Could a plan to build a 2.5-mile-long airfield in Okinawa, Japan, doom a rare manateelike species to extinction? That's the assertion of more than 400 environmental organizations (pdf), which recently sent a letter to President Obama urging him to cancel the plans to expand Camp Schwab, a U.S. Marine Corps base on Okinawa island.

At issue is the Okinawa population of dugong (Dugong dugon), the closest living relative to the extinct Steller's sea cow (Hydrodamalis gigas). Dugongs are listed as vulnerable to extinction by the IUCN Red List of Endangered Species, but the geographically isolated Okinawa population (which numbers just 50 animals) is considered critically endangered.

"The Camp Schwab base expansion project would destroy some of the best remaining habitat for the highly endangered Okinawa dugong, one of the rarest marine mammal populations in the world," Peter Galvin, conservation director at the Center for Biological Diversity (CBD), said in a prepared statement.

The U.S. military has been trying to expand Camp Schwab for years, while also planning to close another base on the island. Previous plans to build in areas that would threaten the dugong were blocked by a federal judge in 2008.

Many Okinawans aren't happy about the base-expansion plans. Last month, more than 20,000 people showed up to protest U.S. military presence on the island.

Dugongs have special cultural significance in Okinawa. "For Okinawans, the dugong compares only to the American bald eagle in terms of cultural and historical significance," Takuma Higashionna, a council member from Nago City where the base is located, said in the CBD's release.

The military is currently reconsidering all of its options regarding Camp Schwab as part of a complex series of political negotiations with Japan which could, eventually, result in moving 8,000 Marines from Okinawa to Guam. But no one—neither the military, Japan's government nor the people or Okinawa—seems happy with any of the options on the table.

Meanwhile, on the other side of the world, the U.S. Navy has sent its own letter, this time expressing concerns about plans by the U.S. Fish & Wildlife Service to protect the dugong's close relative, the West Indian manatee (Trichechus manatus). Fish & Wildlife has proposed expanding protected habitat for the manatee in Florida and Georgia, but the Navy says that could, potentially, impact their ability to conduct training exercises in the area.

Image: Dugong, via Wikipedia