Florida's manatees are dying, in unprecedented numbers this year, with 959 documented deaths as of mid-October. That's already more than any full year in state records, and now colder weather could bring even more deaths. Scientists blame food scarcity. The so-called sea cows mostly eat seagrass, and that's also dying as water quality declines. The problem is manmade. Fertilizer runoff, wastewater discharges and polluted water is diverted on purpose from Lake Okeechobee to the coastal estuaries where manatees live. These pollutants can cause algae blooms so thick that seagrass can't get the sunlight it needs to survive.