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Annual Lake Cycles can also
affect the nutrient movement in a lake, and increase or decrease the
possibility of eutrophication.
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Threemile Pond is dimictic,
which means that the water in the lake turns over twice every year: once in
the spring and again in the fall.
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�Lake water turnover begins with temperature variations, which create
different water densities, and consequently a stratified water column
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Based on temperature and
plant and animal life, different layers have varying amounts of oxygen.
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Turnover occurs in the
spring and fall as water temperatures and densities change, which oxygenates
the lake.
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However, When a lake is
stratified for an extended period of time, such as in the late summer,
oxygen levels become depleted, particularly in the deepest layer (called the
hypolimnion) causing anoxic conditions.
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Under anoxic conditions,
phosphorus is released from the sediment into the water column. This
nutrient feeds algal growth, which can cause eutrophication.
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