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Entries in marine mammals (6)

Sunday
Oct172010

One of the best things about marine biology

To me, the best bit about working in marine biology is the terrific moment of surprise when you discover a new expression of natural diversity.  Little kids know this - you can see it on their faces every time they turn over a rock in a stream or rock pool.   I think one of the reasons I enjoy it so much is that it almost takes you back to a state of childish wonder, and you get to appreciate something with truly fresh eyes, even if only for a moment.   In my early career in taxonomy, I became completely addicted to the idea of seeing a species that no-one else has seen before (of course, then you have to describe it, and some of the gloss wears off by the time you submit!).  These days, I get the same buzz just from learning about a species I didn’t know existed, and so it was when I recently read a story about an hourglass dolphin (Lagenorhynchus cruciger) that had washed up on a beach in New Zealand for the first time in a century.  Now, I’m not much of an expert on marine mammals, but I had never heard of or seen this animal before, and it was surprising to me because I usually expect the unknowns to come from among the other 95% (invertebrates), and not the more familiar mammals.  It was all the more surprising to me because of the stunning and bold markings of the animal, which are so distinctive, you’d think it would be more well-known (hey, maybe its just me).  Anyway, on the off chance that perhaps you, too, have never met this beautiful creature, I give you the hourglass dolphin, Lagenorhynchus cruciger:

Hourglass dolphins in the Great Southern Ocean. Image: South Georgia Heritage Trust (click for more)

Beautiful, aren’t they?  Have you ever had the feeling I’m talking about?  If so, what was the animal?

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

 

Sunday
Sep262010

Bring a change of wetsuit, just in case...

Wouldn’t it be awesome to be a National Geographic wildlife photographer?  Yeah, I thought so too until I saw this video in which NatGeo snapper Paul Nicklen describes his prolonged encounter with a huge leopard seal that took an unusual interest in his lack of predatory skill by offeri… you know what, just watch it.

 

My wife and I had the good fortune to meet some leopard seals in person a couple of years back, thanks to our colleagues at Taronga Zoo.  My two take-aways from that experience were (a) that they have big scary jaws and (b) that they have unusually gentle and melodic songs.  They had two at Taronga in separated enclosures, and they sang to each other more gently and sweetly than their bulk and dentition would suggest.  Amazing animals.

Sunday
May022010

A whaling conundrum

With tip of the cap to jfang at The Great Beyond

A recent proposal to limit whaling has been rejected by Japan and Australia, for opposite reasons. Japan, which takes almost a thousand whales a year, mostly Minke, objects to the 400 annual quota, which steps down after 5 years to 200 for another 5 years. Australia, which has a long history of opposing whaling, says the proposal doesn't go far enough; they're basically looking for a zero tolerance whaling policy.

Honestly, much as I hate the idea of even a single whale dying in the name of the imaginary research that Japan uses to defend commercial whaling, I think the Aussies might be being a little hard nosed in this case. Lets say the proposal is rejected, then the Japanese continue to take a thousand whales a year - how is that better? The art of negotiation is compromise, and in my view its always better to accept steps in the right direction, even if you don't get everything you want. Its like selling a car: you advertise for 10 grand, hope for 9, expect 8 and accept 7. If you hold out for 10, you're going to be disappointed most of the time.  Obstinacy doesn't help the cause.

In his vision for whaling, Peter Garret (Australia's environment minister) states that the right solution is to restructure the International Whaling Commission.  That may be so, but in the 2 years that it might take to do that, you could have saved 1,200 whales if you accept the current proposal first, and then go after the recalcitrant nations through a restructured IWC with more teeth.

There's a key line in the Great Beyond post linked above, from IWC chair Cristian Maquieira: “I don't think anybody will be happy with the numbers."  I often recognise that as the sign of a successful negotitation: a good outcome is not when everyone is happy, but when everyone is equally unhappy.

Monday
Apr262010

While we're talking genomes...

...here's something distinctly more marine. 

ResearchBlogging.orgA little while ago I drew attention to Andrea Marshall's paper showing that there's not one but possibly three species of manta ray (see Whats A Manta Do?).  In the preamble for that post, I drew analogy between mantas and killer whales as monotypic species; that is, the only members of their genus, a taxonomic one-of-a-kind.  Well blow me down if some new genomics work with killer whales doesn't suggest that there's more than one species of those, too!  Morin and colleagues used a different approach than Marshall, whose work was mostly based on colors and patterns and tooth shape.  Instead, they used "massively parallel pyrosequencing" (try saying that with a mouth full of marbles) to show genetic differences in the mitochondrial genome.  So what the heck does that mean?  Well, lets just say its sequencing a whole bunch of DNA at once, using DNA not from the nucleus of the cell, but from its engine room: the mitochondrion.  The technology is actually a really, fantastic example of miniaturisation; perhaps I'll write about it one day.  But, I digress...  Morin and friends recommend three species of Orcinus orca, with two more subspecies as well.  Subspecies are not required by the taxonomic code, but they are eligible for separate protections under the Endangered Species Act, so its a meaningful result for conservation biologists too; they'll now have to make assessments of each species and subspecies to see which, if any, require additional protections.

To the experts, its not a total surprise that there are multiple species in either of these groups.  You can bet your bum that they set out to confirm a hunch that there are more than one, leaving the surprise for the rest of us less familiar with these beasties and who never saw the subtle differences.  That's OK, I like surprises, especially when they involve new and unexplored diversity, right under our noses.  Maybe we should take a harder look at a few more monotypics, for the inevitable species flocks hiding in the details or the DNA.  Whale sharks, basking sharks, Mola, anyone?

Morin, P., Archer, F., Foote, A., Vilstrup, J., Allen, E., Wade, P., Durban, J., Parsons, K., Pitman, R., Li, L., Bouffard, P., Abel Nielsen, S., Rasmussen, M., Willerslev, E., Gilbert, M., & Harkins, T. (2010). Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species Genome Research DOI: 10.1101/gr.102954.109

Friday
Mar192010

If you can catch lightning in a jar, why not gas in a puddle?

Imagine if you could take all the greenhouse gases and somehow keep them away from the atmosphere, where they would otherwise contribute to global climate change.  Well that's kind of the idea behind SOFEX, a huge experiment done by marine scientists a few years back (my buddy and fellow Aussie Pete Strutton was involved).  The idea stemmed from an observation that the growth of plankton (which absorb carbon dioxide as they grow and multiply) in the oceans is limited by some nutrients, especially iron.  So, if we fertilise the oceans with iron, perhaps we can get the plankton to "bloom", suck up all the carbon and then sink to the bottom, taking the greenhouse gases with them.  The colour picture hereabouts shows a satellite view of an artificial bloom created by adding iron to the ocean.  It was actually a neat idea, except I could never shake off the feeling that the stuff would resurface one day and that it was just delaying the inevitable; it depends to some degree on whether the sunken material gets buried on the bottom or not, I guess.

Well, the idea recently received another blow; a new paper in PNAS reports that the sort of plankton that bloom after iron fertlisation are the same ones (Pseudonitzschia ) that produce domoic acid, a nasty toxin that causes horrible problems as it accumulates higher up the food chain, especially in sea lions and other marine mammals.

Marine mammals are kind of a sacred cow in biology, so my guess is that that will be that for iron fertilisation.  Ironically enough, the whole problem with domoic acid in the oceans, which is a relatively new phenomenon, may have climate change as its root cause anyway - blooms of Pseudonitzschia are supposed to have increased in frequency and intensity because of environmental changes.  You can't win, sometimes.