Navigation Links
Video study shows which fish clean up coral reefs, showing importance of biodiversity

Using underwater video cameras to record fish feeding on South Pacific coral reefs, scientists have found that herbivorous fish can be picky eaters a trait that could spell trouble for endangered reef systems.

In a study done at the Fiji Islands, the researchers learned that just four species of herbivorous fish were primarily responsible for removing common and potentially harmful seaweeds on reefs and that each type of seaweed is eaten by a different fish species. The research demonstrates that particular species, and certain mixes of species, are potentially critical to the health of reef systems.

Related research also showed that even small marine protected areas locations where fishing is forbidden can encourage reef recovery.

"Of the nearly 30 species of bigger herbivores on the reef, there were four that were doing almost all of the feeding on the seven species of seaweeds that we studied," said Mark Hay, a professor in the School of Biology at the Georgia Institute of Technology. "We did not see much overlap in the types of seaweed that each herbivore ate. Therefore, if any one of these four species was removed, that would potentially allow some macroalgae to proliferate."

The research has been published online ahead of print by the journal Ecology and will be included in a future print edition. The study was supported by the National Science Foundation (NSF), the National Institutes of Health (NIH) and the Teasley Endowment to Georgia Tech.

Macroalgae known as seaweeds pose a major threat to endangered coral reefs. Some seaweeds emit chemicals that are toxic to corals, while others smother or abrade corals. If seaweed growth is not kept in check by herbivorous fish, the reefs can experience rapid decline. Overfishing of coral reef ecosystems has decimated fish populations in many areas, contributing to overgrowth by seaweed, along with the loss of corals and their ability to recover from disturbance.

To determine which fish were most important information potentially useful for protecting them Hay and Georgia Tech graduate student Douglas Rasher moved samples of seven species of seaweed into healthy reef systems that had large populations of fish.

They set up three video cameras to watch the reef areas, then left the area to allow the fish to feed. They repeated the experiment over a period of five days in three different marine protected areas located off the Fiji Islands. In all, Rasher watched more than 45 hours of video to carefully record which species of fish ate which species of seaweed.

"The patterns were remarkably consistent among the reefs in terms of which fish were responsible for removing the seaweed," said Rasher. "Because different seaweeds use different defense strategies to deter herbivores from eating them, a particular mix of fish each adapted to a particular type of seaweed is needed to keep seaweeds off the reef."

Among the most important were two species of unicornfish, which removed numerous types of brown algae. A species of parrotfish consumed red seaweeds, while a rabbitfish ate a type of green seaweed that is particularly toxic to coral. Those four fish species were responsible for 97 percent of the bites taken from all the seaweeds.

"It's not enough to have herbivorous fish on the reef," said Hay, who holds the Harry and Linda Teasley Chair in Environmental Biology at Georgia Tech. "We need to have the right mix of herbivores."

While just four fish species consumed the large seaweeds, Rasher observed a different set of species involved in what he termed "maintenance" the removal of small algal growths before they have a chance to grow.

"Through our videos, we were able to observe both groups in action," he said. "There was not only little overlap in which fishes ate the large seaweeds, but there was also little overlap between fishes that comprised the two groups."

To help determine why certain fish ate certain seaweed, the researchers played a trick on the unicornfish. They removed chemicals from each seaweed species that the unicornfish avoided and coated them individually on a species of seaweed that the unicornfish were accustomed to eating. That caused the fish to stop eating the chemical-laced seaweed, suggesting that chemical defenses kept them from consuming some seaweeds.

The researchers also compared the quality of coral reefs in marine protected areas to those in areas where fishing has been allowed. There are an estimated 300 marine protected areas in the Fiji Islands, most governed by local villages that have considerable autonomy over reef management.

Surveying these larger areas, the researchers found strong negative associations between the abundance or diversity of seaweed on the reef and diversity of herbivorous fishes at the sites they studied.

They found that strict rules against fishing in certain protected areas had led to a regeneration of corals, and that the contrast to fished areas nearby some just 500 meters apart was dramatic. The protected reefs supported as much as 11 times more live coral cover, 17 times more herbivorous fish biomass and three times more species diversity among herbivorous fishes as the unprotected areas.

"What we noted in Fiji is that where reefs are fished, they look like the devastated reefs in the Caribbean," said Hay. "There's a lot of seaweed, there's almost no coral and there aren't many fish in these flattened areas. But right next to them, where fishing hasn't been allowed for the past eight or ten years, the reefs have recovered and have high coral cover, almost no seaweed and lots of fish."

Although both fished and protected areas had only seven percent coral cover ten years ago, today the protected areas have recovered.

"This really demonstrates the value of reef protection, even on small scales," Rasher said. "There is a lot of debate about whether or not small reserves work. This seems to be a nice example of an instance where they do."

Ultimately, the researchers hope to provide information to village leaders that could help them manage their reefs to ensure long-term health while helping feed the local human population.

"Not fishing is really not an option for people in these communities," Rasher said. "Giving the village leadership an idea of which species are essential to reef health and what they can do to manage fisheries effectively is something we can do to help them maintain a sustainable reef food system."


Contact: John Toon
Georgia Institute of Technology

Related biology news :

1. Get off my lawn: Song sparrows escalate territorial threats - with video
2. New American Chemical Society video highlights 5 of chocolates sweet benefits
3. Graduate student video on sequestration wins prize
4. 60th anniversary of NSF Grad Research Fellowship Program; UM fellow Staatermans video recognized
5. Medbox, Inc. Releases Demo Video and Collateral Media Concerning How Their Systems Will Be Used in Massachusetts Medical Marijuana Dispensaries
6. Feature package of Congo Basin forest photos, stories & videos
7. High-speed video and artificial flowers shed light on mysteries of hummingbird-pollinated flowers
8. Video-article shows how to purify magnetic bacteria
9. Can videogaming benefit young people with autism spectrum disorder?
10. Video-gaming fish play out the advantages of groups
11. Chemistry on Mars video with Curiosity Rover from the American Chemical Society
Post Your Comments:
Related Image:
Video study shows which fish clean up coral reefs, showing importance of biodiversity
(Date:11/12/2015)... 11, 2015   Growing need for low-cost, ... has been paving the way for use of ... discrete analytes in clinical, agricultural, environmental, food and ... used in medical applications, however, their adoption is ... to continuous emphasis on improving product quality and ...
(Date:11/10/2015)... Nov. 10, 2015 About ... that helps to identify and verify the identity ... considered as the secure and accurate method of ... a particular individual because each individual,s signature is ... especially when dynamic signature of an individual is ...
(Date:11/4/2015)... ALBANY, New York , November 4, 2015 /PRNewswire/ ... According to a new market report published by Transparency ... Size, Share, Growth, Trends and Forecast 2015 - 2022", ... value of US$ 30.3 bn by 2022. The market ... during the forecast period from 2015 to 2022. Rising ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... November 25, 2015 Studies reveal ... human plaque and pave the way for more effective treatment ... cats     --> ... diagnosed health problems in cats, yet relatively little was understood ... collaborative studies have been conducted by researchers from the WALTHAM ...
(Date:11/25/2015)... 25, 2015 Orexigen® Therapeutics, Inc. (Nasdaq: ... a fireside chat discussion at the Piper Jaffray 27th ... . The discussion is scheduled for Wednesday, December 2, ... .  A replay will be available for 14 days ... , Julie NormartVP, Corporate Communications and Business Development , ...
(Date:11/24/2015)... 2015 Cepheid (NASDAQ: CPHD ) today ... following conference, and invited investors to participate via webcast. ...      Tuesday, December 1, 2015 at 11.00 a.m. Eastern Time ...      Tuesday, December 1, 2015 at 11.00 a.m. Eastern Time ... New York, NY      Tuesday, December 1, 2015 ...
(Date:11/24/2015)... 24, 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS) (TSX: ... behalf of the Toronto Stock Exchange, confirms that as ... no corporate developments that would cause the recent movements ... --> About Aeterna Zentaris Inc. ... --> Aeterna Zentaris is a specialty biopharmaceutical company ...
Breaking Biology Technology: