Featured Research

from universities, journals, and other organizations

'Fishy lawnmowers' help save Pacific corals

Date:
November 11, 2011
Source:
University of California - Santa Barbara
Summary:
Can fish save coral reefs from dying? Researchers have found one case where fish have helped coral reefs to recover from cyclones and predators.

Crown-of-thorns sea star feeding on a coral.
Credit: Gerick Bergsma

Can fish save coral reefs from dying? UC Santa Barbara researchers have found one case where fish have helped coral reefs to recover from cyclones and predators.

Related Articles


Coral reefs worldwide are increasingly disturbed by environmental events that are causing their decline, yet some coral reefs recover. UCSB researchers have discovered that the health of coral reefs in the South Pacific island of Moorea, in French Polynesia, may be due to protection by parrotfish and surgeonfish that eat algae, along with the protection of reefs that shelter juvenile fish.

The findings are published in a recent issue of the journal PLoS ONE. The UCSB research team is part of the Moorea Coral Reef Long-Term Ecological Research (MCR LTER) project, funded by the National Science Foundation.

In many cases, especially in the case of severely damaged reefs in the Caribbean, coral reefs that suffer large losses of live coral often become overgrown with algae and never return to a state where the reefs are again largely covered by live coral. In contrast, the reefs surrounding Moorea experienced large losses of live coral in the past -- most recently in the early 1980's -- and have returned each time to a system dominated by healthy, live corals.

"We wanted to know why Moorea's reefs seem to act differently than other reefs," said Tom Adam, first author, research associate with MCR LTER, and postdoctoral fellow at UCSB's Marine Science Institute. "Specifically, we wanted to know what ecological factors might be responsible for the dramatic patterns of recovery observed in Moorea."

The research team was surprised by its findings. The biomass of herbivores on the reef -- fish and other animals that eat plants like algae -- increased dramatically following the loss of live coral. "What was surprising to us was that the numbers of these species also increased dramatically," said Andrew Brooks, co-author, deputy program director of MCR LTER, and associate project scientist with MSI. "We were not simply seeing a case of bigger, fatter fishes -- we were seeing many more parrotfishes and surgeonfishes, all of whom happened to be bigger and fatter. We wanted to know where these new fishes were coming from."

The researchers also found that not all of the coral reefs around Moorea were affected equally by an outbreak of predatory crown-of-thorns sea stars or by cyclones. The crown-of-thorns sea stars did eat virtually all of the live coral on the barrier reef -- the reef that separates the shallow lagoons from the deeper ocean. However, neither the sea stars nor the cyclones had much impact on the corals growing on the fringing reef -- the reef that grows against the island.

"We discovered that these fringing reefs act as a nursery ground for baby fishes, most notably herbivorous fishes," said Brooks. "With more food available in the form of algae, the survivorship of these baby parrotfishes and surgeonfishes increased, providing more individuals to help control the algae on the fore reef. In effect, the large numbers of parrotfishes and surgeonfishes are acting like thousands of fishy lawnmowers, keeping the algae cropped down to levels low enough that there is still space for new baby corals to settle onto the reef and begin to grow."

A major reason the reefs in the Caribbean do not recover after serious disturbances is because these reefs lack healthy populations of parrotfishes and surgeonfishes, due to the effects of overfishing, explained Adam. "Without these species to help crop the algae down, these reefs quickly become overgrown with algae, a situation that makes it very hard for corals to re-establish themselves," he said.

Managers have tried to reverse the trend of overfishing through the creation of Marine Protected Areas (MPAs), where fishing is severely restricted or prohibited. "Our results suggest that this strategy may not be enough to reverse the trend of coral reefs becoming algal reefs," said Brooks. "Our new and very novel results suggest that it also is vital to protect the fringing reefs that serve as nursery grounds. Without these nursery grounds, populations of parrotfishes and surgeonfishes can't respond to increasing amounts of algae on the reefs by outputting more baby herbivores."

In short, the research team found that by using MPAs, managers can help protect adult fish, producing bigger, fatter fish. "But if you don't protect the nursery habitat -- the babies produced by these bigger fish, or by fish in other, nearby areas -- you can't increase the overall numbers of the important algae-eating fish on the reef," said Brooks.

According to the scientists, it appears that Moorea's reefs may recover. "One final bit of good news is that we are seeing tens of thousands of baby corals, some less than a half-inch in diameter, on the fore reefs surrounding Moorea," said Brooks.

MCR researchers will follow the coral reef recovery process over the next decade or more, in search of additional information that can aid managers of the world's coral reefs.

Additional co-authors are Russell J. Schmitt and Sally J. Holbrook of UCSB's Marine Science Institute and the Department of Ecology, Evolution, and Marine Biology; Peter J. Edmunds and Robert C. Carpenter of California State University, Northridge; and Giacomo Bernardi, of UC Santa Cruz.


Story Source:

The above story is based on materials provided by University of California - Santa Barbara. Note: Materials may be edited for content and length.


Journal Reference:

  1. Thomas C. Adam, Russell J. Schmitt, Sally J. Holbrook, Andrew J. Brooks, Peter J. Edmunds, Robert C. Carpenter, Giacomo Bernardi. Herbivory, Connectivity, and Ecosystem Resilience: Response of a Coral Reef to a Large-Scale Perturbation. PLoS ONE, 2011; 6 (8): e23717 DOI: 10.1371/journal.pone.0023717

Cite This Page:

University of California - Santa Barbara. "'Fishy lawnmowers' help save Pacific corals." ScienceDaily. ScienceDaily, 11 November 2011. <www.sciencedaily.com/releases/2011/11/111110130100.htm>.
University of California - Santa Barbara. (2011, November 11). 'Fishy lawnmowers' help save Pacific corals. ScienceDaily. Retrieved November 21, 2014 from www.sciencedaily.com/releases/2011/11/111110130100.htm
University of California - Santa Barbara. "'Fishy lawnmowers' help save Pacific corals." ScienceDaily. www.sciencedaily.com/releases/2011/11/111110130100.htm (accessed November 21, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Friday, November 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
Powered by NewsLook.com
5 Hot Months, 1 Warm Year And All The Arguments To Follow

5 Hot Months, 1 Warm Year And All The Arguments To Follow

Newsy (Nov. 21, 2014) The NOAA released statistics Thursday showing October was the fifth month this year with record temps and 2014 will likely be the hottest on record. Video provided by Newsy
Powered by NewsLook.com
Nations Pledge $9.3 Bn for Green Climate Fund

Nations Pledge $9.3 Bn for Green Climate Fund

AFP (Nov. 20, 2014) Nations meeting in Berlin pledge $9.3 billion (7.4 bn euros) for a climate fund to help poor countries cut emissions and prepare for global warming, just shy of a $10bn target. Duration: 00:46 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins