Aquatic Macroinvertebrate Responses to an Extreme Drawdown

An extreme drawdown conducted on Lake Tohopekaliga, Florida. improved littoral substrate. stimulated development of aquatic macrophytes and increased invertebrate standing crop. Benthic macroinvertebrates increased from 98 to 244 organisms per square foot in limnetic areas after reflooding; littoral benthos rose from 154 to 250 organisms per square foot. Phytomacrofauna increased from a predrawdown high of304. to 1364 organisms per sample unit after reflooding, Standing crops decreased to predrawdown estimates within two years following peak production periods. These decreases were attributed mainly to predator cropping. Fish food organisms were favored by the drawdown, and their incidence in largemouth bass stomachs increased. As a final expression of increased production. sportfish populations which utilized these organisms nearly doubled.

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