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Entries in Caribbean (8)

Friday
Oct012010

Look who's talkin'

Interesting news in a study thats in pre-publication in Ethology about mixed species schools of dolphins and the communication patterns that take place within them.  The author, Laura May-Collado of the University of Puerto Rico, hypothesised that when bottlenosed dolphins and Guyana dolphins school together, differences between their respective songs ought to be exaggerated in order to avoid confusion and enhance communication within species.  [Whales have been shown to alter their song to meet surrounding conditions, most recently in papers that describe long-term increases in song volume to offset the increasing background of human-made noise in the oceans.]  What she found was the exact opposite: calls became more homogeneous (with less variation between species), with the signal stucture (the waveform of the whistle as seen, for example, on an oscilloscope) converging on a form intermediate between the bottlenosed and Guyana whistles. Her first conclusion is that this represents a change on the part of the smaller Guyana dolphin to reduce social stress (placation, if you will) but its also possible that the dolphins might be using a common language.  If so, that would be one of the first examples of interspecies communication and it would be quite different from how humans do it, wherein one participant nearly always tries to change to the other participants language, not that boh participants find an intermediate language (I guess this is because human languages are too complex to easily invent intermediate forms).  Dr. May-Collado was unable to determine which explanation was the correct one because her equipment couldn’t distinguish which individuals were making the sounds, but its certainly a tantalizing view into the chatter that goes on between species in the ocean.

Guyana dolphin in front, bottlenosed behind. Click pic for original story

 

Thursday
Sep232010

Whale Sharks on Nat Geo Inside Wild

Some of the work we did in Mexico this summer will be featured on the National Geographic blog Inside Wild over the last quarter of this year.  The latest installment penned by Jodi Kendall, who accompanied us to Mexico, can be found here.  Check it out, and watch that space for future installments!  Learn more about Georgia Aquarium whale shark research here.

Monday
Aug302010

Wanted: Lionfish, dead or alive

Loved this banner, which was hanging in the lobby at the hotel in Mexico where we were based last week and where, coincidentally, there was a lionfish eradication strategy meeting going on.  I think Se Busca literally means “you see” but in this case I think it means “Wanted”, as in an old-time wanted poster. Perhaps a Spanish speaking reader can clarify for us.  Pez Leon is definitely Lionfish.

He’s terrifically grouchy-looking.  Love it.

Monday
Aug162010

Dancing with a Giant - the reprise

You might remember an earlier post about Dancing with a Giant, in which I was pretty emotional about an amazing swim I had just done with a whale shark in Mexico.  Well I can now share the video of that animal.  There’s a good bit at around 0:50 where you can see right into his mouth, and see the filter pads they use for sieving their planktonic food from the water. In this case, he’s filtering fish eggs, which you can’t see because they are too small and are also transparent; thats good for us though, because it gives us a nice clear view.  Without further ado then, here he is, MXA-181:

Monday
Jul122010

Whats in a name? Origins of the word "shark"

To a recent roundup of whale shark news, I appended a sort of human interest one-liner about how “shark” is the only word in the English language that derives from a Yucatec (Mayan) Indian word – “Xoc” (pronounced like “shock”). It was just one of those factoid tidbits picked up somewhere along the line of life, maybe while working in Mexico, I don’t remember. It tickled some interest from blogger @hectocotyli on Twitter, who posted a follow-up tweet questioning whether this was actually true, and citing a paper by Tom Jones, from the 5th Palenque Roundtable in 1983. That paper is entirely devoted to the question of the origins of the word shark. I read it and was transported, what a great story! So here it is then, a deeper look at the origins of this word "shark", with thanks to @hectocotlyi for having an inquiring mind and for finding the paper.

According to Jones, the very first mention of the word shark in association with the animal for which we use the name today was in a 1668 work by John Wilkes. One of the first mentions of the word in a diuctionary, however,  is in an anonymous work from 1689, which defines a shark as a “shifting knave”. In other words, a crook, dodgy sort or general baddie. That was surprising to me, because I had just assumed that the use of shark for a shifty character was a much more modern one derived from the noun referring to the animal wif de big nasty teef. Bailey’s Dictionary in 1724 used “scearan” as the likely origin for the word: a saxon term meaning “cut to pieces”. Webster took a different tack in his 1828 dictionary, accepting a theory that it comes from the greek word “carcharias” (sharp tooth), even though that word clearly has a typical Greek hard c sound, not the soft start of shark. These days, Oxford English Dictionary just says “of obscure origin” and to me that might be the best answer, if you insist on a European etymology.

The major alternative explanation is that the word comes from the Yucatec Indian word “xoc”. Now, explaining what the word xoc means in Mayan is not as simple as it would be for European languages; Mayan language groups are apparently among the most arcane and problematic for linguists to study, especially for the bizarre glyphic written forms. Jones goes into the issues in great detail, and its a fascinating read, but I could summarise by saying that at best the word refers specifically to sharks as we know them, and at worst to an ill-defined group of toothy aquatic animals that might also include large fish, crocodiles and toothed whales, in both fresh and salt water. There’s lots of usage examples to support the idea that it means sharks, though, including “xoc yee halal” which are arrows with sharks teeth for points, and “uayab xoc” which is a sort of demon or were-shark, part man and part shark. Its not that simple though, because xoc can also mean “to count to” or to refer to dates ahead or behind. In Mayan glyphic writing, glyphs are apparently freely substituted for other words or parts of words that are pronounced in similar fashion, even though the agreed meaning of the glyphs (or bits of ther glyph, sort of like syllables) may be radically different, which really confuses the issue and is a big part of the reason why written Mayan took so long to decode. In the glyphs from the Jones paper shown below, for example, the middle glyph is a counting glyph with the same meaning as the one on the right, but incorporates the glyph for xoc, of which the stand alone version is shown on the left. To me another obvious clue here is that the glyph for xoc is the head and mouth of a beast, even when used to mean "to count",  which seems to fit well the definition in the broad sense. The beast even has a rostrum of sorts, and triangular teeth.

If the usage roughly matches, then, how would a Mayan word make it to English?  Given that the Spanish and Portuguese were in closer contact with the New World earlier than the English, why would English not pick up the Spanish “tiburón”.  Put another way, why does the Iberian word not also resemble “xoc”? If it’s true that shark is of Mayan origin, then it must be a standalone jump – somehow going from Yucatec to English, skipping Spanish and Portuguese.  For the etymologists, it seems that this lack of intermediate steps or of words that share the same origin, which they call “cognates”, is a real problem for accepting the Yucatec origin of “xoc”.

Jones proposes a way that this could have happened, on the expeditions of John Hawkins from England to the Caribbean in the late 1560’s (incidentally, Hawkins was a pioneer of the English slave trade). Further, Jones proposes that the critical moment may have been an unanticipated battle between Hawkins and some Spanish ships forced to share moorings near Campeche in 1569.  The fight resulted in the destruction of several vessels from both sides and some pretty heavy losses, with over 200 of the English eventually consolidating onto a single ship called the Judith and heading for home.  Jones suggests that a shark frenzy feeding on the unfortunate victims of the battle – and on those who died of hunger and disease on the crowded Judith over subsequent days - might have created an indelible impression on the English (only 15 of whom made it back to Cornwall), enough to cement in their lexicon the local name for these demons of the sea.

As a complete linguistic noob, I find the proposed Mayan origins of shark to be more plausible than the Greek or Saxon suggestions. More importantly, though, it’s a way better story, and when there’s that much uncertainty, I’ll always choose the explanation that involves the greater ration of mysterious glyphic languages and dramatic ship battles on the high seas, wouldn’t you?

Friday
May212010

The Travel Bug bites hard, but it hurts so good

Just once in life I did the totally reckless thing of looking at a photo (in a Lonely Planet guide, if I remember) and saying "Thats it, I am going there, now" and then doing exactly that.  The place was Leh, which is in region called Ladakh, in the province of Jammu & Kashmir in Northern India.  Not once did I ever regret that decision; Leh was one of the most magical places I ever visited, probably made moreso because of the liberating decision to go half way round the world to see it and the good buddies I shared the experience with.

Well, I feel the same bite about Saba in the Netherlands Antilles.  Every time I look at a photo of that little volcanic speck and imagine the hair-raising landing at the airport, followed by the equally follicle-lifting drive through a myriad switchbacks clinging to the side of that impossibly steep volcanic plug, I can barely resist the urge to just walk out the door, head for Hartsfield-Jackson and jump on a plane.  I have assiduously suppressed these feelings for years in favour of pedestrian realism, but now PLoS One has published a series of papers about the diversity of critters on the bank reef adjacent to Saba.  How am I supposed to resist that?  Thanks a lot PLoS...

Somebody help a travel junkie out; either convince me to go, or talk me down!  Ever been there?  Whats it like?

Picture from Throwingpoo.com (I kid you not)

Tuesday
Mar302010

Ocean Conveyor running AMOC

This post was chosen as an Editor's Selection for ResearchBlogging.orgResearchBlogging.org

If you’ve ever seen the disaster movie “The Day After Tomorrow”, then you’ve been introduced to the idea that one day the global ocean conveyor might stop.  Its a pity (or perhaps not) that the movie was such a sensational introduction to the concept, because its a pretty serious possibility.  By way of short explanation: one of the things that makes life possible on this rock is that the ocean redistributes heat that arrives on the earth’s surface between the tropics, sending it to the higher latitudes by way of warm surface currents.  There, the waters are cooled and made more dense (both colder and saltier) by the polar ice caps; they then sink and begin a slow meander back to the tropics, eventually returning to the surface to complete the cycle.  Without effective redistribution of this sort, the tropics would bake and the polar zones would sink into a deep hard freeze (in both cases much more so than “normal”).  The climate in the UK, for example, would be much more like Siberia were it not of the tempering effects of the Gulf Stream continually bringing heat from the Caribbean to the North Sea.  An important point about the conveyor is that it is driven from both ends: by the suns heat near the equator and by the cooling effect of all that ice at the poles.

 Why would the conveyor grind to a halt?  The equatorial heat doesn’t show any sign of stopping; if anything its getting hotter.  No, the biggest fear is for the other driver: if the polar ice caps melt too much, there will no longer be a big enough reservoir to chill and brine the surface waters and they will cease to sink.  Some data from recent years suggested that this was happening, and happening fast.  Well, it seems as though Armageddon isn’t here just yet.  A new paper by CalTech/NASA’s Josh Willis in the journal Geophysical Research Letters uses a more complete data set than ever before to conclude that the conveyor, or more specifically a major section of it called the Atlantic Meridional Overturning Circulation (AMOC - hence the corny title of my post) measured at 41°N (near where it says “Atlantic” on the figure above), is not slowing.  In fact, there is some evidence that it may have sped up marginally in recent years, perhaps in response to warming and expansion of Atlantic waters.  The data were consistent across both satellite sources and sensor arrays deployed in the oceans, so it would seem like a pretty robust study (though I am no physical oceanographer).

I am sure I speak for everyone on the bonnie British Isles when I heave a sigh of relief.

But wait?  What light through yonder ice-shelf breaks?  Tis Greenland, and its seeing more of the sun!  In the very same issue of Geophysical Research Letters, a different group of authors report that ice loss is increasing from the Greenland ice sheet.  This is one of the major impacts of recent climate warming and the greatest contributor to increases in sea level globally.  It would also freshen the north polar waters, further reducing the driving force behind the global ocean conveyor.


My response to this news is to marvel at - and grapple with - the complexity and dynamics of the earth and its climate system.  Scientific results with seemingly opposite implications can come out (in this case in the same journal issue), but without threatening the major underlying pattern; I doubt, for example, that Dr. Willis would disagree with the concept of man-made climate change.  Faced with this seeming contradiction, its perhaps no wonder that many folks grapple with the Big Ideas at the heart of global climate change, and even doubt that it exists at all.  I for one have no doubt  that things are changing, and changing fast.  It may just be that some of the really big features of the climate system (including ocean currents) are slower to respond than others.  Its a bit like turning an oil tanker, which may be an unfortunately apt analogy…

Willis, J. (2010). Can in situ floats and satellite altimeters detect long-term changes in Atlantic Ocean overturning? Geophysical Research Letters, 37 (6) DOI: 10.1029/2010GL042372

Khan, S., Wahr, J., Bevis, M., Velicogna, I., & Kendrick, E. (2010). Spread of ice mass loss into northwest Greenland observed by GRACE and GPS Geophysical Research Letters, 37 (6) DOI: 10.1029/2010GL042460

Friday
Mar262010

Lionfish - more spectacular than your average invasive, but still a right pest.

When we think of invasive species, flamboyant fish from coral reefs are not usually the first thing that comes to mind.  Indeed, if you put together a list of characteristics of successful invasive species (like this one), "boring" would probably be close to the top, along with being quick to reproduce, not fussy about what you eat, having a large natural range, a great tolerance for extremes in the environment, and lacking natural enemies such as predators or parasites.  Think of some of the most successful invaders and decide for yourself if these predictions hold true: carp, starlings, mosquitofish, rats, sparrows, mice, rabbits, dogs, cane toads, cats, foxes, kudzu, chickweed... 

All this makes the invasion of the Atlantic seaboard by the Pacific lionfish, Pterois volitans, all the more remarkable.  Lionfish are flat-out spectacular!  Long prized as an aquarium specimen, they have bold stripes that spill over onto their fantastically long and showy fins; their scientific name even means "fluttering wings".  The sheer beauty of lionfish doubtless plays a role in how they came to invade the Atlantic in the first place; most likely they were an escaped or released aquarium species that found itself able to survive quite nicely in the conditions of the coastal Atlantic.  The beauty of lionfish conceals a dangerous secret - venomous spines on their dorsal (back) and pelvic (bottom) fins.  While they won't kill a person; they cause excruciating pain.  I've never been stung by one, but I have been stung by related scorpionfish (most recently the short-spined wasp fish) and the feeling is not one I'd care to go through again!

Over the course of just a few years, mostly since 2000, lionfish have spread dramatically along the coast of the Atlantic, from North Carolina down to the southern Caribbean and Mexico's beautiful Yucatan peninsula.  Typically considered to be a rocky or coral reef species, they've now been found swimming in the intracoastal waterway; that labyrinth of salt-marshes, channels and estuaries, engineered to allow safe passage of boats along the US coast in wartime.  This is sort of an unusual location, but it speaks to the adaptability of this remarkable fish.

So, what to do about such an animal??  Well, that's a tough one.  Invasive species (or more accurately, moving species around) are one of the greatest impacts humanity has had on natural environments, and there are very few cases where we have successfully eradicated or controlled an invasive (but see prickly pear in Australia), more often they just become part of the furniture and we get used to their impacts on the local ecosystem.  Introducing natural enemies (diseases, predators) like they did for prickly pear is a dangerous game; if you tried to get the Cactoblastus moth introduced to Australia in these days of stricter biosecurity, you'd almost certainly be denied.  You can easily get into a "spider to catch the fly" situation too; in fact that's how cane toads were introduced to many places - to control sugar cane beetles (which they suck at).  Perhaps the best approach is to do what we do best - create a market that will promote human efforts to exploit them, and then rely on the Tragedy of the Commons to do the work for you.  This has already been proposed with Asian carp.  Fortunately, it turns out that lionfish are not only spectacular aquarium fish, but also delicious in a white wine sauce.  I am sure that if we set our minds to it, we could do as good a job wiping out this species as we have with so many others.  So c'mon everyone and grab a fork; Save a reef - eat a lionfish, today!

(Photo and graphic from NOAA)