Rising water is usually good for the food chain, from the bottom up. IF area soils are fertile with the right nutrients, I think the phytoplankton base should get a shot in the arm. As BarO noted, newly submerged grass, etc. previously above the water level provide beau coup hiding places for invertebrates and little fish. From there on, the bounty trickles up to the big fish.

"Live like you'll die tomorrow, but manage your grass like you'll live forever."
-S. M. Stirling
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