Caribbean conservationists can now help save threatened island species thanks to Durrell
November 2011. Conservationists in the Caribbean are now armed with a range of new skills and tools to help them recover some of their most threatened island species, thanks to a successful training programme run by Durrell Wildlife Conservation Trust.
Recently the Punta Cana Ecological Foundation in the Dominican Republic played host to eighteen participants from the Dominican Republic, Haiti, Puerto Rico and Montserrat as they attended the eight day Island Species-Led Action (ISLA) course. This specialist programme focuses on the recovery of endangered birds and mammals, with particular attention on threats such as invasive species and habitat loss, along with providing a rare opportunity for island conservationists and researchers to explore some of the issues concerning the recovery of island species and habitats.
Commenting on the success of the recent course Dr. Jose Nunez-Mino, Field Project Manager for Durrell said, "Hispaniola, or the Dominican Republic and Haiti combined, support some of the world's most threatened yet unique wildlife. By bringing together conservationists from across the island the course has forged links between different institutions that are now starting to think about how we can work together to conserve the unique species found on Hispaniola."
The training programme was made possible thanks to funding from a Jersey-based trust fund and forms part of a longer-term project to conserve Hispaniola's remaining native land mammals.
Backed by Durrell
Designed to encourage participants to think broadly about problems they face and ways to overcome them, the course was first developed by staff from Durrell's Jersey based International Training Centre (ITC). It draws upon the ITC's experience and expertise in delivering applied conservation training courses to more than 3000 conservationists from 128 countries, since it was established in 1985. The training programme also makes use of knowledge gained from Durrell's long history of practical interventions in the Indian Ocean, Caribbean and Pacific Ocean.
Since its launch in Jersey, the ISLA course has been run in the Seychelles, Mauritius, St. Lucia, Galapagos, Guam, Fiji, the Philippines and now the Dominican Republic.
http://www.wildlifeextra.com/go/news/carribean-species.html
More about Durrell Wildlife Conservation Trust
Showing posts with label Caribbean. Show all posts
Showing posts with label Caribbean. Show all posts
Wednesday, November 16, 2011
Saturday, August 27, 2011
Darwin's Butterflies? Spectacular Species Radiation in the Caribbean Studied With 'DNA Barcoding'
ScienceDaily (Aug. 25, 2011) — In one of the first taxonomic revisions of Neotropical butterflies that utilizes 'DNA barcoding', Andrei Sourakov (University of Florida, Florida Museum of Natural History) and Evgeny Zakharov (University of Guelph, Canadian Centre for DNA Barcoding at the Biodiversity Institute of Ontario) uncovered a spectacular degree of evolutionary divergence within the satyrine butterfly genus Calisto.
The study was published in the open-access journal Comparative Cytogenetics.
The Caribbean has a remarkable diversity of habitats and wildlife. More than 200 species of butterflies belonging to some 100 genera live on the islands, with most genera represented by a single species. Many species are endemic to the region, that is they do not occur anywhere else. This distinctive fauna apparently arose as a result of species immigrating from the mainland at some point during the islands' history, and later evolving mostly into island isolates.
The satyrine butterfly genus Calisto is the most notable of them, because it has the largest number of extant species compared to other butterfly genera found in the region. Until the present revision, Calisto had comprised 54 named taxa, which occupy an extremely diverse array of habitats, suggestive of adaptive radiation on the scale of other classic examples, such as the Galápagos or Darwin's finches.
The authors of the study applied a new set of molecular characters to clarify the classification and evolution of Calisto butterflies. The 'DNA barcoding' technique is based on the analysis of short, standardized gene region within mitochondrial DNA, and provides an efficient method for species identification. As a result, Calisto now contains 34 species and 17 subspecies and new data shed light on the general evolutionary history of the genus.
The discovered spectacular degree of DNA divergence suggests a diversification period of 4-8 million years. Species of Calisto that occur only in Puerto Rico, Cuba, and Jamaica were found likely to have evolved from various Hispaniolan ancestors. The study found no support for previously advocated theories of evolution through geographic separation events due to plate tectonics. The evolutionary time-frame and the phylogenetic position of non-Hispaniolan taxa suggest that ancient dispersal events from Hispaniola to other islands and adaptive radiation within Hispaniola are likely responsible for the diversification within the genus Calisto.
http://www.sciencedaily.com/releases/2011/08/110825102245.htm
The study was published in the open-access journal Comparative Cytogenetics.
The Caribbean has a remarkable diversity of habitats and wildlife. More than 200 species of butterflies belonging to some 100 genera live on the islands, with most genera represented by a single species. Many species are endemic to the region, that is they do not occur anywhere else. This distinctive fauna apparently arose as a result of species immigrating from the mainland at some point during the islands' history, and later evolving mostly into island isolates.
The satyrine butterfly genus Calisto is the most notable of them, because it has the largest number of extant species compared to other butterfly genera found in the region. Until the present revision, Calisto had comprised 54 named taxa, which occupy an extremely diverse array of habitats, suggestive of adaptive radiation on the scale of other classic examples, such as the Galápagos or Darwin's finches.
The authors of the study applied a new set of molecular characters to clarify the classification and evolution of Calisto butterflies. The 'DNA barcoding' technique is based on the analysis of short, standardized gene region within mitochondrial DNA, and provides an efficient method for species identification. As a result, Calisto now contains 34 species and 17 subspecies and new data shed light on the general evolutionary history of the genus.
The discovered spectacular degree of DNA divergence suggests a diversification period of 4-8 million years. Species of Calisto that occur only in Puerto Rico, Cuba, and Jamaica were found likely to have evolved from various Hispaniolan ancestors. The study found no support for previously advocated theories of evolution through geographic separation events due to plate tectonics. The evolutionary time-frame and the phylogenetic position of non-Hispaniolan taxa suggest that ancient dispersal events from Hispaniola to other islands and adaptive radiation within Hispaniola are likely responsible for the diversification within the genus Calisto.
http://www.sciencedaily.com/releases/2011/08/110825102245.htm
Friday, May 27, 2011
new bat uncovered in the Caribbean
Researchers have declared a new species of bat from the Caribbean island of St. Vincent. While the new bat had been documented before, it was long believed to be a member of a similar species that is found throughout South America and a few Caribbean Islands, that is until PhD student Peter Larsen noticed it was far larger than its relative down south.
"A year or so went by [after collecting the species] and I happened to look at this species […] and compared it to what we thought it was–a species from Trinidad. But the St. Vincent bat was huge comparatively speaking," said Larsen, who is studying at Texas Tech University, in a press release.
Larsen told mongabay.com that the bat is "a few grams heavier and is a few millimeters longer in most measurements that we took" than its closest relative the aptly named little big-eared bat (Micronycteris megalotis). While this may not sound like much, the nre bats weigh only around 8 grams and measure around 30 millimeters, so a few grams and millimeters here or there makes a big difference in these animals.
The paper describes the bat as "medium-sized" in comparison to the nine or so other known species of Micronycteris bats.
Researchers believed the new bat species became stranded from the mainland population between 600,000 and a million years ago, theorizing that sea-level rise due to melting glacier eventually cut St. Vincent off. Once stranded, the bat species took its own evolutionary path, including becoming noticeably larger and changes in its cranium.
Larsen and his team decided to name the species the Garifuna big-eared bat (Micronycteris garifuna) after the Garifuna people who inhabit St. Vincent and other areas of the Caribbean and Central America. The Garifuna ancestry includes native Carib, Arawak, and West African.
The Garifuna bat preys on insects, providing an ecosystem service to the island by keeping insect populations in check. In fact, according to another graduate student, Lizette Siles, who worked on the study, the Garifuna bats are especially adept hunters.
"They can actually pick their insect prey off the surface of rocks and leaves," Siles explained in a press release. "Not all insectivores can do that, because most insectivores catch their prey on the fly. Their big ears, wide wings and membranes between the rear feet and tail allow them to maneuver better."
Bats are one of the most diverse mammal families in the world (second only to rodents) with around 1,100 known species. Although they are often unfairly loathed by people, they provide a number of important services including pest control and seed dispersal.
Thousands of new species are discovered every year, but new mammals are among the least likely. In 2008, researchers documented the discovery of 18,225 new species, only 41 (0.22 percent) of which were new mammals.
CITATION: Peter A. Larsen, Lizette Siles , Scott C. Pedersen, Gary G. Kwiecinski. A new species of Micronycteris (Chiroptera: Phyllostomidae) from Saint Vincent, Lesser Antilles. Mammalian Biology (2011). doi:10.1016/j.mambio.2011.01.006.
Jeremy Hance
mongabay.com
May 26, 2011
http://news.mongabay.com/2011/0526-hance_newbat.html
"A year or so went by [after collecting the species] and I happened to look at this species […] and compared it to what we thought it was–a species from Trinidad. But the St. Vincent bat was huge comparatively speaking," said Larsen, who is studying at Texas Tech University, in a press release.
Larsen told mongabay.com that the bat is "a few grams heavier and is a few millimeters longer in most measurements that we took" than its closest relative the aptly named little big-eared bat (Micronycteris megalotis). While this may not sound like much, the nre bats weigh only around 8 grams and measure around 30 millimeters, so a few grams and millimeters here or there makes a big difference in these animals.
The paper describes the bat as "medium-sized" in comparison to the nine or so other known species of Micronycteris bats.
Researchers believed the new bat species became stranded from the mainland population between 600,000 and a million years ago, theorizing that sea-level rise due to melting glacier eventually cut St. Vincent off. Once stranded, the bat species took its own evolutionary path, including becoming noticeably larger and changes in its cranium.
Larsen and his team decided to name the species the Garifuna big-eared bat (Micronycteris garifuna) after the Garifuna people who inhabit St. Vincent and other areas of the Caribbean and Central America. The Garifuna ancestry includes native Carib, Arawak, and West African.
The Garifuna bat preys on insects, providing an ecosystem service to the island by keeping insect populations in check. In fact, according to another graduate student, Lizette Siles, who worked on the study, the Garifuna bats are especially adept hunters.
"They can actually pick their insect prey off the surface of rocks and leaves," Siles explained in a press release. "Not all insectivores can do that, because most insectivores catch their prey on the fly. Their big ears, wide wings and membranes between the rear feet and tail allow them to maneuver better."
Bats are one of the most diverse mammal families in the world (second only to rodents) with around 1,100 known species. Although they are often unfairly loathed by people, they provide a number of important services including pest control and seed dispersal.
Thousands of new species are discovered every year, but new mammals are among the least likely. In 2008, researchers documented the discovery of 18,225 new species, only 41 (0.22 percent) of which were new mammals.
CITATION: Peter A. Larsen, Lizette Siles , Scott C. Pedersen, Gary G. Kwiecinski. A new species of Micronycteris (Chiroptera: Phyllostomidae) from Saint Vincent, Lesser Antilles. Mammalian Biology (2011). doi:10.1016/j.mambio.2011.01.006.
Jeremy Hance
mongabay.com
May 26, 2011
http://news.mongabay.com/2011/0526-hance_newbat.html
Thursday, December 30, 2010
Environmental Factors Limit Species Diversity, Lizard Study Finds
ScienceDaily (Dec. 29, 2010) — New research on lizards in the Caribbean demonstrates that species diversification is limited by the environment. The finding supports and extends the MacArthur-Wilson theory of island biogeography.
It's long been accepted by biologists that environmental factors cause the diversity -- or number -- of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.
The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.
Glor and Rabosky focused on species diversity -- the number of distinct species of lizards -- not the number of individual lizards.
"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.
Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."
Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
http://www.sciencedaily.com/releases/2010/12/101220163248.htm
It's long been accepted by biologists that environmental factors cause the diversity -- or number -- of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.
The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.
Glor and Rabosky focused on species diversity -- the number of distinct species of lizards -- not the number of individual lizards.
"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.
Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."
Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
http://www.sciencedaily.com/releases/2010/12/101220163248.htm
Environmental Factors Limit Species Diversity, Lizard Study Finds
ScienceDaily (Dec. 29, 2010) — New research on lizards in the Caribbean demonstrates that species diversification is limited by the environment. The finding supports and extends the MacArthur-Wilson theory of island biogeography.
It's long been accepted by biologists that environmental factors cause the diversity -- or number -- of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.
The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.
Glor and Rabosky focused on species diversity -- the number of distinct species of lizards -- not the number of individual lizards.
"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.
Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."
Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
http://www.sciencedaily.com/releases/2010/12/101220163248.htm
It's long been accepted by biologists that environmental factors cause the diversity -- or number -- of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.
The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.
Glor and Rabosky focused on species diversity -- the number of distinct species of lizards -- not the number of individual lizards.
"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.
Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."
Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
http://www.sciencedaily.com/releases/2010/12/101220163248.htm
Sunday, May 30, 2010
Displaced Fish Is Ravaging Caribbean Reefs
One of the prime suspects in the destruction of Caribbean coral has been found guilty, but researchers were wrong about its motive. For years scientists thought that the threespot damselfish was nibbling star coral to death because overfishing had reduced its natural predators. But a new survey shows that the damage is being done because the damselfish was forced from its natural habitat—and in fact the fish is also suffering. The good news is that it might be possible to restore the reefs to health, though that effort could take at least a decade.
The case begins not with the star coral but with another species, the branching staghorn coral (Acropora cervicornis). Once, the dominant coral in the Caribbean, staghorns—and their less-common relative, the elkhorn—were decimated in the 1970s and '80s, the victims of a bacterial infection called white-band disease. More than 90% of the coral died, and populations hit their lowest levels in over 3000 years.
That was bad news for the damselfish (Stegastes planifrons), which survived on the staghorn coral. The ill-tempered fish, which has been known to bite the fingers of divers who approach its territory, nibbles incessantly on the coral—not to eat it but to kill the living tissue so that algae, the fish's favorite food, can grow on the dead coral skeletons. The damselfish never destroyed the staghorn coral, because the coral grew fast enough to recover from the constant nibbling.
But when the damselfish was forced to relocate to star coral (Montastraea), this coral began dying. Many scientists concluded that overfishing had thinned the ranks of damselfish predators, such as snappers and small groupers, and that the population of damselfish had exploded, wreaking havoc on star coral reefs.
But no one had tested this hypothesis. So a team of researchers set up surveys at 10 coral sites in the Florida Keys, Bahamas, and Cayman Islands and off the coasts of Belize and Jamaica. "We wanted to find out if the more heavily fished reefs had more threespot damselfish, and if not, what was controlling the abundance of threespots," says paleontologist Richard Aronson of the Florida Institute of Technology in Melbourne. He explains that the team chose the sites to compare the heavily fished areas, such as off Jamaica, with the moderately fished reefs of the Keys and Bahamas and the protected reefs of the Caymans and Belize.
Damselfish are indeed responsible for the star coral die-off, the team found, but not because their numbers are booming out of control. In fact, the researchers report this week in PLoS ONE, the fish's numbers have declined overall. Aronson says that's because star corals offer fewer places to hide than the staghorn, leaving the damselfish more vulnerable to predation.
So why is star coral dying? Aronson and colleagues conclude that it grows back much slower than the staghorn, so it doesn't recover from the damselfish algae farming. The change has placed all Caribbean reefs—already in jeopardy from pollution, silting, warming waters, and oil spills—in even greater danger. "The threespots have now killed substantial amounts of star coral, and [they] are doing damage that will take decades or centuries to fix," Aronson says.
But the reefs may not be lost. One practical solution, Aronson explains, is to restore the staghorn and elkhorn to the reefs. This can be done via a painstaking aquatic form of tree farming. Biologists first grow nubbins, or small baby coral, on cinder blocks that have been submerged, and then they transplant the growing corals to the reefs. "Once the staghorn is restored, the threespots will move back into their preferred neighborhoods," Aronson says.
The paper "drives home the fundamental importance of disease outbreaks in the changes we've seen on Caribbean coral reefs over the last several decades," says marine biologist John Bruno of the University of North Carolina, Chapel Hill. It's "an important contribution from a group of scientists who know more about these reefs than anyone else in the world."
Phil Berardelli
http://www.sciencemag.org/
The case begins not with the star coral but with another species, the branching staghorn coral (Acropora cervicornis). Once, the dominant coral in the Caribbean, staghorns—and their less-common relative, the elkhorn—were decimated in the 1970s and '80s, the victims of a bacterial infection called white-band disease. More than 90% of the coral died, and populations hit their lowest levels in over 3000 years.
That was bad news for the damselfish (Stegastes planifrons), which survived on the staghorn coral. The ill-tempered fish, which has been known to bite the fingers of divers who approach its territory, nibbles incessantly on the coral—not to eat it but to kill the living tissue so that algae, the fish's favorite food, can grow on the dead coral skeletons. The damselfish never destroyed the staghorn coral, because the coral grew fast enough to recover from the constant nibbling.
But when the damselfish was forced to relocate to star coral (Montastraea), this coral began dying. Many scientists concluded that overfishing had thinned the ranks of damselfish predators, such as snappers and small groupers, and that the population of damselfish had exploded, wreaking havoc on star coral reefs.
But no one had tested this hypothesis. So a team of researchers set up surveys at 10 coral sites in the Florida Keys, Bahamas, and Cayman Islands and off the coasts of Belize and Jamaica. "We wanted to find out if the more heavily fished reefs had more threespot damselfish, and if not, what was controlling the abundance of threespots," says paleontologist Richard Aronson of the Florida Institute of Technology in Melbourne. He explains that the team chose the sites to compare the heavily fished areas, such as off Jamaica, with the moderately fished reefs of the Keys and Bahamas and the protected reefs of the Caymans and Belize.
Damselfish are indeed responsible for the star coral die-off, the team found, but not because their numbers are booming out of control. In fact, the researchers report this week in PLoS ONE, the fish's numbers have declined overall. Aronson says that's because star corals offer fewer places to hide than the staghorn, leaving the damselfish more vulnerable to predation.
So why is star coral dying? Aronson and colleagues conclude that it grows back much slower than the staghorn, so it doesn't recover from the damselfish algae farming. The change has placed all Caribbean reefs—already in jeopardy from pollution, silting, warming waters, and oil spills—in even greater danger. "The threespots have now killed substantial amounts of star coral, and [they] are doing damage that will take decades or centuries to fix," Aronson says.
But the reefs may not be lost. One practical solution, Aronson explains, is to restore the staghorn and elkhorn to the reefs. This can be done via a painstaking aquatic form of tree farming. Biologists first grow nubbins, or small baby coral, on cinder blocks that have been submerged, and then they transplant the growing corals to the reefs. "Once the staghorn is restored, the threespots will move back into their preferred neighborhoods," Aronson says.
The paper "drives home the fundamental importance of disease outbreaks in the changes we've seen on Caribbean coral reefs over the last several decades," says marine biologist John Bruno of the University of North Carolina, Chapel Hill. It's "an important contribution from a group of scientists who know more about these reefs than anyone else in the world."
Phil Berardelli
http://www.sciencemag.org/
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