Have worked on reservoirs from 300 ac to 100k+ ac in the southeast, varying trophic levels from oligotrophic to hypereutrophic. Highly complex systems influenced by age (influences depth, nutrient levels), inflow/outflow (landscape drainage, annual rainfall, hydroelectric manipulation), morphology (fetch a big player), trophic status, and fish species present. I'd say soil types, nutrient levels and cycles, and fetch the dominant players in FA occurrence. Fairly common to see small patches of various FA in secluded areas during spring and fall in nearly all trophic levels. Large populations of rough fish e.g.common carp also figure into the mix of many variables.
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