Fish and aquatic news

Barnacles are capable of attaching themselves to virtually any underwater surface; from whale skin and turtle shells to ship hulls and pier structures. Just how they manage to keep themselves anchored has remained a mystery; a multimillion mystery since barnacles increase fuel consumption by adding additional drag to the submerged parts of marine vessels. Scientists knew that the barnacles used a type of glue, but they didn’t understand how it worked and why it was so strong.

Traditionally, toxic paint has been used to keep the barnacles away but dry-docking huge cargo ships every so often to have them repainted is naturally expensive. Also, the toxic paint is not only affecting the barnacles; it is causing problems for entire ecosystems and many countries have therefore decided to ban or limit the use of some of the most harmful ones.

Using modern techniques such as force microscopy and mass spectrometry, a team of scientists from Duke University’s Marine Laboratory in Durham has now managed to find out how barnacles stick to surfaces; a discovery which they hope will lead to the development of more environmentally friendly anti-barnacle remedies.

The research team unveiled that barnacle glue from the species Amphibalanus amphitrite binds together much the same way as red blood cells bind together when our blood clots. When our blood clot, several different enzymes work together to form protein fibres that bind the cells together. In barnacle glue, similar enzymes - known as trypsin-like serine proteases – do the same thing. Interestingly enough, one of these enzymes are remarkably similar to Factor XIII, and essential blood clotting agent present in human blood.

“We’ve found homologous enzymes in barnacles and humans, which serve the same function of clotting proteins underwater, despite roughly a billion years of evolutionary separation,” says research team member Dr Gary Dickinson.

Another team member, Professor Dan Rittschof, explains that this similarity does make evolutionary sense.

“Virtually no biochemical pathway is brand new. Everything is related and really important pathways are used over and over,” says Rittschof. “Really key parts of those pathways can’t change because if they do, the pathway fails and the animal dies.”

According to Dickinson, it wouldn’t be surprising to find this glue in other organisms besides the barnacles.

“The enzymes are highly conserved because they are very effective at what they do, ” says Dickinson. “There are bound to be a number of other organisms that use the same enzymes for the same purpose.”

For more information, read the article in The Journal of Experimental Biology.

http://jeb.biologists.org

A 10-year study of Rockefeller Wildlife Refuge alligators has yielded some surprising results. Despite having plenty of suitable males to choose among, up to 70 percent of the female gators in this Louisiana refuge preferred to mate with the same male year after another. Also, females who mated with more than one male per breeding season and produced young from multiple fathers usually continued to mate with their select group of males year after year, thus displaying a form of polygamous fidelity.

“Given how incredibly open and dense the alligator population is at RWR, we didn’t expect to find fidelity,” biologist Stacey Lance of the Savannah River Ecology Laboratory in South Carolina said in a press release. “To actually find that 70 percent of our re-trapped females showed mate fidelity was really incredible. I don’t think any of us expected that the same pair of alligators that bred together in 1997 would still be breeding together in 2005 and may still be producing nests together to this day.”

Most reptiles are polygamous and will choose a new mate or mates each breeding season, and only a few reptilian species are known to actively choose the same mate or mates over and over again.

Since the Rockefeller Wildlife Refuge is so densely populated with alligators, researchers don’t think that the repeated pairings are the result of chance.

The study has been published in the journal Molecular Ecology.

http://www3.interscience.wiley.com/journal/117989598/home

According to a new UN report, marine plants take 2 billion tonnes of carbon dioxide away from the atmosphere each year as they use the carbon dioxide for photosynthesis. Most of these plants are plankton, but planktons rarely form a permanent carbon store on the seabed. Instead, mangrove forests, salt marshes and seagrass beds are responsible for locking away well over 50 percent of all carbon that is buried in the sea – an amazing feat when you consider that these types of habitat only comprise 1 percent of the world’s seabed.

“The carbon burial capacity of marine vegetated habitats is phenomenal, 180 times greater than the average burial rate in the open ocean,” say the authors of the UN report.

Mangrove forests, salt marshes and seagrass beds are the most intense carbon sinks on our planet and they store away an estimated 1,650 million tonnes of carbon dioxide per year.

Unfortunately, these habitats are being ruined or damaged worldwide and a third of them are believed to have been lost already, although it is difficult to obtain accurate figures regarding the extent of these types of habitats worldwide. What we do know is that half of the world’s population lives within 65 miles of the ocean and that vegetated ocean near habitats are often under severe pressure.

“On current trends they may be all largely lost within a couple of decades”, said Christian Nellemann, the editor of the report.”

To help developing nations protect the remaining marine vegetated habitats the authors of the report suggest that a fund should be launched. They also wish to have a market place created where oceanic carbon sinks are traded in the same fashion as terrestrial forests.

The report, which has been named Blue Carbon, is a collaboration between the United Nations Environment Programme, the Food and Agriculture Organisation and Unesco.

The National Marine Aquarium in Plymouth, UK has received some attention in the press after chartering a Boeing 767 to fly in a 42-tonne cargo of Caribbean fish for a new exhibition.

The fish – 100 specimens from 18 different species – was purchased from the Ocean World aquarium in Barbados and will arrive to the UK in 19 purpose-built tanks. The sharks, rays and other fish will then be escorted by the police to their new homes in the National Marine Aquarium.

Chartering a Boeing 767 for this type of tropical import costs roughly £100,000, which is almost 160,000 USD.

In most species, a male specimen will usually don’t invest a lot of time or energy in caring for young when there is a good chance that he is not their father. There are how ever exceptions to this rule, such as the Ocellated wrasse.

Yale University researchers studying the breeding behaviour of this Mediterranean fish have found that a male Ocellated wrasse is more likely to care for the offspring when there is grave doubt about who actually fathered them.

The study also showed that female Ocellated wrasse will deposit more eggs in a nest where the nesting male is surrounded by non-nesting “sneaker males”; males who are keen to fertilize the eggs but have no plans ever caring for the offspring. Females will also deposit more eggs in nests where there are already large numbers of offspring.

“Parental male oscellated wrasse are more likely to care for offspring in this sperm-filled  environment than in nests in which there is less sexual competition”, said Suzanne H. Alonzo, assistant professor of ecology and evolutionary biology and co-author of the study.

Even though the caring male has a greater chance of ending up taking care of someone else’s offspring if he allow other males to hang around, he still benefits from having a lot of “sneaker males” near his nest since it will make the females deposit more eggs.

“While our simpler theories have trouble explaining the diversity of what we observe in nature, these patterns do have explanations,” Alonzo said. “The paper suggests we may have oversimplified the evolutionary dynamics of how these things work.”

The paper has been published in the edition of the journal Proceedings of the Royal Society of London. The study was carried out by Suzanne H. Alonzo, assistant professor of ecology and evolutionary biology and Kellie L. Heckman, a postdoctoral fellow in the department.

The Jordanian government has announced its plans to extract over 10 billion cubic feet of water per year from the Red Sea and send most of it to a desalination plant to produce drinking water. The salty wastewater will then be sent from the desalination plant to the Dead Sea by tunnel. Jordanian Water Minister Maysoun Zu’bi says the project will begin as soon as funding has been arranged.

Environmentalists warn that the endeavour could damage the ecosystem of both seas. Mixing two types of saltwater could produce algae blooms in the Dead Sea, and some environmentalists also fear that the extraction of saltwater will increase the Salinity of the Red Sea.

Dead Sea info

The Dead Sea is a salt lake shared by Jordan and Israel. Its surface and shores are 422 meters below sea level, which is the lowest elevation on the Earth’s surface on dry land. With almost 34% salinity, the Dead Sea is one of the saltiest bodies of water in the world and 8.6 times as salty as the ocean.

During recent decades, the Dead Sea as shrunk rapidly, chiefly due to the diversion of incoming water from the Jordan River. The diverted water is used for households, agriculture and industry. In 1970, the Dead Sea was 395 meters below sea level. In 2006, that number had increased to 418 meters.

The Dead Sea level drop has been followed by a drop in groundwater level and large sinkholes have begun to appear along the western shore.

In the ocean, krill live together in swarms, some of them stretching for tens of kilometres. Krill swarms are some of the largest gatherings of life on the planet and this naturally poses some puzzling questions to science: Why are krill living together? How do they find each other? Why are some swarms enormous when others are more moderately sized?

In an effort to shed some light on the mystery, a team of British Antarctic Survey (BAS) researchers headed by Dr Geraint Tarling set out to study the composition and structure of 4525 separate krill swarms in the Scotia Sea. Despite its name, the Scotia Sea is not located close to home for these British scientists – it is a vast expanse of water situated partly in the Southern Ocean and partly in the Atlantic; between Argentina and the Antarctic Peninsula.

Using echo-sounding equipment, the Tarling team tracked down the krill living in this 900,000 km² area and what they found surprised them. According to this new research, krill normally gather into two different types of swarms. The first type is relatively small, typically not exceeding a length of 50 meters and a depth of 4 meters. In this comparatively small type of swarm, the density of krill isn’t very high – you will just find an average of ten krill per cubic meter.

The other type of swarm – dubbed “superswarm” by the researchers – is on the other hand a very densely packed group with up to 100 krill per cubic meter. These dense congregations are the ones that grow really big, often stretching over one kilometre in length and averaging almost 30 meter in depth.

“I was coming at it thinking there might be small swarms tightly packed, and then large swarms that were a bit more diffuse,” says Dr Tarling. “But what we actually found was the opposite. There were small swarms that were quite diffuse and large swarms that were tightly packed.”

This means that a majority of the krill living in the Scotia Sea at any one time will be found within one of just a few enormous superswarms.

“We talking trillions of krill in one aggregation,” explains Dr Tarling. “Ten or 12 swarms could explain 60 or 70% of the biomass in an area the size of the eastern Atlantic. It was astonishing how much biomass could be concentrated into such a small area.”

A fishing flee scooping up a whole swarm of krill may therefore be removing the majority of krill from the Southern Ocean in just one short fishing trip if they happen to target one of the superswarms instead of a small swarm.

How does a superswarm come about?

Although they weren’t able to fully answer this question, Tarling and his colleagues managed to pinpoint certain factors that make superswarms more likely to appear.

“The factors we identified included whether there was more likely to be a lot of food around or not, and when there wasn’t that much food around, they tended to form larger swarms,” says Dr Tarling.

Age is also of importance. The smaller, diffuse swarms typically contained adult krill, while the enormous superswarms consisted of densely packed juvenile individuals.

“Where the animals were less mature, they were more likely to form the larger swarms,” says Dr Tarling, adding that he doesn’t know why.

It might be a question of safety in numbers; it is common among prey animals to live in large groups to reduce the risk of getting eaten, and krill is after all a favoured meal by a long row of sea living creatures.

“All types of swarms are probably to a greater or lesser extent an antipredator response,” Dr Tarling says.

But although living in a swarm reduces the risk of being eaten, it also means having to compete with all the other members of the group for food. Juvenile krill are more buoyant than adults, which mean that they spend less energy swimming. Perhaps this is why adult krill prefers to live in smaller congregations; their negative buoyancy forces them to eat more so they can’t afford living in a huge swarm densely surrounded by competitors.

On the other hand, being in a swarm has been shown to be more energetically efficient than being isolated.

“For a juvenile that wants to grow very quickly, saving energy could be a bonus for them,” says Dr Tarling.

Night-time mystery

As a scientist, you often find yourself in a situation where new findings answer one question but simultaneously create three new ones. One of the new conundrums that Dr Tarling has brought back home from his research trip is the following: Why are superswarms more likely to form at night?

“That is more puzzling for us to explain,” says Dr Tarling. “Up until this point, most polar biologists believed that the swarms dispersed [at night], because that’s the time they feed. When daylight comes they get back into the swarm again for the antipredator benefit. But we found the opposite to that.”

The research has been published in the journal Deep Sea Research I.

Florida anglers are being sharply criticized after a video of them free-gaffing a Mako shark off South Florida this week was made public on the Internet.

In the video, which was uploaded to Youtube and also displayed on the website of a Florida TV station (can be seen below), the anglers can be seen trying to gaff a free-swimming shark. The shark ventured close to the boat after being attracted to a swordfish that the anglers had alongside their vessel.

Since no rods or reels appear to have been used by the anglers as they captured the 748-pound Mako shark, they may have acted in violation of state and federal law. “I’d hazard that I’m not the first to pick up on these fine points of the law but if the video does indeed tell the full tale then these laws need to be enforced,” said Luke Tipple, a marine biologist and director of the Shark-Free Marina Initiative. “If however the fishermen can provide video evidence of them using PRIMARY tackle (i.e. hook and line) to initialize the capture then they would be within their rights to have landed the shark. If this turns out to be the case then I will instead turn this report into a cautionary tale of how the media should be more responsible in reporting on shark harvests, particularly when dealing with species considered by some to be globally threatened.”

The rare Gangetic dolphin (Platanista gangetica) has been declared National Aquatic Animal of India. A few days after the formal declaration, which took place at a National Ganga River Basic Authority meeting in New Delhi earlier this week, Bihar chief minister Nitish Kumar announced that he has directed state authorities to put a halt to dolphin hunting in the Ganga.

“A close watch is being kept on the ghats of river Ganga by the magistrates, police officials and block development officers to stop hunting and fishing of the mammals,” senior officials said.

Patna District Magistrate J K Sinha said that instructions from chief minister has been passed
to senior officials, including sub-divisional officers, magistrates, police officers and block development officers to ensure close surveillance and act swiftly to stop hunting of the aquatic animal.

“Schools will take steps to aware the students about the gangetic dolphin which would

boost eco-tourism in the region,” he added.

Although the Wildlife Protection Act of India mandates dolphin conservation as a priority, little has been done at the government level to implement or enforce the law.

Where is Bihar?

Bihar is an Indian state located in the eastern part of the country. It is bordered by Nepal to the north, Jharkhand to the south, Uttar Pradesh to the west, and West Bengal to the east. The state is bisected by the Ganga River which flows through the middle of the state from west to east.

What is Ganga?

Outside India, the Ganga River is more commonly known as the Ganges River.

What is the Gangetic dolphin?

The Gangetic dolphine, also known as Ganges dolphin, Ganges river dolphin, Blind dolphin, and Side-swimming dolphin, is a dolphin endemic to the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Nepal, India, and Bangladesh. Its scientific name is Platanista gangetica and it is listed as Endangered on the IUCN Red List of Threatened Species. The current population consists of 1,200-1,800 individuals, and roughly half of these are found in Bihar and Uttar Pradesh.

It is referred to as the Blind dolphin due to its poor eye-sight which is probably an adaptation to the murky waters of the Ganga River.

Lack of iron is a limiting factor for plankton growth in many parts of the ocean, especially in the southern oceans and parts of the eastern Pacific. Scientists at the University of Leeds, UK, have now showed that acid in the atmosphere breaks down large particles of iron found in dust into small and highly soluble iron naonparticles; particles which can be easily absorbed and utilized by oceanic plankton.

Since plankton absorb carbon dioxide from the atmosphere, more available iron could trigger increased movement of carbon dioxide from the air to the ocean.

“This could be a very important discovery because there’s only a very small amount of soluble iron in the ocean and if plankton use the iron nanoparticles formed in clouds then the whole flux of bioavailable iron to the oceans needs to be revised,” says Dr Zongbo Shi, lead author of the research from the School of Earth and Environment at the University of Leeds.

Polluting industries that causes a high degree of acidic particles to be present in clouds can therefore strangely enough simultaneously be combating global warming.

“Man made pollution adds more acid to the atmosphere and therefore may encourage the formation of more iron nanoparticles,” says Dr Shi.

“This process is happening in clouds all over the world, but there are particularly interesting
consequences for the oceans. What we have uncovered is a previously unknown source of
bioavailable iron that is being delivered to the Earth’s surface in precipitation,” says Professor Michael Krom, the principal investigator of the research, also at the University of Leeds.

The Maldives is planning to ban shark fishing in its waters, a move which would make the Maldives the first nation in the region to enact such a protective law.

The announcement was made by the Maldives Minister of State for Fisheries and Agriculture, Dr Hussein Rasheed Hassan, at the South West Indian Ocean Fisheries Commission steering committee meeting in Mombasa.

“We have realised that it is more economically viable to leave the shark and other sea creatures unharmed because the country currently earns about $7 million annually from the diving industry,” said the minister.

In 1998, the Maldives imposed a 10-year moratorium banning shark fishing around seven atolls that received a lot of vacationers from abroad. Now, the country intends to expand the ban to include all reef shark fishing across the Maldives within a 12 nautical mile radius (22km).

During recent years, the number of sharks in the Maldives has plummeted due to overfishing for the lucrative shark fin market.

“The marine ecosystem is very fragile and that is why we have to regulate activities that coupled with the treats of climate change could adversely affect the major sources of income for the country,” Hassan explained.

The Maldives is an island country consisting of a group of atolls stretching south of India’s Lakshadweep islands. Despite having a population of no more than roughly 300,000 individuals, the Maldives receives over 600,000 tourists each year.

Compared to the record-setting low years of 2007 and 2008, the Arctic Sea ice has made a slight recovery in 2009, according to the University of Colorado at Boulder’s National Snow and Ice Data Center. Despite this positive change, the minimum sea ice extent in 2009 was the third lowest since satellite record-keeping started in 1979.

“It’s nice to see a little recovery over the past couple of years, but there’s no reason to think that we’re headed back to conditions seen in the 1970s,” said NSIDC Director Mark Serreze, also a professor in CU-Boulder’s geography department. “We still expect to see ice-free summers sometime in the next few decades.”

The standard measurement for climate studies is the average ice extent during September. This September, the average Arctic Sea ice extent was 5.36 million square kilometres, which is 1.06 million square kilometres more than September 2007 and 690,000 square kilometres more than September 2008.

According to Mike Steele, Senior Oceanographer at the University of Washington, the decrease in ice loss is probably due to cloudy skies during late summer. Sea surface temperatures in the Arctic were higher than normal this season, but slightly lower than in 2007 and 2008 – most likely due to the presence of clouds this year. Atmospheric patterns in August and September also helped spreading the ice pack over a larger area.

Arctic sea ice follows an annual cycle of melting during the warm season and refreezing in the winter, and the extent of Arctic sea ice has always varied due to changing atmospheric conditions. During the past 30 years, there has however been a dramatic overall decline in Arctic sea ice extent.

A gigantic underwater museum filled with 400 sculptures will be created in Mexico’s West Coast National Park in on the Yucatán Peninsula. The artistic director is Jason de Caires Taylor, famous for his underwater sculptures, but other artists will also be involved in the project.

The Subaquatic Sculpture Museum is designed to relieve some of the pressure placed on the regions natural reefs by divers and snorkelers; the national park currently receives almost 300,000 visitors each year and quit a few of these vacationers do not behave as careful around the reefs as they should.

“If they [the tourists] swim near the corals, the divers with little experience might kick them with a fin or hit them with the oxygen tank,” says national park director Jaime

González, adding that some tourists even climb coral reefs and walk on top of them, breaking and shattering them.

In 2005, the park administration submerged 110 hollow domes and concrete structures in layers in the Sac Bajo area in a similar effort to divert tourists from the natural reefs, and this project has already become a success story.

“At first the people of Isla Mujeres told us that they were never going to bring tourists there, but after a few years it became a must-see attraction,” says González.

The park administration is planning to launch the new underwater museum next month by submerging four sculptures in human form. All 400 sculptures in the museum will be made from pH neutral concrete to allow rapid growth of algae and incrustation of marine invertebrates, such as corals. Eventually, the new habitat will also begin to attract reef fish – just like the Sac Bajo project.

“The underwater museum will draw many tourists, allowing us to give a rest to the natural reefs. It’s like a restoration process,” says González.

If everything goes according to plan, some 250 sculptures will have been submerged by April 2010. Each sculpture will be human sized and rest on a four square meter base. Some parts of the museum will be theme based, such as the “Coral Collector” gallery and the “Dream Catcher” section which features bottles filled with messages sent by castaways. There will also be a series of sculptures depicting Maya warriors.

A marine park will be formed at Camden Sound, Australia, in an effort to protect the Humpback whale (Megaptera novaeangliae). Once hunted to the brink of extinction, the humpbacks have already bounced back considerably thanks to conservation efforts and they are now much sought after by whale-watchers, particularly off parts of Australia, Canada, and the United States.

“The Government recognises the Kimberley as one of Australia’s special places,” said Premier Colin Barnett as he unveiled the plans for the park. “That is why we are protecting Camden Sound, making it a marine park, and developing and implementing our Kimberley Science and Conservation Strategy. This strategy will balance the need to develop industry and create wealth with the expectation that the environment and special places will be protected. This remarkable area warrants protection as a first step in the broader conservation of the Kimberley.”

Environment Minister Donna Faragher added that Camden Sound is the largest calving area for humpbacks in the southern hemisphere.

“More than 1000 humpback whales can be found in the Camden Sound ‘maternity ward’ during the calving season,” Faragher said. “They are part of the biggest population of humpback whales in the world - numbering about 22,000 - that migrate from Antarctica every year to give birth in the waters off the north of our State.”

Faragher said the park will be created in consultation with the local indigenous community and all stakeholders with an interest in the area.

Allowing for consultation, including a public comment period of three months, a marine park could be established as early as mid-2010.

Camden Sound

Camden Sound is a bay in the Indian Ocean situated in the Kimberley region of Western Australia. The sound is a highly bio-diverse region; home to animals such as dugongs, crocodiles, sea-snakes, sharks, rays, and three species of sea turtle. Indo-Pacific humpbacked dolphins, Bottle-nosed dolphins, and the newly recognized Snub-fin dolphin can all be found within the borders of the proposed marine park. The sound is also visited by several species of whale, including False Killer whale, Bryde’s whale, Minke whale, and Dwarf Sperm whale. The corals reefs in the region are still fairly unharmed and varied the extensive mangrove forests found along the shores acts as nursery areas for fish and invertebrates.

Humpback whales born in Camden Sound stay there for several months after birth to grow big and strong enough to survive the long journey to the chilly Arctic waters where the humpbacks feed during the summer.

An international team of researchers have shown how one single gene mutation is capable of making the medaka, a Japanese killifish, loose its attractive colours and display a drab grey colour which renders them significantly less attractive to medakas of the opposite sex – unless that potential mate is grey too.

In the wild, medakas come in a wide range of colours, including orange, brown and drab grey.

“We observed that the grey medaka were often rejected in favor of their brown or orange rivals“, says lead author Shoji Fukamachi. “This is the first demonstration of a single gene that can change both secondary sexual characteristics and mating preferences“.

As mentioned above, you don’t have to fear ending up without a mate just because you happen to be a grey medaka – you just have to go out looking for another grey specimen since the study showed greys to be preferentially selective for each other. This preference for choosing a member of your own colour suggests that sympatric speciation could occur in medakas as the colour determining gene is mutated, i.e. new species may form as the medakas choose to mate with specimens of their own colour.

The research is a collaborative effort by researchers from the University of Konstanz, Germany and from the University of Tokyo, Japan. The study has been published in the open access journal BMC Biology.