The silent threat of low genetic diversity

Across the Caribbean, protected coastal waters have served as primary feeding and breeding grounds for the endangered Antillean manatee. Unfortunately, these same coastal waters are also a popular “habitat” for humans. In the past, the overlap between human and manatee habitat allowed for manatee hunting and threatened the survival of these gentle marine mammals. Today, however, threats are much more inadvertent and are often related to coastal development, degraded habitats and boat strikes.

In the state of Florida, decades of research on the species’ biological needs have helped conservationists address threats to its survival. For example, low wake zones and boater education have protected manatees from boat strikes, and many of their critical winter refuges are now protected. The Florida population has grown steadily, thus increasing from approximately 1,200 in 1991 to more than 5,000 in 2010. It is conceivable that in Florida manatees may one day be reclassified as “threatened” rather than “endangered.”

Yet, in other parts of the Caribbean, threats still loom. This includes small, isolated manatee populations found on islands that can be more susceptible to extinction and lack of genetic diversity. To ensure the species’ long-term viability, scientists have turned their sights to the overall population dynamics of manatees throughout the Caribbean. Molecular genetics has provided new insights into long-term threats the species faces. Fortunately, the emerging field of conservation genetics provides managers with tools and strategies for protecting the species’ long-term viability.