A sound environment reproducing the noises made by fish and shrimp encourages coral larvae not to desert degraded reefs.
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Certain sounds broadcast underwater could come to the aid of damaged corals, according to a study published Wednesday March 13 by American researchers. The audio recording in question, which at first glance sounds like the noise made by someone taking a shower or a crackling wood fire, is actually a mixture of noises made by fish and shrimp. This ambiance represents the soundtrack found in healthy coral reefs. Researchers from the Massachusetts Oceanographic Institute have demonstrated that this aquatic symphony, when broadcast through speakers underwater, encourages coral larvae to stay in place, within a radius of 30 meters nearby, including on degraded reefs. The sound environment is very important for corals seeking to establish themselves, explain the authors of this study.
When this soundscape is broadcast underwater, the rate at which coral larvae settle can be up to seven times higher than when the sound is turned off. For more than 10 years, this team and others around the world have been interested in and recording the acoustic atmosphere in coral reefs. They noticed that when corals are degraded, the atmosphere is much quieter. Obviously the speakers will not be enough to save all the corals in the world, but the installation of the larvae is an important step and the acoustic ambiance could therefore be a valuable tool for future restorations, alongside temperature factors, and chemical environment. The world has lost half of its coral reefs since the 1950s, notably due to global warming, overfishing and pollution. But corals are home to around a quarter of marine life.
Reefs more resilient to climate change
To save the corals, other solutions exist. One way is to grow naturally more resilient corals. Swiss researchers have, for example, developed a calculation tool that makes it possible to identify the coral families that best tolerate global warming.
When the temperature rises, the coral becomes stressed and no longer recognizes the zooxanthellae, the microalgae, with which it normally lives in symbiosis and which provide it with colors and nutrients. At the same time, other scientists are also trying to create “super corals”, by gradually forcing them to get used to warmer waters in breeding tanks. They hope to create an adaptive memory in new generations.