From the Sea of Tranquility to Galveston Bay, Artemis II mission Serves as a reminder of the links between the moon and coral reproduction
Full moon spawning events keep reefs growing in the Gulf and beyond
As NASA’s Artemis II mission starts the return to earth after carrying humans around the Moon for the first time in more than 50 years, the lunar spotlight once again reminds humanity of a powerful truth: while exploration reaches outward into space, the Moon continues to shape life on Earth —especially beneath the sea.
To many, the moon is a familiar gray sphere waxing and waning across the night sky. But to marine scientists, its predictable cycles serve as a biological clock that governs some of the most critical events in ocean ecosystems. Nowhere is that connection more visible than in coral reefs, where full‑moon spawning events drive reproduction, renewal, and long‑term reef survival.
Once each year, when lunar phase and ocean temperature align under near‑perfect “Goldilocks” conditions, entire coral colonies release millions of tiny eggs and sperm—called gametes—into the water column simultaneously. Researchers often describe the event as an underwater blizzard, with clouds of white, yellow, red, and orange drifting upward beneath the glow of the full Moon. The spectacle is brief but vital: for most coral species, gametes remain viable for only a few hours.
Under lunar illumination, the blizzard of gametes, full of fatty substances called lipids, take a slow ride to the ocean surface, where the process of fertilization begins.
Dr. Jay Rooker, Regents Professor, Marine Biology, Director of the Gulf Research Institute for Highly Migratory Species (GRHIMS), College of Marine Sciences & Maritime Studies, Texas A&M University at Galveston, leads a team of researchers from Texas A&M University, Louisiana State University, Mississippi State University, the University of Florida, and University of Texas-Rio Grande Valley who are working together in NOAA’s Flower Garden Banks National Marine Sanctuary, and NOAA’s Southeast Fisheries Science Center to observe habitat requirements and connectivity for reef fishes in the Gulf. Part of a healthy reef environment centers on healthy coral.
“We work closely with resource managers to translate our results in order to effectively protect vulnerable habitats and species that depend on these banks for their survival,” said Dr. Rooker.
The project studies a wide range of key reef-associated fishes to determine how they utilize the reefs and banks of Flower Garden Banks National Marine Sanctuary and surrounding areas. Using acoustic and satellite telemetry to track fish movement, bioacoustics to capture fish vocalizations, and biophysical modeling to determine larval dispersal, the project evaluates the habitat use and ecological connectivity of native and invasive mesopredators, foundational reef fishes, and demersal/pelagic fishes that from aggregations. This research expands the understanding of how fish populations use Flower Garden Banks National Marine Sanctuary to improve protected area design and management.
Part of that management includes ensuring conditions are right to support new coral. Fertilization is just the beginning of the journey to a coral reef. Once a coral egg and sperm join together as an embryo, they develop into a coral larva, called a planula. Planulae float in the ocean, for days and on occasion weeks, before descending to the ocean floor. Depending on seafloor conditions, the planulae may attach to the substrate and grow into a new coral colony at the slow rate of about .4 inches a year.
Ensuring that new coral forms is crucial to ensuring the long-term success of coral reefs, which have experienced significant loss over many decades. Coral reefs around the world face existential threats due to climate change, pollution, and unsustainable human activity. Rising ocean temperatures cause widespread fatal bleaching. Coral bleaching is a stress response where corals expel symbiotic algae called zooxanthellae that live in their tissues. The zooxanthellae turn the coral white, or bleached, which leaves them vulnerable to starvation and disease Additionally, ocean acidification hinders coral growth. Other threats to coral include, overfishing, agricultural runoff, and coastal development.
Coral reefs around the world are in a fight for their very survival. Thanks to the pull of the moon, coral spawning by moonlight helps keep reefs growing and fish swimming
