From the Sea of Tranquility to Galveston Bay, Artemis II Highlights the Moon’s Role in Sea Turtle Survival
Researcher Dr. Christopher Marshall outlines how sea turtles use the light of the moon to plot their course
For centuries, sailors have relied on the Moon to navigate their vessels across open water. As the Artemis II mission sets its sight on a return trajectory towards Earth—culminating in an ocean splashdown after carrying humans around the Moon for the first time in over 50 years—the enduring connection between lunar light and life in marine environments comes sharply into focus. Consider if you will, the relationship between the moon and sea turtles.
“Our Kemp’s ridley sea turtles are the smallest sea turtles in the world and are day nesters and are the only species to nest during the day. Like other sea turtles the hatchlings tend to emerge from the nests at night. When they do, often the moon is the brightest object on the horizon, and they will use the moon to guide them to the ocean,” said Dr. Christopher Marshall, Regents Professor, Marine Biology Director of the Gulf Center for Sea Turtle Research (GCSTR) College of Marine Sciences & Maritime Studies, Texas A&M University at Galveston.
While many sea turtles emerge at night, Dr. Marshall notes that sea turtle hatchlings can emerge at twilight and in the very early morning as well. When sea turtles emerge from their nests as long as the brightest light they see is a reflection on the water from the moon or another celestial source, they are positioned for a greater chance of reaching the water and beginning their life at sea. When the light source sea turtles fixate on is artificial, problems arise for the hatchlings.
“A major issue for many nesting beaches is coastal lighting and light pollution, which can confuse hatchlings and steer them away from the ocean and often across roads,” Dr. Marshall said. “Many Texas coastal communities are modifying business and residential lighting at night, using many techniques such as downlighting methods to reduce the brightness that can lead sea turtle hatchlings astray. Sea turtle hatchlings need quiet dark beaches and a bright horizon often illuminated by the moon but also reduced coastal lighting at night.”
One of the most effective solutions is downlighting on beaches. Downlighting involves utilizing lights that are shielded, downward-directed, and low-intensity (amber/warm LED) to minimize light pollution and prevent sea turtle disorientation. This “turtle-friendly” lighting creates illumination on pathways or specific areas rather than projecting light onto the beach or ocean, significantly reducing disorientation risk for hatchlings.
Along with physical steps residents along the coastal waters of Texas can take to reduce light pollution, the Gulf Center for Sea Turtle Research is working to address data gaps and research needs to conserve sea turtles in Texas, the western Gulf and throughout the Gulf. Organizing sea turtle biologists in the region and speaking with one voice to attract attention, and funding, for sea turtle research activities and conservation priorities that will protect sea turtle populations and their vital habitats from the beaches to the ocean is a major area of focus for the GCSTR.
Just like the mariners of old navigating by moonlight, sea turtles are just trying to follow the light home. Ensuring that the light that the turtles see will point them in the right direction is one of the ways to help make it a little easier to help endangered sea turtles thrive.
