Summer love: how corals find mates and why it matters

Finding mates – What is coral spawning?

Do you feel that heat? Summer is here and that means it’s time for corals to find mates. As air
temperatures climb, the ocean begins to warm, too, which sends a signal to corals that they should
prepare to spawn (the process through which corals reproduce).

In the dark—hidden beneath the waves—corals are participating in one of the most important events of
their lives. However, because corals are sessile organisms and can’t move, they depend on cues to
release their gametes (reproductive cells) into the water column in synchronized events.

Rising water temperatures, paired with sunset and moonlight cues, help trigger one of the most
incredible natural events in the sea: mass coral spawning. Depending on the species, corals synchronize
and spawn on different days and times, releasing either eggs, sperm, gamete bundles (eggs and sperm
together) or larvae, boosting their chances of creating genetically diverse, resilient offspring.

Corals are not the only ones that use environmental cues to spawn, other reef creatures such as soft
corals, brittle stars, sea urchins, worms, and even sponges also tend to spawn around the same time as
coral, so the underwater world truly goes into a reproductive frenzy!

Finding the Perfect Time – When does coral spawning happen?

Scientists around the world have been studying coral spawning events. In Curaçao, located in the
southern Caribbean, spawning predictions based on more than 30 years of research help other locations
understand when spawning happens.

In The Bahamas, specifically in South Eleuthera, The Bahamas Coral Innovation Hub (BCIH), a
collaboration between the Cape Eleuthera Institute and the Perry Institute for Marine Science that is
supported by The Nature Conservancy, has been monitoring coral spawning since 2019. The BCIH team
shares their predictions to the public, focused on coral spawning predictions in The Bahamas. These
predictions have consistently proven accurate, pinpointing peak spawning dates for coral mass spawning
events in the region. Check out the 2025 Coral Spawning predictions and tips at https://capeeleutherainstitute.figshare.com/ to plan a dive or snorkel of your own!

How Scientists Are Involved in Eleuthera – How You Can Be Too!

The BCIH utilizes their spawning predictions to conduct fieldwork. Dives are not only to monitor the
events and help narrow down spawning windows, but also to collect gametes from the water column.

Under specific research permits, the team utilizes nets with test tubes at the top to catch gametes
released by corals. The collected sperm and eggs are fertilized and can then be brought back to the
lab-based facilities for larval propagation, monitoring growth and outplanting new corals on Eleuthera’s
reefs. Assisted coral reproduction is key for coral restoration and conservation efforts.

Coral spawning is not just limited to scientific researchers. To experience this magical event and witness
the unique beauty of nature, check out the predictions, and find a shallow area that has a large amount
of coral reef coverage. It is truly a breath-taking experience and gives a peek into the beauty of nature’s
operations. Certain species also have overlapping spawning windows and can be observed at the same
time. In The Bahamas, the peak dates for spawning fall on August 15th and August 16th. If you observe
spawning or have some questions, don’t hesitate to contact our scientist on site
(nataliahurtado@islandschool.org). Whether for recreation or research your sightings can help provide
us with valuable information about the spawning of these important species.