Nav: Home

Coral reefs grow faster and healthier when parrotfish are abundant

January 23, 2017

Caribbean coral reefs have become biologically and economically degraded habitats. The relative weight of the big factors in this ecological catastrophe--pollution, overfishing, warming and ocean acidification--is hotly debated by marine biologists. A new study compiling 3,000 years of change in reefs in the western Caribbean by Smithsonian scientists and colleagues reveals compelling evidence that parrotfish, which eat the algae that can smother corals, are vital to coral-reef health.

The team extracted cores from reefs in Panama's Bocas Del Toro archipelago and identified thousands of exquisitely preserved parrotfish teeth in slices representing different time periods. Using advanced uranium-thorium to date these segments, researchers show that when parrotfishes were more common, the reef grew faster. The findings were published in Nature Communications Jan. 23.

"This fossil record of reefs provides evidence that parrotfishes were actually causing faster reef growth, rather than the other way round, or the two simply being driven by a third factor," said Aaron O'Dea, a co-author of the study and scientist at the Smithsonian Tropical Research Institute in Panama. "Because of this intimate causal relationship between parrotfishes and healthier reefs, we support the call that parrotfish conservation be made a priority for the recovery and persistence of Caribbean coral reefs."

The team collected six 33-foot-long cores on three reefs using a scuba-operated coring system and dated the fossil corals along their length using uranium-thorium isotopes at the University of Queensland, an approach that gives an incredible resolution of just a few years to each coral piece. Samples ranged from 997 B.C. to the 1980s, and represent life on these reefs before disease outbreaks killed large swathes of the reef-building staghorn coral and wiped out the long-spined sea urchin Diadema, which also eats algae.

A recent unrelated study by Smithsonian scientists Caitlin Kuempel and Andrew Altieri found that in the absence of Diadema, algae on the reefs in Bocas are held in check by smaller sea urchins. This new study, however, finds that the role of these smaller urchins in maintaining reef health in the past was minimal.

"Even though we are working on the same reefs I think we are comparing two different systems," O'Dea said. "Small urchins are clearly important grazers under current conditions but the reefs of today are quite unlike those that existed for the 8,000 years before human impact. The past and the present are worlds apart and function differently."

A team of scientists and students at Scripps Institution of Oceanography at the University of California San Diego picked hundreds of thousands of fish teeth, coral pieces and urchin spines to build a picture of natural and human-induced change on the Caribbean reefs. Scripps researcher and lead author Katie Cramer and colleagues used the empirical dynamic modeling approach to assess cause-and-effect relationships amongst community members.

"These findings reveal that parrotfish indeed have a positive and critical role in coral health, a hotly debated issue in coral reef research that cannot be resolved with studies of modern reefs which have already been greatly altered by human activities," said Cramer, who conducted the Panama portion of the research while a Smithsonian MarineGEO post-doctoral fellow. "Using the fossil record to analyze the natural state of reefs before human disturbance, we have conclusively shown that if we want to protect corals we have to protect parrotfish from overfishing."
-end-
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a part of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems. STRI website. Promotional video.

Scarus vetula image y LASZLO ILYES (laszlo-photo) from Cleveland, Ohio, USA (Flickr) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Smithsonian Tropical Research Institute

Related Algae Articles:

Algae team rosters could help ID 'super corals'
U.S. and Australian researchers have found a potential tool for identifying stress-tolerant ''super corals.'' In experiments that simulated climate change stress, researchers found corals that best survived had symbiotic algae communities with similar features.
Algae shown to improve gastrointestinal health
A green, single-celled organism called Chlamydomonas reinhardtii has served as a model species for topics spanning algae-based biofuels to plant evolution.
How do corals make the most of their symbiotic algae?
Corals depend on their symbiotic relationships with the algae that they host.
Algae and bacteria team up to increase hydrogen production
A University of Cordoba research group combined algae and bacteria in order to produce biohydrogen, fuel of the future
Algae as a resource: Chemical tricks from the sea
The chemical process by which bacteria break down algae into an energy source for the marine food chain, has been unknown - until now.
Left out to dry: A more efficient way to harvest algae biomass
Researchers at the University of Tsukuba develop a new system for evaporating the water from algae biomass with reusable nanoporous graphene, which can lead to cheaper, more environmentally friendly biofuels and fine chemicals.
Algae could prevent limb amputation
A new algae-based treatment could reduce the need for amputation in people with critical limb ischemia, according to new research funded by the British Heart Foundation, published today in the journal npj Regenerative Medicine.
Turning algae into fuel
A team of University of Utah chemical engineers have developed a new kind of jet mixer for creating biomass from algae that extracts the lipids from the watery plants with much less energy than the older extraction method.
The algae's third eye
Scientists at the Universities of Würzburg and Bielefeld in Germany have discovered an unusual new light sensor in green algae.
How some algae may survive climate change
Green algae that evolved to tolerate hostile and fluctuating conditions in salt marshes and inland salt flats are expected to survive climate change, thanks to hardy genes they stole from bacteria, according to a Rutgers-led study.
More Algae News and Algae Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Clint Smith
The killing of George Floyd by a police officer has sparked massive protests nationwide. This hour, writer and scholar Clint Smith reflects on this moment, through conversation, letters, and poetry.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.