Abstract: We examined the influence of sea ice break-out on seasonal diving patterns and diet of a top predator, the Weddell seal, to understand how phytoplankton blooms impact the vertical distribution of the food web. We captured female seals during the November and December lactation period and attached a LOTEK LAT1800 time-depth recorder (TDR) flipper tag with a 6 second sampling interval. Data were processed using the Iknos toolbox in MATLAB. Benthic dives (1% of all dives) were excluded from analyses because we were interested in quantifying seasonal changes in mid-water dives. Thus, we analyzed dives from 59 Weddell seals to characterize the diving depth and foraging effort of each seal across the austral summer over four years. We characterized seasonal changes in diving depth by calculating the mean across all seals of the maximum dive depth on each day for each seal. For more information see: Beltran, R. S. Bridging the gap between pupping and molting phenology: behavioral and ecological drivers in Weddell seals PhD thesis, University of Alaska Fairbanks, (2018).