Tis the season of sailfish!

This time of year sailfish gather to feed off the coast of the Yucatan Peninsula in Mexico.  One day I’ll go and see it in person, but in the meantime, David Attenborough will have to do:

From blue to black - diving in a cenote

If the idea of swimming through narrow stone tunnels with no access to overhead air scares you, then you and I have something in common.  SCUBA is great - the 3D freedom can’t be beaten - but the idea of SCUBA in caves has always carried with it a special kind of terror.  I mean, caving on foot is scary enough, but to do it in a suffocating medium, into the darkness, carrying all your air in a bottle on your back is freaky indeed.  So when the opportunity arose on a recent research trip to Mexico to do a “cavern dive” in a cenote, or sinkhole, I approached the idea with a mix of adolescent excitement and centenarian incontinence.

Luckily, my travelling partners were all experienced divers.  Oh, sorry, I should say Experienced Divers.  Two of them - Marj Awai and Dr. Bruce Carlson - are lifelong SCUBA scientists with thousands of dives in service of ichthyology and aquarium collections.  The other two - Elliott Jessup and Jeff Reid - are dive safety officers and experienced cave divers.  I am comfortable in the water, but admit being a little uncomfortable with my newbie status, especially with respect to diving in caves. Their experience is a source of some comfort. What could go wrong, right? Right??

Purist cavers will note that I earlier said “cavern” dive, which technically is not a cave dive, because if you extinguish artificial light you can always see some natural light to navigate your way back to the opening.  But, let me tell you, having done it, that that is as far underground as I have ever been and it was, in all practical respects a Cave as far as I was concerned; certainly enough so for a first timer.

The particular cenote we dove was Dos Ojos, which is part of the longest mapped cave system yet discovered, incorporating hundreds of kilometers of anastomosing voids in the limestone slab that makes up the eastern Yucatan, not far from Mayan ruins and the town of Tulum.  Most of the system is flooded, meaning that the caves and their spectacular salactite and stalagmite formations formed in dryer times when the sea-level was lower and the caves were full of air, then later the systems filled with water as the sea level rose and freshwater percolated through the stone to fill the voids.  Many cenotes are thus connected by tunnels of water under the stone floor of the jungles of Quintana Roo, and both our dives that day involved descending into one cenote and traveling underground to surface in a second.  Although Dos Ojos itself is very well-known and receives dozens of tourists a day, the same cannot be said of the rest of the cave system.  There are many parts that have yet to be explored, including where the system meets the sea.  That’s right, this flooded freshwater system connects to the ocean, somewhere along the Rivera Maya, maybe somewhere near Xel-Ha. 

Click the map to see the REST of the cave system!

How is it that some parts are a tourist destination and some parts unexplored?  The answer lies in the technical nature of diving these sorts of systems.  What we did was a simple in and out in a very superficial part of the system - we figuratively dipped out toe in the bathtub - but to go to the far reaches of the cave system, especially the uncharted parts, is a huge technical challenge that only a select few experienced divers are able to do.  Such exploratory dives often involve multiple staged dives, with the earlier dives aimed at laying out a guide line to follow on future dives and clipping off SCUBA tanks at regular intervals so that bottom time can be extended and the final push can be a long and penetrating dive that pushes into new territory.

For our much more superficial tourist dive, I was more than happy to be on a single tank and within sight of the blue glow of daylight.  As a diving experience it was, in a word, exquisite.  From the first cooling dip into the water (Q.Roo in August is H.O.T.), to some of the best visibility I’ve seen, to the incredible rock formations and the inquisitive tetras and cave shrimp, it was quite the best dive I have ever done that wasn’t primarily about animals. And as for the terror about being underground and all that noise?  It melted away in the pure joy of the experience.  Nonetheless, it was exciting to think that you could just keep going through tunnel after chamber, for hundreds of kilometers, all underground and underwater and that you could easily discover new rooms and new paths never seen before.  Its a thrill that such opportunities for discovery still exist today; there’s no app for that!

Sometimes *they* look at us too

Check out this cool bit of footage from our recent research visits to Mexico to study whale sharks with the Georgia Aquarium team.  We were diving under a large aggregation of whale sharks when one of them broke from the surface to come and visit, checking out first one diver, and then the other, possibly attracted by the bubbles.  Whale sharks normally cruise around at the surface, largely indifferent to human presence except for occasionally rolling their eye across you as they pass, but this one was clearly interacting with us.  Colleague Betty Galvan tells me about a small (if 4m could be considered small) female that followed her for 20 minutes in Honduras one time, so interactive she described it as being like a puppy.  I suspect, when conditions are right, whale sharks can be curious or even inquisitive critters.  Its hard to prove, but I don’t think there’s much doubt from the video.  The aquarium has been conducting a behavioural study on the collection animals for some time, but more work on their behaviour in the natural setting is desperately needed.  Hopefully the aquarium study can refine the techniques needed to get out there and understand what they do in the field.

You can follow my YouTube channel here, or the aquarium’s channel here. Footage Copyright 2010 Bruce Carlson/Georgia Aquarium and used with permission

Can you ID this jellyfish?

In Mexico this summer we came across a nice jellyfish and scientist/videographer Bruce Carlson caught some footage.  I admit that Scyphozoans are a real weak point for me.  Can anyone identify this for us?

Elegant little thing, right? See more videos on my YouTube channel

Man vs. Fish - amazing remora video

Most people consider remoras to be no-good hangers-on, sponging off well-meaning marine megafauna. But on one of our research trips to Mexico to study whale sharks this summer, one of the staff divers, Elliott Jessup, had an incredible encounter with one of the most inquisitive fish any of us have ever seen, and scientist/videographer Bruce Carlson caught the whole thing in HD. The waters were full of whale sharks and their attendant remoras, when this little guy took leave of his usual hosts and instead took a real liking to Elliott, even attaching to his butt, and eating his hair.  Learn more about our whale shark research here and you can follow my YouTube channel here and the Georgia Aquarium channel here.

The footage is copyright 2010 Bruce Carlson/Georgia Aquarium and used with permission. 

Whale shark research on National Geographic

Georgia Aquarium’s whale shark work from Mexico this summer is featured in a story by Jodi Kendall on the main web page for National Geographic’s new show Great Migrations. Cool!

Cross your fingers for the Yucatan

Long time readers will know that I have a lot of colleagues in the Yucatan part of Mexico, mostly in the northeastern tip in the state of Quintana Roo.  That area is in the firing line for Hurrican Paula (yes, its still hurricane season!).  Cross your fingers in that ever-futile-but-nonetheless-self-soothing symbol of good luck for our colleagues and friends down there, especially the folks on Isla Mujeres, which is pretty exposed.  The map below shows the forecast cone for hurricane force winds in the next 24 hrs.  The cone for tropical storm force winds is MUCH bigger.

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Devil rays win! (and no, I don't mean baseball)

This fantastic picture of a huge school of devil rays (Mobula sp.) just scooped the top prize at the 2010 CIWEM Environmental Photographer of the Year competition.  According to photographer Florian Schulz, no-one in Baja California seems to remember a devil ray aggregation of this size before.  Chances are, its a breeding aggregation, since other myliobatids (like cow-nosed rays) also gather in huge numbers for that purpose.

Click the photo to see the full sized version over at the Telegraph website.

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.

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.

A photo post from field work in Mexico

Sorry things have been a bit quiet on the blog lately.  Our field work season has reached a crescendo, with several back-to-back trips to Mexico where I and others from Georgia Aquarium are studying whale sharks that aggregate annually in the coastal waters of the Yucatan, and thats left little time for writing.  To learn more about the whale shark project, go here.  Its been a real treat lately, with hundreds of sharks feeding in the area east of Isla Contoy and Isla Mujeres.  Between the boat work, which focuses on photo cataloguing and ecological sampling, and aerial surveys, which focus on counting and distribution, we’ve been gathering a ton of data that will help shed light on why these aggregations form, and how to better protect them in the future.  Rather than write about it, I figured I’d let the pictures do some talking.  Required legalese: all these images are copyright 2010 Alistair Dove/Georgia Aquarium and may not be reproduced without permission.

Flating mats of Sargassum are home to all sorts of things. These baby jacks were seeking shelter from me and caught a red reflection off my rashguardThis is what we came for: a whale shark feeding east of the Yucatan.Any port in a storm: this tiny 2 inch barracuda was hitching a ride with a moon jelly

Most filefish live on rocky and coral reefs, but this one was vigorously defending a little bit of SargassumIts hard not to feel like the whale sharks are checking you out sometimes

Georgia Aquarium senior aquarist Marj Awai wielding the 7D and housing: stills AND HD video *drool*People are the biggest threat to whale sharks. This male had a close encounter with a boat but luckily came away with only shallow scrapes. We see deeper cuts from propellers sometimes, and utmost caution is warranted when moving among the animals.The most common view of a whale shark. Even though they seem to swim effortlessly, keeping up with them is only possible for short distances. This is the last one we’ll see until next years field work season. Adios amigo!

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:

Hola de nuevo, México!

Headed back to Quintana Roo in light of a good weather forecast and a chance to finish some chemical ecology sampling we aimed to do last time but were denied due to weather and other concerns.  What’s chemical ecology?  Its the study of how animals interact with the chemicals in their environment and shape their behaviour accordingly.  In this case, we’re especially interested in what whale sharks can smell, what sort of “odor landscape” they live in, and how they exploit this to find food.

Unlike a lot of “big” marine scienctists that work off ships in the UNOLS fleet, we actually work from small boats close to the coast, so weather is a key factor.  Do me a favour and pray to whatever deity or natural force works for you, in order that we get some favourable conditions to finish this work so we can move on to other things, OK?  Me?  I’ll be praying to Chaac, the mayan rain god, not for rain, but for no rain.  More importantly, I’ll pray to the head honcho of all Mayan gods, who also happens to be the wind god - Kukulcan - for no wind.  I may as well pray to Joe Pesci, but it can’t hurt.

If you have to go, go big!

When you want to learn about the biology of a charismatic species, any species really, sometimes you end up learning about the grosser side of life too.  Thats kind of how I came to take this picture last week in Mexico, where I and several others from the team at Georgia Aquarium have been doing research on whale sharks lately (see several other blog posts heareabouts).  It was taken during an aerial survey we did from an altitude of 1,500 ft in a Cessna 206 and shows a whale shark that has just defecated.  Now, whale sharks tend to do everything on a giant scale, so perhaps we shouldn't be too surprised, but I estimate the animal to be between 8 and 11m (25-35ft) in length and so, based on that estimate, thats a cloud of poo behind him thats over 30ft in diameter!  Its unusual to see wild sharks in the act of pooping, but this group of animals was so numerous and feeding so heavily, that you could actually see several clouds like this at any given time.  Whats feeding heavily got to do with it?  Well, unlike mammals, which tend to have a relatively fixed gut passage time for food, a lot of cold-blooded critters can, well, sort of push it out the back end, simply by pushing more in the front end.

Far from being a trivial observation of one of life's less savoury moments, it could actually become a really important research opportunity if we can manage to catch some of that magical egesta in a container of some sort, for analysis back at the lab.   Scientists can do all sorts of stuff with poo, like looking for parasite eggs or other pathogens, sequencing the DNA of both the shark and its prey species, or comparing nutrient values of food (from plankton tows) and comparing them to values from faeces to work out how much nutrition they are gaining from their food.  Its a great way to learn a lot in a short time and do it in a totally non-invasive way.

Mostly though, its a cool photo to gross people out at parties...