Biodiversity on the Brink: The Role of “Assisted Migration” in Managing Endangered Species Threatened with Rising Seas

By Jaclyn Lopez

Coastal areas in the United States are already experiencing the effects of sea-level rise, and the best available science predicts significant additional sea-level rise this century. In addition to sea-level rise, storm intensity and storm surge are also increasing. In some coastal areas, continuing population growth is compounding the threats of climate change and sea-level rise.

At the same time, one in six of the federally listed endangered and threatened species in the United States is threatened by sea-level rise. Coastal species face displacement, extirpation, and even extinction due to loss of habitat. They are at risk of being trapped between rising sea levels and human development. This threat is exacerbated by unyielding human-made coastal fortifications. This coalescence of factors leads to the phenomenon known as “coastal squeeze”—the loss of transitional habitat between land and sea.

For coastal areas this means that some of the most imperiled species will be pushed closer to the brink of extinction. “Assisted migration” refers to one policy prescription to address this problem. The federal government, through the U.S. Fish and Wildlife Service, has the authority—and responsibility—to consider active and passive assisted migration under the Endangered Species Act in managing species threatened with habitat loss due to sea-level rise. The federally protected Florida panther, loggerhead sea turtle, Key tree-cactus, and Lower Keys marsh rabbit inhabit critically imperiled habitat in south Florida and are analyzed to examine this issue from the perspective of species from differing taxa, habitat types, and natural histories. This Article concludes that assisted migration, coupled with preserve and corridor protection and dramatic reductions in greenhouse gas emissions, are necessary for the conservation of imperiled species threatened with sea-level rise.

Cite as: Jaclyn Lopez, Biodiversity on the Brink: The Role of “Assisted Migration” in Managing Endangered Species Threatened with Rising Seas, 39 Harv. Envtl. L. Rev. 157 (2015).

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