A new study has revealed that male bottlenose dolphins impress females by carrying pieces of plants and twigs defying earlier beliefs that it is their playful behaviour that does the trick for them.

It is quite rare in the animal kingdom that animals indulge in sexual display through object-carrying, with only humans and chimpanzees doing anything similar.

However, the habit has been observed in isolated populations of dolphins in river dolphins in Brazil, Venezuela and Bolivia suggests it has either been passed on through generations or evolved separately in different groups.

This discovery could provide proof of the existence of dolphin culture that is defined as a non-hereditary, complex skill taught to some members of a population by others and passed down through generations.

Until recently, culture was seen as a defining human characteristic not shared by other species. This is why the suggestion that dolphins also exhibit cultural behaviours is controversial.

Dr Tony Martin of the British Antarctic Survey in Cambridge, and Dr Vera da Silva, from the National Institute of Amazonian Research in Brazil studied 6,026 groups of dolphins in Mamiraua, a flooded rainforest reserve in Brazil.

Out of these 221 groups, at least one individual was carrying an object such as weed, a stick or a lump of clay.

Such groups usually contained adult females, and the carriers were nearly always adult males. Aggression between males was also 40 times more likely in the object-carrying groups.

The scientists said that if the object-carrying was just playfulness, females and juveniles would also have been expected to carry objects, however they did not.

DNA analysis of tissue samples collected from adults and calves was also carried out, which backed up their theory.

“I was struck by how many of the most frequent object-carriers were on the list of probable fathers of individual calves,” Telegraph quoted Dr. Martin, as saying.

He added: “It’s so unusual that many of my colleagues were sceptical when I first suggested the idea, but now I think the evidence is overwhelming.”

Bottlenose dolphins in Shark Bay, western Australia, break off pieces of marine sponge carrying them on their snouts in order to protect themselves as they probe the ocean floor.

It is the only known example of tool use among dolphins, and the scientists who made the discovery also concluded this was evidence of cultural behaviour.

“I’m now convinced this behaviour is social learning – and from that point of view, you can call it a culture,” said Dr Michael Krutzen, from the University of Zurich in Switzerland.

The findings of the study will be presented at a conference organised by the Society for Marine Mammalogy in Cape Town, South Africa. (ANI)

Professor Brian Robinson has revealed that he started developing the gel after his son, Wellington surgeon Simon, asked him to do so.

Every year, doctors in New Zealand conduct several thousand endoscopic sinus operations to relieve sinusitis.

The operation leaves about a third of patients with a type of scarring known as “adhesions”, which can block sinus passages and require further surgery.

Professor Robinson has revealed that university chemists decided to try using a chemically modified form of the polymer chitosan, derived from the body part of squid and crabs.

“We were lucky. The first thing that we tried worked,” the NZPA quoted him as saying.

University of Adelaide researchers have tested the gel on sheep, which have a similar sinus structure to humans.

The researchers have also conducted a small patient trial, and now plan to undertake larger ones.

So far as using the gel is concerned, the researchers have revealed that they mix ingredients from two tubes and spray it into the patient’s nose. The gel then forms a thick, sticky layer, which gradually leaves the nose over two days.

As it reduces bleeding during surgical procedures, doctors can have a better view of what they are doing.

Professor Robinson has revealed that despite being made from a fish extract, the gel does not smell.

“It’s really a very exciting product which may have a profound effect on a lot of people around the world, not only for the sinuses but other surgery,” he said. (ANI)

The findings lengthen Europe’s list of freshwater fish to 522 species.

Study authors say many more undescribed fish have been found or are suspected to exist, potentially taking the total number of confirmed species to 600 or higher.

The new species were discovered during a seven-year assessment of the conservation status of freshwater fish in Europe that was conducted in collaboration with the World Conservation Union (IUCN).

“The new species come from all over Europe,” said co-author Jörg Freyhof of the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin, Germany.

According to Freyhof, the new freshwater species might have remained undiscovered for so long because until now, scientists had not compared fish closely enough across countries’ boundaries.

“Fish are a massive part of our fauna, but people don’t tend to notice them because they are out of sight,” said Kevin Smith of the IUCN Freshwater Biodiversity Unit.

“Unlike free-ranging animals such as birds and mammals, fish are often isolated from each other because river basins and lakes act as barriers that keep unique populations apart,” he said.

The new species include various types of fishes.

One of them is the world’s smallest known fish cisco, which is a type of whitefish. It was found in Germany’s Lake Stechlin, north of Berlin.

This fish, silvery pink in colour, was found to be distinct from a much larger cisco species from the same lake.

Another remarkable discovery was of two new species of trout like Charr in alpine lakes in Germany and Switzerland.

The study team also named eight new Sculpin, a type of small, squat river fish often found under stones.

One of these freshly named species, ‘Cottus perifretum’, had been labeled as another European sculpin, ‘ Cottus gobio’.

But according to Freyhof, the two species are relatively easy to tell apart.

“The skin of Cottus gobio is very smooth, but perifretum’s is like sandpaper,” he said. “There are many molecular markers which also distinguish the two species,” he added.

Another species which were even harder to tell apart were members of a group of lake fish from Central and Eastern Europe called Shemayas.

But the study team was able to identify four new Shemaya species.

“At first glance, they appear like herrings. But you really have to look at them in detail,” said Freyhof. “Shemayas have a wide distribution, but they are highly localized and are usually difficult to collect,” he added.

“There are very few of these species in the museum collections. Only after we checked almost all the populations in detail did we realize there are so many,” said Freyhof.

“Once you realize a fish looks different, then you can go into more detail, analyzing its bones, scales, DNA, and so on,” Freyhof added.

A recent research also determined that more than a third of Europe’s 522 freshwater fish species are at risk of extinction and that 12 species are already extinct.

Regions where freshwater fish face the highest risk of extinction include the lower reaches of the Danube, Dnister, Ural, and Volga rivers in Eastern Europe. (ANI)

Walter Salzburger, Ingo Braasch and Axel Meyer studied 19 cichlid species reared at Konstanz University.

They discovered that a gene involved in producing yellow pigment cells in oval spots on the fishes’ fins, known as egg-dummies, are found on the anal fins of the male fish and are crucial to mating.

The fish are known as maternal mouthbrooders because once the female has laid her eggs, she picks them up in her mouth, according to the background information in an article published in online open access journal BMC Biology.

According to the researchers, the female fish gets attracted by the egg-dummy markings believing them to be eggs, and approaches the male.

When the female is close to the anal fin, the male discharges sperm into the female’s mouth to fertilize the eggs.

The researchers have revealed that the gene involved in producing the egg-dummy markings is called the colony-stimulating factor 1 receptor a (or csf1ra).

They have also shown that the gene was expressed in the egg-dummies of a distantly related species, in which the spots developed on the pectoral fins rather than the anal fins.

“The two kinds of independently evolved egg-dummies serve as a model system to test whether the same genetic pathways are involved in the morphogenesis of both types of dummies,” say the authors. (ANI)

The report benchmarks for the first time the number of annual deaths caused globally by pollution from marine vessels, with coastal regions in Asia and Europe the most affected.

The study, undertaken by James Corbett and James Winebrake, correlates the global distribution of particulate matter (black carbon, sulfur, nitrogen and organic particles) released from the smoke stacks of ships with heart disease and lung cancer mortalities in adults.

The results indicate that approximately 60,000 people die prematurely around the world each year from shipping-related emissions. Under current regulation, and with the expected growth in shipping activity, it is estimated that the annual mortalities from ship emissions could increase by 40 percent by 2012.

Annual deaths related to shipping emissions in Europe are estimated at 26,710, while the mortality rate is 19,870 in East Asia and 9,950 in South Asia. North America has approximately 5,000 premature deaths, concentrated mostly in the Gulf Coast region, the West Coast and the Northeast, while the eastern coast of South America has 790 mortalities.

The primary reason for the health risk is the residual oil, on which the ships run. It has sulfur content thousands of times greater than on-road diesel fuel. “Residual oil is a byproduct of the refinery process and tends to be much dirtier than other petroleum products,” said Winebrake.

“We needed to know what the benefits are of cleaning up this fuel,” explains Winebrake. “Now we can evaluate the human health impacts of policies to require low-sulfur fuels for the shipping industry or that require ships to put emissions control technology on their vessels. Our study will help inform this policy debate,” he adds.

Up until recently, researchers had little information with which to work. Emissions data for marine vessels had to be linked with data tracking the movement of these vessels around the world. In the new report, researchers have mapped marine pollution concentrations over the oceans and on land. This has helped to estimate global and regional mortalities from ship emissions by integrating global ship inventories, atmospheric models and health impacts analyses.

“This study will help inform policymakers about some of the health impacts associated with ship emissions and the long range transport of those emissions to population centers,” said Winebrake. “We now have a benchmark by which we can begin to evaluate the benefits of emission reduction policies,” he added.

“Our work will help people decide at what scale action should be taken,” says Corbett. “We want our analysis to enable richer dialogue among stakeholders about how to improve the environment and economic performance of our freight systems,” he added.

The report has come in the midst of current discussions by the International Maritime Organization to regulate emissions from ships. (ANI)

A team from the University of Alaska Fairbanks surveyed the western region of the Aleutians this year. Last year, an assessment of the eastern region was undertaken.

The organisms were found while surveying more than 1000 miles of rarely-explored coastline, from Attu to the Tigalda Islands. Logging more than 300 hours underwater, the divers collected hundreds of water, biological and chemical samples during 440 dives. Armed with underwater cameras and video cameras, the divers took hundreds of photographs and dozens of short movies of the creatures that inhabit the coast of the Aleutians.

During the dives, two potentially new species of sea anemones have been discovered, whose size ranges from that of a softball to the size of a basketball.

“These are ‘walking’ or ’swimming’ anemones because they move across the seafloor as they feed. While most sea anemones are anchored to the seabed, a ’swimming’ anemone can detach and drift with ocean currents,” says Stephen Jewett, a professor of marine biology and the dive leader on the expedition .

Another new species is a kelp or brown algae that scientists have named the “Golden V Kelp” or Aureophycus aleuticus. Up to ten feet long, the kelp was discovered near thermal vents in the region of the Islands of the Four Mountains. According to Mandy Lindeberg, a member of the expedition, “The kelp may represent a new genus, or even family, of the seaweed”.

Samples from the dives are being used to catalog biodiversity in the region, assess water quality and potential contaminants. According to Jewett, this is the first time the remote nearshore region of the Aleutian Chain has undergone an in-depth marine assessment.

“Since the underwater world of the Aleutian Islands has been studied so little, new species are being discovered, even today,” said Jewett. He adds that even more new species may be revealed as samples collected during the dives continue to be analyzed. (ANI)

According to a report released by the World Conservation Union (IUCN), 200 out of a total of 522 freshwater fish species in Europe are at a serious risk of extinction.

The report also states that the European eel figures on the critically endangered list of freshwaterfish species. The number of these eels reaching rivers from their breeding waters in the Atlantic Ocean has dropped between 95 and 99 percent since 1980.

Another endangered species includes the Chornaya Gudgeon (Gobio delyamurei), known to live in a single river in Ukraine. It is also in danger of being wiped out because of the divertion of its waters for farmland irrigation.

The Jarabugo (Anaecypris hispanica), which is found in southwest Spain and Portugal, has suffered losses of more than 50 percent in the last ten years due to multiple factors.

Listed among the already extinct species is the houting, a herringlike coastal fish that migrated up rivers in northern Europe to spawn. Most of the extinct fish recorded in the study lived in Central Europe during the 1970s and ’80s and were most likely victims of pollution.

In general, the declines are largely due to the last hundred years of human environmental impacts, such as dam construction and water extraction. Water removal in some parts of Europe has also caused rivers to dry up in summer months, a problem aggravated by climate change impacts.

Another reason for the decline is the introduction of non-native species in Europe.

“In Spain and Portugal, for instance, predatory pike introduced from Central Europe and largemouth bass introduced from North America have proved disastrous. These fish eat all the native fauna, which are not adapted to predation at all,” said Jörg Freyhof, co-author of the research. “Likewise, introduced brown trout from northern Europe have seriously jeopardized endemic trout populations in Balkan countries,” he added.

According to IUCN’s Darwall, “The endangered fish are an important part of our heritage and are critical to the freshwater ecosystems upon which we depend, such as for water purification and flood control.”

“Many of these species can be saved through relatively simple measures. All we need is the public and political will to make it happen,” Darwall added.

Other regions where freshwater fish face the highest risk of extinction include the lower reaches of the Danube, Dnister, Ural, and Volga rivers in Eastern Europe. (ANI)

The research team has also appealed for the introduction of alternatives to ensure proper marine and sewage management.

Published today’s issue of Nature, the study claims that coral reefs are becoming unhealthy and overrun by seaweed.

In the 1980s, reefs in the Caribbean were hit by the devastating impact of the near-extinction of the herbivorous urchin, Diadema antillarum, with devastating results.

Along with parrotfish, this grazing urchin kept seaweed levels down, creating space for coral to grow. Parrotfish are now the sole grazers of seaweed on many Caribbean reefs, but fishing has limited their numbers.

With insufficient parrotfish grazing, corals are unable to recover after major disturbances like hurricanes and become much less healthy as a result.

According to Professor Peter Mumby, the lead author of the study, “The future of some Caribbean reefs is in the balance and if we carry on the way we are then reefs will change forever. This will be devastating for the Caribbean’s rich marine environment, which is home to a huge range of species as well as being central to the livelihood of millions of people.”

The paper argues that in order to secure a future for coral reefs, particularly in light of the predicted impact of climate change, parrotfish need to be protected.

Parrotfish are frequently caught in fish traps that are widely used in the Caribbean, with many ending up on restaurant diners’ plates.

Mumby says practical steps can be taken to protect parrotfish and help reef regeneration, and has recommended a change in policy to establish controls over the use of fish traps, which parrotfish are particularly vulnerable to.

The US Environmental Protection Agency, the Royal Society, the Natural Environment Research Council and the National Science Foundation funded the research. (ANI)

Scientists have dated the mollusc as having been alive since the time of Queen Elizabeth I and William Shakespeare.

However, 3.4-inch clam died by the time scientists verified its true age at 405 years.

Researchers who discovered the clam, say it could yield valuable information to help research into ageing.

Marine biologists from the Bangor University School of Ocean Sciences found the clam from the species ‘ocean quahog’, among a haul of 3,000 empty shells and 34 live molluscs while dredging the Atlantic seabed north of Iceland.

“We had no idea it would be that old,” said Alan Wanamaker, one of the researchers on the team, who is using the growth patterns on the molluscs’ shells to study climate variations.

It was only when they examined it earlier this month that they realised how old it really was.

But by that time, the clam’s flesh had been thrown away and only its shell remained.

Wanamaker said the age of the mollusc – nicknamed Ming, after the Chinese dynasty on the throne when it began its life – could be calculated precisely by counting the layers in its shell under a microscope.

He said the shell only grew in summer when the water was warmer and the plankton it ate was plentiful.

Each year a layer as thin as 0.1mm is laid down, said Wanamaker.

He said when the team cut the clam’s shell in half, they counted 405 lines, which made it 31 years older than the previous oldest animal, another ocean quahog now in a German museum, reports Times Online. (ANI)

Hidden away inside rotten branches and trunks, these remarkable creatures temporarily alter their biological makeup so they can breathe air.

Dr Scott Taylor of the Brevard County Environmentally Endangered Lands Programme in Florida, who discovered these fish while wading through swamps in Belize and Florida, said, he found hundreds of these creatures hiding out of the water in the branches and trunks of trees.

The fish had flopped their way to their new homes when their pools of water around the roots of mangroves dried up. Inside the logs, they lined up end to end along tracks carved out by insects, said Dr Taylor.

Around two inches long, the mangrove killifish, known by the biological name Rivulus marmoratus Poey, normally live in muddy pools and the flooded burrows of crabs in the mangrove swamps of Florida, Latin American and Caribbean.

Dr Taylor said though the fish are fiercely territorial, they curb their aggression when hiding inside logs or tree trunks, where conditions are often cramped.

Dr Taylor said the creatures are a little odd.

“They really don’t meet standard behavioural criteria for fish,” the Daily Mail quoted him as telling New Scientist magazine.

Incidentally, a previous study published earlier this year had shown that these fish alter their gills to retain water and nutrients while excreting nitrogen waste through the skin.

These changes are reversed as soon as they return to the water.

Previously, mangrove killifish’s biggest claim to fame was that they were the only known vertebrate – animal with a backbone – to reproduce without the need for a mate.

Killifish can develop both female and male sexual organs, and fertilise their eggs while they are still in the body, laying tiny embryos into the water. (ANI)

What’s more, like humans they also suffer from insomnia.

Scientists led by Philippe Mourrain, PhD, conducted their research on mutant Zebrafish in which the hypocretin system, which plays a key role in providing sleep to fish, was disrupted.

First author on the study Tohei Yokogawa, PhD, found that when kept awake, overall sleep decreased 30 percent in mutant fish, and when they finally did drift off, they remained asleep only half as long as normal fish.

The relationship between the hypocretin system and other sleep regulatory brain systems in zebrafish were also examined in the study.

Differences in expression patterns in the brain were also found, which may explain the differences in behavioural effects.

Emmanuel Mignot, MD, PhD, professor of psychiatry and behavioural sciences and a co-researcher in the study provided proof that zebrafish are a powerful new animal model for studying sleep disorders.

This he attributes to the fact that not only do zebrafish have backbones -thereby better representing the human nervous system, but that their young reveal many details because they are see-through.

“The fact that zebrafish larvae are transparent means you can look directly at their neuronal network, even in living fish,” Mignot said.

“The idea is to try to use this as an entry point to understand the neurobiology of sleep regulation,” he said.

The study is published in Biology. (ANI)

Earlier in August, zoo Reproductive Scientist, Dr. Mary Hagedorn, and Invertebrates Keeper Mike Henley, travelled to Puerto Rico with marine scientists involved with SECORE (SExual COral REproduction) to collect and artificially inseminate coral.

Dr Hagedorn is pioneering the cyropreservation (freezing, storing and thawing) of coral sperm and eggs. Working in collaboration with SECORE, she is trying to create a genome resource bank, which will help preserve the genetic diversity of corals.

The team captured spawning coral gametes in nets during night dives and transferred them back to their laboratory on the beach for research and artificial insemination.

Using 75 feet of specially designed flexible PVC piping that could be bent around the coral so as not to harm it, the team created a water-flow system that allowed water from the ocean to continuously flow in and out of the coral larvae enclosure located in the beachfront laboratory.

Keeping the water fresh and at a constant temperature is essential for corals that flourish in stable environments.

“Conservation of a delicate underwater species is always a challenge. We achieved some important milestones this year, including learning more about the larvae rearing process, and we were able to cryopreserve the endangered coral sperm. Given more research, this technique may become instrumental in helping re-establish healthy coral populations in the Caribbean,” said Dr Hagedorn.

Elsewhere, at the Zoo’s Invertebrates Exhibit, keeper Mike Henley tried coaxing the 12,000 coral larvae to settle in a specially designed tank.

The 90-gallon, salt-water tank features high-wattage lights and a custom-built surge device that mimics the movement of the surf in the coral’s native Caribbean habitat.

From the original 12,000, 158 larvae settled onto specially designed tiles and formed polyps – millimetre-sized corals that could eventually grow to be 10 feet wide.

Henley plans to continue planting the corals throughout the next few months, as it is very difficult to rear a fragile species in captivity.

“We hope we can establish a captive population of Elkhorn that can be reintroduced to the wild. If this year’s collection does not meet the criteria, hopefully future SECORE ‘recruits’ will yield possible candidates,” said Henley. (ANI)

Ethane, propane butane, and methane are the major constituents of natural gas. Biological processes may lead to the degradation of these hydrocarbons in underground petroleum reservoirs and other geological habitats.

Now, new research has shown that the bacteria employ an unprecedented biochemical mechanism for transforming what are essentially un-reactive hydrocarbons into reactive metabolites, which may then be further oxidised to carbon dioxide.

Heinz Wilkes, a leading biogeochemist at GeoForschungsZentrum Potsdam (GFZ), said, “the bacteria isolated here for the first time from marine sediments use sulphate instead of oxygen for respiration and utilize propane and butane as their sole source of carbon and energy”.

“These organisms are tough specialists that have become adapted to strictly utilising only these and no other substrates,” Wilkes said.

The findings appear in the current online issue of Nature. (ANI)

As part of the study, the researchers conducted a whole-ecosystem experiment, increasing the mercury load to a lake and its watershed by the addition of enriched stable mercury isotopes.

The isotopes allowed the scientists to distinguish between experimentally applied mercury and mercury already present in the ecosystem and to examine bioaccumulation of mercury deposited to different parts of the watershed.

The researchers found that fish methylmercury concentrations responded rapidly to changes in mercury deposition over the first three years of study.

“Up to now a direct link has been difficult to establish because of all the other factors that affect mercury levels in fish and large pools of mercury already in the environment. By adding stable mercury isotopes to an entire ecosystem for several years, our team was able to zero in on the effects of changing atmospheric mercury deposition,” said lead author Reed Harris of Tetra Tech.

“The results were very dramatic. Using the stable isotope approach has revealed a great deal about the cycling of mercury in watersheds. We look forward to continuing our study to provide guidance in mitigating the legacy left by the years of high mercury deposition,’ added co-author Dr. Andrew Heyes of the University of Maryland Center for Environmental Science Chesapeake Biological Laboratory.

Dr. Heyes said the study showed the “clear benefits of regulating mercury emissions, and the near-term effectiveness of emission reductions”.

“This is good news. It means that a reduction in new mercury loads to many lakes should result in lower mercury in fish within a few years,” added Harris.

The international research began in 2001 at the Experimental Lakes in Northern Ontario, and is featured in this week’s Proceedings of the National Academy of Sciences. (ANI)

Unlike native crabs that eat baby oysters, mussels and fish, the green porcelain crab Petrolisthes armatus is a filter feeder, extracting its food from the water much as oysters do. The fast-reproducing invader therefore isn’t directly attacking oyster populations, though it may be competing with them for food – and may impact the predators that normally attack the oysters.

Researchers at the Georgia Institute of Technology have spent more than three years studying the effects of the crab, and are reporting their findings in the journal Biological Invasions. The research, believed to be the first to document effects of the crab on oyster and mussel populations off the Southeast coast, was supported by the U.S. Environmental Protection Agency, the National Oceanic and Atmospheric Administration, and the Harry and Linda Teasley Endowment to Georgia Tech.

“We’re seeing opposing effects from these crabs,” said Mark Hay, a professor in Georgia Tech’s School of Biology. “They are probably having more impact on the ecosystem by being prey than by being predators. Other members of the ecosystem are feeding on them, and that is changing the rate at which fish and other crabs are feeding on the native species.”

The impact of the crabs is important because oysters are a “foundation species” essential to the health of coastal ecosystems because their reefs provide homes to dozens of other creatures.

“These non-native crabs slow the rate of growth for organisms like oysters that they compete with, but they enhance the ability of those same organisms to survive when young,” Hay noted. “They are probably competing with the oysters for food, but the native crabs have switched to eating these green porcelain crabs rather than eating the baby oysters. Even though their growth is suppressed, the baby oysters are not being attacked as much now by the native consumers.”

Though the crabs aren’t killing existing populations of oysters, their long-term impact could still be significant. For instance, Hay noted, their availability as food could potentially increase the population of native crabs, disrupting the delicate balance between those predators and the oysters.

But assessing the long-term impact of the crabs has been difficult because the creatures reproduce and grow rapidly, flooding the shallow coastal waters with their young. In research conducted off Skidaway Island and Sapelo Island on the Georgia coast, the researchers found “extraordinarily high” populations of the crab – as many as 11,000 individuals per square meter.

To assess the impacts of the non-native crab population, graduate student Amanda Hollebone placed oysters and mussels into large baskets and located them on mud flats away from existing oyster reefs. Some of the baskets contained only oysters and mussels and were intended to serve as controls, some had a community of oysters, mussels, oyster drills and native mud crabs, while others had the same community spiked with non-native crabs. The distance from the existing oyster reefs was expected to prevent adult green porcelain crabs from reaching the baskets.

However, the researchers found that within a month, the control baskets also had large populations of the green porcelain crabs that had reached the containers as juveniles settling from the water column. Entry of the crabs to the control baskets interfered with the researchers’ ability to compare the traits of communities with and without the non-native crabs.

“You get a true understanding of the sheer densities of these crabs only when you actually pick up or dig through clumps of oysters and oyster shell hash,” said Hollebone, who is now a temporary assistant professor at Georgia Southern University in Statesboro. “Particularly in the summer months, I was never able to find a patch of oysters in the Savannah area that did not have the green porcelain crab.”

Because the green porcelain crabs quickly took over the control baskets, the researchers only had valid comparison data for 4-6 weeks. However, information from their baskets supported the observations made under more controlled – but less natural – conditions at Georgia Tech’s laboratory at the Skidaway Institute of Oceanography near Savannah.

As in the lab experiments, the researchers found that the crabs slowed the growth of small oysters, but not small mussels — another common filter-feeder.

The long-term effects of the massive crab population are difficult to predict. Their large numbers could lead to population growth among the native crabs and fish that now prefer eating them instead of their normal diet. But if the predator population should grow large enough to control the non-native crabs, that could lead to a decline in their numbers – and force the predators back to their traditional prey of oysters and mussels.

“We’re not sure what’s going to happen,” Hay said. “We can’t really raise the alarm because we don’t have the data to say these crabs are doing something bad. It’s possible that they will not have a huge effect at all.”

Long-term observation of the oyster reefs may ultimately provide answers.
“We have observed both positive and negative impacts on oysters and oyster-related biota at small scales, but we cannot definitively answer our concerns about oyster reefs at larger scales,” Hollebone added. “With continued monitoring of large expanses of reefs, we may begin to understand the long-term, large-scale effects.”

The green porcelain crabs were observed in Florida during 1990s, but have since appeared in large numbers in coastal waters of Georgia and South Carolina. Researchers don’t know if they hitched a ride northward in the ballast of ships, whether warming water temperatures encouraged a northerly migration – or both.

Though not much is known about them in their native habitat, Hay said the crabs appear to be thriving in their new home. Population densities observed in the South Atlantic Bight are as much as 37 times higher than the greatest densities reported in their native habitat.