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A new study has predicted that if current trends continue and the world fails to reduce greenhouse gas emissions, nearly all of the world’s coral reefs, including many in the Caribbean, will suffer severe bleaching — the gravest threat to one of the Earth’s most important ecosystems — on annual basis.
The finding is part of a study funded by the United Nations Environment Programme (UNEP) and partners, which reviewed new climate change projections to predict which corals will be affected first and at what rate.
The report is published in the journal Nature Scientific Reports. Researchers found that the reefs in Taiwan and the Turks and Caicos archipelago will be among the first to experience annual bleaching, followed by reefs off the coast of Bahrain, in Chile and in French Polynesia.
Calling the predictions “a treasure trove” for environmentalists, the head of the UN agency, Erik Solheim, said the projects allow conservationists and governments to prioritise reef protection.
“The projections show us where we still have time to act before it’s too late,” Solheim said.
On average, the reefs started undergoing annual bleaching from 2014, according to the study.
Without the required minimum of five years to regenerate, the annual occurrences will have a deadly effect on the corals and disrupt the ecosystems which they support, UNEP said.
However, it said that if governments act on emission reduction pledges made in the Paris Agreement, which calls on countries to combat climate change and limit global temperature rise to below two degrees Celsius, the corals would have another 11 years to adapt to the warming seas.
Between 2014 and 2016, UNEP said the world witnessed the longest global bleaching event recorded.
Among the casualties, it said, was the Great Barrier Reef, with 90 per cent of it bleached and 20 per cent of the reef’s coral killed.
As the climate changes and temperatures warm, corals are becoming more susceptible to bleaching. Now, researchers have looked at bleaching in detail and have discovered when and where bleaching will occur in the coming years.
“Our new local-scale projects will help resource managers better understand and plan for the effects of coral bleaching,” said Ruben van Hooidonk, the lead author of the new study, in a news release. “At some locations, referred to in our study as ‘relative refugia,’ lower rates of temperature increase and fewer extreme events mean reefs have more time to adapt to climate change. Managers may decide to use this information to protect these locations as refuges, or protected areas. Or they may take other actions to reduce stressed cause by human activities.”
Coral bleaching is primarily caused by warming ocean temperatures. This phenomenon is a major threat to coral reef health. When the water is too warm, corals expel the algae living in their tissues; this causes the corals to lose their vibrant colours and turn white. These bleached corals are under more stress and are more likely to die, which can leave reefs barren and lifeless.
In order to project future bleaching occurrences, the researchers used a regional ocean model and an approach called statistical downscaling. This allowed them to calculate the onset of annual severe bleaching at a much higher resolution. The resulting local-scale projects of bleaching conditions may help managers include climate change as a consideration when making conservation decisions.
There are certain regions, of course, that will be more impacted than others. Countries that are projected to experience bleaching conditions 15 or more years later than neighbouring regions include the reefs in Florida, the Bahamas, Cuba, Puerto Rico, the Dominican Republic, the Turks and Caicos and Mexico. These areas could potentially be conservation priorities.
The findings reveal a bit more about bleaching conditions, which could help managers make better decisions in the future.
The findings are published in the journal Global Change Biology.
With only about one-sixth of the original coral cover left, most Caribbean coral reefs may disappear in the next 20 years, primarily due to the loss of grazers in the region, according to the latest report by the Global Coral Reef Monitoring Network (GCRMN), the International Union for Conservation of Nature (IUCN) and the United Nations Environment Programme (UNEP).
The report, Status and Trends of Caribbean Coral Reefs: 1970-2012, is the most detailed and comprehensive study of its kind published to date – the result of the work of 90 experts over the course of three years. It contains the analysis of more than 35,000 surveys conducted at 90 Caribbean locations since 1970, including studies of corals, seaweeds, grazing sea urchins and fish.
The results show that the Caribbean corals have declined by more than 50% since the 1970s. But according to the authors, restoring parrotfish populations and improving other management strategies, such as protection from overfishing and excessive coastal pollution, could help the reefs recover and make them more resilient to future climate change impacts.
“The rate at which the Caribbean corals have been declining is truly alarming,” says Carl Gustaf Lundin, Director of IUCN’s Global Marine and Polar Programme. “But this study brings some very encouraging news: the fate of Caribbean corals is not beyond our control and there are some very concrete steps that we can take to help them recover.”
Climate change has long been thought to be the main culprit in coral degradation. While it does pose a serious threat by making oceans more acidic and causing coral bleaching, the report shows that the loss of parrotfish and sea urchin – the area’s two main grazers – has, in fact, been the key driver of coral decline in the region. An unidentified disease led to a mass mortality of the sea urchin in 1983 and extreme fishing throughout the 20th century has brought the parrotfish population to the brink of extinction in some regions. The loss of these species breaks the delicate balance of coral ecosystems and allows algae, on which they feed, to smother the reefs.
Reefs protected from overfishing, as well as other threats such as excessive coastal pollution, tourism and coastal development, are more resilient to pressures from climate change, according to the authors.
“Even if we could somehow make climate change disappear tomorrow, these reefs would continue their decline,” says Jeremy Jackson, lead author of the report and IUCN’s senior advisor on coral reefs. “We must immediately address the grazing problem for the reefs to stand any chance of surviving future climate shifts.”
The report also shows that some of the healthiest Caribbean coral reefs are those that harbour vigorous populations of grazing parrotfish. These include the Flower Garden Banks National Marine Sanctuary in the northern Gulf of Mexico, Bermuda and Bonaire, all of which have restricted or banned fishing practices that harm parrotfish, such as fish traps and spearfishing. Other countries are following suit.
“Barbuda is about to ban all catches of parrotfish and grazing sea urchins, and set aside one-third of its coastal waters as marine reserves,” says Ayana Johnson of the Waitt Institute’s Blue Halo Initiative which is collaborating with Barbuda in the development of its new management plan. “This is the kind of aggressive management that needs to be replicated regionally if we are going to increase the resilience of Caribbean reefs.”
Reefs where parrotfish are not protected have suffered tragic declines, including Jamaica, the entire Florida Reef Tract from Miami to Key West, and the U.S. Virgin Islands.
The Caribbean is home to 9% of the world’s coral reefs, which are one of the most diverse ecosystems on the planet. Caribbean reefs, spanning a total of 38 countries, are vital to the region’s economy. They generate more than US$ 3 billion annually from tourism and fisheries and over a hundred times more in other goods and services, on which more than 43 million people depend.
This video, featuring the report’s lead author Jeremy Jackson, explains the significance of the report:
Peruse the full report.
Credit: The International Union for Conservation of Nature (IUCN)
Sustainable Fisheries Partnership Brief Highlights Climate Change Impacts on Fisheries and Aquaculture
The Sustainable Fisheries Partnership (SFP) has issued a brief,’Climate Change: Implications for Fisheries and Aquaculture,’ which details the threats of climate change and ocean acidification to fisheries, aquaculture and marine resources as relayed in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5).
The brief highlights that climate change and ocean acidification are altering ocean ecosystems, leading to a loss of marine biodiversity and changes in seafood production levels, including through the displacement of stocks and rising mortality of shellfish. It notes that other factors such as over-fishing, habitat loss and pollution worsen the impacts of climate change on marine resources. The publication also highlights impending issues such as: the rapid decline of coral reef ecosystems, with the risk of collapse of some coastal fisheries; the likely increase in coral bleaching; potential increases in illegal, unreported and unregulated (IUU) fishing from changes in coastal resources and food insecurity; and possible mass die-offs in farmed fish due to harmful algal blooms.
The brief explains that fishers can adapt to some of the impacts, through, inter alia: changing gear or target species; increasing aquaculture; and moving to dynamic management policies. Additionally, some positive impacts of climate change are highlighted, including faster growth rates and food conversion efficiency, longer growing seasons, and new growing areas due to decreases in ice cover.
Regarding the potential for mitigation in the fisheries sector, the brief highlights options such as strengthening coastal zone management to reduce land-sourced pollution, over harvesting and physical damage to resources. It also suggests creating new habitats, such as artificial reefs, to act as fish nurseries in areas where coral reef destruction occurs. According to the report, protecting some ocean ecosystems will help moderate the speed and scale of climate change, as well as build ecosystem health.
The brief is published jointly by the SFP and the University of Cambridge Institute for Sustainability Leadership and Cambridge Judge Business School, and is supported by the European Climate Foundation. It is one of a series of publications synthesizing the most relevant AR5 findings for specific economic and business sectors, and grew from the idea that the fisheries and aquaculture sector could make better use of the AR5, if distilled into an accessible and succinct summary.
Credit: SFP News Story from the Climate Change: Implications for Fisheries and Aquaculture publication.