Dancing with a Giant

A lot of people think science is soulless, sterile or austere in its objectivity; there’s a prevalent stereotype of the scientist as a lab nerd in a white coat, out of touch with the “real world” and with the more emotive aspects of life. That couldn’t be further from the truth, of course. Most scientists I know – me included - are motivated precisely by a profound wonder and amazement for the natural world around them; its usually why they get into science in the first place. When biologists go into the field, they often end up reconnecting with those feelings, established during their formative years, and end up resorting to a sort of childish state of pure joy over whatever biological phenomenon that they happen to be studying. I just had such an experience, one that was so extraordinary that it may well have changed the way I think about biology forever.

As part of the research program at Georgia Aquarium, we are in Mexico to study the biology of whale sharks, which gather annually in the coastal waters of Quintana Roo, from Isla Mujeres north and west to Isla Holbox. Its bliss just to be out on the water again (its been a while), admiring the everchanging seascape, marveling at the myriad forms of life that make their home in the ocean, and reminding yourself that the endless stream of doom and gloom news about “the environment” isn’t really the full picture. Flying fish skip from wave crest to wave crest, pursued by sinister-looking frigate birds that swoop in to grab them on the wing, while turtles lazily periscope their heads above the surface to spy on pods of spotted dolphins that race around as if there were somewhere important that they really needed to be.

In due time, we found our objective, a group of whale sharks feeding at the surface, attended by a flotilla of ecotourist boats. Each of our team had a chance to swim alongside these spectacular behemoths as they were cruising effortlessly among the boats and patches of food, at speeds that exhausted a mere human to match.  We also photographed many of them for an identification database.  Then we took some time to gather data on the physical and chemical properties of the water, during which the ecotour boats petered away, returning their cargo of tourists to their respective all-inclusives in time for lunch and leaving us with the whale sharks mostly to ourselves. They continued to feed, constantly inhaling bathtubs of plankton from the surface tension, their gills flapping loosely on the rejected water current like flags in a gentle breeze.

It was at this point that I got in the water a second time. Rafael, our captain and colleague from Project Domino, had put us on a large animal that was feeding below the surface in a more vertical pose than their normal surface “ram filtering” style. This more upright type of feeding, which they use when food is especially dense, sees their tail sink down towards the bottom and cease its rhythmic swinging and, hanging suspended like this, the animal begins to actively suck in enormous gulps of water. In this state I was able to approach the animal much more closely, a large male, and to see how each pulse of that fantastic mouth was pulling in not only water but tiny silver vortices of air down from the surface, such was the force of suction. He was suspended like this for what seemed like an eternity, but was realistically perhaps 15 or 20 minutes, during which he continued to feed and appeared completely indifferent to my presence. I was able to swim over every part of his massive frame and inspect every detail, from his tremendous girth to the creamy white belly distended with food, and from the remoras that pestered his every fin to the tiny copepod parasites grazing across his skin like herds of hoofstock might roam a savannah.  His body was home to a veritable community of hangers-on. I watched his eye roll carelessly over me while he continued to inhale vast amounts of water and plankton, all of which disappeared into that cavernous mouth with its 20 jet-black filtering pads. We continued to dance together like this – or rather I danced around him - close enough that I could have reached out to touch him at any point, until with a tiny shake of his head and a hefty sweep of his tail he was done with the meal and headed off in search of another patch to vacuum, leaving me breathless from a cocktail equal parts exertion and exhilaration.

Back on the boat I did my best to relay to the others what I had just experienced. Despite apparently talking “a mile a minute”, I struggled to find the right words, but they were probably unnecessary anyway. Certainly everyone who had been in the water with the animals that day had experienced many of the same feelings, and I am sure they were writ large on my face (in big black and white spotted letters!). In swimming with this one particular animal, I experienced a profound connection with a truly spectacular natural phenomenon, one that will provide ample motivation to continue the search for a better understanding of the nature of such things, for long into the future.  These are the moments that launch and tie together a career in biology, and that was the best one I have ever had.

The latest from the Whale Shark Festival in Isla Mujeres

I am down here with other folks from the aquarium as well as other scientists, government folks and ecotour operators for the 3rd annual Whale Shark Festival in the beautiful Yucatan location of Isla Mujeres.  Here's some short videos that might give you the flavour of whats been going on.

Here's Beatrix and Rafael de la Parra from Proyecto Domino explaining the importance to Isla Mujeres of whale shark movements to and from Utila in Honduras.  The audience is mostly ecotour operators and members of the public.  Bob Hueter from Mote spoke about threats to whale sharks, while Darcy Bradley from ECOCEAN talked about their program and I chimed in for a talk on whale shark research at Georgia Aquarium

Check out this inflatable whale shark from the festival parade - that thing is made of awesome!  Later that night they illuminated it from the inside and it watched over the stage show and the Ms Whale Shark awards, where they elected a grandma as queen of the festival!

This is Teatro del Mar, and educational puppet show that Amigos de Isla Contoy have shown to thousands of school kids to improve ocean literacy.  The kids were completely rapt!

And I couldn't resist putting in this clip of turtle hatchlings at the state run hatchery in Isla Mujeres.  There's a lot of problems there with beach erosion and disturbance, so when turtles nest, they excavate the eggs and bring them to the hatchery, where they have a cool fenced off area where the eggs are reburied and incubated until they hatch.  Warning, cuteness overload a distinct possibility...

You can follow along on Twitter too

Fieldwork here we come!

Things will probably get a little irregular around here over the next couple of weeks.  I'm part of a group of Aquarium folks leaving for Mexico tomorrow to participate in the Whale Shark Festival on Isla Mujeres, just near Cancun, followed by some intensive field work with colleague Rafael de la Parra, who you may remember from previous posts.  We'll be tagging animals, photographing their spot patterns for the ECOCEAN project (their spots are like fingerprints!), collecting plankton samples and sampling the chemistry of the water to look for differences where they are feeding and where they are not.  I'll try to post some stuff as we go along, even if its only a picture or a video here and there (there wont be much time for writing, unless the weather closes us out)

All of this is part of our partnership called Project Domino, which aims to understand and protect whale sharks in Mexican waters.  Its bigger than that, however, because many of those same animals travel from the Yucatan to the Caribbean, the West Atlantic and the Gulf of Mexico; sharks dont pay attention to sovereign borders.  Obviously concerns are running high for any animals that travel into the GoM, due to the Deepwater Horizon disaster.  Keep your fingers crossed that those animals avoid the affected area and that this latest attempt to cap the wellhead is successful.

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?

Whale shark news roundup

Photo: Bruce Carlson/Marj Awai

There’s a heck of a lot going on in the world of whale sharks right now, so I thought a news roundup was in order.

Blogger GrrlScientist has a nice blog post up about whale sharks right now, over at Scientist Interrupted

Sad news about a whale shark that was trapped in fishing nets in Pakistan and died. I have no idea what the scientist is talking about when he describes them as “inefficient swimmers”; as far as we know they are paragons of efficiency. I also have my suspicions about whether this animal was actually dead when it was brought back to shore. In a different story about the same event, it described the animal as being alive when the fisherman found it, tail-looped it and dragged it back to the beach, and how its illegal to fish for them, but legal to use them as you like if they die accidentally, hmmm....  Without witnesses, I guess we'll never know.

Our collaborator Bob Hueter from the Shark Research Lab at Mote Marine Laboratory is following an animal dubbed Sara in the Gulf of Mexico, who has been affixed with a real-time satellite tag. So far she is avoiding the worst affected area of the BP oil spill, which is a relief. Follow her movements here.

Unfortunately, other whale sharks don’t appear to be avoiding the pollution. NOAA scientists last week observed whale sharks among ribbons of surface oil, not 4 miles from the Deepwater Horizon wellhead. If whale sharks are unable to avoid the oil, it’s a potential disaster because the anatomy of their gills and filter-feeding apparatus are superbly susceptible to fouling, as I discussed in a recent blog post.

One of my projects is getting a bit of press this week. Georgia Aquarium has entered into a collaboration with the Core Sequencing Facility at Emory University to start sequencing the genome of the whale shark. It’s a huge job, but the lab at Emory, led by Dr. Tim Read, are up to the task! They’re using Roche 454 pyrosequencers to generate a survey sequence right now, from DNA we isolated in the lab at the aquarium. Its exciting stuff and was picked up on the AP wire. Read an example here, or just google “whale shark genome emory”

University of Southern Mississippi research Eric Hoffmayer was lucky enough to observe an aggregation of about 100 whale sharks off the coast of Louisiana last week, accompanied by legendary marine explorer and Nat Geo guru Sylvia Earle.  Eric has been working with that population for some time, but as far as I know thats the most he's ever seen in one place.  Lets hope they are animals avoiding the oil spill.

And, finally, the 3rd annual Whale Shark Festival is scheduled to get underway in Isla Mujeres, Mexico, next Friday the 16th.  I'll be there with other scientists including Bob Hueter and Rafael de la Parra, talking publically about whale sharks in the Gulf and the other amazing marine biology of the Yucatan.  There's also going to be a film festival and cultural activities highlighting Quintana Roo.  Did you know that "shark" is one of the only English words with a Yucatec Indian origin?  Its comes from the Mayan "Xoc".  Hope you can join us!

Two videos from our recent Mexico sojourn

Below are two short videos showing some of what we got up to on a recent lightning fast trip to Mexico, footage that our AV folks spliced together from a FLIP camera I took along.  We had heard word of whale sharks gathering at one of our research sites, so I threw together a quick trip and Jeff Reid, the Aquarium's DSO, and I went down to scope it out.  It wasn't hard science this time; mostly a reconnaissance boat survey and an aerial survey, and getting to grips with the logistics for the big trips that will happen later this summer (more about those in future posts).  But at least they give a sense of what its like down there.  Next time I will try to hold the camera a bit more steady, but in the meantime - enjoy.

Testing, testing...

I'm posting this video I took of a whale shark in Mexico, to test the embedding of YouTube videos in Blogger posts.

Thanks New England Aquarium!

In my post about surveying pelagic species from the air in Mexico, I mentioned schools of cownosed rays, which the locals call "chuchas" (dogs).  New England Aquarium has a perfect picture to illustrate what I mean:

 

Beautiful, aren't they?

The water is ALIVE!

Its easy to get discouraged about the plight of marine ecosystems and the future of all those incredible marine species that we love so much. This is especially so of late, with all the bad news about the oil spill in the northern Gulf of Mexico and the impacts that it may well have on several habitats. Consider this post, then, as your good news story for the week. I am here to tell you that there is still amazing stuff to see in the ocean. Incredible stuff. Stuff that will blow your mind. I can tell you this with supreme confidence, because for the last two days, that’s exactly what I have been seeing. As part of the research program at Georgia Aquarium, I am with colleagues in Quintana Roo, Mexico, studying whale sharks and other species that live in the azure waters of the Yucatan peninsula. Jeff Reid, who is the aquarium’s dive safety officer, is here and our main colleague in Mexico is Rafael de la Parra of Project Domino, who has been working on whale sharks and other marine species in the area for many years. This is a remarkable part of the world, with a lot of great terrestrial activities (can you say Cenotes, anyone? No? How about Mayan ruins?), exceeded only by the marine life, which is truly spectacular.

Yesterday Jeff and Raffa and I spent the day boating around the northeastern tip of the Yucatan along with videographer Jeronimo. Now, when you’re on a boat, you can only see a small strip of ocean either side of the vessel, and yet over the course of the day we saw lots of mobula (devil rays), turtles, flying fish, manta rays, spotted dolphins and whale sharks. We snorkeled alongside some of these animals and, in the case of whale sharks and mantas, took samples of their food for later analysis. They dine on the rich plankton soup of this tropical upwelling area, much of which consisted of fish eggs, which hints at other fish species – yet unseen – taking advantage of the plankton to start their next generation by spawning in the surface waters. Snorkeling next to a whale shark in the natural setting was a special thrill; I’ve been lucky enough to work with the animals in the collection at Georgia Aquarium since 2006, but this was my first encounter with them in the wild. Except for the slightly different “faces” (we do get to know our animals pretty well) and the parasitic copepods visible on the fins of the wild animal, it could have easily been the very same sharks Jeff and I have been working with in Atlanta.

Today, Jeff and Raffa and I joined Lilia (from the Mexican department of protected areas CONANP) and pilot Diego for an aerial survey of the waters around the northeastern tip of the Yucatan. In contrast to the boat, you can’t get in the water from a plane (its not advisable anyway), but you can see a whole lot more at once and cover a much greater area in a relatively shorter time. From the air, lots of sharks, cownosed rays, manta, dolphins, fish schools and whale sharks were all visible, and I am told that flamingos and manatees can be seen at other times too. The manta rays, which numbered in the hundreds, were especially impressive and included at least two species (see my post about taxonomy of mantas). The sheer number of cownosed rays, called chuchas in the local slang, was staggering (muchas chuchas, if you will). They formed huge schools that looked for all the world like the rafts of sargassum weed that accumulate on the wind-lines at the water’s surface offshore. Many of the turtles and mobula seemed to be in the mood for love; most turtles were in pairs (or a pair being followed by other hopeful males), whereas the mobula followed each other in lazy tandems, their wingtips breaking the surface with every stroke. Whale sharks were also there – lots of them – with their attendant flotilla of tourist boats and tiny orange specks of snorkelers in life-vests, doing their best (and largely failing) to keep up with the gentle giants.

When you have experiences such as those I have shared with my colleagues over the last two days, you are reminded why we do this stuff in the first place. Its not just for the papers, or the salary or the glory of new discovery (yeah, right!), its for those moments working with animals when you and a colleague become friends because you shared an experience of the oceans that most folks will never have. We should seek to share and recreate those moments with everyone we can, whether its in an aquarium or on the open ocean. I am pretty sure that if we could all do that, then public empathy for the plight of the oceans would skyrocket, and many of the threats that face them would be addressed quick smart.

Take a Levy walk on the wild side

I've mentioned before that this summer I’ll be part of some whale shark field work studies in Mexico. Some of it will focus on how these amazing animals find patches of their planktonic food in the ocean. There’s a pretty good likelihood that they have an incredibly sensitive sense of smell and can detect food from miles away. They’re a bit different than toothy sharks though, because they aren’t detecting “blood in the water” as such; rather, they need to be able to distinguish patches of ocean where plankton is denser from places where its less dense. How do they do that, and what chemicals are they smelling exactly? These are among the questions we will be trying to answer.

In reading up for this work, I came across the idea of Levy Walks. This is not a walk in the sense of your evening constitutional down to the Piggly Wiggly for a 6-pack and some Slim Jims. No, it really is just the name for a certain pattern of animal movement (shown at the right), one in which animals make several short “legs” of directed motion, usually in bunches, separated by longer legs with major reorientations. Its not random motion, but neither is it all that predictable, except that the pattern exists at all scales: its fractal. In other words, if we sketched the motion of an animal on paper, and drew it to scale, it would look similar if we zoomed out to the range of kilometers instead of meters and drew the pattern again. It turns out that moving by way of Levy walks increases your chances of running into patches of food, or the trails of scent they leave behind. At that point, more directed motion takes over and the animal zig zags towards the source of that delicious scent (whereupon it becomes not too different from homing in on the Slim Jims at the Piggly Wiggly after all). Sims et al. show that Levy walks are almost ubiquitous among animals that seek mobile prey; they conclude that its a sort of biological rule for finding food that has a patchy distribution.

It’s a fascinating idea; I wonder if you could apply a deliberate Levy walk pattern if you were looking for your sunglasses, trying to find Waldo, or trying to find an empty patch of beach to put your towel on. People might look at you a bit funny, but who’d have the last laugh?

Sims, D., Southall, E., Humphries, N., Hays, G., Bradshaw, C., Pitchford, J., James, A., Ahmed, M., Brierley, A., Hindell, M., Morritt, D., Musyl, M., Righton, D., Shepard, E., Wearmouth, V., Wilson, R., Witt, M., & Metcalfe, J. (2008). Scaling laws of marine predator search behaviour Nature, 451 (7182), 1098-1102 DOI: 10.1038/nature06518

No rest for the wicked

Returned from the Eastern Fish Health Workshop in the DC area yesterday, after our flight got canceled on Friday.  It was a fantastic meeting, for all the reasons I cited in my previous post. 

I've got one day at work today and then off to Mexico for field research with Mexican government colleagues this week (more about that later), but not for long, because teaching duties in NY on Friday and Saturday call.  While I am in NY, I'll be giving a public lecture about whale sharks at Stony Brook Southampton on the 4th at 1930hrs.  Its part of the SoMAS Spring lecture series; I'd love to see you there!

Something eerie is happening, down Mexico way...

After a youth spent on the dry side of the water (another post for another day), I have come to love SCUBA diving with a passion. I also love art and photography projects that explore the way nature reclaims all things, in time. (My wife dubbed this obsession “elegant decay” – stuff that’s falling apart and looks good doing it.) Soon there’s going to be an opportunity to combine those passions in one of my favourite places – the Yucatan Peninsula of Mexico. Artist Jason de Caires Taylor is installing the largest underwater sculpture garden in the world, in the waters adjacent to Isla Mujeres, not too far from Cancun. I find this idea captivating. Normally the human world and the underwater world are so forcibly separated by medium, light and a host of other factors, and this project will bring them into eerie juxtaposition. The proposed 200 human figures reclining, working, or even riding a bicycle, contrasting with the reef, fishes and rippling filtered sunlight is just great. How do I know, if it hasn’t been built yet? Because he’s already done similar work on a much smaller scale in the Keys and Grenada.

Some might argue that this stuff is visual pollution of a reef that should just be appreciated for the biological wonder that it is, but I couldn’t disagree more. Especially when the reef begins to claim the sculptures as its own, in time incorporating their forms into its structure and adding its own patina of life, like a painter stepping back from the canvas and daubing the final blobs of color here and there. By then, we and the reef will be one and the same, and that idea really resonates with me. Installation begins in June. I can’t wait to see it when I am down in Mexico this summer.

What do you think – art or pollution?

SAC's revisited

A little while back I wrote about how we can use Species Accumulation Curves to learn stuff about the ecology of animal, as well as to decide when we can stop sampling and have a frosty beverage. There’s a timely paper in this month’s Journal of Parasitology by Gerardo Pérez-Ponce de Leon and Anindo Choudhury about these curves (let’s call them SACs) and the discovery of new parasite species in freshwater fishes in Mexico. Their central question was not “When can we stop sampling and have a beer?” so much as “When will we have sampled all the parasites in Mexican freshwaters?”. They conclude, based on “flattening off” of their curves (shown below, especially T, C and N), that researchers have discovered the majority of new species for many major groups of parasites and that we can probably ease up on the sampling.

Trying to wrap your arms (and brain) around an inventory of all the species in a group(s) within a region is a daunting task, and I admire Pérez-Ponce de Leon and Choudhury for trying it, but I have some problems with the way they used SACs to do it, and these problems undermine their conclusions somewhat.

In their paper, the authors say “we used time (year when each species was recorded) as a measure of sampling effort” and the SACs they show in their figures have “years” on the X-axis. Come again? The year when each species was recorded may be useful for displaying the results of sampling effort over time, but its no measure of the effort itself. Why is this a problem? For two reasons. Firstly, a year is not a measure of effort, it’s a measure of time; time can only be used as a measure of effort if you know that effort per unit of time is constant, which it is clearly not; there’s no way scientists were sampling Mexican rivers at the same intensity in 1936 that they did in 1996. To put it more generally: we could sample for two years and make one field trip in the first year and 100 field trips in the next. The second year will surely return more new species, so to equate the two years on a chart is asking for trouble. Effort is better measured in number of sampling trips, grant dollars expended, nets dragged, quadrats deployed or (in this case) animals dissected, not a time series of years. The second problem is that sequential years are not independent of each other, as units of sampling effort are (supposed to be). If you have a big active research group operating in 1995, the chances that they are still out there finding new species in 1996 is higher than in 2009; just the same as the weather today is likely to bear some relationship to the weather yesterday.

OK, so what do the graphs in this paper actually tell us? Well, without an actual measure of effort, not much, unfortunately; perhaps only that there was a hey-day for Mexican fish parasite discovery in the mid-1990’s. It is likely, maybe even probable, that this pattern represents recent changes in sampling effort, more than any underlying pattern in biology. More importantly, perhaps, the apparent flattening off of the curves (not all that convincing to me anyway), which they interpret to mean that the rate of discovery is decreasing, may be an illusion. I bet there are tons of new parasite species yet to discover in Mexican rivers and lakes, but without a more comprehensive analysis, it’s impossible to tell for sure.

There is one thing they could have done to help support their conclusion. If they abandoned the time series and then made an average curve by randomizing the order of years on the x-axis a bunch of times, that might tell us something; this would be a form of rarefaction. The averaging process will smooth out the curve, giving us a better idea of when, if ever, they flatten off, and thereby allowing a prediction of the total number of species we could expect to find if we kept sampling forever. Sometimes that mid-90’s increase will occur early in a randomised series, sometimes late, and the overall shape for the average curve will be the more “normal” concave-down curve from my previous post, not the S-shape that they found.  After randomizing, their x-axis would no longer be a “calendar” time series, just “years of sampling” 1, 2, 3… etc.  There's free software out there that will do this for you: EstimateS by Robert Colwell at U.Conn.

The raw material is there in this paper, it just needs a bit more work on the analysis before they can stop sampling and have their cervezas.

Perez-Ponce de León, G. and Choudhury, A. (2010). Parasite Inventories and DNA-based Taxonomy: Lessons from Helminths of Freshwater Fishes in a Megadiverse Country Journal of Parasitology, 96 (1), 236-244 DOI: 10.1645/GE-2239.1

Gratuitous cenote diving photo post

Doesn't it just make you want to quit your job, grab some gear and catch the first flight to Tulum?  Some of these pics are from commercial operators, but I have never used any of them and endorse none in particular. 

That's it, I'm leaving tomorrow.  Just as soon as I take care of this thing, and some stuff....and that other junk...