In a surprising twist on ‘what doesn’t kill you makes you stronger’, scientists found that the droppings of coral-eating fish provide a massive payload of important microscopic organisms that strengthen coral reefs. I discovered that
The findings show that the droppings of coral-eating fish (corallivores) are packed with symbiotic dinoflagellates that are essential for coral survival. Overturning the conventional view that these fish were damaging reef structures, instead it was herbivores that fed on debris and bushy algae that kept the corals healthy. It also opens the door for scientists who may use ‘dung transplants’ to support stressed corals that have displaced beneficial symbionts, such as the devastating phenomenon of coral bleaching.
“You’re not alone in helping sustain coral dominance,” says Adrian Correa, a marine biologist at Rice University.
“When many baby corals settle on the bottom of a reef, they need to get their symbionts from the environment,” Correa added. But we’ve never really looked at how those microbes get to all those places.”
This amazing discovery was made during an expedition to the Moorea Coral Reef Long-Term Ecological Research Station in French Polynesia. Meanwhile, the team tracked coral reefs and herbivores. Scientists have mapped excretion sites and taken dung samples to find out some surprising ways how coral reef symbiosis really works and how healthy dung from predatory fish is. I found
In fact, researchers were amazed at the number of symbionts found in flamboyant butterflyfish dung samples (The most decorated butterflyfish) and mailed butterflyfish (C. reticulatus). Each species spreads an estimated 100 million living symbionts across a coral reef the size of just six parking spaces. Just as honeybees pollinate plants, this nutritious photosynthetic fertilization delivery service is essential to coral reef survival.
Scientists knew that symbionts were encased in fish droppings, but this study reveals a vast number of benevolent organisms. Its overall effect appears to be more beneficial than herbivores whose droppings leave coral with great damage and are suspected of containing pathogens.
“many [corallivores] Carsten Grupstra, a graduate student at Rice University and lead author of the study, said: Some species may be important to coral reef conservation in ways we never imagined. ”
The discovery opens the door to investigating what role coral-eating fish play in maintaining the health of plagued reefs. The team plans to conduct experiments on young and stressed adult corals to see if “fecal transplants” offer benefits beyond what nature leaves to them.
When and how corals embrace symbionts is still a mystery, but researchers hope that biological interventions could lead to new ways of dealing with coral ‘bleaching’. Leave them without color.
“This opens up the way we think about the role of coral-eating fish on reefs,” Correa said. “Not only does it break down the reef skeleton, it also disperses the symbionts that corals and other organisms need.”
Watch the video below to see how the research team made their amazing discovery.
Corals may need predator droppings
The study was published in a journal Frontiers of marine science.
Source: Rice University
