A systematic review of research on biodiversity in Japanese retarding basins

We conducted a systematic review of literatures on biodiversity in retarding basins to grasp the status of knowledge regarding effects of constructions and managements of them on biodiversity. Six taxonomic groups (birds, amphibians, fish, insects, shellfish, and plants) were included in the review to examine multi-taxonomic responses. Totally 9,183 literatures were reviewed, and 242 were selected for this systematic review. The total number of sites in the selected literature was 33, which cover only 22 ％ of the number of retarding basins in Japan. Birds were reported most frequently (94) whereas amphibians were most scarce (6). For all the taxa, reports on the occurrence of rare species or invasive species, and new record of species distribution, were common. Only 15 studies were based on the BACI design, suggesting a lack of scientific knowledge regarding biodiversity assessments in retarding basins. Thus, we could not fully clarify the effects of retarding basins on biodiversity. However, some studies suggested that the artificial disturbances, wetland creation, vegetation management, and soil excavation, had positive effects on many taxa.