A few days after a full moon, corals participate in an incredible mass spawning event. Stony corals release their sperm and eggs at the same time, creating a giant underwater cloud of gametes.
A team of scientists led by Rutgers University set out to investigate how the sperm and eggs survive for several hours while they are exposed multiple threats from predators, microbes, and environmental stressors such as warming waters.
Despite coral eggs being very large and sperm cells being tiny, the scientists discovered that eggs and sperm appear to perform similar genetic functions during the planktonic stage.
The researchers also identified two genes that may be involved in how coral sperm and eggs recognize each other in dynamic ocean waters and come together for fertilization.
Study senior author Debashish Bhattacharya is a distinguished professor in the Department of Biochemistry and Microbiology in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick.
“Much more attention needs to be paid to coral gametes because both egg and sperm are vulnerable to climate change and other insults,” said Professor Bhattacharya.
“It goes without saying that without robust sperm and egg, the coral reproductive cycle will be significantly weakened. Therefore, we need to understand in more detail how natural selection has acted on coral gametes to ensure their survival, leading to successful fertilization.”
According to the National Oceanic and Atmospheric Administration (NOAA), coral reefs provide food for about 500 million people, protect coastlines from erosion and storms, and support thousands of fish species.
Corals are severely threatened by various aspects of climate change, including ocean acidification, sea-level rise, and hotter temperatures that cause bleaching events.
Tropical storms, unsustainable fishing, and pollution are also major threats to the future of coral reefs.
Through their genetic analysis of the Hawaiian stony coral Montipora capitata, the scientists have revealed a blueprint for how coral eggs and sperm function. Next, the team hopes to identify the substances they produce to ensure their survival and fertilization.
“Our results pave the way for future genetic investigations, particularly in the context of climate change influences on the marine environment,” said Professor Bhattacharya.
The study is published in the journal PeerJ.
By Chrissy Sexton, Earth.com Staff Writer