Manatees

They detest water temperatures below 20 degrees Celsius.

An excerpt from the article 16 facts about manatees

Manatees inhabit shallow coastal, marine, and fresh waters. They often choose areas near power plants where hot water is drained. Although manatees migrate seasonally, some, accustomed to water heated by power plants, have stopped migrating.

Lowering the water temperature to 15 degrees Celsius can be life-threatening for manatees.