Tag Archives: coral

coral bleaching sun shield trial

Coral bleaching prevented through reef sun shield

A ‘sun shield’ made from an ultra-thin surface film is showing promise as a potential weapon in the fight to protect the Great Barrier Reef from the impacts of coral bleaching.

Great Barrier Reef Foundation Managing Director Anna Marsden said the results from a small-scale research trial led by the scientist who also developed Australia’s polymer bank notes were very encouraging.

The project was supported by The Tiffany & Co. Foundation, made possible through a grant to the University of Melbourne USA Foundation.

“We’ve partnered with scientists from the University of Melbourne and the Australian Institute of Marine Science to develop sun protection for the Reef,” Ms Marsden said.

“The ‘sun shield’ is 50,000 times thinner than a human hair and completely biodegradable, containing the same ingredient corals use to make their hard skeletons – calcium carbonate. It’s designed to sit on the surface of the water above the corals, rather than directly on the corals, to provide an effective barrier against the sun.

“While it’s still early days, and the trials have been on a small scale, the testing shows the film reduced light by up to 30%.

“Scientists tested the effectiveness of the one molecule thick film on seven different coral species in simulated coral bleaching event conditions at the Australian Institute of Marine Science’s National Sea Simulator (SeaSim).

“The surface film provided protection and reduced the level of bleaching in most species.”

With the surface film containing the same ingredient that corals use to make their skeletons, the research also showed the film had no harmful effects on the corals during the trials.

“This is a great example of developing and testing out-of-the-box solutions that harness expertise from different areas. In this case, we had chemical engineers and experts in polymer science working with marine ecologists and coral experts to bring this innovation to life,” Ms Marsden said.

“The project set out to explore new ways to help reduce the impact of coral bleaching affecting the Great Barrier Reef and coral reefs globally and it created an opportunity to test the idea that by reducing the amount of sunlight from reaching the corals in the first place, we can prevent them from becoming stressed which leads to bleaching.

“It’s important to note that this is not intended to be a solution that can be applied over the whole 348,000 square kilometres of Great Barrier Reef – that would never be practical. But it could be deployed on a smaller, local level to protect high value or high-risk areas of reef.

“The concept needs more work and testing before it gets to that stage, but it’s an exciting development at a time when we need to explore all possible options to ensure we have a Great Barrier Reef for future generations.”

The research team comprised of Professors Greg Qiao and David Solomon and Dr Joel Scofield from the University of Melbourne, Dr Emma Prime (formerly University of Melbourne, now Deakin University), and Dr Andrew Negri and Florita Flores from the Australian Institute of Marine Science. Professor Solomon (AC) was the winner of the Prime Minister’s Prize for Science in 2011 for his exceptional contributions to polymer science.

First published by the Great Barrier Reef Foundation 

Ocean acidity devastates corals

Ocean acidity devastates corals

Featured image above by Kennedy Wolfe

Increasing carbon emissions in the atmosphere from activities such as the burning of fossil fuels and deforestation are changing the chemistry in the ocean. When carbon dioxide from the atmosphere is absorbed by seawater, it forms carbonic acid. The increased acidity, in turn, depletes carbonate ions – essential building blocks for coral exoskeletons.

There has been a drastic loss of live coral coverage globally over the past few decades. Many factors – such as changing ocean temperatures, pollution, ocean acidification and over-fishing – impede coral development. Until now, researchers have not been able to isolate the effects of individual stressors in natural ecosystems.

In an article published in Nature on 24 February 2016, researchers working at the University of Sydney’s One Tree Island Research Station at the southern end of the Great Barrier Reef (GBR) found that they could improve coral development by reversing the acidity of the reef waters.

“Our oceans contribute around $45 billion each year to the economy”

The international team – led by Dr Rebecca Albright from Stanford University in the USA – brought the acidity of the reef water back to what it was like in pre-industrial times by upping the alkalinity. They found that coral development was 7% faster in the less acidic waters.

“If we don’t take action on this issue very rapidly, coral reefs – and everything that depends on them, including wildlife and local communities – will not survive into the next century,” says team member Professor Ken Caldeira.

Destruction of the GBR would not only be a devastating loss because it’s considered one of the 7 Natural Wonders of the World, but would be a great economic blow for Australia.

Our oceans contribute around $45 billion each year to the economy through industries such as tourism, fisheries, shipping, marine-derived pharmaceuticals, and offshore oil and gas reserves. Marine tourism alone generates $11.6 million a year in Australia.

Impact of acidification on calcification

Corals absorb carbonate minerals from the water to build and repair their stoney skeletons, a process called calcification. Despite the slow growth of corals, calcification is a rapid process, enabling corals to repair damage caused by rough seas, weather and other animals. The process of calcification is so rapid it can be measured within one hour.

Manipulating the acidity of the ocean is not feasible. But on One Tree Island, the walls of the lagoons flanking the reef area isolate them from the surrounding ocean water at low tide – allowing researchers to investigate the effect of water acidity on coral calcification.

“We were able to look at the effect of ocean acidification in a natural setting for the first time,” says One Tree Reef researcher and PhD candidate at the University of Sydney, Kennedy Wolfe.

ocean acidity
The University of Sydney’s Kennedy Wolfe collecting water samples on One Tree Reef. Photo credit: Ken Caldeira

In the same week, an independent research team from CSIRO published results of mapping ocean acidification in the GBR. They found a great deal of variability between the 3851 reefs in the GBR, and identified the ones closest to the shore were the most vulnerable. These reefs were more acidic and their corals had the lowest calcification rates – results that supported the findings from One Tree Reef.

Marine biologists have predicted that corals will switch to a net dissolution state within this century, but the team from CSIRO found this was already the case in some of the reefs in the GBR.

“People keep thinking about [what will happen in] the future, but our research shows that ocean acidification is already having a massive impact on coral calcification” says Wolfe.

– Sue Min Liu