Human excrement caused the disappearance of corals
Last reviewed: 16.10.2021
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Specialists on coral reefs decided another puzzle.
The reindeer (six-ray) coral (Acropora palmata) was once the most widespread ripostroitelnik of the Caribbean, but over the past ten years, the population decreased by 90%. This was partly due to the so-called white smallpox, which exposes the skeleton of the coral, killing its soft tissues.
Finally, it was possible to establish the true cause of the disaster - human excrement. This is the first example of the transfer of a pathogen from a human invertebrate.
Nine years ago, a group of researchers led by Catherine Sutherland (now working in Rollins College, Florida, USA) and James Porter of the University of Georgia (USA) linked the smallpox with the bacterium Serratia marcescens, which lives in the intestines of humans and some other animals . In humans, it can cause respiratory infections and urinary tract infections. Even then, the researchers had good reason to believe that the source of smallpox in corals is the Florida-Keys archipelago, but they had no evidence that the disease was not transmitted from reef deer, cats, gulls and other Caribbean bacteria.
Therefore, scientists had to spend years on additional research of healthy and sick corals, other animals, and sewage of the city of Key West. A special enzyme was added to the samples, which destroys the genome of bacteria. Since the genomes of different strains of bacteria differ, for each of them, a unique picture of DNA-ruptures was obtained.
Comparing the strains found in the samples, the researchers saw only one correspondence - between the strain isolated from human waste, and the strain that causes white smallpox in corals.
To dispel the remaining doubts, experts have grown small fragments of healthy corals in the laboratory, and then put them under the impact of the human strain. In just four days, healthy corals showed signs of infection.
For the islands of Florida Keys and the Caribbean, the tourism industry of which earns billions, the discovery is of great importance. The authorities will no longer turn away from modernization of waste treatment systems. Scientists note that since Key West moved to the advanced treatment facilities in 2001, there have been no cases of white smallpox in corals in its vicinity.