Researchers at the IRD institue of reshearch and development have recently discovered that guano has an impact on corals that absorb some of the nitrogen contained in the excrement.
It was by working around the archipelagos of Entrecasteaux and Chesterfield that the scientists were able to make this discovery. These islets host thousands of seabirds that breed here and stay there for several months. This occupation, of long duration, results in the accumulation of enormous quantities of avian dejections.
The analysis of the samples taken shows the presence of nitrogen in the waters of the lagoon as well as in the corals. “We have shown that the nitrogen contained in the guano enriches locally the marine waters, explains the biologist Anne Lorrain, It is even assimilated by the corals! “.
Guano good or bad for corals?
On the other hand, researchers cannot explain the presence of bird excrement in water, nor the way in which corals assimilate nitrogen. “This nutrient is may be integrated by plankton, which in turn is absorbed by corals. Nitrogen can also be captured in dissolved form by zooxanthellae, microalgae living in symbiosis with corals” says Fanny Houlbrèque, specialist in coral physiology.
Another question arises, what impact will this contribution on the coral reefs, will it be positive or negative? This is what the IRD’s future work will tell us.
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