28 March 2012


World Ocean currents. Click for larger view. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.
NASA/Goddard has stunning images up at their Scientific Visualization Studio showing sea surface currents colored by sea surface temperature data. From the explainer:

This visualization was produced using NASA/JPL's computational model called Estimating the Circulation and Climate of the Ocean, Phase II or ECCO2. ECCO2 is high resolution model of the global ocean and sea-ice. ECCO2 attempts to model the oceans and sea ice to increasingly accurate resolutions that begin to resolve ocean eddies and other narrow-current systems which transport heat and carbon in the oceans.The ECCO2 model simulates ocean flows at all depths, but only surface flows are used in this visualization.

Pacific Ocean currents. Click for larger view. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.

Here's the insanely beautiful eddies of my home ocean, the Pacific. Note the superhighways of the Equatorial currents that run so much of Earth's climate via the El Niño/La Niña-Southern OscillationAnd note the powerful Kuroshio Current off Japan (upper left) currently carrying that nation's tsunami debris towards North America.

North Atlantic Ocean currents. Click for larger view. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.
In this view of the North Atlantic you can see the data-rich regions—the places where oceanographers have been cranking out the studies for decades—throughout the Caribbean and up the Gulf Stream through to the North Atlantic Drift en route to Europe.

Indian Ocean currents. Click for larger view. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.

What pops for me in this Indian Ocean image is the crazy interference patterns around the Cape of Good Hope (bottom left quadrant) where the Benguela and the powerful Agulhas currents spin up some stuff known as mesoscale eddies... and the way those ripple through the system into the Antarctic Circumpolar Current.

The movement in the animation is subtle and hypnotic.

27 March 2012


Hector's dolphin. Credit: James Shook via Wikimedia Commons.
A new study provides the first empirical evidence that a marine protected area (MPA) has robustly improved the survival of a marine mammal. In this case, one of the world's most endangered marine mammals, the Hector's dolphin (Cephalorhynchus hectori) of New Zealand.
The IUCN Red List describes the problems facing this diminutive cetacean:
This species is considered to be Endangered due to an ongoing and projected decline of greater than 50% over 3 generations (approx. 39 years)... Hector’s dolphin has the most limited range of any marine cetacean other than the vaquita (Phocoena sinus)... The main cause of population decline is ongoing bycatch in [gillnet and trawl] fisheries.
Concerned for the future of this rare species (population: 7,270 individuals), New Zealand in 1988 established the Banks Peninsula Marine Mammal Sanctuary in 1,170-square-kilometers (451-square-miles) of waters off the South Island. 

Banks Peninsula, South Island, New Zealand. Credit: NASA Astronaut Photo ISS013-E-67242.

The research, ongoing since 1986, involved identifying 462 individual Hector's dolphins through photographs and then analyzing the photographic re-sightings using a Bayesian mark-recapture technique. The team applied a population model to assess the impact of the MPA on the dolphins.

Their results show that since the designation of the sanctuary, the Hector's dolphins' survival rate has increased by 5.4 percent: 

  • From a decline of ~6 percent per year
  • Now slowed to a rate of decline of ~1 percent per year

As good as that sounds, the researchers were surprised survival rates hadn't increased further, since they expected the establishment of the MPA to solve the problem entirely.
Hector's dolphin. Credit: David Searle via Flickr.

Instead they discovered the dolphins don't spend the whole year in the sanctuary. Co-author Liz Slooten tells me:

Their distribution with respect to depth and distance offshore changes. In winter they are almost evenly distributed with respect to depth and distance offshore. In summer they are strongly concentrated close to shore. This means that in summer about 80% of the population is inside the sanctuary and protected. In winter this drops to only about 40%. Too many dolphins are still being caught in fishing nets to allow the population to stabilise, let alone recover from the massive decline they've suffered over the last three decades.

"The MPA hasn't quite yet 'saved' the dolphins," says Slooten, "but it's been a major step in the right direction. 
The take home message is that size matters. Marine Protected Areas work, but they have to be large enough in order to be effective."

The paper in early view at the Journal of Applied Ecology:

  • Andrew M Gormley, Elisabeth Slooten, Steve Dawson, Richard J Barker, Will Rayment, Sam du Fresne and Stefan Brager (2012). First evidence that Marine Protected Areas can work for marine mammals. Jour. App. Ecol. DOI: 10.1111/j.1365-2664.2012.02121.x

26 March 2012


Puffinus shearwater. Credit: Jofre Ferrer via Flickr. 
The Balearic shearwaters (Puffinus mauretanicus) who breed on the Spanish Balearic Islands don't go far when they migrate... out the Strait of Gibraltar then north to summering grounds off the Atlantic coasts of Portugal and France.
Yet, curiously, only the females go to France. 
Perhaps because of these longer migrations, they also spend longer away from their breeding grounds than the males: 

  • Median duration of time away for females: 91 days
  • Median duration of time away for males: 83 days

Credit: Tim Guilford et al. PLoS ONE. DOI:10.1371/journal.pone.0033753.
These are the findings of a team of researchers who tagged 26 shearwaters with miniature geolocation trackers and followed their annual movements from the Balearic Islands. The results are published in a new paper in PLoS ONE.
You can see in the maps above the routes of the individual birds, each with its own color track:
  • Inset map shows where all the birds occurred statistically half the time throughout the year.
  • Larger maps shows where all the birds occurred statistically half the time on migration to and from their breeding islands.
  • The colored circles mark where four birds made trips back into eh Atlantic after their migrations.
  • The red symbol is the position of the breeding colony at Sa Cella cave on Mallorca.
Longline hooks. Credit: Isaac Wedin via Flickr.

The gender-specific migrations are more than a curiosity. They're vitally important knowledge since Balearic shearwaters are Europe's only critically endangered seabird. From the IUCN Red List:
This species has a tiny breeding range and a small population [known breeding population: ~3,200 pairs] which is undergoing an extremely rapid population decline owing to a number of threats, in particular predation at breeding colonies by introduced mammals [cats, genets, rats, rabbits] and at-sea mortality as a result of interactions with commercial fisheries [hooked and drowned on longlines]. Population models predict an extremely rapid decline over three generations (54 years), qualifying the species as Critically Endangered.
Balearic shearwater. Credit: Roger Montserrat via Flickr.

Obviously if you have a large proportion of the females flocking and feeding in one location then the entire species becomes susceptible to mass mortality fishing events like the one that killed ~50 birds off Spain in 1999-2000. As the authors note:
[F]or approximately ¼ of the year, a large percentage of the world's population of breeding birds will be vulnerable to [fisheries] by-catch in these two core areas within the territorial waters of Portugal and France.    
The paper:

  • Guilford T , Wynn R , McMinn M , Rodríguez A , Fayet A , et al. (2012) Geolocators Reveal Migration and Pre-Breeding Behaviour of the Critically Endangered Balearic Shearwater Puffinus mauretanicus. PLoS ONE 7(3): e33753. doi:10.1371/journal.pone.0033753

23 March 2012


BIOdiversity from tresvampiros on Vimeo.

Great animated short explaining biodiversity made for the Humboldt Institute in Bogotá, Colombia (my birthplace).

16 March 2012


Credit: NASA/JPL-Caltech/UCLA.
In a great mapping milestone, NASA's WISE (Wide-field Infrared Survey Explorer) space telescope has compiled this mosaic image of the entire sky. 
That's more than 2.7 million images taken at four infrared wavelengths of light for a total of more than 15 trillion bytes of data in just over two years

As for what you're looking at, here's the WISE page description:
This map is centered on the Milky Way Galaxy. The plane of the Galaxy runs along the equator, and the center of the Galaxy is at the center of the map, where projection distortions are minimal. The distortions are most pronounced at the edges of the map. The right and left edges of this oval shape are the same location in the sky.
Credit: NASA/JPL-Caltech/UCLA.
There are 560 million objects in this view—many seen for the first time—stars, galaxies, planets, asteroids, and more:
WISE observations have led to numerous discoveries, including the elusive, coolest class of stars. Astronomers hunted for these failed stars, called "Y-dwarfs," for more than a decade. Because they have been cooling since their formation, they don't shine in visible light and could not be spotted until WISE mapped the sky with its infrared vision

And here's a zoomable version of the WISE map so you can boldly go where no one has gone before. Click here for humongous version.

13 March 2012


Hermit crab with anemone n shell. Credit: mirtai via Flickr.

My recent hermit crab post included a video of hermits trying on new homes, and included the the way some defend their shells with stinging anemones (above).
But I also found myself wondering what will become of hermit crabs in a world of increasing ocean acidity and dwindling seashells? (You can read more about that in my latest article in OnEarth magazine.)

In the above image you can see the fate of a shell dissolving over 45 days in acidified water. 
Now via Discover Magazine I see this interesting photo (below) of a nude hermit crab donning an anemone: 

Greg Rouse and colleagues found this critter during an expedition off the coast of Costa Rica in 2010. The area is lacking in large snail shells, says Dr. Rouse, and there has been a previous report of this species, Parapagurus foraminosus, covered by an anemone.
Credit: Greg Rouse, Scripps Institution of Oceanography at UC San Diego.
Crabs—survivors since at least the early Jurassic—are crafty!

09 March 2012


Bowhead whale. Via.
A new paper in Biology Letters reports on two satellite-tagged bowhead whales from different oceans meeting in the ice-free waters of the Northwest Passage in September 2010. 
One whale was from West Greenland. The other from Alaska. Their paths crossed in the Parry Channel in the Canadian Arctic Archipelago (maps, below). 
From the paper:
It is not known what attracted the whales to this area, given the region has relatively low marine production in autumn compared with other known bowhead whale feeding areas.
Bowhead whale bones on ceremonial ground, Point Hope, Alaska. Credit: rnoblin via Flickr.

This was not the first times whales from different waters have met in an ice-free Northwest Passage. From the paper:
During the commercial whaling period (i.e. pre-1900), several harpoon heads of Atlantic origin were discovered in bowhead whales harvested in the Chukchi Sea/western Arctic, but this information was largely dismissed as anecdotal by scientists. 
Further evidence appears in the genetic record:
Recent genetic studies compared DNA of whales from Foxe Basin, Canada to whales from Alaska and suggest genetic mixing, although results are based on a small sample size from a highly segregated population. The lack of genetic differentiation between whales in the Pacific and the Atlantic, acknowledging that samples are taken several thousand years apart, suggests that some exchange of individuals occurred between whales in Svalbard and Alaska
Credit: Mads Peter Heide-Jørgensen, et al. Biol Lett. DOI:100.1098/rsbl.2011.0731. 

The maps show the individual tracks of the two whales from late spring through early autumn. The inset map shows where they overlapped. From the paper:
The Northwest Passage with tracks of four bowhead whales and extent of sea ice with greater than 50% concentration (white fields). (a) Track of a whale tagged on 4 May 2002 in West Greenland and ice extent on 20 September 2002. (b) Track of a whale tagged in Alaska on 12 May 2006 and sea ice extent on 8 August 2006. (c) Track of a whale tagged on 24 May 2010 in Alaska, one tagged on 15 April 2010 in West Greenland, and sea ice extent on 14 September 2010. The insert shows the area where whales occurred together in 2010. The whale from Alaska was present in Viscount Melville Sound between 19 August and 18 September while the whale from Greenland was present from 11 to 28 September.
1980: Sea ice coverage 1 Nov-31 Jan. Credit: NASA Earth Observatory.
2012: Sea ice coverage 1 Nov-31 Jan. Red star marks approximately where the two whales met in 2010. Credit: NASA Earth Observatory.
These latest images posted by NASA's Earth Observatory give you a sense of how the passage has opened up in the last three decades for whales... and presumably for others too. I marked (red star) approximately where the two whales met in 2010.
The authors conclude:
Given recent rates of sea ice loss, climate change may eliminate geographical divisions between stocks of bowhead whales and open new areas that have not been inhabited by bowhead whales for millennia (e.g. North of Greenland and north of the Canadian Archipelago).
The documented movements of bowhead whales in the Northwest Passage are perhaps an early sign that other marine organisms have begun exchanges between the Pacific and the Atlantic Oceans across the Arctic. Some of these exchanges may be harder to detect than bowhead whales, but the ecological impacts could be more significant should the ice-free Arctic become a dispersal corridor between the two oceans.

Foxe Basin Bowhead Whales from Stephen Ambruzs on Vimeo.

The open-access  paper:
  • Mads Peter Heide-Jørgensen, Kristin L. Laidre, Lori T. Quakenbush, and John J. Citta. The Northwest Passage opens for bowhead whales. Biol Lett. DOI:10.1098/rsbl.2011.0731.

08 March 2012


My mother always told me to carry a cowry shell in my wallet for good luck. Since she comes from India, I began to wonder about the roots of this belief.
We know that cowry shells are the longest-lived and most widely-spread currency of our species—in use perhaps as early as 4,000 years ago, and important to cultures ranging from Oceania to West Africa and most everything in between.

Credit: Bin im Garten via Wikimedia Commons.
They've been found in association with coins from sites in India dating to the first century AD according to the Conchological Society of Great Britain and Ireland.
But they seem to have been used even earlier in ancient China. Here's an excerpt from an interesting paper by Colin Narbeth:
The use of cowry shells as a medium of exchange goes back to the dawn of Chinese civilization. One of the earliest written references is that of an historian, Ssu-ma Ch'ien, of c. 145-86 BC. He mentions cowries as being used as money in the Shang and Chou periods. In the Shang Dynasty [1766-112BC] the character PEI was part of the Chinese language. The earliest form, the archaic script which developed into Seal Script, was merely a rough picture of the ventral side of a cowry [貝]. It was so important that PEI was adopted as one of the 214 radicals—the foundations characters of the language. Today 84 Chinese characters have PEI as the main foundation. Finds of cowry shells, sometimes in very large quantities, have come to light in tomb excavations and the opinion of most Chinese archaeologists today is that they were there as money.

There were times the Chinese couldn't get enough shells and manufactured them from wood, stone, bone, bronze, gold, silver, jade, and other semi-precious stones
The first metal currency was actually imitation cowry shells.

Copper/bronze imitation cowry shell money. Via.

Stone imitation cowry shell money. Via.
Pottery imitation cowry shell money. Via.

The species most commonly used as currency—the money cowry—was named by the father of modern taxonomy Carl Linnaeus as Cypraea moneta in 1758. 
Today's scientific name is Monetaria moneta.

Live money cowry. Via.

They were collected in vast numbers from the waters around the Maldives Islands off southern India. More from Colin Narbeth:

From the Arab merchant Sulayman (851 AD) we learn that at one time, in the 9th century, the Maldives had a very beautiful and wealthy Queen. Having used up her Treasury of cowries she resorted to sending the Maldive maidens to collect large palm leaves from the coconut trees. These were then laid in the shallow water. Soon thousands of cowries would crawl onto the leaves—to be suddenly pulled out of the water and left high and dry to die before being sent to replenish the Queen’s Treasury. This account was confirmed by Masudi of Baghdad, famous Arab historian of the 10th century.
In the 17th century Pyrard de Laval was wrecked on the Maldive Islands and stayed there for two years. He wrote: "They called them (cowries) Boly and export to all parts an infinite quantity, in such wise that in one year I have seen 30 or 40 whole ships loaded with them without other cargo. All go to Bengal for there only is there a demand for a large quantity at high prices. The people of Bengal use them for ordinary money although they have gold and silver and plenty of other metals; and what is more strange, kings and great lords have houses built expressly to store these shells and treat them as part of their treasure."    

Modern Maldives currency with cowry shell design. Via Wikimedia Commons.

As you might imagine, with so much pressure on the stocks, Monetaria moneta eventually became scarce in Maldivian waters. Attention switched to a similar species, Monetaria annulus. From Narbeth:

These could be found in huge quantities off the Zanzibar coast... By 1851 inflation was undermining the trade. Cowries were so plentiful and so cheap that counting them became a very time consuming matter. Town governors packed them in sacks—20,000 to the sack. But when used between private individuals they had to be counted, in fives. Barth wrote: "The general custom is to count them in fives, in which operation some are very expert, and then to form heaps of 200 or 1000 each. The counting of 500,000 shells is a really heroic work."

Credit: Sarah Starkweather via Flickr
My mother and her kin came from Bengal. So perhaps the habit of carrying a cowry shell in your wallet as good luck—specifically, as monetary good luck—is left over from the time when cowry shells were real money.
Interestingly, Narbeth writes about periods of transition in China when rulers tried to abolish cowry currency in favor of a metal currency, only to have the next ruler abolish the upstart metal in favor of cowry currency. 
Cowry eggs. Via.

In times of such uncertainty, it might have been a good idea to keep some cowry power in your wallet. Just in case it got valuable again. 
I'm still doing it.

06 March 2012


Gentoo penguin and chick. Credit: © Julia Whitty.
There are big changes underway in penguin colonies in the Antarctic Peninsula.
Why? First up, it's one of the fastest warming regions on Earth.
And we know that a warming climate can shift the phenology—the timing of annually recurring lifecycle events like migrations and flowering—of species. 
Phenological shifts can leads to "trophic mismatches." That is, where interacting species fall out of sync.
Caribou. Credit: NPS.
For instance, a study in Proceedings of the Royal Society B showed a trophic mismatch between caribou (whose seasonal migration to summer calving ranges is cued by changes in day length) and the plants they feed on in their summer ranges (whose growing season is cued by local temperatures).
Trophic mismatches are increasingly likely in a warming world, especially among migratory species that have no way to know the schedule is speeding up hundreds or thousands of miles away.
Adélie penguin and chick. Credit: © Heather Lynch.
A new paper in MEPS (Marine Ecology Progress Series) takes an interesting look at another aspect of phenological change—the possible effects on species that breed (and compete) together.
Specifically on three penguins on the Antarctic Peninsula: Adélie, chinstrap, and gentoo
Adélies and chinstraps migrate to their breeding colonies. The gentoo is resident year round.

Warming in Antarctica in degrees C per year between 1981-2007.Credit: NASA Earth Observatory, image by Robert Simmon, based on data from Joey Comiso, GSFC.
You can probably already hypothesize a dynamic among these three species competing for breeding space and to some extent food resources in a rapidly warming area.
The authors of the MEPS paper investigated changes in clutch initiation dates (the date the first egg is laid) of the three species in the Western Antarctic Peninsula (WAP)—that's the pointy bit at the upper left of the map, above. 

The results were striking. From the paper:
We found that clutch initiation was most significantly correlated with October air temperatures such that all 3 species advanced clutch initiation to varying degrees in warmer years. Gentoo penguins were able to advance [clutch initiation dates] almost twice as much (3.2 d°C−1) as Adélie (1.7 d°C−1) and chinstrap penguins (1.8 d°C−1). 

Chinstrap penguins and chicks. Credit: Hannes Grobe/AWI via Wikimedia Commons.
What jumps out here is that resident gentoos, who are already on the breeding ground, appear able to accurately judge the advancing spring dates and lay earlier. And this may be the reason, at least in part, as to why Adélies and chinstraps are suffering population declines and gentoos are thriving in the WAP:

  • Adélies declining in 18 of 24 surveyed breeding sites
  • Chinstraps declining at 16 of 29 surveyed breeding sites
  • Gentoos increasing at 32 of 45 surveyed breeding sites
Those numbers are forthcoming in another paper from some of this same team.
Heather Lynch counting gentoo penguins at Port Lockroy, Antarctica. Credit: © Julia Whitty.
BTW, I first wrote about two of these researchers—Heather Lynch and Ron Naveen—in my Mother Jones article March of the Tourists a while back.

The papers:

  • Heather J. Lynch, William F. Fagan, Ron Naveen, Susan G. Trivelpiece, Wayne Z. Trivelpiece. Differential advancement of breeding phenology in response to climate may alter staggered breeding among sympatric pygoscelid penguins. MEPS. DOI:10.3354/meps09252.09252
  • Eric Post and Mads C Forchhammer. Climate change reduces reproductive success of an Arctic herbivore through trophic mismatch. Phil. Trans. R. Soc. B. DOI:10.1098/rstb.2007.2207

03 March 2012


Great footage of hermit crabs checking out potential new digs. Including an unlikely looking glass house made from a broken bottle.

Filmmakers Anna & Ned DeLoach wrote about filming hermits at their fun site, The Blennywatchers Blog:

The straight bottle lacked the spiral of a shell so the crab had trouble gaining traction but it gave us an excellent view of the parts of the hermit crab that we would never see otherwise. Click here to read the article Ned and I wrote about the encounter in Scuba Diving Magazine.

Very large hermit crab making queen triton shell home. Hawaii, Papahanaumokuakea Marine National Monument. Credit: NOAA Photo Library via Flickr.
Hermit crabs have been using gastropod shells since at least the late Cretaceous, 99–65 million years ago.

Before that they used ammonite shells—as you can see in the fossils below.

Fossil hermit crabs in ammonite shells. Via RMCG. 

Sometimes other creatures make homes on hermit crab homes. 
In the photo below you can see an anemone living atop a snail shell that a hermit crab has commandeered. The crabs place anemones on their shells as stinging defenders. 

Credit: NOAA Okeanos Explorer Program via Flickr.

And some anemones are home to the symbiotic algae known as zooxanthellae.

As I wrote in my new OnEarth article, The End of a Myth:
Honing our technological eyesight, we begin to observe what was once too small to be seen, in an exercise that mirrors infinity.
Credit: Ian Yarret via The Robert Savage Image Award at Swarthmore.

The red cells are symbiotic zooxanthellae inside the tissues of the sea anemone Aiptasia pallida.

H/T @deepdeanews and @echinoblog for the video link.