Nav: Home

Large-scale study reveals new insights into coral and symbiotic algae partnership

November 04, 2016

A large-scale study of Caribbean coral has yielded discoveries on the pairing process between an endangered coral and the microscopic symbiotic algae they rely on for survival.

In the largest study of its kind to date, a team led by the University of Exeter analysed 632 coral samples from 33 sites across the Caribbean and revealed that environmental factors drive this relationship, rather than host-symbiont genetics.

The research, published in the journal Proceedings of the Royal Society B, could have implications for work to protect and promote recovery in reefs. It examined the coral Orbicella annularis, a reef-building coral found throughout the Caribbean. The single celled alga - Symbiodinium - colonises tropical corals worldwide and provides nutrients that are key to the coral's survival, through photosynthesis, which the coral on its own cannot perform. Unfortunately, the important relationship between Symbiodinium and coral can become disrupted by warming sea temperatures. Coral bleaching is triggered by a sustained increase in water temperature, which causes the algae to separate from their host coral and can often lead to the coral dying. In the Caribbean, 14 per cent of reefs have suffered severe coral death, with a further 46 per cent of reefs considered threatened. With coral playing the key role in many tropical marine ecosystems, the knock on effects of such damage on broader ecosystem health and marine biodiversity can be catastrophic.

Dr Jamie Stevens, of the University of Exeter, who oversaw the research, said: "The relationship between coral and symbiotic algae is crucial to the survival of coral, and the more we can understand about how and why it occurs, the better our chances of protecting and reinstating the reefs that are fundamental to a healthy marine ecosystem. This is the first time anyone has had enough data to explore this in detail. Unlike many other symbiotic relationships, we have found that this one is not predetermined by particular genotypes pairing up. Instead, it is dictated by geographical and environmental factors, meaning that the symbiodinium must already be present on the reef before it pairs with its host coral and thrives, to the benefit of both."

There are hundreds of different species of Symbiodinium, and while many corals pair with one specific type, Orbicella annularis is interesting because it can team up with different types, and sometimes contains mixes of several species. Different types of Symbiodinium have different qualities, and this can determine how the coral behaves.

Dr Emma Kennedy, lead author of the paper, explained: "Genetically identical corals containing different algae mixes may grow differently or respond differently to stress, depending on the hardiness of the algae, how efficiently it photosynthesises, or how many nutrients it supplies to the host. Who you're paired up with might well be the difference between life and death for a coral experiencing a mass bleaching event."

The team found big regional differences in the relationships between the boulder star coral and its symbiotic algae - for example in the Bahamas the coral was almost always paired exclusively with a hardy and common Symbiodinium type, 'B1', while corals from the Lesser Antilles - Barbados, Tobago and Curacao - paired with other types. Corals from the Caymans were found to contain the most diverse pairings, with nearly all containing different Symbiodinium types.
The research was carried out in collaboration with the University of Queensland. It was funded by the Natural Environment Research Council (NERC), UK, and the European Union. It used DNA samples from both coral and algae across 33 sites in the Caribbean and The Bahamas, hand collected on SCUBA.

The paper, 'Symbiodinium biogeography tracks environmental and geographic patterns rather than host genetics in a key Caribbean reef-builder, Orbicella annularis', is published in the journal Proceedings of the Royal Society B, by Emma Kennedy, Linda Tonk, Nicola Foster, Iliana Chollett, Juan Ortiz, Sophie Dove, Ove Hoegh-Guldberg, Peter Mumby and Jamie Stevens.

University of Exeter

Related Algae Articles:

Scientists clarify light harvesting in green algae
A new study by Chinese and Japanese researchers has now characterized the light-harvesting system of Chlamydomonas reinhardtii, a common unicellular green alga.
Algae and bacteria team up to increase hydrogen production
A University of Cordoba research group combined algae and bacteria in order to produce biohydrogen, fuel of the future
Algae as a resource: Chemical tricks from the sea
The chemical process by which bacteria break down algae into an energy source for the marine food chain, has been unknown - until now.
Left out to dry: A more efficient way to harvest algae biomass
Researchers at the University of Tsukuba develop a new system for evaporating the water from algae biomass with reusable nanoporous graphene, which can lead to cheaper, more environmentally friendly biofuels and fine chemicals.
Algae could prevent limb amputation
A new algae-based treatment could reduce the need for amputation in people with critical limb ischemia, according to new research funded by the British Heart Foundation, published today in the journal npj Regenerative Medicine.
Turning algae into fuel
A team of University of Utah chemical engineers have developed a new kind of jet mixer for creating biomass from algae that extracts the lipids from the watery plants with much less energy than the older extraction method.
The algae's third eye
Scientists at the Universities of Würzburg and Bielefeld in Germany have discovered an unusual new light sensor in green algae.
Could algae that are 'poor-providers' help corals come back after bleaching?
How much of a reef's ability to withstand stressful conditions is influenced by the type of symbiotic algae that the corals hosts?
How some algae may survive climate change
Green algae that evolved to tolerate hostile and fluctuating conditions in salt marshes and inland salt flats are expected to survive climate change, thanks to hardy genes they stole from bacteria, according to a Rutgers-led study.
Feeding plants to this algae could fuel your car
The research shows that a freshwater production strain of microalgae, Auxenochlorella protothecoides, is capable of directly degrading and utilizing non-food plant substrates, such as switchgrass, for improved cell growth and lipid productivity, useful for boosting the algae's potential value as a biofuel.
More Algae News and Algae Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Accessing Better Health
Essential health care is a right, not a privilege ... or is it? This hour, TED speakers explore how we can give everyone access to a healthier way of life, despite who you are or where you live. Guests include physician Raj Panjabi, former NYC health commissioner Mary Bassett, researcher Michael Hendryx, and neuroscientist Rachel Wurzman.
Now Playing: Science for the People

#544 Prosperity Without Growth
The societies we live in are organised around growth, objects, and driving forward a constantly expanding economy as benchmarks of success and prosperity. But this growing consumption at all costs is at odds with our understanding of what our planet can support. How do we lower the environmental impact of economic activity? How do we redefine success and prosperity separate from GDP, which politicians and governments have focused on for decades? We speak with ecological economist Tim Jackson, Professor of Sustainable Development at the University of Surrey, Director of the Centre for the Understanding of Sustainable Propserity, and author of...
Now Playing: Radiolab

An Announcement from Radiolab