Drainage Canal System Survey

Abstract

AbstractThe importance of paddy field ecosystems is being emphasized in consideration for biodiversity. However, we do not know what kind of paddy ecosystem is most effective for biodiversity. To research this problem, I investigated the distribution and life history of aquatic animals in a consolidated paddy field. I surveyed various aspects of the paddy field, such as canal levels with the main, lateral and farm drains, areas with the presence or absence of a year-round water flow, as well as sections with different canal bed materials. These findings provide knowledge for determining an agricultural and rural development project that can be harmonized with the environment. In this study, I selected six survey sites for drainage canals in Shimodate City (now Chikusei City), Ibaraki Prefecture, Japan. The sampling interval was one month from April 2001 to March 2002. A survey of fishes revealed that Opsariichthys platypus and Misgurnus anguillicaudatus were concentrated in the main drains and the lateral and farm drains, respectively. Among aquatic insects, damselfly Calopteryx atlata and dragonfly Orthetrum albistyrum speciosum were observed in the lateral drains and the farm drains, respectively. Thus, the drainage canal system was believed to function as a spawning ground and habitat for four species. It is especially important for four species to have a year-round water flow and natural materials for canal beds. To enrich biodiversity in consolidated paddy fields, it is effective to create a wetland as a wintering site for four species.KeywordsAgricultural and rural development projectAquatic animalBiodiversityDistributionDrainage canalFarmland consolidationGrowthPaddy fieldWetlandWintering siteYear-round water flow