Featured Research

from universities, journals, and other organizations

Underwater elephants: Mixed impacts of the world's largest -- and threatened -- parrotfish

Date:
July 29, 2014
Source:
University of California - Santa Barbara
Summary:
Scientists recently got back to basics in order to discover the positive and negative effects that bumphead parrotfish exert on coral reef ecosystems. Using direct observation, animal tracking and computer simulation, the researchers sought to understand whether the world's largest parrotfish is necessary for positively shaping the structure and functioning of ecosystems. The answer is yes and no.

The world's largest parrotfish, the bumphead (Bolbometopon muricatum) is often more than 4 feet long and can weigh in at more than 100 pounds.
Credit: Klaus Stiefel

In the high-tech world of science, researchers sometimes need to get back to basics. UC Santa Barbara's Douglas McCauley did just that to study the impacts of the bumphead parrotfish (Bolbometopon muricatum) on coral reef ecosystems at two remote locations in the central Pacific Ocean.

Using direct observation, animal tracking and computer simulation, McCauley, an assistant professor in the Department of Ecology, Evolution and Marine Biology, and his colleagues sought to understand whether the world's largest parrotfish is necessary for positively shaping the structure and functioning of ecosystems. The answer, published in a recent issue of the journal Conservation Biology, is yes and no.

"We actually swam alongside bumphead parrotfish for close to six hours at a time, taking detailed data on what they ate and where they went," McCauley explained. "It was one of the more exhausting but wonderful experiences I've had as a field scientist."

Often more than 4 feet long and weighing in at more than 100 pounds, bumpheads are major coral predators; one fish can consume just over 2 tons of living coral in a year. They are also a threatened species in serious decline across the Pacific. Hunted throughout the region -- often at night in sea caves where they sleep -- they have cultural significance (i.e., they're coveted for feasting ceremonies) among many Pacific islanders.

"These large parrotfish crunch off entire pieces of reef and audibly grind them up into sand in their pharyngeal mill -- specialized teeth in the back of their throat," McCauley explained. "You know bumpheads are near when you begin noticing branches lopped off stony corals and golflike divot scars marking the reef."

McCauley's research demonstrates that bumpheads exert a complex mix of positive and negative effects on reefs. On the plus side, bumpheads reduce the abundance of fast-growing algae that compete with corals for light and space. Their feeding helps corals reproduce by opening up space on reefs. In addition, when feeding, they can disperse small coral fragments around reefs that can later grow into adult coral colonies, just as birds disperse plant seeds.

Conversely, bumpheads eat coral and this predation reduces its abundance and diversity. "They can completely consume small coral colonies, and the feeding scars they leave on large corals can be a source of physiological stress," McCauley said. "The coral skeleton that they grind up and excrete falls also back atop corals as biosediment and this can amount to 50 tons of sediment a year from a school of bumpheads. Sedimentation in other contexts is known to contribute to the smothering of corals."

The team's results highlight the diverse effects that species can have on ecosystems, adding a deeper perspective on understanding the ecological role of endangered species. McCauley noted that conservation often tacitly advances the expectation that endangered species must be good for the environment.

"This viewpoint is ecologically misleading," he added. "Most species do things to ecosystems that we would construe as both positive and negative. Endangered species are no different from their more abundant counterparts." McCauley is quick to add that these findings by no means suggest that declining species like bumphead parrotfish are undeserving of protection.

"We can, in fact, strengthen the integrity of the field of conservation biology by being rigidly objective about the observations we make in nature -- even if this means reporting occasionally that rare species can damage ecosystems," he added. "If anything, better understanding the full complement of ways that at-risk species use and affect their environment empowers us to more effectively protect them.

"The case of the bumphead parrotfish is analogous in interesting ways to the African elephant," McCauley continued. "African elephants are a vulnerable and imperiled species that can be agents of deforestation and reduce regional biodiversity. These effects are particularly strong in areas where elephants have been artificially confined in high-density aggregations. Science that describes how elephants reshape ecosystems can help managers more effectively approach the complicated task of reversing severe global elephant declines while protecting local ecosystems. Bumphead parrotfish are to coral reefs what elephants are to African savannas."


Story Source:

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


Journal Reference:

  1. Douglas J. Mccauley, Hillary S. Young, Roger Guevara, Gareth J. Williams, Eleanor A. Power, Robert B. Dunbar, Douglas W. Bird, William H. Durham, Fiorenza Micheli. Positive and Negative Effects of a Threatened Parrotfish on Reef Ecosystems. Conservation Biology, 2014; DOI: 10.1111/cobi.12314

Cite This Page:

University of California - Santa Barbara. "Underwater elephants: Mixed impacts of the world's largest -- and threatened -- parrotfish." ScienceDaily. ScienceDaily, 29 July 2014. <www.sciencedaily.com/releases/2014/07/140729152919.htm>.
University of California - Santa Barbara. (2014, July 29). Underwater elephants: Mixed impacts of the world's largest -- and threatened -- parrotfish. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/2014/07/140729152919.htm
University of California - Santa Barbara. "Underwater elephants: Mixed impacts of the world's largest -- and threatened -- parrotfish." ScienceDaily. www.sciencedaily.com/releases/2014/07/140729152919.htm (accessed September 20, 2014).

Share This



More Earth & Climate News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Climate Change Rally Held in India Ahead of UN Summit

Climate Change Rally Held in India Ahead of UN Summit

AFP (Sep. 20, 2014) Some 125 world leaders are expected to commit to action on climate change at a UN summit Tuesday called to inject momentum in struggling efforts to tackle global warming. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
New Music With Recycled Instruments at Colombia Fest

New Music With Recycled Instruments at Colombia Fest

AFP (Sep. 19, 2014) Jars, bottles, caps and even a pizza box, recovered from the trash, were the elements used by four musical groups at the "RSFEST2014 Sonorities Recycling Festival", in Colombian city of Cali. Duration: 00:49 Video provided by AFP
Powered by NewsLook.com
Raw: Wildfires in CA Burn Forest Asunder

Raw: Wildfires in CA Burn Forest Asunder

AP (Sep. 18, 2014) An out-of-control Northern California wildfire has nearly 2,800 people from their homes as it continues to grow, authorities said Thursday. Authorities said a man has been arrested on suspicion of arson for starting the fire on Saturday. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
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:
from the past week

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