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Study: Ritual human sacrifice maintained social stratification

THE EARLIEST PROFESSION WAS THE SHAMAN, DRUID, WHICH BECAME THE PRIESTHOOD
"Human sacrifice provided a particularly effective means of social control," said researcher Russell Gray.

Ritual sacrifice helped maintain social order in early Austronesian societies. Photo by tlorna/Shutterstock

AUCKLAND, New Zealand, April 5 (UPI) -- New research suggests a strong link between ritual human sacrifice and social hierarchy.

Researchers from the University of Auckland confirmed the correlation while analyzing the traditional cultures of Austronesia -- a region encompassing dozens of islands, including those of Micronesia, Melanesia and Polynesia.

The scientists used prior ethnographic research to plot the changes in social stratification and the use of ritual sacrifice. Cultures that featured human sacrifice were more likely to be strongly stratified. More egalitarian cultures were less likely to use sacrifice.

Their analysis also showed the two cultural phenomena co-evolved. Ritual sacrifice ensured that socially stratified cultures would remain so.

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Though methods of sacrifice varied across Austronesia cultures -- burning, drowning, strangulation, bludgeoning, live burial, decapitation -- the victims and perpetrators were largely the same. Those killed were typically of low social status, often slaves. The perpetrators were mostly of high stature, chiefs or priests.

"By using human sacrifice to punish taboo violations, demoralize the underclass and instill fear of social elites, power elites were able to maintain and build social control," researcher Joseph Watts, a professor at the University of Auckland's School of Psychology, explained in a news release.

Watts is the lead author of new paper on the findings, published this week in the journal Nature.

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"Human sacrifice provided a particularly effective means of social control because it provided a supernatural justification for punishment," added co-author Russell Gray. "Rulers, such as priests and chiefs, were often believed to be descended from gods and ritual human sacrifice was the ultimate demonstration of their power."

Computer models helped Watts, Gray and their colleagues decipher the order of evolutionary changes and determine that changes in ritual sacrifice preceded social change -- not the other way around.

"What we found was that sacrifice was the driving force, making societies more likely to adopt high social status and less likely to revert to egalitarian social structure," said co-author Quentin Atkinson.

Toxic mineral selenium to blame for spinal deformities in California Delta fish

Scientists found selenium exposure was responsible for spinal deformities in juvenile Sacramento splittail, fish native to the California Delta. Photo by Fred Feyrer / U.S. Geological Survey

Feb. 24 (UPI) -- Exposure to elevated levels of the toxic mineral selenium caused fish native to the Sacramento-San Joaquin Delta, sometimes called the California Delta, to develop spinal deformities.

In 2011, biologists collected hundreds of minnows, juvenile forms of the Sacramento splittail, from the California Delta. Of the approximately 1,000 specimens studied, 80 percent had deformed spines.

"This was not just a few fish, it was the majority of them," Fred Feyrer, fish biologist at the U.S. Geological Survey's California Water Science Center, said in a news release.

Feyrer is co-author of a new study, published Monday in the journal Environmental Science and Technology, detailing the dangers of selenium exposure for fish in the Sacramento-San Joaquin Delta.

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To pinpoint where the fish were exposed to the toxins responsible for their deformities, scientists exposed test fish to selenium in the lab and developed methods for measuring the chemical signatures trapped in layers of the minnows' ear bones, or otoliths.

"We found that the otoliths record a diary of selenium exposure from birth to death, and were the key to unraveling this mystery," said lead study author Rachel C. Johnson, a research biologist at NOAA Fisheries' Southwest Fisheries Science Center and the University of California Davis.

Using the methods they perfected in the lab, scientists used high-intensity X-rays at Cornell University's Cornell High Energy Synchrotron Source to measure selenium concentrations in the otoliths of the juvenile fish originally collected from the California Delta.

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The results showed the fish were exposed to selenium from their mothers and while feeding in the San Joaquin River.

"They got it from both directions," Johnson said.

Another study, published late last year in the journal Science of the Total Environment, showed adult splittail were exposed to elevated levels of selenium while feeding in the San Francisco Estuary. Scientists suspect the fish are exposed to the naturally occurring toxin while eating Asian clams. The filter feeding clams, which concentrate selenium from the river water, are a favorite food source of the splittail.

When the clam-eating splittails lay eggs, the selenium gets passed on to the next generation, leading to spinal deformities.

Researchers also previously found evidence that birds exposed to selenium concentrated in agricultural runoff suffered deformities in the 1980s.

Scientists still aren't sure of the causes of the elevated selenium levels in the Sacramento-San Joaquin Delta. The element is essential to life, but it is toxic at high concentrations. Though selenium is naturally occurring, it can also be leached from coal ash and crude oil processing, as well as mining and metal smelting.

Finding living evidence of selenium exposure is rare, as most fish exposed to the toxin quickly perish or get eaten by a predator. It's possible scientists have missed the signs of previous episodes of selenium exposure.

"Was this a one-time event?" said co-author Robin Stewart, a research hydrologist at the U.S. Geological Survey. "What we don't know is how frequently this could be happening, because no one is out there looking for these fish before they disappear."

Sweet potatoes came to Polynesia before humans did, study suggests
Scientists studied Polynesian sweet potatoes collected by Captain Cook in 1769.

Rows of sweet potatoes are pictured growing in Peru. Photo by Oxford University

April 13 (UPI) -- The sweet potato made its way to Polynesia without human assistance, new research suggests, colonizing the islands prior to the arrival of the first humans.

When European explorers first visited Polynesia, they found an abundance of sweet potatoes, a root vegetable native to the Americas. Researchers led by a team at Britain's University of Oxford have interpreted their discovery as proof of early contact between Polynesians and Americans prior to the arrival of European explorers and colonists.

New genomic evidence, however, undermines such an interpretation. Analysis of the remains of Polynesian sweet potatoes collected by Captain Cook in 1769 showed the vegetables were of a variety that colonized before the arrival of the earliest Polynesia peoples.

Researchers sequenced the genomes of several varieties of sweet potatoes, both planted and wild varieties, using historic and modern samples. Their analysis, published this week in the journal Current Biology, linked the historic wild varieties with the cultivated crop.

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The research suggests that wild sweet potatoes came to Polynesia through natural means. It's possible the seeds were carried to the islands by migrating birds. Scientists also determined that several other species of morning glories closely related to wild sweet potatoes colonized Polynesia during pre-human times.

"The sweet potato's early presence in Polynesia has been widely interpreted as strong evidence for human contact between Polynesia and America in the Pre-Columbian era," Pablo Muñoz-Rodríguez, a researcher at Oxford, said in a news release. "However, our finding is that the plant probably reached the Pacific Islands through natural dispersal by birds, wind or sea currents in pre-human times, as did several other species of morning glory."

Survey shows pollution in Gulf 10 years after Deepwater Horizon spill

Researcher Erin Pulster, marine scientist at the University of South Florida, is pictured identifying fish specimens alongside research partners from the National Autonomous University of Mexico. Photo by USF

April 15 (UPI) -- For the first time, scientists have a conducted a Gulf-wide survey of oil pollution among fish populations.

The massive study -- comprising samples from 2,500 fish representing 91 species spread across 359 locations in the Gulf of Mexico -- suggests contamination from oil pollution remains widespread roughly 10 years after the Deepwater Horizon spill.

Researchers published the results of the record survey on Wednesday in the journal Scientific Reports.

"This is the largest comprehensive fish survey ever conducted in a large marine ecosystem and provides the first spatial and temporal baselines for polycyclic aromatic hydrocarbon in fishes in the Gulf of Mexico," study author Erin L. Pulster, marine scientist and postdoctoral researcher at the University of South Florida, told UPI in an email.

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Polycyclic aromatic hydrocarbons, or PAHs, are one of the most toxic chemical components found in crude oil. The toxins, which have been linked to heart disease and cancers in humans, get trapped in the bile of fish.

"This study demonstrates the chronic and widespread oil pollution in this ecosystem," Pulster said. "Given the extensive oil and gas extraction activities in the Gulf of Mexico for the last eight decades, it is unclear why this has not been conducted prior to the Deepwater Horizon oil spill."

The new survey revealed elevated levels of PAH in every surveyed fish species living in the Gulf, but the highest levels were found in yellowfin tuna, golden tilefish and red drum.

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Elevated levels were expected in tilefish, which spend most of their lives stirring up seafloor sediment, where oil pollution settles. But researchers were surprised to find such elevated PAH levels in tuna, which live their lives in the water column, where oil pollution tends to persist for only short amounts of time.

As part their research, scientists also mined data from previous PAH exposure surveys. The research team found evidence of elevated PAH levels in the tissue and bile of 10 popular grouper species.

"The elevated and increasing PAH levels in fish is the result of a combination of sources which include both anthropogenic and natural sources," Pulster said. "Anthropogenic sources include the Deepwater Horizon oil spill, leaking infrastructure, riverine discharge, marine vessel traffic and the resuspension of contaminated sediments. Natural sources are mainly natural oil seeps and submarine groundwater discharge located throughout the Gulf of Mexico."

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Not all fish populations show the same levels of contamination. Scientists measure higher concentrations of the toxins near places with greater oil and gas activity. Researchers also found PAH hotspots among fish populations near coastal cities like Tampa Bay, which suggests urban runoff can exacerbate oil pollution problems.

"The continued degradation of the Gulf of Mexico ecosystem is demonstrated by the chronic, widespread oil pollution," Pulster said.

Despite the alarming results, scientists suggest the evidence of PAH contamination is more concerning for the health of Gulf ecosystems and fish populations than the health and safety of consumers of Gulf seafood. Toxin levels in the flesh of commercial fish species are closely monitored and PAH levels in fish flesh remain below public health advisory levels.

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However, prolonged exposure to elevated PAH and other oil-related toxins can cause the liver to shutdown, threatening the health of fish in the Gulf. Previous studies have revealed 50 to 80 percent population declines in deep water, or mesopelagic, fish populations near the Deepwater Horizon blowout site.

Researchers hope their baseline study of PAH contamination among Gulf fish is only the beginning of a more robust monitoring effort.

"Providing funding is available, our research efforts will continue to monitor and evaluate PAH levels in fish and the subsequent sub lethal effects," Pulster said. "Additionally, a major research focus will be geared toward identifying the sources of PAHs in surface waters that are impacting pelagic [openwater] species."

Genomics help scientists estimate the population size of the first Samoans


The earliest population of Samoans measured between 700 and 3,000 individuals, according to a new study. Photo by Charles S. Greene/Talofa, Samoa: A Summer Sail to an Enchanted Isle/Wikimedia Commons
April 15 (UPI) -- New genomic analysis has allowed scientists to estimate the population size of the first Samoans to arrive on the Pacific island some 3,000 years ago.

From approximately 3,000 to 1,000 years ago, between 700 and 3,400 people lived on the island of Samoa. Roughly 1,000 years ago, the island's population exploded from a few thousand to 10,000 individuals.

By analyzing the genomes of 1,197 individuals living in Samoa, scientists were able to gain new insights into one of the last major migrations of humans into previously uninhabited territories.

The results of the genomic analysis -- published this week in the journal PNAS -- could also help researchers explore links between early human history in Samoa and the modern health problems, including obesity, hypertension and Type 2 diabetes, that currently plague the island nation.

"These findings are relevant for our ongoing public health research in Samoan populations because they highlight the importance of population history and size in influencing our ability to identify the effect of novel genetic variations, and their interactions with 21st century environments on population health," study co-author Stephen McGarvey, professor of epidemiology and of anthropology at Brown University, said in a news release.

The prevalence of obesity in Samoa has led to record rates of related problems, including diabetes, cardiovascular disease, kidney disease and cancer, according to McGarvey, who has been studying the island's health issues for many years.

"Smaller populations and the evolutionary mechanisms resulting from them, including genetic drift from bottlenecks and natural selection from novel challenging environments such as experienced by the first settlers of Samoa, make it easier to detect new gene variants and different frequencies of known variants that affect cardiometabolic disease risk factors now in the 21th century," McGarvey said.

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The latest genomic data showed modern Samoans get most of their genetic heritage from from Austronesian lineages. Samoans are the descendants of the aboriginal peoples of Taiwan, the islands of Southeast Asia, coastal New Guinea and other Oceanic islands.

The analysis also showed modern Samoans only derive 24 percent of their genome from the people of Papua New Guinea. Most other Polynesian groups share most larger portions of their ancestry with Papuans.

In addition to revealing the ancestry of modern Samoans, the latest data revealed evidence of the population decline that followed the arrival of the earliest European visitors. Hundreds of Samoans died from diseases brought by the first Europeans. Around 150 years ago, the island's population stabilized and began to grow once more.

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"These findings indicate that the modern Samoan population is a result of these demographic dynamics from the earliest times 3,000 years ago to the very recent colonial period in the 19th century," McGarvey said. "Any questions about putative genetic influences and their interactions with modern ways of life must be asked in the context of population history."
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Newly discovered black iguana species in Caribbean is endangered

Scientists discovered a new species of iguana, the melanistic black lizard, or Iguana melanoderma. Photo by M. Breuil

April 14 (UPI) -- Scientists have discovered a new iguana species in the eastern Caribbean. The novel reptile, Iguana melanoderma, was found on the Saba and Montserrat islands of the Lesser Antilles.

Researchers announced their discovery in the journal ZooKeys. According to the paper, the new species -- the melanistic black iguana -- is severely threatened.

"This new melanistic taxon is threatened by unsustainable harvesting -- including for the pet trade -- and both competition and hybridization from escaped or released invasive alien iguanas," scientists wrote.

The Lesser Antilles are home to three iguana species, but only one is endemic. The Lesser Antillean iguana, Iguana delicatissima, has lived among the northernmost islands of the Lesser Antilles for thousands of years. More recently, the islands have welcomed a pair of newcomers: the common iguana, Iguana iguana iguana, from South America and the green iguana, Iguana rhinolopha, from Central America.

Physically, the new species is differentiated by a black spot located between the eye and its ear cavity. Juveniles also boast a dorsal carpet pattern that darkens as the reptiles age. Genetically, the species is marked by a series of unique mitochondrial patterns.

According to the International Union for Conservation of Nature, the Lesser Antillean iguana remains a species of least concern, but the group's Red List fails to differentiate between different populations. In some parts of the Caribbean, such as Guadeloupe, the common iguana and the green iguana have pushed the Lesser Antillean iguana to the brink of extinction through competition and hybridization.

Similar trends are underway on the islands of the Lesser Antilles, and scientists worry the newly discovered melanistic black iguana will face a similar fate.

"With the increase in trade and shipping in the Caribbean region and post-hurricane restoration activities, it is very likely that there will be new opportunities for invasive iguanas to colonize new islands inhabited by endemic lineages," lead study author Frédéric Grandjean, professor at the University of Poitiers in France, said in a news release.

Researchers hope that future analysis of the region's iguana species will help scientists better differentiate endemic lineages from invasive iguanas.

"Priority actions for the conservation of the species Iguana melanoderma are biosecurity, minimization of hunting and habitat conservation," said Grandjean. "The maritime and airport authorities of both islands must be vigilant about the movements of iguanas, or their sub-products, in either direction, even if the animals remain within the same nation's territory. Capacity-building and awareness-raising should strengthen the islands' biosecurity system and could enhance pride in this flagship species."

Plant diversity in Europe's forests is on the decline

As nitrogen levels have increased in Europe's temperate forests, small-ranged species have declined and disappeared. Photo by Martin Adámek/Czech Academy of Sciences

April 13 (UPI) -- Plant diversity in the forests of Europe is not what it used to be. Rare plant species are being replaced by more common species at an alarming rate, according to a new study published Monday in the journal Nature Ecology and Evolution.

Across the globe, the list of threatened plant and animal species gets longer every year. But on smaller scales, some species are thriving. Researchers wanted to figure out why some plants are becoming more abundant, while others are getting snuffed out.

Scientists surveyed changes in the abundance of 1,162 different herb-layer plant species growing among 68 temperate forest sites in Europe. The survey relied on data collected and shared by a network of forest ecologists, known as forestREplot.

"This network has the advantage that the experts on the actual locations can be asked if something is unclear, and, in this way, it differs from many other large databases," lead study author Ingmar Staude, doctoral student at the German Center for Integrative Biodiversity Research and the Martin Luther University Halle-Wittenberg, said in a news release.

Analysis of the forestREplot data showed species with limited geographical ranges were more vulnerable to extinction in certain forests.

"This is not so much due to the smaller population size of such plants, but rather to their ecological niche," Staude said.

Scientists hypothesized rare and declining species were more likely to be adapted to less common soil nutrients. Further analysis showed species with limited geographical ranges were more likely to be declining in forests with excess nitrogen levels.

The numbers suggest chronic and excessive nitrogen deposition has led to a 4 percent decline in the abundance of plant species with small ranges.

In some cases, the increase in nitrogen levels has allowed rare nitrogen-loving species to thrive, but more typically, species with limited ranges are being replaced by more widespread species.

While the average biodiversity among individual forests remains relatively stable, the latest research showed plant diversity across the temperate forest biome is decreasing. The research was conducted in protected forests; biodiversity declines are likely worse in forests open to logging.

"We now have to find out whether the processes we observe in forests are similar in other biomes," said Staude.

Puerto Rico's coquí is the Caribbean's oldest frog

Today, frogs in the genus Eleutherodactylus, which includes the common coquí, dominate the Caribbean, having diversified into many different body forms and sizes. A newly found fossil shows they have been in the region for at least 29 million years. Photo by Alberto Lopez Torres

April 8 (UPI) -- The discovery of a tiny arm bone suggests the coquí frog has been living in the forests of the Caribbean for at least 29 million years.

The ancient arm bone -- described Wednesday in the journal Biology Letters -- is the oldest evidence of a frog living in the Caribbean. The fossil was found in Puerto Rico, where the coquí frog is much beloved.

"It's a national treasure," lead study author David Blackburn, curator of herpetology at the Florida Museum of Natural History, said in a news release. "Not only is this the oldest evidence for a frog in the Caribbean, it also happens to be one of the frogs that are the pride of Puerto Rico and related to the large family Eleutherodactylidae, which includes Florida's invasive greenhouse frogs."

The fossil was recovered from a river bank outcropping in northwestern Puerto Rico by study co-author Jorge Velez-Juarbe, an associate curator of marine mammals at the Natural History Museum of Los Angeles County.

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The dig site has previously yielded fossil seeds, as well as remains of sea cows and side-necked turtles. Scientists also previously unearthed the oldest remains of rodents and gharials, a group of crocodiles, in the Caribbean.

"There have been many visits from which I have come out empty-handed over the last 14 years," Velez-Juarbe said. "I've always kept my expectations not too high for this series of outcrops."

Previously, scientists have used genetic analysis to estimate that rain frogs lived in the Caribbean during the early Oligocene Epoch, but until now, they had no fossils to prove it. Small, fragile bones and the Caribbean's hot, humid weather isn't a great recipe for preservation.

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After discovering the tiny bone, Velez-Juarbe conferred with experts to identify the frog to which the fossil belonged.

Scientists suspect the Caribbean's first frogs rafted over the islands from South America during the Oligocene. Today, the Eleutherodactylus genus features 200 species. The relatives of coquí dominate the Caribbean forests.

"This is the most diverse group by two orders of magnitude in the Caribbean," Blackburn said. "They've diversified into all these different specialists with various forms and body sizes. Several invasive species also happen to be from this genus. All this raises the question of how they got to be this way."

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Researchers hope additional discoveries will she more light on the early evolution of Eleutherodactylus frogs in the Caribbean.

"I am thrilled that, little by little, we are learning about the wildlife that lived in Puerto Rico 29-27 million years ago," Velez-Juarbe said. "Finds like this help us unravel the origins of the animals we see in the Caribbean today."

Ancient long-lived pioneer trees store majority of carbon in tropical forests

Old-growth forest on Barro Colorado Island, in Panama, hosts 300 tree species. Photo by Christian Ziegler/UT-Austin

April 10 (UPI) -- Trees that grow fast, live long and reproduce slowly, known as long-lived pioneers, store the majority of carbon found in tropical forests.

Scientists arrived at their discovery after analyzing the different development strategies used by various tree species.

"In an earlier study we found that trees pursue different strategies during their development, and those strategies can be classified according to two independent criteria," lead study author Nadja Rüger, a scientist with the German Center for Integrative Biodiversity Research, told UPI.

Some tree species, scientists found, grow fast and die young. Other species grow slow and reach old age. Different tree species also achieve different statures.

Fertility also influences a trees' development pattern. Some trees grow big and tall but are limited in their reproductive abilities. Smaller species like shrubs can reproduce in great numbers, but they fail to get very big.

Long-lived pioneers are a unique group. They grow fast, helping to pioneer new patches of forest. But they also grow old, allowing them to reach great stature. There are trade-offs, of course. Long-lived pioneers, or infertile giants, produce only small numbers of offspring.

To better understand how the different characteristics of tree species influence the formation, composition and evolution of tropical forests, scientists plugged data on growth rates, longevity, stature and fertility into sophisticated computer models.

"We discovered that the nearly 300 unique tree species can be represented in our computer model by just five functional groups and still produce accurate forecasts of tree composition and forest biomass over time," study co-author Caroline Farrior, assistant professor of integrative biology at the University of Texas at Austin, told UPI.

The models showed long-lived pioneers account for a majority of a forest's biomass and carbon storage.

The research -- published this week in the journal Science -- could be used to craft more effective conservation plans, and to prioritize the protection for forests with larger numbers of long-lived pioneers.

When studying forest development and composition in the past, scientists focused mostly on the trade-off between growth and survival -- grow fast and die young, or grow slow and grow old. But the latest analysis showed that balancing the trade-off between stature and reproduction is just as important.

For the most recent study, scientists utilized tree data meticulously collected from dense forests on Barro Colorado Island in Panama. Researchers are currently working to see if they can repeat their predictive modeling efforts for forests that haven't already been extensively studied by scientists.

"One of our goals is to extend this approach to forests with less complete data, very young secondary forests and tropical dry forests," Rüger said. "If this succeeds, it will be much easier than today to scientifically support renaturation projects and sustainable timber use in tropical forests, and also, of course, to estimate how effectively re-growing forests contribute to carbon storage and, therefore, to climate mitigation."

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Hidden armies of crown of thorns starfish can devastate coral reefs

Juvenile crown of thorns starfish eat algae. As adults, they become voracious consumers of coral. Photo by The University of Sydney

April 9 (UPI) -- As adults, crown of thorns starfish are voracious consumers of coral, but as juveniles, the starfish only eat algae.

New research suggests crown of thorns starfish can delay their dietary switch for 6.5 years, proliferating on reefs as coral recover. These hidden armies can devastate reefs made vulnerable by coral bleaching.

"Despite the notoriety of the large adult starfish and their propensity for coral prey, the juveniles eat algae," Maria Byrne, professor of marine and developmental biology at the University of Sydney in Australia, said in a news release. "For outbreaks to arise, these algal-eating juveniles must transition into coral predators."

When coral is abundant, crown of thorns starfish transition to a coral diet after only a few months. But the starfish can bide their time, delaying adulthood, on reefs where the coral supply is depleted.

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"This Peter Pan effect means that populations of juvenile crown of thorns starfish can build up on reefs in the absence of coral," said Dione Deaker, doctoral student at the University of Sydney. "They could become a hidden army waiting to consume reefs as the reefs recover."

Coral damage caused by crown of thorns starfish has been documented across the Great Barrier Reef and the reefs of the Indo-Pacific, but how exactly the starfish transition from their juvenile diet to their adult eating pattern hasn't been closely studied.

For the new study, published this week in the journal Biology Letters, scientists reared crown of thorns starfish in the lab on a diet of algae for 10 months and 6.5 years. Both groups reached the same maximum size, between 16 to 18 millimeters. After both groups were transitioned to a coral diet, they adopted similar growth patterns.

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"Suppression of the switch to a coral diet due to scarcity of prey might occur after coral bleaching events," Deaker said. "The remarkable resilience of juvenile starfish to coral scarcity complicates our ability to age them and indicates the potential for reserves of juveniles to accumulate on the reef to seed outbreaks when favorable conditions arise."

Researchers suggest reef protection and conservation plans need to account for the possibility of a reserve population, a hidden army of crown of thorns starfish, lying in wait among recovering coral reefs.

"Another important implication of our findings is the possibility that the current adult starfish killing programs used to manage crown of thorns starfish might, in fact, trigger a feedback mechanism in the starfishes' transition to coral predator as juveniles are released from adult competition," Byrne said.