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Why
are Warm Water Refuges Important to Manatees? Manatees are regarded as tropical marine mammals. As such, they developed their particular adaptations to an aquatic existence in warm tropical waters. Manatees in Florida are at the northernmost reaches of their range. During the warm season, mostly April to October, manatees freely range throughout the Florida peninsula and to points farther west and north in coastal States of the southeastern U.S. Manatees prefer water temperatures to remain above 68 oF (20 oC). Prolonged exposure to lower water temperatures cause manatees to lose body heat and inadequately digest their food. This can lead to a condition classified as "cold stress" or death. During the cold season, November to March, water temperatures throughout the state can be below this thermal minimum. Manatees seek out areas with warm water to meet their thermal requirements. Such warm water sources can be natural, such as springs (e.g. Crystal River), or artificial, such as power plant outfalls. Large numbers of manatees, often hundreds, can be found together at these sites during the cold season. Without warm water sources and sites in Florida, manatees would have a difficult time during extremely cold winters in our State.
Summary of Artificial Warm Water Refugia Issues - This is a synopsis of the Bureau of Protected Species Management’s endeavors regarding the topic of artificial warm water refuges. Foraging Behavior of Manatees During the Cold Season - It has been speculated that during the winter manatees may be limited to foraging in close proximity to a thermal refuge due to their reliance on warm water. If this is typical manatee behavior it would be reasonable to assume that as the winter progresses food resources near the refuge would become depleted, resulting in manatees moving progressively further away from the refuge to other foraging sites. In response to this speculation a literature review was conducted of published research related to manatee foraging behavior to determine if any stereotypic winter foraging habits have been documented.
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