Abstract
To understand impacts of global warming on benthos communities in stream ecosystems, we analyzed relations of macroinvertebrate densities to water temperature conditions in a set of headwater reaches with various altitude, ranging from 100 to 850m, within the Natori River System. We ran a distributed hydro-thermal model with input data of air temperature in future scenarios (near and far future) and projected changes in water temperature in the headwater reaches in the futures using 8 global climate models (GCMs). We projected the density of benthic macroinvertebrates in the futures using the estimated water temperature as a predictor variable of simple linear regression models obtained in the headwater reaches under present conditions. Considering lower marginal ranges in uncertainty of the density of Plecoptera, it might decrease as much as 85% of present densities or extinct even in the near future with the lowest or highest radiative forcing, respectively.
