Fish habitat evaluation based on width-to-depth ratio and eco-environmental diversity index in small rivers
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WATER ENVIRONMENTAL POLLUTION AND STATE OF THE ART TREATMENT TECHNOLOGIES
Fish habitat evaluation based on width-to-depth ratio and eco-environmental diversity index in small rivers Masahiko Sekine 1 & Jianing Wang 2 & Koichi Yamamoto 1 & Ariyo Kanno 1 Received: 2 October 2019 / Accepted: 30 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract We estimated the performance of river fish habitat evaluation using width-to-depth ratio (WDR) in comparison with ecoenvironmental diversity (EED) to propose an inexpensive and easy-to-use habitat evaluation procedure, which is applicable to small river construction works. WDR calculation costs less than that of EED. For verification, 25 stations in eight rivers were selected and fish were captured using electrofishing. pH, electrical conductivity, turbidity, dissolved oxygen (DO), water temperature, fraction of forest, farmland, and residential area in each basin were measured to examine possible influence of water quality. Results show that there is no major water quality issue in the target rivers. Although fish habitat is classified as good when WDR is higher than 6, it cannot be evaluated by WDR when it is lower than 6. EED has positive relationship with fish habitat for any WDR value. Thus, if a river geometry design in a river work results in WDR higher than 6, no measures need to be taken regarding fish habitat condition; however, if it is less than 6, it is necessary to examine whether the construction work lowers the EED or not. Keywords Fish habitat . River channel form . Eco-environmental diversity index
Introduction River ecosystems provide several services for human life. However, they are also threatened by human activities, e.g., urban stormwater, fishery, water pollution, habitat fragmentation, and degradation (Zhao et al. 2017). Several researches are emerging regarding the protection and management of river ecosystems, such as environmental flow assessment (Christos et al. 2019; Ma et al. 2019; Zhang et al. 2018; Coulter et al. 2019), climate change adaptation (MartinezCapel et al. 2017; Mahdi et al. 2019), and river connectivity Responsible Editor: Philippe Garrigues * Masahiko Sekine [email protected] 1
Division of Environmental Engineering, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
2
Division of System Design and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
improvement (Rolls et al. 2018; Silva et al. 2019). Some of the earliest efforts of these works are summarized by Stalnaker et al. (1994). They claimed the necessity of scientific background in habitat evaluation compared to the traditional flow standard or statistical biomass prediction and introduced physical habitat modeling. In their model, the objective variable is the optimal habitat area and the explanatory variables are velocity, depth, bed material, and/or cover, which represent reproduc
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