Probiotic Supplements Can Help Coral Reefs (Just Like They Help People)
According to the National Center for Complementary and Integrative Health, approximately four million American adults take probiotic dietary supplements to help with issues such as digestion, allergic reactions, and mental acuity. Probiotics are like ‘good guy’ bacteria that help fight ‘bad’ germs, which they do by reseeding an individual’s microbiome. (It is the community of necessary bacteria, fungi, and viruses that live in or on tissues and bodily fluids and help humans maintain general health.) Dietary supplements are not the only way humans can. ingest probiotics. Yogurt, kefir, and fermented vegetables, for example, contain a lot of it. This means that most people don’t need to spend the money to buy probiotic pills. Still, supplements can often help people with stressed physiology.
Surprising new research from an international team of scientists suggests that even stressed coral reefs can benefit from probiotic supplements.
Coral reefs are a lot like Russian nesting dolls
Inside coral reefs are communities of tiny, soft-bodied animals called polyps. Cut, they are related to anemones and jellyfish.
Although polyps are usually transparent and colorless, inside each live millions of microscopic algae with brilliant hues. The relationship between polyps and algae is symbiotic. Polyps provide algae with the compounds it needs to photosynthesize. The algae give the color of the coral as well as the amino acids, glucose and glycerol. Polyps use chemical compounds to make proteins, fats, and carbohydrates.
To sum up the geometry: Inside the reefs live polyps. Inside the polyps live microscopic algae that give the polyps nourishment and bright colors.
Reefs are multi-dwelling housing complexes made of exoskeletons
Polyps extract calcium and carbonate ions from the seawater around them and use the ions to make calcium carbonate (limestone) exoskeletons. Exoskeletons are rigid cup-shaped envelopes that polyps secrete from deep within their anatomy and then settle inside. Exoskeletons are essential to the life of coral reefs. Indeed, they are the reefs. When hundreds of thousands, if not millions of exoskeletons merge, they can weigh several tons.
In addition to protecting polyps, reefs provide hiding places as well as pastures and hunting grounds for a wide variety of marine life, and are therefore important for the health of the oceans in general.
Why is reef bleach
When stressed by factors such as high water temperatures or loss of light or nutrients, polyps cannot physiologically support the algae that live inside. As a result, they expel them. With the disappearance of algae, polyps lose their color, just like reefs. (Limestone is white. It’s the polyps that come out of their homes that color the reefs.) Bleached coral reefs aren’t necessarily full of dead polyps, but they are full of physiologically endangered polyps.
Unfortunately, over the past decades, coral reefs have been under unprecedented stress from global warming. As the reefs turn white and then die off, the hiding and feeding sites for thousands of fish and other marine life disappear.
Probiotic treatments for bleached coral
Just as a human’s health depends on their microbiome, the health of every component of a coral reef, from limestone to algae, depends on communities of bacteria, fungi and viruses. New research conducted by an international team of scientists and published in the peer-reviewed journal Scientists progress demonstrates that at least one type of coral reef can benefit from probiotic treatment, as some humans do. In this new study, beneficial microorganisms for coral treatments (BMCs) were used to save polyps and reefs from the effect of drastic increases in temperature.
Scientists have worked with a species of coral called Mussismilia hispida, which they collected in 80 fragments from the Atlantic Ocean off the coast of Brazil and placed in an aquarium that mimicked natural conditions. The team caused the fragments to bleach by gradually increasing the water temperature from about 26 degrees Celsius to 30 degrees over the course of eight days. They kept the temperature high for ten days, and then gradually for four days, they lowered the temperature to 26 degrees. After that, the temperature was kept stable for a 23 day “recovery” period. Before and during the increase in temperature as well as during the decrease in temperature and the recovery period, a group of corals were regularly treated with BMCs made up of six different bacterial strains. Coral fragments in a control group were treated with a placebo saline solution.
All corals that had been treated with BMCs survived the bleaching event. Like Raquel S. Peixoto from the Institute of Microbiology of the Federal University of Rio de Janeiro and the Saudi Arabian Red Sea Research Center at the King Abdullah University of Science and Technology explained in an email that “probiotics have not “only” improved bleaching, but also (and in fact!) prevented coral dying. While 100% of the coral fragments treated with BMC survived, only 60% of the fragments treated with the placebo survived.
Unsurprisingly, the team of scientists suggested that with global warming and the increased frequency and severity of ocean warming events, a new intervention like probiotic inoculations could end coral mortality. and what they suggest should be called “post-heat stress disorder.” If probiotic inoculations work, they could save not only corals, but also the thousands of marine animals that depend on reefs for grazing, security, and hunting grounds.
A huge challenge yet to be resolved, however, is how to inoculate large-scale reefs into the wild. In his email, Peixoto suggested, “We have several strategies, some of which are worked in collaboration with engineers and involving robots and artificial intelligence as well as the development of slow release delivery systems. These could include bacterial pills that could slowly release bacteria onto the corals for 20 to 30 days. With such an approach, we may only need to inoculate the reef one to three times during a bleaching episode. Our idea would be to use the National Oceanic and Atmospheric Administration (NOAA) bleach alerts to know when and where a bleach event would occur, then inoculate the reef just before and during the event.
As Peixoto also explained, time is running out for coral reefs. Whatever approach scientists test and choose, they must act quickly.
The investigation team consisted of Erika P. Santoro, Ricardo M. Borges, Josh L. Espinoza, Marcelo Freire, Camila SMA Messias, Helena DM Villela, Leandro M. Pereira, Caren LS Vilela, João G. Rosado, Pedro M. Cardoso, Phillipe M. Rosado, Juliana M. Assis, Gustavo AS Duarte, Gabriela Perna, Alexandre S. Rosado, Andrew Macrae, Christopher L. Dupont, Karen E. Nelson, Michael J. Sweet, Christian R. Voolstra, Raquel S. Peixoto.