Effects of modern drainage systems on the spatial distribution of loach in rice ecosystems

Abstract

Abstract Although rice fields support many aquatic species, recent agricultural intensification in Asia has led to loss of biodiversity, such as freshwater fish, in exchange for increased agricultural productivity. In Japan, modern drainage systems have been introduced in recent decades. This study investigated the effects of several aspects of modern drainage systems on the spatial distribution of dojo loach Misgurnus anguillicaudatus, a dominant fish species in Japanese rice fields. Multimodel inference approaches and hierarchical partitioning were used to estimate the direction and degree of the effect of each system on the spatial distribution of dojo loach. Three variables related to modern drainage systems (gaps between fields and ditches, the type of drainage ditch, and the presence of underground drainage pipes), flooding dates, and spatial autocovariates showed significant influence on the abundance of loach. In particular, gaps had the largest impact among all the variables on loach in the later part of the survey (June). Based on the results, the effectiveness of several conservation methods implemented for paddy‐dwelling fish in Japan was discussed. The knowledge will be a guide to the appropriate conservation of freshwater fish in Asia and other countries. Copyright © 2011 John Wiley & Sons, Ltd.