Tag Archives: coral reefs

Nobel-winning market theory could help us better protect coral reefs

A group of researchers from Australia’s University of Queensland used a revolutionary stock market theory to identify 50 coral reefs around the world that will likely be less affected by the climate crisis and use them as ‘arks’ to help repopulate other reefs. The researchers suggest focusing future conservation efforts in specifically protecting these reefs. 

Image credit: Flickr / WorldFish.

Coral reefs are threatened by local and global stressors, including declining water quality, overfishing, and ocean warming. They are likely to disappear entirely or almost entirely by mid-century if the target of the Paris Agreement on climate change to limit global warming to 1.5 degrees Celsius isn’t met. And even if it is, an estimated 70% to 90% of the world’s corals would still vanish.

However, the remaining coral populations are still very important to replenish coral reefs once ocean surface temperatures hopefully stabilize in the future. The challenge is to identify these reefs and direct resources focused on achieving long-term coral conservation amid the climate crisis, according to the Australian researchers behind the new study. 

Seeking to address this, the team applied the Modern Portfolio Theory or MPT (a mathematical framework from the 1950s to help investors maximize returns) to identify coral reefs sanctuaries that could survive the climate crisis and repopulate other reefs when things stabilize. They identified 50 reefs from around the world.

“By applying MPT to conservation planning, the expected variance in those conservation outcomes can be reduced by investing in areas that tend to behave in different ways. This is of particular interest when decisions about where to act are informed by uncertain projections about future states of the world,” the researchers wrote.

Better protecting corals

For the study, the researchers classified the world’s coral reefs into bioclimatic units (BCU) of 500 square kilometers (190 squared miles). They used over 170 metrics in five categories to classify each coral reef’s odds of surviving (including risks from invasive species, temperature and ocean acidification). Then, they produced estimates for the future of each BCU, capturing different possibilities. 

The team then applied MPT to identify the corals with the best chances for conservation. The market theory is based on the idea that you have stocks that are high risk and high reward, and stocks that are low risk and low reward — and you want to balance your portfolio to include both in different proportions, based on your tolerance to risk.

Researchers applied this idea to coral reefs as well, finding the 50 coral reefs most likely to survive climate change, and recommend using them as arks to repopulate the other corals. For this list, they identified reefs all over the world, including Pacific Islands, South America, northern and eastern Africa, Australia and south-east and south Asia. The list includes parts of the Great Barrier Reef in Australia and the “coral triangle” in the Pacific but also excluded ecologically relevant areas, such as Central America’s Barrier Reef. 

For the researchers, while widespread loss and degradation of corals are soon expected because of climate change — it’s not a matter of ‘if’, it’s a matter of ‘when’. But there are still things we can do. Strategic management of threats and the use of emerging technologies provide opportunities to improve conservation of corals. Nevertheless, success in saving them ultimately depends on reducing our greenhouse gas emissions as quickly as possible. 

The study was published in the journal Conservation Letters. 

Corals are dying off but not only because of climate change

Mostly associated with climate change, coral reefs are one of the most threatened ecosystems of the planet, currently dying at record rates across the world. But while the rising temperatures are affecting them, they are just one part of the story.

The corals are threatened by rising temperatures — but there’s more to the story than that. Credit: USFWS (Flickr)


Researchers at Florida Atlantic University’s Harbor Branch Oceanographic Institute worked with 30 years of data from Looe Key Reef in the lower Florida Keys and discovered that coral bleaching isn’t happening just because of global warming but also from human pollution.

Improperly treated sewage and agricultural run-off have flowed for many years into the ocean waters of Florida, causing an increase in the nitrogen levels and lowering the reef’s temperature threshold for bleaching, according to a study published in the journal Marine Biology.

“Our results provide compelling evidence that nitrogen loading from the Florida Keys and greater Everglades ecosystem caused by humans, rather than warming temperatures, is the primary driver of coral reef degradation at Looe Key Sanctuary Preservation Area during our long-term study,” said Brian Lapointe, study senior author.

This has led to a steep decline in coral cover in the region, going from nearly 33 percent in 1984 to just six percent in 2008.

The researchers discovered that three bleaching events that occurred during that period only happened after heavy rainfall and increased land-based runoff. This means that if the amount of local pollution is reduced, the damage to coral reefs could be reduced.

An excess of nitrogen feeds blooms of algae that block out the light, also causing an imbalance of nutrients in the water that affects the coral’s life cycle. This leads to the corals being starved of phosphorus, making them unhealthy and susceptible to diseases, ultimately causing coral bleaching.

“Anthropogenic nutrient loading from local sources in the Florida Keys and regionally from the greater Everglades ecosystem is interacting with a changing climate to create conditions unfavorable for living coral,” the study reads.

Previous studies have also shown that between 1992 and 1996 – when Florida’s freshwater flows were directed south — there was a 404% increase in coral diseases throughout the Florida Keys National Marine Sanctuary (FKNMS), which also sits downstream from the Everglades.

The findings in Florida shows that actions taken by residents can have an impact on the health of coral reefs. The authors claimed better sewage and storm-water management can reduce nitrogen pollution, plus a better management of fertilizers used on lawns.

Coral reefs are considered the ocean’s most diverse and complex ecosystems, supporting 25% of all marine life, including 800 species of reef-building corals and more than one million animal and plant species.

A 2011 study by Burke said that 60% of coral reefs around the world are already seriously damaged by processes such as overfishing and coral bleaching. Rising ocean temperatures are also a massive issue for corals. It’s currently estimated that 75% of reefs are threatened.