Study on Hydraulic Environments and Fish Behavior in Agricultural Canals

为了保护和恢复农业运河生态系统，不仅要量化较好的栖息地的特征，如水质和水力条件，而且要量化鱼类或野生动物的环境偏好。本研究通过室内实验和实地考察，研究了日本青竹鱼的环境选择性和农家渠的水力学环境。本研究选择日本青冈鱼作为河鱼作为研究对象，因为青冈鱼现在被认为是日本农村生态系统恢复的象征鱼。根据最近在农业运河中修建鱼巢的人工区块及其周围的水力测量，选择了水深、流速和盖度三个环境因素作为影响…鱼类栖息地可用性和质量的主要因素更多的农用运河。基于鱼的行为本质上是不确定的，并且对环境变化的行为反应在个体和环境之间差异很大的背景，通过模糊逻辑建模和实验室明渠实验，量化了青竹对这三个环境因素的偏好强度。引入一种简单的遗传算法来搜索偏好强度的最优函数表示。通过实验室水箱实验和现场检测，成功地验证了模糊遗传算法偏好强度模型的有效性。在考虑流速和盖度两个因素的情况下，预测的分布与观测结果吻合较好，表明这两个因素对青竹的环境偏好有明显的影响。为了利用基于个体的模型方法评价鱼类栖息地的环境，分析了青竹的觅食行为，以确定个体之间的相互作用：个体之间的间距、个体的空间分布和交流过程。引入行为模式模型来描述鱼群的行为。该模型的数值模拟结果在极化、最近邻距离、展开度和分维等多方面与实验数据吻合，并通过计算游动轨迹、游动速度和转弯角度的回归图、分维、关联维和小波变换，量化了个体间游动行为的差异。利用计算结果验证了特定环境中鱼类的紧张程度或休息程度的评估以及水环境中化学污染物的鱼基生物监测的可行性。较少

For the preservation and restoration of ecosystems in agricultural canals, it is important to quantify not only the characteristics of preferable habitat such as water quality and hydraulic condition but also environmental preference of fish or wildlife. In this research, environmental preference of Japanese Medaka Fish (Japanese killifish, Oryzias latipes) and hydraulic environments in agricultural canals were investigated by laboratory experiments and on-the-spot examinations. Japanese Medaka Fish was selected as a river fish subject to this research because Japanese Medaka is now regarded as the symbolic fish for the restoration of countryside ecosystems in Japan.Judging from the hydraulic measurements in and around artificial blocks that are recently constructed for providing fish nest in agricultural canals, the three environmental factors of water depth, current velocity and cover were selected as the principal factors affecting the availability and quality of the fish habitat in … More agricultural canals. Based on the background that fish behavior is essentially noncommittal and that the behavioral responses to an environmental change vary widely among both individuals and circumstances, the preference intensities of Japanese Medaka to the three environmental factors were quantified by fuzzy logic modeling and laboratory open-channel experiments. A simple genetic algorithm was introduced to search for the optimal functional representation of preference intensity. The fuzzy-GA preference intensity model was then successfully verified by laboratory water-tank experiments and on-the-spot examinations. The good agreement between the predicted and observed distributions in considering the two factors of current velocity and cover indicated that the two factors obviously affected the environmental preferences of Japanese Medaka.For the purpose of evaluating the environment of fish habitat through the individual-based model approach, the schooling behavior of Japanese Medaka was analyzed to determine the interactions between individuals : the spacing between individuals, the spatial distribution of individuals and the communication processes. The behavioral pattern model was introduced to describe the behavior of fish schooling. The results of the numerical simulations using the model agreed with the experimental data in many regards, including the polarization, the nearest neighbor distance, the expanse and the fractal dimension.The differences of swimming behavior among individuals were also quantified by calculating return map, fractal dimension, correlation dimension and wavelet transform for swimming trajectory, swimming velocity and turning angle respectively The feasibility of the assessment for the degree of tension or rest of fish in specific environment and the fish-based biomonitoring for chemical contaminants in water environment was examined using the calculated results. Less