Basin-specific effect of global warming on endemic riverine fish in Korea

The differences in geographical setting among basins create variation in regional climate and local assemblages. Global warming might induce varying degree of changes in the biodiversity and distribution of freshwater fish through water temperature increase in each basin. We investigated the effect of global warming on the thermal habitat suitability of endemic riverine fish in the basin scale and the relationship between change in species loss rate and altitude within a basin. Surface air temperature projections based on A1B emission scenario were used to estimate water temperatures in the major basins of South Korea in the future decades. The thermal tolerances of 39 endemic fish species were estimated from water temperatures and abundances in the habitats using the weighted average regression model. The minimum water temperature was compared with the maximum thermal tolerances to simulate the change in thermal habitat suitability of each species in a basin. Global warming is expected to drive 2-20 species to the risk of removal at 4.3-35.5% of their thermal habitats during 2060-2080s. The effect was variable according to the species' thermal tolerances and the level of basin-specific water temperature increase. The correlation between species loss rate and altitude was positive only when the relationship was considered separately for each basin. The results implied that global warming would greatly affect the suitable habitats of endemic fish before 2060s in Korean rivers. It was suggested that the biodiversity conservation efforts needs to incorporate the spatial heterogeneity in thermal regime among the basins.