Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Tiny 'housekeeper' crabs help prevent coral death in South Pacific

Tiny crabs that live in South Pacific coral help to prevent the coral from dying by providing regular cleaning "services" that may be critical to the life of coral reefs around the world, according to scientists from the University of California, Santa Barbara.

The story of the relationship between the crab and the coral is described in the November 2006 issue of the journal Coral Reefs and is now available on-line. The coral provides a home and protection for the crabs. The crabs provide "housekeeping" duties for the coral, routinely "sweeping" out sediment that falls onto the coral, according to the study.

Thus the relationship between the corals and the trapeziid crabs is mutually beneficial, or symbiotic. The little crabs, measuring only a centimeter wide, make their home in branching corals like Acropora or Pocillopora. The research was done on coral reefs near the shore of the French Polynesian island of Moorea, in the South Pacific.

"Although we don't know much about these crabs, we do know that they are 'picky,' and are always tasting and exploring," said Hannah L. Stewart, first author of the paper and a postdoctoral researcher at UCSB's Marine Science Institute (MSI). "They use their front appendages to manipulate and shovel out the sediment."

Stewart said that this family of crabs is common around the world. "This relationship probably occurs all over the Pacific and is likely more ubiquitous than we know," she said. "Crabs are in corals everywhere. There are major ecological implications to this research; species of crabs that associate with corals may be more important than we realized."

She explained that coral reefs are one of the most productive and diverse ecosystems in the world. They support more than nine million species and provide a livelihood for millions of people around the globe.

The accumulation of sediment on coral tissue is known to reduce metabolic and tissue growth rates of coral, increasing the probability of bleaching and coral death. Many corals can remove some sediment from their surfaces but high sediment loads can be deadly. Predicted increases in sedimentation threaten coral reefs in many near shore areas around the world.

Coral reefs are threatened by a variety of environmental changes. For example, higher water temperatures and increased ultraviolet radiation, which are associated with climate change, are sources of widespread coral bleaching.

Changing land use patterns, caused by population increase on the coasts, are another threat because population growth increases the sediment load on coral. This is due to the higher amount of water run-off from development, deforestation with erosion, and expansion of agriculture.

The studies were conducted as part of The Moorea Coral Reef Long Term Ecological Research Site (MCR LTER), located in the complex of coral reefs and lagoons that surround the island of Moorea. Stewart performed the research with Sally Holbrook, professor and vice chair of UCSB's Department of Ecology, Evolution and Marine Biology; Russell Schmitt, a professor in the same department and the director of the MSI's Coastal Research Center; and Andrew Brooks, assistant research biologist at the MSI and deputy director of the MCR LTER. Experiments were carried out in the coral reef as well as in the laboratory.

The scientists showed the importance of trapeziid crabs by gently removing crabs from sections of the two species of branching corals on a coastal reef. This resulted in 50 to 80 percent of those corals dying in less than a month. By contrast, all corals with crabs survived. The nature of this common symbiotic relationship had not been recognized until this study. For surviving corals that lacked crabs, growth was slower, tissue bleaching was greater, and sediment load was higher. Laboratory experiments revealed that corals with crabs not only shed substantially more of the sediments deposited on coral surfaces, but also that crabs were most effective at removing grain sizes that were most damaging to coral tissues. These were the largest grains studied, those measuring two to four millimeters in width.

Gail Gallessich | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>