Tuesday , January 26 2021

New algae threaten the conservation of Caribbean coral reefs



Caribbean coral reef, PAC
© Shawn Jackson

Human activities make it difficult to protect Caribbean coral reefs, but new algae threat increases pressure on already precarious situation

Corals are marine invertebrates that build large exoskeletons from which reefs are made. Unfortunately, they are so beautiful that people regularly want to see them whenever they can. This leads to physical disruption and stress within the coral itself, which can kill these delicate but vital components of the ecosystem.

How do algae affect a coral reef?

To grow new reef structures, free-floating small corals must first successfully attach themselves to a stable surface. They prefer to settle on a crunchy surface created by a specific kind of friendly algae that grow on the local rocks. These coral crustacean algae (CCAs) act as beacons for coral larvae, producing biochemical signals along with their accompanying microbial community that encourages small corals to attach to them.

“These PAC shells have biochemical and structural defenses that they use to stop fish and other sea creatures from grazing,” explained Chen-Ming Fan of the Carnegie Institution for Science.

“It is possible that the same mechanisms by which they successfully invade marine biological space also scare corals away.”

An experiment in the Caribbean

For the past four years, Bryan Wilson of the University of Oxford, Fan Chen-Ming of Carnegie, and Peter Edmunds of California State University Northridge have studied the biology and ecology of Peyssonnelid (PAC) algae shells in the US Virgin Islands. – competing with coral larvae for a limited area and then growing over the existing reef architecture, significantly destroying the fragile ocean ecosystems.

What does this mean for Caribbean coral reefs?

The team wanted to find out how the golden-brown PAC affects Caribbean coral reefs. They found that PAC creates a microbial community that differs from others that attract corals.

“There is a new genomic and evolutionary frontier that needs to be explored to help us understand the complexity of interactions between organisms on the reef, both mutually and antagonistically,” Fan added.

“This alga seems to be something of an ecological winner in our changing world,” lead author Wilson described, noting that various other threats to the coral community make it more susceptible to algae crusts.

The research team believes that algae could be the cause of death in a coral reef – possibly. They intend to do more work to find out if the Caribbean reef will survive this new challenge.

Peter Edmunds further commented: “Corals and their ecosystem are as fragile as they are. They are under attack by environmental pollution and global warming. We made their lives so fragile and they’re still stuck there.

“And now this is thrown into the mix. We don’t know if it’s the straw that breaks the camel’s back, but we need to find out. ‘

Read their findings here.

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