It was the winter of 2007. I had recently graduated from the University of Havana with a degree in biology when I received a call from a power plant official 40 miles away in North Havana. Two manatees had been found inside the plant's intake canal. He was looking for a biologist who could see if they were okay. I didn't have a car, so I hitchhiked to the power plant. I got there, was asked for my identification and given a helmet. I walked through what felt like the ruins of an old and rusty factory, kept cranking with the sheer ingenuity of the Cuban people. Then I saw them, a mother manatee with her calf, resting peacefully in a small canal. They looked powerful, majestic — and incredibly vulnerable.Seeing a wild Cuban manatee for the first time filled me with joy. That moment solidified my career choice, to research manatee biology and help these creatures survive the age of humans.A few weeks later, James "Buddy" Powell, executive director of the nongovernmental organization Sea to Shore Alliance, saw pictures of the two manatees and then told me: "I'm sorry but this is not a Cuban manatee."Powell, a scientist dedicated to manatee conservation in Florida, Africa, Central America and the Caribbean, was right. The scars on the adult, caused by propellers, suggested she wasn't from Cuba, where the seas are largely silent of the buzz of boat motors so familiar in Florida.I was deflated but also more determined than ever to pursue my career because it had taken on new meaning. I began to realize how little we really know about these animals and the way they move and cross deep ocean passages like the Florida Straits — and how crucial it is that the United States and Cuba work together to learn about the marine resources we share across only 90 miles.Powell sent the photographs to Cathy Beck, a biologist with the U.S. Geological Survey who oversees the agency's photo identification database of known manatees. Beck found that the female manatee was indeed known and registered in Florida, by the code CR131. In Cuba, she'd been named "Daysi."Two names, two countries, one manatee."Daysi lived in the west coast of Florida for more than 30 years," said Powell, who had first photographed Daysi in 1979. Beck said Daysi had last been sighted in Florida in 2006, in the Wakulla River. After that, she started a journey to the unknown. Daysi and her almost-one-year-old calf traveled to Cuba before President Barack Obama announced the reopening of relations between the two countries. Their journey demonstrated the ecological bridge between our nations, stronger than any political force.Political and economic tensions between Cuba and the United States began to build in 1959. But while the two governments stewed over politics, ecosystems and wildlife maintained their natural connection.A manatee swimming from Florida to Cuba with no ID other than her body full of scars is only one story in a sea full of them. It's hard to say why Daysi set off across the straits. "It might have happened because she got lost on her way to find warm water," Powell said. It may also have been getting increasingly hard for Daysi to find a suitable place to live, as population growth, development, freshwater depletion and other pressures impact habitat in Florida.Manatees in Florida are a different subspecies than those in the West Indies and Cuba. After being isolated for a long time, the two populations developed differences in the shape of their skulls.While found primarily in Florida, the Florida manatee occasionally ventures as far north as Virginia and, rarely, farther on to Massachusetts. Along the Gulf of Mexico, Florida manatees may be found as far west as Texas. Before the report of Daysi, a Florida migrant to Cuban waters was unknown. It was thought that individuals of this population could reach only the Bahamas and as far south as the Dry Tortugas.The Cuban and Florida manatees have different habitat requirements. "A Florida manatee depends on warm water refuges and the skill to evade boaters," said Powell. "A manatee in Cuba is more influenced by the accessibility of freshwater and the challenge to stay alive among poachers." Likewise, different histories of interactions with humans pose different challenges for their conservation in the two regions.Florida manatees are a federally listed endangered species, due to a significant decline in the population between the late 1800s and passage of the Endangered Species Act in the 1970s. During the last 40 years, their numbers have climbed from 800 individuals in the 1970s to at least 6,000 today, said Robert Bonde, a USGS manatee biologist who has spent his career studying manatees in Florida.The Cuban population, on the other hand, has been declining for many years. While they may not be sliced by boat propellers, manatees in Cuba, like other marine species, face many challenges, including lack of enforcement for existing regulations and human threats. Poaching and inappropriate fishing gear are, at the moment, uncontrolled pressures that, in combination with the country's economic situation, kill untold numbers of manatees in Cuba. Lack of scientific research there also means a lack of data about the population.The recovery of the Florida manatee may be a model to reverse the plight of the Cuban manatee, especially when the region may be exchanging individuals like Daysi.Other creatures, of course, also move through this common sea with no concern for visas and political issues. Turtles, sharks and bottlenose dolphins also have strong drives to cross the Florida Straits. Scientists say species that move long distances or migrate across countries are more vulnerable to extinction because of a greater variety of threats and differences in conservation.At Mote Marine Laboratory in Sarasota, shark biologist Robert Hueter is working to understand the connection between sharks from Cuba and the United States. "There is ample evidence of connectivity between Cuba and the U.S. in shared stocks of sharks, primarily through tagging studies that have demonstrated shark movements between the two countries," he said. "Among the shark species that we know move back and forth are the shortfin and longfin mako, tiger, bull and hammerhead."Hueter and other scientists stress that it's in both countries' best interests to work together to conserve and manage shark and other fish populations. Preventing overfishing and managing fisheries for sustainability are crucial, as is protection of critical habitats. "If one country does its part and the other does not, and the sharks occupy waters in both countries, then the action of the one may be canceled by the inaction of the other, and vice versa," Hueter said.Telemetry studies and physical tagging show that turtles and bottlenose dolphin also move from Florida to the north coast of Cuba. It is more and more evident that the two countries enjoy a bidirectional movement of life and energy and should join hands to ensure species' survival.Ecological risks and benefits flow in both directions, too. Severe environmental events on the American coast can put at risk coastal habitats in Cuba. The BP oil spill, carried by winds and oceanic currents, almost reached the island's north coast.Those same currents could be transporting millions of fish larvae from Cuba to the United States — replenishing some of South Florida's overfished populations and damaged marine ecosystems. Scientists have found that snapper populations in areas closer to Florida could depend in part on spawning aggregations from the northern regions of Cuba.The same pattern is suspected for bonefish, tarpon and permit. "Some of the larvae produced in the northwest of Cuba could potentially enter in the currents, drift north and end up in the Florida Keys, recruiting populations that support the recreational flats fishing industry," said Aaron Adams, director of science and conservation for Bonefish & Tarpon Trust.Adams said that makes it particularly important for Florida to work with Cuba to ensure bonefish, tarpon and permit populations and spawning locations on the island are protected as it expands tourism.The biological connections among the coral species of Cuba and Florida are not quite so obvious; there is little evidence of coral reef-building species traveling such long distances. Yet many of the coral reef ecosystems as well as seagrass beds and mangroves in Cuba are pristine and healthy. That proves important to the health of fishes in the Caribbean — and possibly to the recovery of coral reefs in Florida."Understanding why Cuba's corals are so healthy is essential to gain insights that can guide our hands to restore coral reef ecosystems not only in Florida but throughout the Caribbean," said David Guggenheim, president of the NGO Ocean Doctor, who has explored Cuba's reefs for 15 years.Part of the reason for the health of Cuba's marine environments could be that the nation's agriculture "is not based on an extensive use of pesticides and other agri-chemicals," said Bill Messina, an agricultural economist at the University of Florida. "Therefore pollution and eutrophication may not be a widespread threat to Cuban fisheries, habitat, biodiversity and human health."Much of what is known about the ecological connections between Cuba and the United States evolved from already existing collaborations between American and Cuban scientists, who overcame significant barriers to work together. The American Association for the Advancement of Science and Cuban Academy of Sciences cite years of constraints from both sides: limited and restricted funding, travel and permit restrictions, mail and shipping limitations, lack of Internet, limited access to research vessels and scientific instruments, restrictions on U.S. training of Cuban students, restrictions on technology transfer and limits on the use of global positioning systems. The list goes on.Now, thawing geopolitical relationships can warm scientific collaboration too. "The U.S. and Cuba should expand joint research and management on a wide range of issues involving shared marine resources and ecosystems," said Dan Whittle, a lawyer and senior director of the Cuba program for the Environmental Defense Fund. Along with research into marine life, Whittle said, are crucial questions on offshore oil exploration, oil spill prevention and response, renewable energy, sustainable agriculture, sustainable tourism, coastal zone management, invasive species and climate change. Specifically, scientists hope to see increased funding for collaborative research, capacity-building and educational projects on both sides of the Straits. The next challenge: co-management of common habitat and natural resources. When it comes to manatees, Daysi's journey and other evidence suggest the distinct species' preferences to stay put in Florida or Cuba is changing, said Bonde."It is likely that manatees today may move between Cuba and Florida and Cuba again, as they have done during periods of population expansion and contraction," Bonde said.But more research is needed to know for sure — research not limited to either nation but shared across the Florida Straits.While politics has taken the lead role in U.S.-Cuban relations for half a century, it's now the ocean's turn. Separated by only 90 miles, Florida and Cuba can work together to safeguard their common bond and common interest in a sustainable sea where creatures like Daysi can swim freely rather than dodge dangers on both sides.I never saw Daysi again in Cuba. She hasn't been seen in Florida either. I keep searching for her, and for the answers to saving our shared seas.Biologist Anmari Alvarez Aleman is a Ph.D. student in the University of Florida's School of Natural Resources and Environment. She wrote this essay in Environmental Journalism class in UF's College of Journalism and Communications. It was adapted exclusively for the Tampa Bay Times.