The arrival of cooler weather this week may mean that Sun Coast manatees will be on the move. Marine biologists say manatees could start seeking warmer areas in which to gather. They say those warm-water havens often include Myakahatchee Creek in North Port and creeks and canals along Charlotte Harbor and Lemon Bay in the Myakka River. Researchers say they’ve already received reports of manatees gathering in warm water areas there, including near power plants.