But reefs appear to be more resistant to one potential menace – seaweed – than previously thought, according to new research by a team of marine scientists from the United States and Australia.
Their study, published in the June issue of the journal Ecology, is the first global-scale analysis of thousands of surveys of individual reefs – in all, more than 3,500 examinations of about 1,800 reefs performed between 1996 and 2006.
“Until now, many scientists have concluded that the world’s coral reefs are being overrun by seaweed,” said John Bruno, Ph.D, associate professor of marine sciences at the University of North Carolina at Chapel Hill and lead author of the study. “Our findings show that’s not the case. Seaweed have taken over and are dominating some reefs, but far fewer than assumed.”
The problem with too much seaweed, researchers say, is that it can smother the baby corals, reducing the ability of reefs to recover from other disturbances such as hurricanes and disease outbreaks. Over recent decades, there have been several dramatic examples of such shifts, with one of the most widely known and striking cases occurring in the Caribbean in the 1980s. Following a series of events that disturbed the marine environment (including two major hurricanes, a disease outbreak and the loss of a seaweed-grazing urchin), coral cover on several reefs in Jamaica plummeted from about 70 percent to less than 10 percent, and macroalgae became the dominant life form.
So Bruno, along with colleagues Hugh Sweatman, Ph.D., from the Australian Institute of Marine Science and William F. Precht, a Florida-based marine ecologist, set out to determine how bad and how widespread the problem of seaweed-dominated reefs really is.
The team came up with a “phase-shift index” to determine the state of each reef. Pristine reefs where coral was still abundant had an index number of -2 to -3, while areas where macroalgae have overwhelmed reefs’ surfaces were given an index ranking of between 3 and 5.
They found that while there were moderate local increases in seaweed cover over the study period, only four percent of reefs worldwide were dominated by macroalgae – that is, more than 50 percent of a reef’s surface was covered in seaweed. Researchers also found overall “phase shift severity” decreased in the Caribbean, did not change in the Florida Keys and the Indo-Pacific, and increased slightly on the Great Barrier Reef due to moderate coral loss.
“Overall, our results indicate that there is no general recent trend (i.e., post-1995) toward marcoralgal dominance,” the researchers wrote.
“The results from this study question many of the prevailing paradigms that coral reef ecologists have developed over the past two decades,” Precht said. “These findings will change the way we view and manage these fragile yet resilient ecosystems.”
Said Sweatman: “I hope this study leads to clearer definition of what coral-algal phase shifts are and broadens our perspective on the serious loss of corals in many parts of the world. Australian reefs have been relatively lucky so far, but there is no reason for complacency.”
The study team noted that while their analysis suggests the threat posed by macroalgae has been exaggerated, individual case studies such as the degradation of Jamaican reefs have been invaluable warnings of the consequences of subjecting reefs to multiple natural and manmade disturbances.
The paper’s co-authors include UNC College of Arts and Sciences marine sciences department researchers Elizabeth R. Selig, Ph.D., and Virginia G. W. Schutte, who is now a doctoral student at the University of Georgia.
The study was funded by the National Science Foundation, the Australian Institute of Marine Science and UNC-Chapel Hill.
Ecology Journal Web site: http://www.esajournals.org/loi/ecol
Patric Lane | Newswise Science News
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus
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...
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...
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...
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...
'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...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences