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A specimen of Leptoseris troglodyta, the cave-dwelling coral, photographed near Indonesia in 2003. Photo courtesy: Bert Hoeksema
A new species of coral has been discovered that clings to the ceilings of underwater caves in the western Pacific's Coral Triangle.
Able to tolerate low levels of light, the species lacks the symbiotic algae that most corals need to survive. The newfound species is related to deep-sea corals that survive in dark conditions below depths of 130 feet (40 meters), but so far, this species has been found no deeper than 115 feet (35 m), according to a description of the species published today in the journal ZooKeys.
The coral forms smaller polyps than its relatives and grows quite slowly, said study author Bert Hoeksema, a researcher at the Naturalis Biodiversity Center in Leiden, Netherlands, in a statement.
A close-up of the trumpet of the newly discovered cave-dwelling coral. Photo courtesy: aquaportail.com
Its range overlaps with the Coral Triangle, a region that's well-known for its high diversity of marine organisms. The species has been dubbed Leptoseris troglodyta. The word "troglodyte" is derived from ancient Greek and means "cave dweller." Troglodyte also refers to some of my old boyfriends!
Investigations into how the coral is able to survive without symbiotic bacteria could shed light on the relationship between the two species. This relationship is critical; when water temperatures increase — as is happening in the world's oceans now — many corals may expel their algae, in a process known as coral bleaching. This often leads to the coral's death.
Coral cover on Australia's Great Barrier Reef has declined by more than half over the last 27 years according to marine scientists. Storms, coral bleaching and a rise in the number of crown-of-thorn starfish which suck out the coral's nutrients, have led to the alarming decline. Scientists warn that unless action is taken the coral will halve again within a decade. Video courtesy: guardian.co.uk
Coral cover in the Great Barrier Reef has dropped by more than half over the last 27 years, according to scientists, a result of increased storms, bleaching and predation by population explosions of a starfish which sucks away the coral's nutrients.
At present rates of decline, the coral cover will halve again within a decade, though scientists said the reef could recover if the crown-of-thorns starfish can be brought under control and, longer term, global carbon dioxide emissions are reduced.
"This latest study provides compelling evidence that the cumulative impacts of storms, crown-of-thorns starfish (Cots) and two bleaching events have had a devastating effect on the reef over the last three decades," said John Gunn, chief executive of the Australian Institute of Marine Science.
Coral reefs are an important part of the marine ecosystem as sources of food and as protection for young fish. They are under threat around the world from the effects of bleaching, due to rising ocean temperatures, and increasing acidification of the oceans, which reduces the corals' ability to build their calcium carbonate structures.
The Great Barrier Reef is the most iconic coral reef in the world, listed as a Unesco world heritage site and the source of $A5bn (£3.2bn) a year to the Australian economy through tourism. The observations of its decline are based on more than 2,000 surveys of 214 reefs between 1985 and 2012. The results showed a decline in coral cover from 28% to 13.8% – an average of 0.53% a year and a total loss of 50.7% over the 27-year period. The study was published on Monday in the Proceedings of the National Academy of Sciences journal (subscription).
Two-thirds of the coral loss has occurred since 1998 and the rate of decline has increased in recent years, averaging around 1.45% a year since 2006. "If the trend continued, coral cover could halve again by 2022," said Peter Doherty, a research fellow at the institute.
The incredibly beautiful; but, deadly crown-of-thorns starfish is causing the rapid decline of coral reefs. Photo courtesy: shells-of-aquarius.com
Tropical cyclones, predation by Cots, and bleaching accounted for 48%, 42%,and 10% of the respective estimated losses. In the past seven years the reef has been affected by six major cyclones. Cyclone Hamish, for example, ran along the reef, parallel to the coast for almost 930 miles (1,500km), leaving a trail of destruction much greater than the average cyclone, which usually crosses the reef on a path perpendicular to the coast.
The starfish problem was first recorded in 1962 at Green Island off Cairns. "When we say outbreaks, we mean explosions of Cots populations to a level where the numbers are so large that they end up eating upwards of 90% of a reef's coral," Gunn said. "Since 1962 there have been major outbreaks every 13-14 years."
The evidence suggests that outbreaks of Cots start two or three years after major floods in northern rivers.
In September, scientists at the International Union for Conservation of Nature announced that Caribbean coral reefs are on the verge of collapse, with less than 10% of the reef area showing live coral cover. The collapse was due to environmental issues, including over-exploitation, pollution and climate change.
David Curnick, marine and freshwater programme co-ordinator at the Zoological Society of London, said many of the most endangered coral species around the world were also under severe pressure from the aquarium trade.
"Corals are notoriously hard to propagate in captivity and therefore the trade is still heavily dependent on harvesting from the wild."."
He said the results of the Great Barrier Reef survey were not surprising and the challenge for conservationists was to limit the localised threats to give reefs a chance to recover and develop resilience against the effects of climate change. "This is challenging but entirely achievable and there are many community-led projects around the world demonstrating this."
Corals can recover if given the chance. But this is slow – in the absence of cyclones, Cots and bleaching, the Great Barrier Reef can regrow at a rate of 2.85% a year, the scientists wrote. Removing the Cots problem alone would allow coral cover to increase at 0.89% a year.
Reducing Cots means improving water quality around the rivers at the northern end of the reef to reduce agricultural run-off – high levels of nutrients flowing off the land feed and allow high survival of Cots larvae. Another option is some form of biological control of populations – Gunn said there were promising results from research on naturally occurring pathogens that could keep Cots in check, but it was not ready to be applied in the field.
He said the future of the Reef lay partly in human hands. "We can achieve better water quality, we can tackle the challenge of crown-of-thorns, and we can continue to work to ensure the resilience of the reef to climate change is enhanced. However, its future also lies with the global response to reducing carbon dioxide emissions. The coral decline revealed by this study – shocking as it is – has happened before the most severe impacts of ocean warming and acidification associated with climate change have kicked in, so we undoubtedly have more challenges ahead."
WHITE OUT: Bleached coral in the Philippines. Picture: WWF-Philippines / Lory Tan
Mass coral bleaching caused by global warming is threatening the health of the Coral Triangle, a vast marine region that is home to 76% of the world's known corals.
The Malaysian government recently closed portions of world-renowned dive sites on the tropical islands of Tioman and Redang, saying they would be off limits until October to give the fragile coral reef ecosystems time to heal.
Meanwhile, in the Philippines, bleaching has been reported in Anilao and Nasugbu, as well as off the cost of the western municipality of Taytay, Palawan. The latter saw corals, which usually exhibit a green and brown hue, temporarily turn unusual shades of pink, orange and yellow - a precursor to complete bleaching.
Numerous other Philippine reefs are likely to have been affected as well, exacerbated by localised outbreaks of Crown-of-Thorns Seastars.
Widespread bleaching has also been recorded in Indonesia, with areas near Sabang, Aceh, Padang, Thousand Island Jakarta, Bali, and many other locations.
"This widespread bleaching is alarming because it directly affects the health of our oceans and their ability to nurture fish stocks and other marine resources on which millions of people depend for food and income," says Richard Leck, Climate Change Strategy Leader of the WWF Coral Triangle Programme.
The Coral Triangle region covers the seas of Indonesia, Malaysia, Papua New Guinea, the Philippines, Solomon Islands and Timor Leste. This nursery of the seas contains more than 600 species of reef-building coral. Since March this year, about 50 different organisations and individuals have reported signs of coral bleaching in the region. Up to 100 per cent bleaching on susceptible coral species have been reported, and in some areas, severe bleaching has even affected more resistant kinds.
COLOUR CONCERN: Bleached corals in Taytay, Palawan. Originally hued green and brown, they are now unusual shades of pink, orange and yellow - a precursor to complete bleaching. Picture courtesy: WWF-Philippines
The National Oceanic and Atmospheric Administration's (NOAA) Coral Reef Watch stated that the current incident is the worst of it kind since 1997-1998, which decimated 16% of the world's coral reefs.
With many areas showing signs of mass bleaching, it has become apparent that more weight needs to be put behind long-term conservation strategies, such as marine protected area management, preventing coastal and marine pollution, as well as promoting sustainable fisheries. Coral bleaching is a phenomenon caused by global warming. Increased seawater temperatures, which in some regions have grown as much as 2°C above the long-term average maximum, can push the algae living inside corals beyond the brink, causing reefs to eventually turn white and die. Aside from increased sea temperatures, other causes of stress include disease, pollution, sedimentation, cyanide fishing, changes in salinity, and storms.
"Well-designed and appropriately-managed networks of marine protected areas and locally managed marine areas are essential to enhance resilience against climate change, and prevent further loss of biodiversity, including fisheries collapse," Leck also added.
Through new sustainable finance mechanisms and investments in climate adaptation, WWF plans to support networks of marine sanctuaries and locally managed conservation areas across the Coral Triangle. Better fisheries management is also key to alleviating the impacts of coral bleaching, ensuring that only viable sites are given access to fishing and that the more sensitive ones are given time to recuperate via strong regulations, enforcement and awareness.
In Malaysia, for instance, WWF is promoting the conservation of herbivorous reef fish, which plays a critical role of keeping algae populations lower, allowing room for coral recruits to settle on the potentially newly-dead coral skeletons. Only a year ago, WWF launched The Coral Triangle and Climate Change: Ecosystems, People and Societies at Risk, a report based on a thorough consideration of the climate biology, economics and social characteristics of the region, showing how unchecked climate change will ultimately undermine and destroy ecosystems and livelihoods in the Coral Triangle.
Via WildlifeExtra
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