Why Do Manatees Like Warm Water?

Manatees like warm water because they require refuges to survive the cold of winter. Despite a weight of 1,000 pounds or more, manatees lack a continuous layer of blubber (like whales have) to keep them warm. The animals have relatively low body fat and a lower metabolic rate compared to other aquatic animals and cannot tolerate cold for an extended period of time. When the water temperature reaches 68 degrees Fahrenheit (20oC) or below, manatees usually seek out warm waters and are often huddled together in warm-water springs and power plant outflows.

How are manatees affected by cold water?

When subjected to cold for a longer period of time, manatees are not able to produce enough metabolic heat to compensate for the heat they lose to the environment. As a result, manatee mortality increases during unusually cold winter months due to cold stress syndrome. The cold stress syndrome is characterized by a number of physiological issues and disorders instigated by cold water and extremely low temperatures. For instance, metabolism slows down in manatees, resulting in diminished appetite, digestion problems and weight loss. That is why manatees exposed to cold water show signs of starvation, such as a generally sunken appearance and a thinned blubber layer. When exposed to cold for a long period of time, the immunity of the animals also drops significantly, making them susceptible to environmental toxins and a variety of diseases, including intestinal infections and pneumonia.

Warm-water options for manatees

In the past, the sea cows relied on warm water springs to survive the cold of winter. However, construction has modified several of these springs. Dams have obstructed the flow of others. Intensive recreational use has compromised certain springs. Overuse has degraded some. Additionally, declining flows result from increased underground water pumping for agricultural and human needs. Therefore, manatees are consistently searching for alternatives to the natural warm-water springs. During winter, they continue to identify the mechanically heated waters of private and municipal power plants.

The power plants continuously pump out warm water to the surrounding ponds or canals. Presently, about two-thirds of all Florida manatees rely on power plant outflows to survive tough winter days. However, the majority of the power plants they currently depend on are projected to have a lifespan of only 35-40 years. This situation raises uncertainty about whether the existing natural warm-water springs will suffice for the current manatee population. Manatees typically revisit the same warm-water spots each winter. They might also return to inactive power plants in the future, potentially leading to their death in the unheated waters. The shutdown of power plants carries significant risks in this regard. So alternative refuges that are independent of power plants are necessary for the survival of manatees.

Warm-Water Gathering Areas

In winter, Florida manatees typically congregate around natural springs. These springs include Homosassa and Crystal Rivers on the west coast of Florida, as well as Blue Spring on Florida’s east coast. These springs maintain a constant water temperature — averaging 72 degrees Fahrenheit — throughout the year. So when the water in surrounding waterways becomes colder, manatees tend to move into these springs to escape the cold. During winter, the U.S. Fish & Wildlife Service closes access to springs like Three Sisters Springs. This decision is made due to the hundreds of manatees that flock to the serene 72-degree waters there.

Cold stress is fatal for these animals. Aside from that, those that find refuge in the springs can lose a lot of weight in winter. Because these springs attract canoeists, kayakers, and snorkelers seeking to swim or boat with these gentle animals, it becomes necessary to close them off during the winter. This action aims to protect the manatees. However, warm-water refugees are at risk of disappearing. This is because spring flows are diminishing due to the increased usage by Florida’s growing population, and aging power plants are going offline. As a result, there is a requirement to enhance spring flows and establish warm-water alternatives for manatees.

Want more information on manatees and manatee tours, visit the “Captain Mike’s Swimming With The Manatees” site.