LAUSR

Abstract We evaluated the effects of 3 successive major hurricanes that impacted Lake Okeechobee, Florida, in 2004 and 2005. Impacts and recovery were compared to a pre-hurricane period, focusing on inferred seston composition and potential phytoplankton limiting factors based on deviations between Carlson’s trophic state index values. Before the hurricanes, the lake was seasonally and spatially variable. At 4 sites examined, summers had larger seston and nitrogen limitation, whereas winters had smaller seston and light limitation. This seasonality was strongest at south and west sites closer to the lake shore in shallower water and weakest at deeper central and north sites overlying flocculent mud sediments. Hurricanes homogenized the lake spatially and seasonally, and for 2 years there was lake-wide light limitation and small seston in summer and winter. Four years after the last hurricane, the composition of seston and nature of limiting factors had recovered to conditions nearly identical to those in a pre-hurricane period, with some localized seasonal exceptions, possibly explained by migration of sediments or differences in submerged plant density. Lakes such as Okeechobee, with a large surface to depth ratio, high nutrient concentrations, and fine flocculent sediments, can recover from hurricanes over time, but a long duration of recovery could make them vulnerable to repeated hurricane impacts, which could keep nutrient concentrations high, transparency low, and work against efforts aimed at lake rehabilitation.