Seagrass and Range Shifts

Like many animals, West Indian manatees have more than one limitation on their population. Seagrass is a major portion of the West Indian manatee's diet and they are dependent on it for food. Thus where seagrass goes, manatees go. Comparing the map below to the West Indian manatee range map on the Range Shift tab we can see it appears that the West Indian manatee is limited by food at it's southern limit, but not at it's northern, where it is likely limited by temperature. This indicates that West Indian manatees will likely shift North more easily since their is already a food source for them. Sea grass is not able to disperse as quickly as manatees, so expansion on the southern limit will likely be slower.

World Distribution of Seagrass from Florida Museum of Natural History
http://www.flmnh.ufl.edu/fish/southflorida/seagrass/Distribution.html

http://www.divephotoguide.com/user/coolwaterphoto/
gallery/featured_gallery_158/photo/2846/

A study looking at seagrass meadows found that 58% of them had decreased in size during the study period. The researchers found that seagrass meadows are being negatively impacted by human activities, as well as climate change and ecological degradation. Without adequate food the West Indian manatees will not be able to expand their range to new areas, which is why it is likely that the West Indian manatee will not be able to disperse south.