Figure 1: In large low-gradient river systems, extreme floods usually submerge vast areas of land. This creates new fish habitat and an abundance of food for invertebrates. Production throughout the aquatic food web tends to increase. Vegetation is damaged, often mortally, during long periods of inundation. Photo shows the Mississippi River reclaiming part of its natural floodplain during the flood of 1993. Photo by Scott Dine, St. Louis Post-Dispatch.