New research has shown that mucus exuded by small polyped stony (SPS) corals contributes significantly towards the primary production of reefs.
Many reef building hard corals contain special symbiotic algae, called zooxanthellae, which consume the corals' wastes and provide a plentiful supply of carbon. According to a recent paper in the journal Nature, a team of scientists from the Max Planck Institute for Marine Microbiology, Germany, have shown that the mucus released traps organic matter from the water column and carries nutrients to the sediment, forming a "biocatalytic mineralising filter", and that the mucus contains up to half of the carbon produced by their symbiotic algae.
A single square metre colony of Acropora on the Great Barrier Reef can produce 4.8 litres of mucus every day, and 56-80% of this becomes dissolved in the water and filters through the substrate. The undissolved component of the mucus traps suspended particles in the water and picks up so much carbon and nitrogen that the levels increase by three orders of magnitude in just a couple of hours.
Tidal movements cause the mucus to collect in lagoons, where it's broken down at a rate of around 7% per hour. This creates a recyling loop system that supports life in and around the substrate and reduces the loss of nutrients from the ecosystem.
For more information see: Wild C, Huettel M, Klueter A, Kremb SG, Rasheed MY, Jorgensen BB. (2004) -
Coral mucus functions as an energy carrier and particle trap in the reef ecosystem. Nature 2004 Mar 4;428(6978):66-70.