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Human activity is making it difficult to conserve the Caribbean’s coral reefs, but a new threat from algae is adding pressure to an already precarious situation
Corals are marine invertebrates that build large exoskeletons from which reefs are built. Unfortunately, they are so beautiful that humans regularly want to see them whenever they can. This leads to physical disturbances and stress on the coral itself, which can kill these fragile but essential elements of the ecosystem.
How do algae affect the coral reef?
To develop new reef structures, free-floating baby corals must first successfully adhere to a stable surface. They prefer to settle on the crunchy surface created by a specific type of friendly algae that grows on local rocks. These coralline crust algae, or CCA, act as guides for the coral larvae, producing biochemical signals along with their associated microbial community, prompting the baby coral to adhere to it.
“These PAC scabs have biochemical and structural defenses that are deployed to deter grazing by fish and other marine creatures,” explained Chen-Ming Fan of the Carnegie Institution for Science.
“It is possible that these same mechanisms, which make them successful in invading marine biospace, also deter corals.”
The Caribbean experiment
For the past four years, Bryan Wilson of the University of Oxford, Chen-Ming Fan of Carnegie and Peter Edmunds of California State University Northridge have been studying the biology and ecology of peyssonnelid algae scabs, or PACs, in the US Virgin Islands – Coral larvae competing for limited surface space and then growing over existing reef architecture, greatly damaging the ocean’s fragile ecosystems.
What does this mean for the coral reefs of the Caribbean?
The team wanted to find out how the golden brown PAC affects Caribbean coral reefs. What they discovered is that PAC creates a different microbial community than others that attract corals.
“There is a new genomic and evolutionary frontier to explore to help us understand the complexity of the interactions of organisms on the reef, both mutualistic and antagonistic,” added Fan.
“This algae appears to be something of an ecological winner in our changing world,” described lead author Wilson, noting that the other threats to coral communities make them more susceptible to algal scabs.
The research team thinks the algae could be a fatal thing to the coral reef, perhaps. They are going to work harder to find out if the Caribbean reef will survive this new challenge.
Peter Edmunds further commented: “Coral and its ecosystem are as fragile as it is. They are under attack from environmental pollution and global warming. We have made their lives so fragile, yet they are still there.
And now this is added to the mix. We don’t know if this is the last straw, but we have to find out. “
Read their findings here.
