there is growing evidence that climate induce changes in precipitation will significantly after wetlands, and exacerbate impacts from human water use in developed river basins Freshwater ecosystem in Mediterranean-montane ecoregions are projected to experience a shortened wet season and prolonged, warmer summer season, increasing the vulnerability of fish communities to drought and floods. shifts in hydrologic regimes in snowmelt systems, including earlier runoff and declining base flows in summer, are projected to alter freshwater ecosystems, through changes in physical habitat and water quality. declining rainfall and increased interannuat variability will most likely increase low-flow and dry-spell duratiin in dryland regiins,leading to reduced water quality in remnant pools,reduction in floodplain egg and seed banks,the loss of permabent aquatic refugia for fully aquatic species and water birds,altered freshwater food webs,and drying out of wetlands.