Jellyfish lake, Palau

JELLYFISH LAKE, PALAU from Sarosh Jacob

Jellyfish Lake is located on Eli Malk island in the Republic of Palau.
>>> geolocalization with the Marine GeoGararage <<<

Twelve thousand years ago these jellyfish became trapped in a natural basin on the island when the ocean receded.
With no predators amongst them for thousands of years, they evolved into a new species that lost most of their stinging ability as they no longer had to protect themselves.
They are pretty much harmless to humans although some people with very sensitive skin may get a minor irritation from them.

These fascinating creatures survive by sharing a symbiotic relationship with algae that live inside of them.
At night, the jellyfish go down to the depths of the lake where the algae feed on nutrients.
During the day, the jellyfish come back to the surface and follow the sun across the lake in a massive migration.
The algae convert the energy of the sun via photosynthesis into a sugar that feeds the jellyfish.

It is not possible to scuba dive in this lake because the nutrient rich layer at around 50 feet and below contains hydrogen sulphide which is highly toxic to humans.
If a scuba diver was to swim in that layer, the toxins would enter the body through the skin and that exposure could be fatal.
Snorkeling however, is perfectly safe and if you ever find yourself in Palau one day, you should make your way to this special place.
The experience of swimming through millions of jellyfish is quite surreal and Palau is the only place in the world where you can do just that!

The man who swims with coelacanths

From Arkive

From Wired

More than seven decades later, the words have the same urgency as when they rolled off Marjorie Courtinay-Latimer’s telegraph machine and into history:
MOST IMPORTANT PRESERVE SKELETON AND GILLS = FISH DESCRIBED.

Courtinay-Latimer was the young curator of a natural history museum on South Africa’s east coast.
The message came from J.L.B. Smith, an icthyologist to whom she’d turned when, shortly before Christmas in 1938, local fishermen brought her a fish unlike any they’d ever seen.

Caught at a depth of 240 feet, it was five feet long, covered in bony scales and had fins reminiscent of legs.
Courtinay-Latimer immediately sent a sketch to Smith, who thought it looked like a coelacanth.
There was just one catch: Coelacanths were extinct, and had been for 70 million years.

The sketch sent by Marjorie Courtinay-Latimer to J.L.B. Smith.
South African Institute for Aquatic Biodiversity

Smith’s famous cable came too late, as Courtinay-Latimer didn’t have an aquarium large enough to preserve the fish.
But even as they despaired, it was just weeks before another arrived.
Far from being extinct, coelacanths were actually caught with some regularity by native fishermen of the Comoros Islands, on whose rocky undersea slopes they’d lived since swimming with dinosaurs.

The coelacanths of the Comoros Islands, along with another population discovered in Indonesia, are now celebrities of the animal kingdom, and nobody has spent more time with them than Hans Fricke.
In 1986, the German explorer and then-freelance photographer convinced a magazine editor to send him and a submarine to the Comoros.
Since then he’s led more than 400 dives, helping to produce much of what is now known about coelacanths.

After the publication of his latest work, published in Marine Biology and entitled “The population biology of the living coelacanth studied over 21 years,” Wired.com talked to Fricke about his time with the mysterious, magnificent creatures.

Wired.com: How did your interest in coelacanths begin?
Hans Fricke: When I was young, I read the book by J.L.B. Smith, Old Four Legs.
I was a keen skin diver, because I was 11, and I said, ‘Good friend, this fish you will see once in your life.’
In 1975, I joined an expedition of the Royal Society to Aldabra Atoll, and then I went to the Comoros, where I did some very stupid, very daring scuba dives to down over 300 feet.
But I found nothing.
I said to my wife, “Next time I come here, I’m coming with a submarine.”
I said it as a bit of a joke, but the next time I came to the Comoros, in 1986, I came with a submarine.

Wired.com: Can you describe that first submersible?
Fricke: It was made by two Czechoslovakian engineers in Switzerland.
We made the first trials in Lake Constance, then I smuggled the submersible over the Swiss-German border, because I would have had to pay customs.
It was covered in a sheet and looked like an American Sherman tank.
The border policeman asked me, “Friend, what is below this sheet?” I said, “A submarine.”
He said, “No.” I said, “Yes it is. I was in the lake diving,” and told him some fish stories.
He found it really interesting, and forgot to ask the crucial question: if I’d paid customs.

Wired.com: When did you first find a coelacanth?
Fricke: We tried hard to find the fish, but we didn’t look carefully enough, we didn’t know about its behavior.
The fish are nocturnal, and hide during the day.
I had to fly back home to Munich, and two of my friends continued for five more days.
They found it.
Of course my friends immediately called my family.
I had a stopover in Paris, called my family, and my little son said, “How is the fish?” And I said, “Which fish?”
He said, “The coelacanth!”
This was a great moment.
I had tears in my eyes.
I went back a couple weeks later, and on the first dive we found them

Wired.com: What is it like to see one?
Fricke: You immediately grasp that something is fishy with this fish.
It is not a normal fish.
Their movements are extremely slow; it has something like a mute character.
I had the feeling I had an amphibian in front of me, because of the movements of the fins.
I discovered a very funny, tetrapod-like movement of the fins, a kind of cross-step that they do.
If you were to cut a coelacanth across the middle, you’d see that it’s almost an ellipse.
If one make a downbeat with its right pectoral, the beast turns.
To counter this, it has to make a counter-downbeat on the far left side.
This produces the tetrapodic cross-step.
It’s a normal thing for an animal on land, but we’re talking about a fish.
This could be a pre-adaptation for the step to land.
They move so slowly.
J.L.B. Smith said this gives you impression they crawl on their fins at the bottom of the sea, but they don’t.
They don’t even touch with their fins.

Wired.com: If they move so slowly, how do they capture prey?
Fricke: They have a giant electroreceptor in their head, called the rostral organ.
They perceive the electric field which a swimming object in salt water produces.
Lava fields have reduced magnetic anomalies, and if you swim as a fish in this field, of course you produce in your own body an electric field which you could measure.
It is very likely the fish orientates himself via detecting magnetic anomalies in seawater.
It’s amazing — it’s a landscape like Hell, like the lava fields in Hawaii, and they go into this field and orient themselves precisely and fast.

Wired.com: How do juveniles find homes?
Fricke: We never found a juvenile.
We are very puzzled by the fact that we see only sub-adults.
That means they must live somewhere else, and we don’t know where.
We had once a pregnant female radio-marked with a pinger, and she did something extraordinary: She went down to 2,300 feet and remained for the day at that depth.
Something must have happened with her.
I believe she gave birth, but I could not follow her and see if her abdomen was still swollen and prove it.
But it makes sense that they live down there.
If a juvenile swam in front of an adult, they’d eat it.
‘They need about 12 grams of food a day. This is probably the secret of their evolutionary success.’

Wired.com: It takes three years for an embryo to develop. Why so long?
Fricke: They have the slowest metabolic rate known among vertebrates.
We made a calculation that a coelacanth needs, for its resting metabolism, 3.8 milliliters of oxygen per kilogram per hour.
A tuna needs 400 milliliters.
Because coelacanths are always burning at a low metabolic flame, they are able to live in low-energy areas, where there isn’t much food.
The lava fields are a low-product habitat.
They need about 12 grams of food a day.
This is probably the secret of their evolutionary success.
They live where hyperactive fish cannot survive.

Wired.com: Is climate change going to be a problem?
Fricke:With each water temperature increase of 10 degrees Fahrenheit, metabolic requirements are doubled, so they have to live under a special temperature regimen.
They live in areas with a temperature of 59 to 64 degrees Fahrenheit.
It’s there that their hemoglobin has the best capacity for oxygen.
They can’t live anywhere else.
They also need caves.
If there are no caves, the fish can’t survive.

We did a study with [Microsoft co-founder] Paul Allen’s fantastic equipment, which let us dive very deep.
And the sad story in the Comoros is, the volcano is eroded below 650 feet.
There’s no place to hide there.
In 1991, when there was an El Niño happening, we found 40 percent fewer coelacanths in our area.
At 720 feet, it was 77 degrees Fahrenheit.
The fish would be in respirational stress.
With climate change, if the water temperature increases, they would have to go deeper, but there are no caves.
And this would be the end of the Comoros population.

Links :

• Australian museum / Smithonian museum : Coelacanth, 1939
• NationalGeographic : Coelacanth
• MarineBio : Latimeria chalumnae, Coelacanth
  

Island at bottom of world boasts incredible biodiversity

South Georgia and the Falkland Islands are two of the most awe-inspiring places on planet earth.
This video vignette introduces you to naturalists and photographers who have been returning to this place for years, to witness the unfolding lives of penguins, elephant seals, fur seals, wandering albatrosses, and sea birds who call these islands home.
In addition to showcasing incredible wildlife footage, this video also takes you under the sea for a look at marine life, and back into the footsteps of Shackleton and his explorations of the region.

From OurAmazingPlanet

A sub-Antarctic island and its surrounding waters appear even richer in marine animal species than the legendary Galapagos Islands, scientists now reveal.
The scientists detailed their findings online May 25 in the journal PLoS ONE.

Investigators studied the marine biodiversity of South Georgia, an island about 105 miles (170 kilometers) long and more than three times the size of Hong Kong located in the Southern Ocean, the southernmost waters of the world's oceans.

"It looks like a giant has picked up the Alps and plonked them down in the middle of the Southern Ocean — beautiful," said researcher Oliver Hogg, a marine ecologist with the British Antarctic Survey.

The new research has shown that the islands host hundreds of marine species, many found there and nowhere else. [Related: Images - Antarctica's Amazing Sea Life]

The position of South Georgia relative to the Polar Front (white line), and the Antarctic Circumpolar Current (black dashes).
>>> geolocalization with the Marine GeoGarage <<<

Southern Ocean survey

The researchers conducted the first comprehensive study of sea creatures in the continental shelf area around South Georgia, a region covering about 17,000 square miles (44,000 square km).

They analyzed more than 25,000 records dating back more than 130 years, collected from scientific cruises, fisheries vessels and by scuba divers from the seas around South Georgia.

"Last November, expert divers from the shallow marine survey group based in the Falkland Islands acted on our behalf to conduct the biggest exploration of South Georgian waters for 85 years," Hogg said.
"Divers braved conditions of 0 degrees [Celsius] [32 degrees Fahrenheit] to collect samples from the northern waters of South Georgia."

Their research found that South Georgia and its surrounding islands were the richest area for marine life in the Southern Ocean.
"Based on current data, South Georgia supports many more species than Galapagos and Ecuador combined," Hogg said.
"During the breeding season, it hosts the densest mass of marine mammals on Earth."

Sea urchins, free-swimming worms, fish, sea spiders and crustaceans were among the 1,445 species recorded from the more than 17,000 specimens analyzed.
Most are rare and many occur nowhere else on Earth.
This figure of 1,445 species is a conservative one.
"Some estimates from marine species of South Georgia are well above 2,000," Hogg told OurAmazingPlanet.

Isolated island

The area is likely so diverse due to a combination of factors.
"The island is old — it started separating from the South American landmass about 45 million years ago," Hogg said.
"This has allowed life to develop here over a long time. Combined with this is that it is very isolated, enabling the evolution of new species."

In addition, the shelf area is large, offering diverse habitats and a big target for potential new colonists.
Moreover, "South Georgia is in close proximity to nutrient-rich currents, which can also supply the island with both Antarctic and temperate species in the form of larvae or adults hitching a ride on kelp rafts."

At the same time, "the island so far seems to have no invasive marine species, allowing the natural community to develop undisturbed by aggressive invaders," Hogg said.
Also, "it is too far north to experience significant ice scour, when an iceberg crashes along the sea floor, crushing much of the wildlife; it is too far south to experience too much human interaction."

When compared with one of its nearest neighbors, the South Orkney Islands, South Georgia's continental shelf is only 75 percent of the size but supports nearly 40 percent more species.
"In terms of other Southern Ocean islands, South Georgia also had the added benefit of not having its shelf completely covered during the last ice age," Hogg said.
"As such, its wildlife has been able to colonize and evolve relatively undisturbed for longer than other islands.

Clues for conservation

These findings are key to monitor how these species might respond to future environmental changes.
The near-surface waters around South Georgia are some of the fastest-warming on Earth, so this project will help identify ecologically sensitive areas and species as well as identify conservation priorities.

"This is the first time anybody has mapped out the biodiversity of a small polar archipelago in the Southern Ocean," Hogg said.
"If we are to understand how these animals will respond to future change, a starting point like this is really important."

The biggest concern is likely to be the wholesale extinction of creatures there unable to cope with changes in their environment.
Still, "we do not know with any certainty the ability of most of the species we report to deal with changing temperatures," Hogg noted.
"Temperature in South Georgia's surface water can vary by as much as 5 degrees [Celsius] annually. As such, it is plausible that some South Georgian species have a predisposition to tolerating temperature change."

In the future, the researchers hope to map the South Georgian waters more completely.
"Of prime interest is the area south of the island, which 'til now has received little attention," Hogg said.
"This opens up the possibility of finding lots of new species."

Links :

• NERC : Stunning broadcast-quality footage and stills of South Georgia
• BAS : South Georgia Marine Biodiversity Database
  

Rogue waves captured

Wave gauges in a water tank spot the peak of a tiny rogue wave.

From ScienceNews

Re-creating monster swells in a tank helps explain their origin

Freak waves that swallow ships whole have been re-created in a tank of water.
Though these tiny terrors are only centimeters high, a devilishly difficult mathematical equation describing their shape may help to explain the origins of massive rogue waves at sea..

Sailors have long swapped stories about walls of water leaping up in the open ocean — even in calm water — without warning or obvious cause.
But for centuries, rogue waves were little more than talk; no one had ever measured one with scientific instruments.

Then on New Year’s Eve of 1995, a laser on an oil rig off Norway’s coast recorded one of these rare events: a wave 26 meters from bottom to top, flanked by deep troughs on either side.

This wave and others measured since look like breather waves, says Amin Chabchoub, a mathematician at the Hamburg University of Technology in Germany.
A breather wave is an anomaly in a series of waves that sucks in the energy of its neighbors and puffs itself up to a great height.

The nonlinear interactions that allow for this energy theft were described by mathematician Howell Peregrine in 1983.
His solutions of nonlinear Schrödinger equations showed that pulselike waves called Peregrine solitons can pop out of sine waves under certain conditions.

“For a long time, nobody really thought this mathematics would be applicable to the ocean,” says Al Osborne, a physicist at the University of Turin in Italy.
“Not only is it applicable, but we’re now undergoing a paradigm shift in understanding ocean waves.”

To make a Peregrine soliton, Chabchoub wobbled a paddle back and forth at the end of a long water tank.
Regularly spaced waves about a centimeter high emerged and rolled across the surface.
Then he gave the paddle a precise jerk – introducing an anomaly.

“It’s possible that the wind could generate a similar modulation or perturbation in the open sea,” says Chabchoub, who describes the experiment in a paper in the May 20 Physical Review Letters.

In the 15-meter tub, this spot grew to a height of about 3 centimeters before dying down — hardly enough to make a rubber ducky quack in fear.
Flanked by two deep troughs, the rising peak moved half as fast as the background waves.
It satisfied both Peregrine’s mathematics and a common statistical view that a rogue wave is something at least two to three times the size of the tallest one-third of the other waves averaged.

In theory, the toy waves in the water tank should scale up to oceanic proportions.
But oceans are much messier than water tanks.
Normal ocean waves come in a variety of sizes and speeds, and other nonlinear effects may play a role in creating rogue waves.

“You add an almost imperceptible amount of noise, and all sorts of wacky and unexpected things can happen,” says Daniel Solli, a physicist at UCLA who created the first Peregrine soliton in light waves.

Chabchoub and his colleagues are exploring ways to introduce a little more mess into their tank to see what other wacky conditions can give rise to freak waves.

Links :

• Marine GeoGarage blog : Science investigates freak waves / Rough seas for tough mariners / Studying and surfing the ocean's monster waves

How to rid the seas of ‘plastic soup’?

Google Earth Tour about Marine Debris
Marine debris is a global problem and affecting everything from the environment to the economy.
To help show the breadth of this problem, the National Oceanic and Atmospheric Administration (NOAA) has created a KML tour for Google Earth.

From NYTimes

Overfishing, oil slicks, acidification — the world’s oceans, which cover 71 percent of the planet’s surface, face plenty of environmental problems.
As I note in this Green Column, we’ve added another serious one to the list: the vast amount of trash, 80 percent of it plastic, that ends up in the seas from year to year.

Actually, scientists and environmental campaigners have been aware of the mounting volumes of plastic in the seas since the 1970s.
But over the last two or three years, the phenomenon has gained wider attention, stirring concern among policymakers in the United States and Europe.

The National Oceanic and Atmospheric Administration, for one, says that marine debris ‘‘has become one of the most pervasive pollution problems facing the world’s oceans and waterways.’’ And the European Union’s commissioner for maritime affairs and fisheries, Maria Damanaki, recently said that the pollution of the Mediterranean had reached ‘‘alarming proportions.’’

Numerous projects have sprung up to combat the problem, including efforts to recycle trash recovered from the seas and campaigns to raise public awareness.

In the United States, NOAA initiated a Marine Debris Tracker mobile application in cooperation with the University of Georgia that enables users to report on trash spotted on coastlines and waterways.

A charity known as Plastic Oceans is working on a major documentary on the issue.
Endorsed by the environmental grandees David Attenborough and Sylvia Earle, it is expected to be released by early 2013.
And in Europe, Ms. Damanaki recently proposed paying fishermen to ‘‘fish for litter’’ to combat the pollution in the Mediterranean.

The problem is not just one of unsightliness, or of sea life getting caught up in plastic grocery bags or choking on plastic bottle tops or cigarette lighters.

There are also the tiny fragments formed by disintegrating items.
Plastic does not fully biodegrade like wood or cardboard, noted Peter Kershaw of the British marine science center Cefas, who advises the United Nations on marine environmental protection issues.
For plastic to biodegrade, you need conditions that are really found only in industrial composters and landfills, including high temperatures.

‘‘You don’t have those conditions in the middle of the sea,’’ he said.
Instead, the plastic trash eventually breaks up into billions of fragments that hover below the surface in vast, soupy patches in the Atlantic, Pacific and Indian oceans.

Easily swallowed by marine life and prone to absorbing contaminants in the water, this gunk is now a key focus of scientific concern, with some researchers worrying that it could end up in the food chain.
‘‘It is everywhere and in every water sample that we have collected since 1999,’’ said Marieta Francis, executive director of the Algalita Marine Research Foundation in California.

Because these ‘‘microplastics’’ are far harder to remove from the sea than chunks of packaging and containers, the main focus has to be preventing more plastic from reaching the oceans in the first place, experts say.

Global plastics production is expected to continue to rise inexorably from the estimated 250 million tons churned out annually now.
One critical solution advanced by experts is better recycling, more re-use of containers and packaging and less waste: do cookies and toilet rolls really need to come individually wrapped in plastic, as they are here in Hong Kong, where I live?

Links :

• YouTube : The Majestic Plastic Bag, highly entertaining and educational ‘‘mockumentary’’ on the life cycle of the plastic bag and its long trip to the oceans
• NYTimes : the peril of plastic
• TED : Captain Charles Moore on the seas of plastic