Swedish Scientists Stop Acorn Barnacles

Marine organisms that fasten to the bottoms of ships have always been a scourge to seafaring. By monitoring how the larvae of acorn barnacles go about finding suitable spots to attach themselves, researchers at Linköping University in Sweden have managed to design surfaces that prevent growths -- without using poisonous chemicals.

Acorn barnacles, which are animals, are among the most notorious stowaways at sea. A vessel with its hull covered by their hard calcium shells moves more slowly and uses more fuel.

The most common method to prevent surface fouling is to apply toxic hull paint. The most effective substance has been tributhyl tin (TBT), which is now totally banned. But until now no really good alternatives to toxic paint have been found.

"Our strategy, instead, is to design surfaces that the barnacle glue doesn't stick to. The idea is for the larvae to swim off and find another place to fasten themselves for the rest of their lives," says Tobias Ekblad, a doctoral candidate in molecular physics and an associate in the EU project AMBIO.

To study how a larva walks around on its 'feet' -- actually the front parts of a couple of antennae -- and leaves micrometer-size footprints, the scientists make use of so-called surface plasmon resonance. This measurement method, based on electromagnetic wave movements in the interface between the surface and sea water, can detect the minimal optical changes that occur when the thin (10 millionths of a millimeter) footprints are made. In this way they can see in real time how the prints occur and monitor their movements back and forth across the surface.

The findings presented in Tobias Ekblad's thesis show that what determines whether the larvae like a surface or not is chemistry. Ekblad has developed a method to cover a material with a thin layer of water-filled gel, a hydrogel, that has been tested with different chemical components. For example, layers containing the polymer polyethylene glycol (PEG) have been shown to yield excellent results.

The researchers have also studied the effect of how blood coagulates on various surfaces, a problem that is encountered when prostheses are operated into the body. As in the barnacle growth project, they have found that the usable materials are those that dramatically decrease the binding of proteins to the surface.
Expertanswer (Expertsvar in Swedish) (2010, April 29). Swedish scientists stop acorn barnacles. ScienceDaily. Retrieved May 3, 2010, from http://www.sciencedaily.com­ /releases/2010/03/100315230916.htm

Barnacles Prefer Upwelling Currents in the Galapagos

There's been a rich debate in marine ecological circles about what happens to a key food source along rocky coastlines dominated by upwelling. The literature is filled with studies suggesting that the larvae of simple prey organisms such as barnacles and mussels hitch a ride on the coast-to-offshore currents typical of upwelling and are thus mostly absent in the coastal tidal zones.That theory is getting a major challenge. In a paper in Ecological Monographs, Brown University marine ecologist Jon Witman and colleagues report that a key thread in the food web, the barnacle -- the popcorn of the sea -- flourishes in zones with vertical upwelling. Working at an expansive range of underwater sites in the Galapagos Islands, Witman and his team found that at two subtidal depths, barnacle larvae had latched onto rock walls, despite the vertical currents. In fact, the swifter the vertical current, the more likely the barnacles would colonize a rocky surface, the team found.The finding "is counter to the prevailing notion about how marine communities are influenced by upwelling," said Witman, professor of biology in the Department of Ecology and Evolutionary Biology.Barnacle communities thrived in the vertical-current sites, the team also found. The group routinely found specimens that had grown from one field season to the next to 3 centimeters (about 1 inch) in diameter -- "big enough to make soup out of," Witman said. The researchers also documented the presence of whelks and hogfish, which feast on barnacles. This predator-prey relationship shows that vertical upwelling zones are "much more dynamic ecosystems in terms of marine organisms than previously believed," Witman said.Professor of Biology Witman and his team, including Brown graduate student Margarita Brandt and Franz Smith of CSIRO Marine and Atmospheric Research in Australia, chose a dozen sites of underwater cliffs, ledges and slopes along a 125-kilometer-long transect in the Galapagos. During three field seasons, the team bolted nearly 1,500 plates at depths of 6 and 15 meters to track the colonization of barnacle larvae and the growth of populations in areas with weak, intermediate and strong vertical upwelling.The team also documented for the first time the strength of currents at the sampling locations, which included a dozen islands or outcrops located in the center of the archipelago. In areas with the most vertical upwelling, the researchers found, the current moved at a brisk 0.6 meters (2 feet) per second; the weakest vertical currents were measured at 5 centimeters (0.2 feet) per second.Scientists who study coastal marine communities had assumed that prey species such as barnacles and mussels would be largely absent in vertical upwelling areas, since the larvae, which float freely in the water as they seek a surface to attach to, would more likely be swept away in the coast-to-offshore currents. Studies of the near-surface layer of the water in rocky tidal zones confirmed that thinking. But the field work by Witman and his group, in deeper water than previous studies, told a different tale: Few barnacles were found on the plates in the weak upwelling zones, while plates at the strong upwelling sites were teeming with the crustaceans. Flourishing barnacle communities were found at both the 6-meter and 15-meter stations, the researchers reported.The scientists think the free-floating larvae thrive in the vertical-current zones because they are constantly being bounced against the rocky walls and eventually find a tranquil spot in micro crevices in the rock to latch on to. "It's a contact game," Witman said.The team suggests the observations could hold true for other rocky tidal ecosystems. "We're one of the few people doing underwater experimental ecology in the Galapagos," said Brandt, who is Ecuadorean. "This project is one of the first attempts to do that."

Barnacles Prefer Upwelling Currents, Enriching Food Chains in the Galapagos

There's been a rich debate in marine ecological circles about what happens to a key food source along rocky coastlines dominated by upwelling. The literature is filled with studies suggesting that the larvae of simple prey organisms such as barnacles and mussels hitch a ride on the coast-to-offshore currents typical of upwelling and are thus mostly absent in the coastal tidal zones.

That theory is getting a major challenge. In a paper in Ecological Monographs, Brown University marine ecologist Jon Witman and colleagues report that a key thread in the food web, the barnacle -- the popcorn of the sea -- flourishes in zones with vertical upwelling. Working at an expansive range of underwater sites in the Galapagos Islands, Witman and his team found that at two subtidal depths, barnacle larvae had latched onto rock walls, despite the vertical currents. In fact, the swifter the vertical current, the more likely the barnacles would colonize a rocky surface, the team found.
The finding "is counter to the prevailing notion about how marine communities are influenced by upwelling," said Witman, professor of biology in the Department of Ecology and Evolutionary Biology.
Barnacle communities thrived in the vertical-current sites, the team also found. The group routinely found specimens that had grown from one field season to the next to 3 centimeters (about 1 inch) in diameter -- "big enough to make soup out of," Witman said. The researchers also documented the presence of whelks and hogfish, which feast on barnacles. This predator-prey relationship shows that vertical upwelling zones are "much more dynamic ecosystems in terms of marine organisms than previously believed," Witman said.
Professor of Biology Witman and his team, including Brown graduate student Margarita Brandt and Franz Smith of CSIRO Marine and Atmospheric Research in Australia, chose a dozen sites of underwater cliffs, ledges and slopes along a 125-kilometer-long transect in the Galapagos. During three field seasons, the team bolted nearly 1,500 plates at depths of 6 and 15 meters to track the colonization of barnacle larvae and the growth of populations in areas with weak, intermediate and strong vertical upwelling.
The team also documented for the first time the strength of currents at the sampling locations, which included a dozen islands or outcrops located in the center of the archipelago. In areas with the most vertical upwelling, the researchers found, the current moved at a brisk 0.6 meters (2 feet) per second; the weakest vertical currents were measured at 5 centimeters (0.2 feet) per second.
Scientists who study coastal marine communities had assumed that prey species such as barnacles and mussels would be largely absent in vertical upwelling areas, since the larvae, which float freely in the water as they seek a surface to attach to, would more likely be swept away in the coast-to-offshore currents. Studies of the near-surface layer of the water in rocky tidal zones confirmed that thinking. But the field work by Witman and his group, in deeper water than previous studies, told a different tale: Few barnacles were found on the plates in the weak upwelling zones, while plates at the strong upwelling sites were teeming with the crustaceans. Flourishing barnacle communities were found at both the 6-meter and 15-meter stations, the researchers reported.
The scientists think the free-floating larvae thrive in the vertical-current zones because they are constantly being bounced against the rocky walls and eventually find a tranquil spot in micro crevices in the rock to latch on to. "It's a contact game," Witman said.
The team suggests the observations could hold true for other rocky tidal ecosystems. "We're one of the few people doing underwater experimental ecology in the Galapagos," said Brandt, who is Ecuadorean. "This project is one of the first attempts to do that."
The National Science Foundation, the Andrew W. Mellon Foundation and the private Banks Foundation funded the research. Jon D. Witman, Margarita Brandt, Franz Smith. Coupling between subtidal prey and consumers along a mesoscale upwelling gradient in the Galápagos Islands. Ecological Monographs, 2010; 80 (1): 153 DOI: 10.1890/08-1922.1

Barnacles become toxic to repel hungry predators

One species of a rare, ancient barnacle has extraordinarily high levels of a toxic chemical in its body, scientists have discovered.

Up to 7% of certain parts of the barnacle's body is bromine, with the chemical concentrated into the animal's most vulnerable parts.

The sessile crustacean likely hoards the chemical as a defence mechanism to repel predators.

The discovery is published in the journal Integrative Zoology.

The crustacean Chaetolepas calcitergum is known as a stalked ibliform barnacle.

Only six specimens are known of the species, which, because of its small size, is unlikely to be spotted by fishermen or researchers.

Ibliform barnacles, a type of goose barnacle, first arose in the Palaeozoic era, making them an ancient lineage that evolved before all other barnacles.

But like other barnacles, ibliformes are sessile, spending their adult lives attached to a substrate such as rock.

Because barnacles cannot move, they are vulnerable to drying out, and to predators from which they cannot flee.

In response, most barnacles have evolved strong protective shells.

However, Chaetolepas calcitergum has only a weakly mineralised outer coating, and is therefore vulnerable.

So it appears to have become toxic instead, in a bid to repel predatory gastropods that like to feed on barnacles.

Professor John Buckeridge and Dr Jessica Reeves of the Royal Melbourne Institute of Technology (RMIT) in Melbourne, Australia made the discovery while conducting a routine chemical analysis of a specimen of Chaetolepas calcitergum.

"The elevated levels of bromine were a surprise, I wasn't expecting this at all," says Prof Buckeridge.

The surface of the whole barnacle comprised about 1.5% bromine by dry mass.

But some regions contained up to 7% bromine by dry mass.

Because the toxic chemical is concentrated in the most vulnerable parts of the crustacean, the researchers strongly suspect it is used by the animal to defend itself against being eaten by predators.

"Bromine and bromine compounds are rather toxic. Their presence would deter predators or grazers from eating the host," says Prof Buckeridge.

The researchers now hope to investigate whether many other barnacle species also compensate for being sessile by having toxic bodies. By Matt Walker Editor, Earth News BBC

Super Sticky Barnacle Glue Cures Like Blood Clots

Barnacles are a big problem for boats. Adhering to the undersides of vessels, carpets of the crustaceans can increase fuel consumption by as much as 25%. Ship owners would love to know how to stop these hitchhikers gluing on, but before you can learn how to disrupt an adhesive, you have to understand the curing process.

Curious about many aspects of the crustacean's lifestyle, Dan Rittschof from Duke University decided to find out how barnacle adhesive polymerizes. "The process must be related to something because glue isn't de novo," says Rittschof, so he wondered what else coagulates under water and came up with two answers: blood and semen.

With a colossal body of blood clotting literature to draw on, Rittschof decided to follow his evolutionarily inspired theory to see whether barnacle glue polymerization is really an extreme example of scab formation and publishes his results on 16 October 2009 in the Journal of Experimental Biology.

Rittschof teamed up with Gary Dickinson and the first thing that Dickinson had to do was work out how to collect the unpolymerised glue and keep it fluid. Building on 30 years of Rittschof's experience and Beatriz Orihuela's expertise at growing and reattaching barnacles, Dickinson learned to gently lift polymerised glue away from the pores that secrete the adhesive and quickly collect the minute drops as they oozed from the shell. Working in the cold room to slow the polymerization process, Dickinson had only 5 minutes before each sample polymerized and the glue set solid.

Next the team had to convince themselves that the viscous secretion was glue and not some other body fluid. Dickinson found that the fluid polymerised rapidly and was packed full of protein, just like barnacle glue. Next Dickinson teamed up with Kathy Wahl to use atomic force microscopy to compare the molecular structures of naturally cured glue (from stuck-down barnacles) and his polymerized samples. The two samples were virtually indistinguishable and Dickinson could clearly see tangled webs of fibres in his glue drops, similar to the tangled fibres in blood clots.

But this evidence was still far from proving that barnacle glue cures by the same process as blood clots. Dickinson and Rittschof needed to identify the key proteins that polymerize the cement. Knowing that blood clots are formed when enzymes, known as trypsin-like serine proteases, trigger a cascade of events that culminates in the formation of the long fibres found in blood clots, Dickinson and Rittschoff began searching for the protease in the unpolymerised glue. Separating the glue's components on a gel, Dickinson could see the tell-tale pattern of bands that suggested that a trypsin-like serine protease was present. And when Dickinson added an inhibitor, to inactivate the protease, to a fresh sample of glue, the sample didn't set.

Having convinced themselves that the glue contained a trypsin-like serine protease, the team began to search for other blood-clot-like proteins in the barnacle's secretions. Teaming up with Joseph Bonaventura and Irving Vega, Dickinson chopped each glue component into minute fragments, measured their sizes with mass spectrometry and matched the fragment pattern to known protein sequences. Amazingly, one of the glue proteins was remarkably similar to human factor XIII: a human blood clotting factor that cross-links clot fibres to form a scab. In fact, some regions of the human and barnacle proteins were completely identical. Dickinson and Rittschof had stumbled across the crucial protein that cross-links the glue fibres to cure barnacle cement and it was very similar to factor XIII, an essential human blood-clotting factor.

Rittschof admits that he is shocked that his hypothesis stands up to the tests. 'It seems likely that barnacle glue polymerization is a specialized form of wound healing,' he says and suspects that many other marine animals that rely on glue to get a grip may use the same polymerization mechanism.

---

Journal reference:

Dickinson, G. H., Vega, I. E., Wahl, K. J., Orihuela, B., Beyley, V., Rodriguez, E. N., Everett, R. K., Bonaventura, J. and Rittschof, D. Barnacle cement: a polymerization model based on evolutionary concepts. Journal of Experimental Biology, 2009; 212, 3499-3510

2 Invasive Species Found in S.C. Waters

2 Invasive Species Found in S.C. Waters
The Associated Press
Tuesday, December 19, 2006; 8:29 PM

CHARLESTON, S.C. -- Two new invasive species have recently been found along
the South Carolina coast _ a massive barnacle that dwarfs those found in the
state as well as the Asian green mussel, which reproduces quickly and can
pose a threat to floating docks.

The barnacle is native to the Pacific coast from southern California to
South America. It is so big, colonies have been known to sink navigational
buoys, slow boats and clog coastal water pipes.

The barnacle, the megabalanus coccopoma, was found by a College of
Charleston student doing research this fall on the Folly River. It
reproduces quickly, and, although only one has been found, scientists worry
it could spread.

"There's not a whole lot known about this guy," said David Knott, an
biologist with the state Department of Natural Resources who deals with
marine invasive species. "Cold water may be a barrier to it."

"This guy could cause a lot of problems just due to size alone," said Sam
Crickenberger, a senior marine biology major at the college who found the
barnacle. "And it's sharp."

The Asian green mussel was found in the Charleston area earlier this year.
It also reproduces quickly and can sink floating docks.

"Man, it's going to be crazy," said Larry Smith of Larry's Diving, who
cleans hulls. People who don't keep up boat maintenance "aren't going to be
able to move."

The new creatures are among the latest invasive species found in the state.
The invaders can be brought from other parts of the world in the ballast of
steamships or can drift in on plumes of warm water.

Scientists have identified nearly 40 invasive coastal aquatic invertebrate
species in the state.

While the state appears to be at the northern end of the range for many
tropical marine species, rising water and air temperatures could extend that
range farther north.

Knott said there may be no stopping invasive species, but that slowing the
spread is critical to preserving the state's coastal environment.

"If you look at the rate of introduced species, it's an exponential curve.
That's a cause of concern."