Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Coral death results from bacteria fed by algae

14.06.2006
Bacteria and algae are combining to kill coral –– and human activities are compounding the problem.

Scientists have discovered an indirect microbial mechanism whereby bacteria kill coral with the help of algae. Human activities are contributing to the growth of algae on coral reefs, setting the stage for the long-term continued decline of coral.


Coral (Acropora) from the Line Islands covered by bubble algae (Dictyosphaeria) Credit: Jennifer Smith

Reporting in the June 5 on-line version of the scientific journal Ecology Letters, scientists described laboratory experiments on coral and algae.

First author Jennifer Smith, a postdoctoral fellow at the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California, Santa Barbara, explained that the team of scientists, as part of a research expedition to the Line Islands, put algae and coral in chambers of seawater with filters between them. All of the corals with neighboring algae died, while coral without neighboring algae did not die. However, with the addition of an antibiotic, coral death even in the presence of algae was prevented, showing that bacteria fed by the algae are the agents of coral death. "We are the first to link these processes together," said Smith.

"This study tightly links the fields of microbiology with coral reef ecology to help guide reef conservation efforts," said senior author Forest Rohwer, assistant professor of microbiology at San Diego State University.

"Our study shows that bacteria are the front line that kill corals," Smith explained. "Algae release sugar, fueling bacterial growth on the corals. These bacteria suffocate the coral by cutting off the supply of oxygen. Once the corals die, this frees more space for more algae to grow. We think this process sets up a positive feedback loop that accelerates the rate of decline in already damaged reef ecosystems."

The report describes the other conditions that put coral reefs at risk. Overfishing reduces the number of fish that graze on algae, thus increasing the amount of algae on the reef. Nutrients from sewage and agricultural run-off fertilize the algae. Warmer water and more intense hurricanes resulting from global climate change are also blamed for coral death.

"Anyone who has been to the tropics and has had the experience of diving on a coral reef will not deny the spectacular beauty of these systems," said Smith. "They support numerous species of animals and plants and many species that remain undiscovered to science. These ecosystems are particularly important to humans because they support abundant fisheries –– commercial, subsistence, and recreational –– and they generate a large tourism industry."

She added that the reefs themselves protect coastal areas from erosion. From a biological perspective, coral reefs are more productive and support more species than any other marine ecosystem on the planet. While more reefs die every year due to an onslaught of human impacts, many scientists are hopeful that it is not too late to stop the destruction. She mentioned that there is a lot of excitement within the scientific community to begin working towards reef restoration and recovery in areas that have been heavily degraded.

Co-author Enric Sala said, "On certain coral heads I witnessed about half of the coral alive and half dead and covered by fleshy algae. In between the living half and the algae there was a 'band of sickness and death.' I thought, as many others did, that the corals were dying because of a disease, something unknown. But what we found is that the algae are enhancing the coral disease."

Sala is leader of the Line Islands Expedition (http://sio.ucsd.edu/lineislands) and is an associate professor at UC San Diego's Scripps Institution of Oceanography. He is also deputy director of the Center for Marine Biodiversity and Conservation there. Sala explained that for hundreds of thousands of years there have been natural disturbances, such as hurricanes, and coral reefs have always recovered. But now, because of threats such as global warming and pollution, the reefs are losing their ability to recover because humans are adding so many more disturbances to the ocean ecosystem. "In the same way that we take care of our bodies and treat illnesses, we cannot pretend to have healthy coral reefs by addressing individual threats," he said. "The human shadow is longer than we thought and there are invisible, lethal threats that we induce."

Co-author Stuart Sandin, a postdoctoral researcher in Sala's group, said, "This research highlights a little-appreciated, yet critically important interaction between algae and corals, key players on the coral reef. As algae become more abundant on reefs, through the effects of overfishing and pollution, there are indirect effects that accelerate further loss of corals. On the flip side, however, if algae are controlled by abundant fish populations, then the reef gains a capacity for recovery from other forms of disturbance, like hurricanes and sea warming."

Gail Gallessich | EurekAlert!
Further information:
http://www.ia.ucsb.edu

More articles from Ecology, The Environment and Conservation:

nachricht Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung

nachricht Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

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: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>