Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fish Diversity May Be Key to Recovery of Coral Reefs

09.10.2008
A report scheduled to be published online this week in early edition the journal Proceedings of the National Academy of Sciences suggests that maintaining the proper balance of herbivorous fishes may be critical to restoring coral reefs, which are declining dramatically worldwide.

For endangered coral reefs, not all plant-eating fish are created equal.

A report scheduled to be published online this week in the early edition of journal Proceedings of the National Academy of Sciences suggests that maintaining the proper balance of herbivorous fishes may be critical to restoring coral reefs, which are declining dramatically worldwide. The conclusion results from a long-term study that found significant recovery in sections of coral reefs on which fish of two complementary species were caged.

Coral reefs depend on fish to eat the seaweeds with which the corals compete, and without such cleaning, the reefs decline as corals are replaced by seaweeds. Different fish consume different seaweeds because of the differing chemical and physical properties of the plants.

“Of the many different fish that are part of coral ecosystems, there may be a small number of species that are really critical for keeping big seaweeds from over-growing and killing corals,” explained Mark Hay, the Harry and Linda Teasley Professor of Biology at the Georgia Institute of Technology. “Our study shows that in addition to having enough herbivores, coral ecosystems also need the right mix of species to overcome the different defensive tactics of the seaweeds.”

By knowing which fish are most critical to maintaining coral health, resource managers could focus on protecting and enhancing the highest-impact species. In situations where local peoples depend on fishing, they might better sustain the reefs on which they depend by harvesting only less critical species.

“This could offer one more approach to resource managers,” Hay added. “If ecosystems were managed for critical mixes of herbivorous species, we might see more rapid recovery of the reefs.”

Believed to be the first study to demonstrate the importance of herbivore diversity in enhancing the growth of coral reefs, the research was conducted at the National Undersea Research Center in Key Largo, Florida. It was supported by the National Oceanic and Atmospheric Administration, the National Science Foundation and the Teasley Endowment at Georgia Tech.

Working 60 feet below the surface near the underwater laboratory Aquarius, Hay and co-author Deron E. Burkpile – who is now at Florida International University in North Miami – constructed 32 cages on a coral reef. Each cage was about two meters square and one meter tall and was sealed so that larger fish could neither enter nor leave.

The number and type of fish placed into each four-square-meter cage varied. Some cages had two fish that were able to eat hard, calcified plants; some had two fish able to eat soft, but chemically-defended plants; some had one of both types, and some had no fish at all. The cages were observed for a period of ten months starting in November 2003, and the change in coral cover and seaweed growth was measured.

“For the cages in which we mixed the two species of herbivores, the fish were able to remove much more of the upright seaweeds, and the corals in those areas increased in cover by more than 20 percent during ten months,” Hay said. “That is a dramatic rate of increase for a Caribbean reef.”

Though the percentage growth was impressive, the actual growth in size of each coral was small, Hay noted. Prior to the experiment, the coral reef areas studied had just four to five percent coverage of live coral. After ten months, the corals caged with the two species showed six to seven percent coverage. Corals caged with just one type of fish or no fish lost as much as 30 percent of their cover during the time period.

Hay and Burkepile attempted to repeat their experiment with a different species of fish, but the underwater cages were wiped away by Hurricane Dennis in July 2005 after only seven months of study.

The researchers studied the effects of the redband parrotfish (Sparisoma aurofrenatum) and the ocean surgeonfish (Acanthurus bahianus) in the first experiment, and the redband parrotfish and princess parrotfish (Scarus taeniopterus) in the second. The two fish per cage was at the “high end” of fish density found on present-day Caribbean reefs, but historic densities might have been much higher before extensive fishing of the Caribbean, Hay said.

Just two decades ago, coral coverage in the Caribbean was commonly 40 to 60 percent. Scientists blame many factors – disease, overfishing, pollution, excessive nutrients and global climate change – for the rapid decline, which has also been seen to differing degrees among coral reefs worldwide.

“Some people would argue that coral reefs really don’t exist as functional ecosystems in the Caribbean anymore,” Hay said. “The best reefs we have today are poor cousins to what was only average 20 years ago.”

For the future, Hay would like to expand the experiments to study the effects of additional species, and repeat the studies in different areas, such as the Fiji Islands, where residents are concerned about sustainability of the coral reefs.

Though dependent on local fish for their protein, he said the Fiji Islanders may be able to change their fishing habits if researchers can determine which fish must be protected to help the reefs.

“The data we are seeing in Fiji suggests that diversity may be even more important there than it was in the Caribbean,” he said. “There are a lot of different species doing a lot of very different things. These consumers are very important, and in areas where they are over-fished, the reefs are crashing.”

The study provides more proof of how important biodiversity can be to maintaining healthy ecosystems.

“Species diversity is critically important, but we are losing critical components of the Earth’s ecosystem at an alarming rate,” Hay said. “There has been little work on the role of diversity among consumers and the effect that has on communities. This study will help add to our knowledge in this critical area.”

Technical Contact:
Mark Hay (404-894-8429);
E-mail: mark.hay@biology.gatech.edu

John Toon | Newswise Science News
Further information:
http://www.gatech.edu

Further reports about: Fish Diversity coral ecosystems coral reefs herbivorous fishes

More articles from Ecology, The Environment and Conservation:

nachricht How does the loss of species alter ecosystems?
18.05.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Excess diesel emissions bring global health & environmental impacts
16.05.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>