Thus, the growth … More and upstream migration of the Japanese mitten crab seemed to be strongly influenced by water temperature in the estuary. The suitable settlement position of megalopa larvae corresponded to the tip of salt water intrusion at neap tide. In this study, it is clarified that the Seseragi-fishway have a fulfill function to mitigate for decreased estuary zone that change aquatic organism phase from freshwater to seawater. Furthermore, the effects of saltwater intrusion characteristics on benthic animal communities and algae were investigated in the fishways of the Nagara estuary barrage under uniform substrate. As a result of the cluster analysis of the benthic animal communities, the fishway zone was divided into three parts ; the freshwater, the saltwater and the transitional section. The benthic animal communities and algae inhabited mainly in these section related to saltwater intrusion characteristics. The megalopa larvae of the Japanese mitten crab (Eriocheir japonica) settled and metamorphosed to crab stage in the upper tidal zone in the fishway. Settlement of megalopa larvae occurred mainly in early summer (June) and early winter (December). The majority of larvae that settled in winter did not survive and metamorphose to the crab stage due to low water temperatures. Thus, the growth and upstream migration of the Japanese mitten crab seemed to be strongly influenced by water temperature in the estuary. The suitable settlement position of megalopa larvae corresponded to the tip of salt water intrusion at neap tide. In this study, it is clarified that the Seseragi-fishway have a fulfill function to mitigate for decreased estuary zone that change aquatic insect and organism phase from freshwater to seawater. Less

根据长良河口拦河闸5年的环境变化监测资料，对长良河口拦河闸4条鱼道的实际效益进行了调查。应该指出的是，在Seseragi（小溪型）鱼道中，每小时和每天都观察到上游迁移的时间集中。小潮期是鱼类向上游洄游的高峰期。在自然条件下，盐水的范围随着潮汐的推进而向上游延伸得更远。本文对日本绒螯蟹（Eriocheir japonica）在Seseragi鱼道中的定居进行了调查。大眼幼体在鱼道内的高潮带定居并变态至蟹期。最年轻的螃蟹甲壳宽度接近两毫米。大眼幼体的定居主要发生在初夏（6月）和初冬（12月）。由于水温较低，大多数在冬季定居的幼虫没有存活下来，并变质到螃蟹阶段。因此，增长 ...更多信息河口水温对中华绒螯蟹的溯河洄游有明显的影响。大眼幼体的适宜附着位置与小潮盐水入侵尖端相对应。在本研究中，阐明了Seseragi-fishway有一个完整的功能，以减轻减少河口区，改变水生生物相从淡水到海水。此外，在长良河口拦河闸鱼道中，在均匀底质下，研究了盐水入侵特征对底栖动物群落和藻类的影响。通过对底栖动物群落的聚类分析，将鱼道区划分为淡水区、咸水区和过渡区。底栖动物群落和藻类主要分布在与盐水入侵特征有关的断面。日本绒螯蟹大眼幼体在鱼道内的高潮带定居并变态为蟹期。大眼幼体的定居主要发生在初夏（6月）和初冬（12月）。由于水温较低，大多数在冬季定居的幼虫没有存活下来，并变质到螃蟹阶段。因此，生长和上游迁移的日本绒螯蟹在河口的水温似乎有很大的影响。大眼幼体的适宜附着位置与小潮盐水入侵尖端相对应。在本研究中，阐明了Seseragi-fishway有一个完整的功能，以减轻减少河口区，改变水生昆虫和生物相从淡水到海水。少