On Monday, American and Japanese conservationists seeking to protect endangered dugongs appealed a U.S. district court ruling in August allowing the construction of a new U.S. military base in Okinawa Prefecture.

The plaintiffs contend that the base will destroy a crucial habitat for the last remaining Okinawa dugongs, an endangered marine mammal and relative of the manatee.

The appeal argues that the court ruling by the Northern District of California overlooked key procedural and public-participation requirements of the U.S. National Historic Preservation Act, or the need for the U.S. Department of Defense to discuss the impact of the planned base construction with local residents.