A similar pattern has been observed in other shallow lakes in the tropics. For example, Erikson (Erikson, 1999) found that in polymictic Lake Xolotlan, Nicaragua, the major factor influencing the net growth of phytoplankton is the ratio of photic to mixed depth; net growth was reduced in winter coincident with increased winter season winds and greater sediment re-suspension. East and Sharfstein (East and Sharfstein, 2006) developed a hierarchical decision model that predicted light limitation versus nitrogen limitation in Lake Okeechobee with 70–85% accuracy, the major determinant being the ratio of Secchi to total depth.