Table 3 Effects of eutrophication on lakes and reservoirs (modified from Smith, 1998) Increased biomass of freshwater phytoplankton and periphyton Shifts in phytoplankton species composition to taxa that may be toxic or inedible (e.g. bloom-forming cyanobacteria) Changes in vascular plant production, biomass, and species composition Reduced water clarity Decreases in the perceived aesthetic value of the water body Taste, odor, and water supply filtration problems Possible health risks in water supplies Elevated pH and dissolved oxygen depletion in the water column Increased fish production and harvest Shifts in fish species composition towards less desirable species Increased probability of fish kills