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At least you could do water changes with a teaspoon

With a grateful hat tip to DSN’s DrCraigMc via Twitter, I give you (well, really the Telegraph gives you)- TA DA! - the world’s smallest aquarium.  Click the link or the pic to see it in all its diminutive glory.

At just 10mls, you have to be *really* careful about overfeeding

Just for scale, the Ocean Voyager exhibit at Georgia Aquarium would hold 2.4 billion of those bad boys.  That means that aquariums effectively span 9 orders of magnitude in size.  We’ve come a long way, Anton Dohrn



Saving bluefin - in one year?


A new website wants you to know how grim the situation has become for Atlantic bluefin.  It includes the stark statement that in all probability, the last bluefin will die in 2012, so we best get cracking on trying to save them.  Is it possible?  Certainly it will take a concerted effort from all nations that currently exploit this species, and a total dismantling of a subsidised tech-heavy industry.  To achieve that in just 12 months, well, forgive me if I wax pessimistic…

That aside, the video is nicely animated and quite information dense, touching on many aspects that plague modern fisheries management like the economies of extinction (when an exploited species becomes ever more valuable, the rarer it gets), tragedy of the commons , bycatch, subsidies and the wasteful nature of feeding cultured predatory fishes.  So, it’s worth your time, and if you live in an EU nation, it’s worth your contacting your country’s responsible ministry to ask what they are doing to help avoid the extinction of one of the oceans noblest creatures.  Finally, it’s worth rejecting bluefin at the market level (in sushi restaurants may be the best place) to help reduce demand. 

Maybe it’s already too late for bluefin, and that’s a tragedy, but the story doesn’t end there.  As we continue to fish down the food web, the crisis will move from bluefin to the next most threatened species and the cycle will reiterate until all that’s left is jellyfish and harmful algal blooms.  If that vision isn’t enough to inspire action, I don’t know what is.


Love is in the

As we go into the season of that most manufactured of holidays - Valentine’s Day - I want to share with you a simple but powerful message.  For every crazy sexual fantasy you have ever had, some creature in the oceans is already doing it.  Whether it’s a solo effort, or a one on two, or a two on one, a three on six or a “countless hordes on untold numbers”, and whether it involves a he, a she, a male, a female, a shemale, or a whatthehellsisthat?, there’s already a species in the oceans to whom it’s old hat.  And however kinky and twisted and perverted you can imagine, nature has already devised and instituted (often to ruthlessly efficient ends, I might add), something even more risque and alarming.

How do I know this?  Well, a couple of years ago Georgia Aquarium asked my wife (who also works there) and I to come up with a talk we could give publically about love in the oceans.  Sure! we said, No problem! It’ll be fun!  Little did we guess the depths of smut and depravity to which the research of our newfound assignment would take us.  But like good company minions, we answered the call, and now, three years later, the talk has become something of a regular thing.  As an aside, I can tell you that our Googling efforts in support of the project attracted the attention of the IT department; I guess we typed in a few too many of the trigger words in the company internet filter - oops!  We had to get special exceptions on my IP address so we could keep working (and I swear I have never used it since….ever).

OK, I’m talking a lot of smack.  How about some concrete examples?  Fair enough.  How about this tiny snippet? Fairly self-explanatory; it’s exactly what it looks like.  Needless to say, a warning that it’s NSFW.

That clear enough for you?

One of our favourite parts of the talk is an homage to George Carlin where Trish and I fire off ever-more suggestive fish names in rapid succession.  There’s so many wonderful names to choose from, but some  of my personal favourites are the cavernous assfish (this is actually the closely related abyssal assfish, I guess the cavernous assfish was just too embarrassed to have his photo taken):

 Three related and almost identifical fish: the rode harder, the keep harder and the diklip harder (and yes, they are a type of mullet):

and how could I not include the hairy hotlips?

There’s dozens more, but to hear them (and see the rest of the walrus video) you’ll have to come to the talk

In my final example, I want to claim some primacy over Ricky Gervais.  You see, we were talking about blowhole sex in boto dolphins long before he put it into his act.  That’s right, lonely male botos will, from time to time, penetrate each other in the blowhole, which is really a nostril.  Nasal: its the new anal…

 And thats just the beginning.  Cross-dressing, orgies, role playing, dom-sub BDSM, genital mutilation, piquerism, even post-coital cannibalism, its all going on every day in the oceans (and you’re swimming in it!).  So, next time you’re blushing at the thought of some new saucy idea that sneaks into your mind sideways when you should really be working on TPS reports, just relax, we humans are actually kind of vanilla.


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:


A site visit to Harbor Branch

The submersible Johnson Sea Link aboard R/V Seward JohnsonOn Thursday morning Bruce Carlson and I rose early and headed out to visit Harbor Branch Oceanographic Institute in Fort Pierce Florida; the first visit for both of us.  I had long been aware of their marine engineering division and the important role of the R/V Seward Johnson and its attendant submersibles - the Clelia (which we had on display at Georgia Aquarium for a while) and the Johnson Sea Link - in NOAA’s UNOLS oceanographic fleet, but there was much more in awaiting us at that storied campus than I think either of us expected.

Harbor Branch was established in the early 70’s as a private non-profit ocean research center by J. Seward Johnson, the son of Johnson & Johnson founder Robert Wood Johnson.  More recently HBOI became a part of Florida Atlantic University, based a ways up the A1A in Boca Raton

As we toured the site with Assistant Executive Director Megan Davis on the first day, I was first surprised and eventually staggered at the scale of their aquaculture actvities.  Their experimental production facilities extend over several acres of spotless Quonset huts on the shores of the Indian River Lagoon and include programs on conch (queen and fighting), clams (hard and sunray venus) and marine snails, though some of their biggest efforts are currently directed towards Florida pompano.  Harbor Branch also has an extensive marine drug discovery program that searches for active compounds among the thousands of species in their collection, which might then be used to treat human diseases.  There’s a great synergy between that program and the ocean exploration group in that submersibles can bring back new candidate species (especially deep sea sponges) from research cruises around the world, which the clever biochemists and microbiologists can then go to work studying for their potential applications.  Its painstaking and tremendously challenging work, but they’ve had at least one anti-cancer drug through to Phase I clinical trials, so the potential is there.  Finally there’s a well-established marine mammal program at Harbor Branch, which includes studies on the health of dolphins and manatees in Indian River Lagoon and is responsible for responding to all strandings on that part of the Atlantic Florida coast and the pathology research on those unfortunate animals that don’t make it.  The aquarium is intimately involved in these studies because our Cheif Veterinary Officer Dr. Greg Bossart was based at HBOI for many years

On the second day we also toured Oceans, Reefs and Aquariums: a private ornamental fish and coral culture company that is co-located on the HBOI campus and breeds over 70 varieties of marine ornamental fishes.  Many people are surprised to learn that marine ornamentals like clownfish, dottybacks, cardinal fish, mandarin gobies and seahorses can be and are bred on commercial scales; there seems to be a well-entrenched dogma that marine species don’t breed in aquariums.  Of course, thats not true, they breed all the time.  But, as Bruce would say, its not the spawning thats the problem, its the early rearing and especially the need for speciality foods.  Why so hard?  Well, many species cultured for food have large yolky eggs and big larvae that can feed on common foods like brine shrimp nauplii straight out of their eggs, but reef fishes are different; they often have tiny eggs and larvae that are smaller than many of the food items they might otherwise be fed.  Perhaps not surprisingly, those marine ornamentals that have been bred so far have larger eggs than some of their relatives, but successfully rearing fishes like angels and butterfly fish is still proving to be a tremendous challenge.  Not so with corals.  ORA’s coral culture greenhouse is replete with relatively low-tech trough systems where technicians skillfully “frag” coral colonies (cut little bits off the branches) in exactly the same way as a horticulturist might take cuttings from a plant.  The end result is successful multiplication and large scale propagation of many branching, plating and massive corals.  This provides a premium marketable product while reducing impact on natural reef systems because no further extraction is needed after the earliest parent colonies.  In cheesy business-speak: it’s truly a win-win.

Happy acroporid coral frags at the ORA facility

While we were there, Bruce and I also gave seminars about our respective studies - his on resiliance of Fijian coral reefs to bleaching and mine on (what else?) whale sharks.  It was a lot to fit into two days, but I came away with a much deeper appreciation for the breadth and depth of programs at one of the world’s best-known marine science facilities.  I hope it was the first of many such visits because they’ve got a lot of great stuff going on there.


Where is your line?

I am pretty sure I’ve found mine.  A fellow student when I was at college was from Taiwan and used to tell me about a fish dish cooked in such a way that the fish was alive when it was brought to the table and that you ate it while it was still “gilling”.  I never believed him until now.  The following video may be disturbing to you, because it shows exactly the dish my colleague described.  It comes from Discovery News story (hat tip to @sharkb8t on Twitter) in reference to a new book from Penn State Researcher Victoria Braithwaite about whether or not fish can feel pain.  I am agnostic on the question - I just don’t feel I know enough to make a sound judgement - but in this case, doesn’t it seem best to err on the side of caution?  Does the culinary novelty, the ability to say thats really fresh, outweigh even a slim possibility that this fish could feel some part of the process and is, or was, suffering as a result?  I’m inclined to think not, but what do you think? 


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. 


Six fish parasites you don't want to miss...or catch

Are you one of those people who just can’t stand the idea of parasites? You find the idea of some slimy  critter living in or on you and feeding on your very flesh just repulsive?  If so, this post may be best viewed through a crack between fingers clamped tight across your eyes.  If, on the other hand, you’re more like me and find the idea just fascinating (enough in my case to study them for grad school), then enjoy the following, which comprise a six-pack of the some of the best parasites you’ll find in fish.  I’m not just restricting it to fish because this is a marine science blog, but because fish truly get some of the worst (best?) parasites around.  Its probably got a lot to do with the diversity of available hosts (28,000+ species of fish = parasite smorgasboard!) and the supportive medium in which they live.  Here they are then, six fish parasites you don’t want to miss.

1. Bite my tongue

Delightful little critters, tongue biters are a type of isopod, vaguely related to the pill bug/roly poly/slater bug you might see in a wood heap from time to time.  They’re actually crustaceans more related to shrimp and crabs than to insects, so in a sense the common pill bug is more of a weirdo than the tongue biter; at least tongue biters have the decency to be truly aquatic, but I digress.  Cymothoid isopods live on all sorts of fish in both fresh and salt water.  They have a tick-like life-cycle where they periodically jump on and off the fish, taking a meal of blood or tissue each time they are on, and moulting each time they are off.  Lots live on the skin or gills, and some even invade the body cavity, but the most famous are those that live in the mouth and hang onto the bottom lip, peering out over the teeth like a motorcyclist peeking over the windshield.  They have quite good eyes, so they can probably see whats going on pretty well.  Why live on the tongue?  Not sure - oxygenated water supply perhaps?  Maybe they just like the view.  Whatever the reason, it would be a bit like you or I carrying a rhinoceros beetle around in your mouth all the time.

Image credit: Australian Museum

 2. Size does matterImage: NOAA

Your typical free-living planktonic copepod looks like the thing on the right here: tiny (<1mm or 1/20th in.), clearly crustacean, with delicate swimming antennae and one or two simple egg clumps hanging off the abdomen.  Not so their parasitic cousins.  In a pattern repeated often in the evolution of various parasite groups (parasitism having arisen in practically every phylum), the parasitic ones are much bigger than their free-living relatives.  Why?  It could be many reasons, like predator evasion, reproductive efficiency or just a result of living la dolce vita off some other poor sod.  Whatever the reason, pennellid copepods take this size disparity to the extreme.  In a group where the average size is less than 1mm, adult pennellids can be 30cm or more in length, even longer if you count the strands of eggs that trail behind them in the water like a string of pearls, popping little parasitic progeny off the end like pez.  That’s three and half orders of magnitude in body size, and there aren’t many animal groups that can claim that sort of range.  The largest  pennellids look like big brown toilet bImage:Oceansunfish.orgrushes sticking out of the flesh of their hosts, which tend to be large pelagic things like sunfish, marlin and sharks (sometimes even dolphins!).  The brush bit is the tail end and serves as a sort of gill, with countless tiny filaments to provide a high surface area and thereby facilitate oxygen exchange.  If the brush is the back end, then that means the head is - you guessed it - buried deep in the flesh, usually T-ing into a blood vessel like a wall anchor and providing the copepod with a continuous source of food to fuel those ever-lengthening egg strands. 

There’s a great scene in the BBC series Blue Planet (that paragon of marine biologist porn!) where a sea gull valiantly tries to remove pennellids from the skin of a basking sunfish, but in vain.  It proves nicely that a large body size confers on a parasite both robustness and protection from predators.  Its one of the best and most remarkable scenes in the entire film series.


 3. Going to great lengths

This isn’t Nematobibothrioides, but a similar species from Hawaiian jobfish. Image:HIMBThe ocean sunfish, Mola mola, is also host to the third in our set: the didymozoid Nematobibothrioides histoidii.  I know, awful names, right?  Didymozoids (pronounced like P-Diddy) are a family of parasitic flatworms in the digenean (“fluke”) group.  Most digeneans live in the gut, but didymozoids have invaded the flesh.  That’s not what makes this worm special, though, there are lots of worms that live in flesh.  No, its the length of N. histoidii that sets it apart.  In the best paper on the subject Glenn Noble (1975) describes finding them up to 12 meters long!  That’s a 40 foot worm, as Noble says “snaking” its way through the tissues, leaving a trail of eggs in its wake.  Chances are, N. histoidii may even grow larger than that.  Scientists don’t know, partly because dissections of Mola aren’t all that common and partly because dissecting an entire sunfish to extract the fragile, threadlike worm in one piece is practically impossible.  Didymozoids have incredibly complex life cycles that likely involve flaoting snails and copepods and all sorts of other intermediate hosts.  Despite this, or perhaps because of it, they’ve been very successful in infecting a wide range of pelagic fishes.  I probably shouldn’t tell you that a significant proportion of the tuna you’ve ever eaten probably hosted didymozoids somewhere in its body when it was alive.  Oh wait, I just did…

 4. Beauty in the beast

Trichodina is my favourite protistan (single-celled) parasite; it’s one that parasitology students and researchers alike are drawn to for its spectacular marriage of form and function and for the startling and beautiful complexity inherent in a single cell.  Trichodinids are ciliated parasites of the skin, fins and gills (mostly) of fishes (mostly) in both fresh and salt water, and they’re shaped as discs or hemispheres, sucking onto the surface of the fish with their flattened underside.  Everyone always shouts “Scubbing bubbles!” when I show them in parasitology classes, and I guess I can see why:

Trichodina and Scrubbing Bubbles - separated at birth?

What makes Trichodina so amazing is a ring of interlocking structures just under the cell membrane, called denticles, that are used to aid in attachment to wet fish skin, which is pretty slippery stuff.  When the pins in the middle of the denticle pull up, the blades on the outside bite down into the skin, with the added bonus of creating suction on the underside.  The blades are revealed by staining the cells in silver nitrate and then exposing them to UV light to develop them, exactly like a photograph, and their structure is very important for telling species apart, which is good, because there’s over 150 in the genus!  Some of them are definitely parasitic and can cause nasty disease, but most are probably commensals, which means they’re just using the host as a home and means of conveyance while they feed on bacteria and other detritus suspended in the water.  One of the most captivating things I ever saw was a trichodinid cell dividing, under a microscope.  The way a single-cell could disengage all those blades (each daughter cell gets half), successfully divide and then replicate the missing denticles and reassemble their intricate structure was just mesmerizing.

 5.  Stop it, or you’ll go blind

 Diplostome metacercariae in a fish’s lens. Eyes are sensitive things, so the thought of some freeloading bug making a home in your precious orbits is just creepy, and yet parasites in the eyes are pretty common.  Why?  There’s several possibilities, but the two best are, firstly, that the eye is a relatively inactive place as far as the immune response goes (not a lot of blood inside your eyeball, normally anyway) and that, secondly, infecting the eyes can help you get where you’re going next.  If we, ahem, focus on the second reason for a minute, I can tell you about diplostomes.  These are another family of digenean flatworms, but unlike Nematobibothrioides in the Mola, these mature in birds - fish-eating birds to be exact.  The stage that infects fish is an immature form that lives in the lenses of the eye.  They’re very common, almost ubiquitous, among freshwater fishes, but nearly always only in one eye.  If we, um, look at some fish and find that a third of individuals have diplostomes in the left eye and third of fish have them in the right eye, then a ninth of fish (1/3 x 1/3 = 1/9) should have it in both eyes, but this is not what we, ahem, see.  Where are the dual infections?  You guessed it - nailed, um, in the blink of an eye by one of the aforementioned piscivorous birds.  A fish, it seems, can get by with being functionally blinded in one eye, but being blind in both makes you, er, a sight for sore eyes to your average heron.  In this way the parasite is playing probability statistics to get its life-cycle completed; worms are good at math, who knew?

6. When the worm turns

Our first 5 candidates were all parasites OF fish, but the title of the post was “Six fish parasites” and that could just as easily mean the fish IS the parasite.  I thought about doing the male anglerfish, which parasitises his mate so intimately that their circulatory systems fuse, or the candiru, that tiny terror of the Amazon: a catfish that swims into the human urethra and locks its spines erect, making removal a matter for a skilled surgeon.  But in the, um, end, I had to go with the pearlfish (I’m sorry, I’ll stop now, promise).  Thats because this delightful fish, rather humourously called Carapus, chooses to live in the lower digestive system of sea cucumbers, a lumbering sausage-like relative of urchins and starfish that spends its days lazily sifting food particles from sand on coral reefs.  Pearlfish may not, strictly speaking, be parasites, since it seems that they feed while on day-trip excursions out of the sphincter, rather than on the cucumber itself, but I’m told they can and do feed on the respiratory tree of the host if the need arises.  Its a good thing sea cucumbers are masters of regeneration.  I’ve never actually seen one, but then again I dont spend a lot of time peering into beche-de-mer butts

Image: Claude Rives/Fishbase

Its often said that parasitism is the most common lifestyle on the planet, and nowhere is this better seen than among fish hosts.  From forty foot flukes to tongue-biting isopods, fish are home to the most amazing variety of parasitic symbionts.  Estimates of how many species of fish parasites there are run into the hundreds of thousands; vastly more than the diversity of fish, which are themselves the most diverse vertebrate phylum.   Next time you look at a fish, then, try to see it for what it really is: a little swimming city, replete with enclaves of surprising parasite diversity in practically every tissue.


The solution to Bit-o-Critter round 30

I was so impressed with Sarah F. solving round 30 of Bit-o-Critter that I forgot to post the solution for everyone else.  It was, as she correctly surmised, a baby sailfish.  I drew the particular bit of image from this Flickr set, which has a sort of abstract look to start with. 

Even though baby sailfish are cute as they come, they’re aggressive predators from a very early age.  Just look at the size and investment in the mouth! 



Its not a tumour. Oh wait, it IS a tumour!

I admit it, I LOVE the movie Total Recall.  I love its cheesy special effects, I love The Governator pulling a bug out of his brain through his nose, and I love Sharon Stone in all her over-permed 80’s pant suit glory.  But most of all I love Kuato, the mysterious little conjoined-twin character who leads the Martian rebels in their fight against the Richter character (played by the terrifically melodramatic Michael Ironside) and his cronies.

Thing is, there are weirder things in the world than Kuato, and one of the all-time weirdest is a type of cancerous tumour called a teratoma.  Teratoma’s take the cake in my book for the strangest and most fascinating of all pathologies, and fish get really good ones, as you’ll see.

Typically, tumours arise when a cell in the body is transformed by a mutation that interferes with the normal cycle of cell growth and death that’s essential for regulating tissues.  Instead, the cell multiplies in an uncontrolled or inappropriate fashion.  These mutations are sometimes built into our genes, and sometimes caused by viruses, by contaminants in the environment, by radiation, or even by spontaneous mutations from mistakes in DNA replication.  Anyway, the type of tumour that develops depends on the tissue of origin, and there’s a whole taxonomy of names that describe them accordingly.  For example, a malignancy in the liver is a hepatocellular carcinoma, while a cancer of the pigment cells in the skin is a melanoma. 

But what happens when you get a tumour of a pluripotent or stem cell?  That is, a cell that hasn’t yet decided what to be when it grows up.  The answer is a teratoma.  What makes teratomas so cool and gross and awesome and weird is that as the cells in the tumour multiply, they can and do turn into other different cell types as they go, which is a perversion of the normal differentiation that stem cells would go through when they are maturing into a liver cell, a skin cell or whatever.  The result is a tumour that, at the tissue level, may resemble or contain one or more other tissues!  My colleague and pathologist extraordinaire Jeff Wolf introduced me to teratomas when I took the AQUAVET course at Woods Hole and I was horrified and fascinated.  I saw Jeff last week at the ISAAH meeting in Tampa and asked him if I could share one of his fish teratoma cases with you.  So here it is:

What you’re looking at is a very thin slice of the gonads of a medaka (a type of small fish thats used a lot as a model in biomedical research) stained with haematoxylin (blue) and eosin (pink), to reveal the structure of the tissue.  Ovaries and testes have a pretty high population of stem cells, so teratomas tend to be more common in gonads, but they can turn up anywhere that stem cells occur in the body.  Lets take a closer look, for those who may be unfamiliar with histopathology:

I outlined the tumour in yellow.  Most of the tissue surrounding it is gonad, and you can even see a few big blue oocytes scattered here and there, but you may also see how the tumour is sort of squishing the surrounding tissue.  But what’s cool is all that stuff inside.  The concentric structure marked 1, thats a bit of an eye - you can see the pigment layer of the retina and the alternating layers of rod and cone cells.  All that stuff marked 2 that goes from 12-4 on the clock face, thats all brain tissue.  The stuff marked 3, thats cartilage, and at 4, fish scales (the thin pink lines) and skin, complete with rows of mucus cells along the outside!  There’s just 4 or 5 tissue types in this lesion, but it could just as easily form a bit of gut, some pancreas or a bit of kidney, anything really.

How does this happen?  How can seemingly intact retina grow inside a tumour, a lesion whose very nature implies uncontrolled growth?  The answer seems to lie in cell-cell signalling.  As the first teratoma cell differentiated into a retinal cell, it sent out signals to surrounding cells to say “right lads, we’re forming an eye” and those cells fell into line as the lesion developed.  This is a normal process thats essential for proper development of embryos, but in a perverted recapitulation, we instead get bits of intact tissue forming in tracts within a tumour.  If you think its weird in a fish, wait till you see the ones in mammals: they can have bones, teeth, even fur, growing embedded within the tumour.

Teratomas: fantastically interesting and creepy, no?



Host, pathogen, and ... ammonia?

In  either a happy accident or a particularly clever piece of scheduling, there were two talks back to back in todays ISAAH program that dealt with the role of ammonia (NH3) in fish diseases.  But these two talks gave surprisingly different perspectives on the role of this nitrogen waste compound in the mechanism of disease.

In the first, Ron Thune from LSU talked about a bacterial disease of catfish cased by Edwardsiella ictaluriEdwardsiella is an obligate intracellular parasite of macrophages, which is to say that the bacterium must live inside a host cell, in this case a the major scavenging cell in the immune system.  How does that work, that a parasites can (indeed NEEDS to) live inside the very cell that the host would use to attack it?  In a normal macrophage, an offending bacterium would be engulfed in a small bubble in the cell called a vacuole, and the macrophage would drop the pH inside that vacuole, to kill the bacterium.  Edwadsiella cannot survive at those sorts of low and corrosive pH’s, but it cleverly produces ammonia, which forms a sort of pH buffering system that raises the pH to a level where E. ictaluri not only survives but thrives.  What makes this unusual is that ammonia is normally a waste product that is in itself toxic to many biochemical systems.  The idea that a pathogen uses this waste chemical to improve its own conditions is fascinating.

In the second, even more surprising talk, Drew Mitchell looked at a different bacterial disease called columnaris.  Some other researchers had noticed that fish survival in the face of columnaris outbreaks was better in cruddy water quality, which is totally counter-intuitive.  So Drew and his co-authors did a controlled study of the progression and resolution of columnaris disease at different concentrations of ammonia in their water; ammonia being the greatest component of excreted fish waste.  Sure enough, at concentrations of the toxic unionised form of ammonia that most folks would avoid for fear of killing their fish (0.4ppm and higher), the columnaris agent was effectively eliminated and fish survival actually increased!  The idea that a toxic metabolic waste product could serve to protect a fish from a pathogenic bacterium was, to me, completely counter-intuitive and surprising!  We would normally think of ammonia as an environmental stressor that might make a fish MORE susceptible to disease, not less.  What Drew discovered was more like the protection against the malaria parasite conferred on people by the genetic disease sickle cell anaemia.

Lets recap for a second.  The first study showed that a bacterium can use ammonia to create conditions conducive to survival within host cells, making a disease worse.  The second showed that ammonia can (somehow, as yet unspecificed) protect fish from a different bacterial pathogen, making the disease better.  I guess it goes to show that any single chemical player can have a range of roles in the complex biological landscape of disease, and that we have to be careful about thinking that any given chemical is “good” or “bad”.  Best of all, both studies involve a big element of surprise, and that always makes biology fun and exciting.


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!


The solution to that pesky Bit-o-Critter, round 23b

Commenter Will Edwards just successfully identified the BoC wrasse from Round 23 as Ophthalmolepis lineolatus, or what we Aussies like to call a Maori wrasse.  I think the common name comes from the blue lines on the face and their resemblance to the facial tattoos of several Polynesian peoples.  Its a temperate rocky shore wrasse not to be confused with the humphead maori wrasse or Napoleon wrasse Cheilinus undulatus, which is a huge beast of a thing from coral reefs.

I grew up catching O. lineolatus off the rocks in S.E. Australia with my dad, usuallly using a peeled shrimp on a No. 2 hook on a paternoster rig.  We would also catch mado sweep, which we called "footballers" (striped jersey), mono's, which we called "butter bream" and the occasional luderick, which we called "blackfish".  I looked on jealously while older guys would cast ganged pilchards with an Alvey, way out into the wash in the hopes of tailor (Americans call them bluefish) or even a kingfish (US = yellowtail) or mulloway.  I also remember my dad dressing me down one one time because I left a packet of shrimp bait in the trunk ( get the idea).  When we went to pile into the car and drive home the next day, well, lets just say I wasnt so comfortable sitting down...  Good times, good times...

Picture - Australian Museum