Wednesday, March 31, 2010

When can we stop sampling and have a beer?

This post was chosen as an Editor's Selection for ResearchBlogging.orgResearchBlogging.org
Yesterday I got a very kind email from a fellow scientist, Eric Seabloom at Oregon State University, letting me know that a paper I wrote with my PhD advisor Tom Cribb (University of Queensland) a few years ago had influenced a recent publication of his.  My paper was about one of those patterns in nature that just seem to be universal.  They're called species accumulation curves and, at the heart of it, they represent the "law of diminishing returns"* as it applies to sampling animals in nature. Basically, they show that when you first start looking for animals - maybe in a net, a trap or a quadrat - pretty much everything you find is new to you, but as you go along, you find fewer and fewer new species, until eventually you don't find any more new species.  Simple, maybe even obvious, right?  Well it turns out that that simple observation has embedded within it all sorts of useful information about the way animal diversity is spread around, and even about how animals interact with each other in nature.  Consider the figure on the above right, which represents two sets of 5 samples (the tall boxes), containing different animal species (the smaller coloured boxes).  The first thing to note is that both set (a) and set (b) consist of 5 samples, and both have a total diversity of 5 species (i.e. 5 different colours).  In set (a), all the diversity is present in every sample, but in set (b) there's only one species per sample, so you have to look at all 5 samples before you find all 5 species.  If you were to plot a graph of these findings, you'd get very different species accumulation curves; they would both end at 5 species, but they would be shaped differently.  They'd look much like what you see below:

 Set (a) would be more like the curve on the left (in fact, it would be a perfect right angle), while set (b) would be more like the curve on the right (in fact, it would be a straight diagonal line).  You can see some other properties on the two types of curves above also, for the more ecologically inclined, but the gist is, the shape of the curves means something about the communities they describe.

Tom and I wrote our paper after many nights in the field spent dissecting coral reef fishes to recover new species of parasitic worms - a time consuming and sometimes tedious process (sometimes thrilling too, depending on what you do or don't find).  We were often motivated by another far more important factor too - when can we stop all this bloody sampling so that we can go and have a beer on the beach?!?   Species accumulation curves therefore have a very practical aspect to them - they tell you when its OK to stop sampling because you've either sampled all the available species, OR, you've sampled enough to extrapolate a good estimate of how many species there might be.

Back to Eric Seabloom.  He and his colleagues wrote a paper about the diversity of aphid-borne viruses infecting grasses of the US Pacific northwest and Canada.  While the environment that they sampled was about as far away as its possible to be from the coral reefs that Tom and I looked at, the patterns of saturated and unsaturated communities they observed were the same. I get a huge buzz out of that, and that out of the morass of published science out there, Dr. Seabloom found a scientific kindred spirit who had had the same thoughts and ideas about nature, however different the specific areas of study.  While Tom and I sipped beers on the beach and watched the sunset over the reef, I wonder if Eric and his colleagues blew the froth off a few while they watched the wind waves spread across the grasslands.  There's something so unifying about science; it can give you common ground with someone you never would have otherwise known, and that's just one reason why I love it so much.

*The tendency for a continuing application of effort or skill toward a particular project or goal to decline in effectiveness after a certain level of result has been achieved. Answers.com 

DOVE, A., & CRIBB, T. (2006). Species accumulation curves and their applications in parasite ecology Trends in Parasitology, 22 (12), 568-574 DOI: 10.1016/j.pt.2006.09.008

ERIC W. SEABLOOM, ELIZABETH T. BORER, CHARLES E. MITCHELL, & ALISON G. POWER (2010). Viral diversity and prevalence gradients in North American Pacific Coast grasslands Ecology, 91 (3), 721-732 (doi:10.1890/08-2170.1)

Not the Dry Tortugas, as such...

ResearchBlogging.org
...more like the Floating Tortugas.  An article in Science Now and The Journal of Experimental Biology reports on mysterious gatherings of loggerhead turtles in the Mediterranean, resembling an island made out of turtles.  It seems the critters gather to soak up the midday sun.  We probably should be surprised given how common basking is among reptiles, but loggerheads are known to spend most of their time on the bottom, so its a bit unusual.  What I find even more cool about this story is that its only now just being described, even though its in the middle of one of the busiest bits of sea in the world; how did no-one ever report on this before?  I love that there's still new stuff to discover everyday, and 90% of it is in the ocean, even the most familiar stretches.  A virtual island raft composed entirely of turtles - can you just imagine?


Knight, K. (2010). LOGGERHEADS STAY AT SURFACE TO SOAK UP SUN Journal of Experimental Biology, 213 (8) DOI: 10.1242/jeb.043901

Tuesday, March 30, 2010

Ocean Conveyor running AMOC

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

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

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

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

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


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

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


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

CITES epic fail?

David Helvarg has a scathing OpEd piece in the Huffington Post yesterday, and rightfully so.  CITES, the Council for International Trade in Endangered Species recently failed to give proposed protections to the northern bluefin tuna and several species of threatened sharks, apparently caving to the desires of Japan and other nations with similar pro-harvest agendas.  I dont know how much data you need to be convinced that these populations are threatened to the point of collapse, but even if if there were equivocation on the science (and there's not), why not err on the side of safety?  Just as line calls in baseball go to the batter, decisions regarding endangerment should always go to the organism.

The way I see it, bluefin are stuck in a positive feedback loop of ever increasing commodity value, feeding more intense searching/fishing efforts, further reducing the population and thereby driving the value yet higher.  Its a trajectory that only ends one way, and it ain't a good one.

Oh, and if what Helvarg says is true about the Japanese embassy serving bluefin sashimi at a reception for the CITES delegates, then wow. Just, wow.  I sincerely hope those were artificially reared and not ranched or wild-caught...

More on the geo-hacking idea

Not so long ago I posted about the idea of capturing all the extra atmospheric CO2 into the worlds oceans by fertilising them and thereby creating enormous plantkon blooms that would convert all the CO2 to plant tissues, which would then sink to the bottom and be buried in the ocean depths.  This new scientist article probes a different angle that I didn't think of, which is Who decides what we will or won't do to change these things?  The author Jim Giles refers not just to ocean fertilising, but engineering the whole planet to combat climate change - what has become popularly known as "geo-hacking" - including sensible concepts like reforestation and cloud seeding, as well as the more absurd notions such as building giant reflectors to bounce the sunlight away.  Its a thought provoking question, so who do you think should decide these issues?  The US? UN? UNESCO?  Perhaps we need a new body with that as its sole charter?

Saturday, March 27, 2010

The ghost of fishers past

The folks you see out on their boats on the bay are not the only ones fishing; those who came before them still get a slice of the action, as this recent article about the retrieval of "ghost gear" from the Chesapeake Bay illustrates.  In many trap-based fishing industries, like lobsters and crabs, a significant number of traps are lost during the course of regular fishing efforts.  In addition, when a fishery turns bad, as happened in the Long Island Sound lobster fishery in 1999, some fishers cut their losses, and their marker floats, quit the fishery and just leave their gear where it is on the bottom of the bay.

The problem is, ghost gear like this keeps on fishing, long after the fisher has moved on to other endeavours.  The design of the trap continues to attract animals, even without bait, because the trap is basically a refuge or cave.  Those that enter are unable to leave and as they die they may act as bait to attract yet more animals to feed on their body.  In this way, the trap becomes a sort of "biomass black hole", sucking in animals from all around, for as long as the trap holds together.  Nets can ghost fish too, especially gillnets or any kind of trawl that can trap fish or strangle a reef

We used to trawl up ghost lobster gear all the time when I was working in Long Island Sound.  Indeed, few days on the water went by without snagging someone's old gear at some point, which speaks to the density of gear that's out there in some inshore waters.  I'm glad the fishers and the resource management agencies are working together to address the problem, because its one of those awful chronic out-of-sight, out-of-mind issues that can erode a fishery despite everyone's best efforts to manage things properly.  If you find ghost gear, call your local DEP or DEC, even the EPA, and let them know so they can come and retrieve it.

Picture of ghost gear on a coral reef from NOAA

Friday, March 26, 2010

Funny scientific names - Abra cadabra

I started my career in taxonomy.  Its a serious business, the naming of new species, and you're not supposed to make light or fun out of an animal (or plant) name.  After all, they are stuck with it for all time.  Nonetheless, people can't help themselves and from time to time, you get some real crackers!  A fella by the name of Arnold Menke at USDA put together a list of them, so did Doug Yanega.  Here's some of my favourites.  Which do you like best?

Agra vation (a beetle)
Colon rectum (another beetle)
Ba humbugi (a snail)
Aha ha ( a wasp)
Lalapa lusa (a wasp)
Leonardo davinci (a moth)
Abra cadabra (a clam)
Gelae baen, Gelae belae, Gelae donut, Gelae fish, and Gelae rol (all types of fungus beetles)
Villa manillae, Pieza kake and Reissa roni  (bee flies)
Ytu brutus (a beetle)

and my personal favourite (whenever possible):
La cerveza (a moth)

I'll drink to that - here's cheers to creative taxonomists!

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

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

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

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

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

(Photo and graphic from NOAA)

Thursday, March 25, 2010

Your calamari wants a flat screen

ResearchBlogging.orgOctopuses and their relatives are just incredible animals.  Not only do they manage to coordinate hundreds of suckers on 8 arms simultaneously without tripping over themselves (I can't even remember what I ate for breakfast) and have the most advanced eyes in the invertebrate world, but they can do other cool stuff like eat sharks,  fit through holes much smaller than themselves, use tools and learn from each other.  Now a new study has shown that they can tell the difference between regular TV and HD.  How did they determine this?  Simply, as it turns out.  The octopus show no reaction to footage of other octopus or crabs shown to them on regular TV screens.  When shown real crabs or crab footage in hi-def, however, the octopus lunged as if to attack the hapless decapod (video link).  In other words, octopus can tell the difference between real and imagery, if the image is not of high enough quality.
The explanation appears to lie not in the resolution of the screen (how small the pixels are) so much as how fast the picture can be draw and redrawn on the screen.  The picture on a TV screen is constantly being created line-by-line from the top of the screen in a process called rastering.  We don't perceive this rastering because it happens faster than we can see; faster than our "critical flicker frequency".  Well, not everyone has the same critical flicker frequency, and nor do all televisions have the same rastering rate.  Most hi-def TV's have a higher frequency (120 or even 240Hz, or times-per-second).  It may be that low-def TV is below the octopus critical flicker, but hi-def is above it.  In this way, they would see a sort of strobing effect in normal footage, but the hi-def stuff would look like, well, a crab.
The authors also noticed that the octopus showed "episodic personality", which is to say they were interested in the crab (or footage of another octopus) some times but not others.  I'm not sure I would class that as evidence of personality, just a less-than-100%-predictable response to a stimulus.  Having said that, ocotpus do have obvious personalities, which is one reason people are so drawn to them.  That, and sweet chilli sauce...

Pronk, R., Wilson, D., & Harcourt, R. (2010). Video playback demonstrates episodic personality in the gloomy octopus Journal of Experimental Biology, 213 (7), 1035-1041 DOI: 10.1242/jeb.040675

Wednesday, March 24, 2010

2 of the 10 worst jobs in science

Popular Science has just published its annual "Ten worst jobs in science" issue, and two of them are in marine science!  How is this possible?  Marine science is clearly the best job since, well, ever.  Hmmmm, lets take a closer look.

1. Oceanic Snot Diver.  The name sounds gross enough, but what does it mean?  Well, it turns out that they are talking about collecting "sea snot" true enough, but to call it nasty is a bit of a beat-up, IMHO.  Scientists call this stuff "aggregates", and its an incredibly important part of the nutrient cycle in the ocean.  Really, sea snot is just the secreted mucus and fecal casts of hordes of plankton.  Wait a sec, when you write it like that, it does sound gross!  Its biggest role is in "exporting" nutrients from the surface layers of the ocean, where the sun sponsors all that plankton growth, to the dark depths, where sunlight never penetrates, but life nonetheless thrives.  Not only do some animals down there eat the stuff (ew), but at those crushing depths, some of the snot also dissolves under the immense pressure of all the water above it, much like snow melting before it reaches the ground.  In this way, the snot plays a very important part in taking nutrients produced at the surface, and dissolving them in the water at great depths.  Maybe not the most attractive concept, but pretty important in the grand scheme of things.  Like Tom Cruise says in The Firm: "Its not sexy, but its got teeth". 

2. Whale slasher.  OK, I have to concede that one.  I've seen a few stranded whales being cut up on the beach (this is called a necropsy, not an autopsy, which is reserved for people only), and it pongs.  I'm not talking sweat sock pong, or even doggy-breath-after-eating-goose-poo pong, but serious, invasive, gets-into-your-hair, throw-your-clothes-away stink.  While the cause of death is always interesting, wading through week-old whale giblets that have been baking on the beach?  Not so fresh...

Monday, March 22, 2010

Fish as filters?

ResearchBlogging.org There's been a bit of press lately (see for example) surrounding a new paper from VIMS that concludes that the Atlantic menhaden or Bunker (Brevoortia tyrannus) is not very good at cleaning the Chesapeake Bay.  This seems an odd sort of paper but its actually not that crazy an idea.  Its turns out that lots of bivalve species like hard clams and soft clams actually pump enough water through their gills, sifting food as they go, that they can actually have a significant impact on the water clarity and nutrient content of the water.  Indeed, the zebra and quagga mussels that have invaded the Great Lakes have changed the entire ecosystem by doing exactly that.  With clearer water, there's less plankton productivity in the water column and more macrophytic plants and algae growing on the bottom.  Menhaden are filter feeders too, and they can occur in large schools, so perhaps its logical to think that they might be able to do the same sort of thing as the clams.  Alas, based on the VIMS experiments, it seems that they can't.

This is an interesting example of a negative result publication.  Often times you'll hear folks say we shouldn't publish negative results because, technically, you failed to prove that they clean the water, which is not the same as proving that they don't.  Well, as long as everybody is aware of that distinction, I still think negative results like that are useful to know, for two reasons.  One, its likely that they don't; if they do, then the effect is so minor that it was difficult to detect.  And two, it might save someone else from having the same idea and trying the same futile experiment.

The Chesapeake has some sporadic problems with hypoxia, which is ultimately a nutrient pollution issue, so I applaud the researchers for looking at a biological solution for what is otherwise a pretty intractable problem.

Cyclone Ului hits the Queensland coast

Tropical cyclone Ului hit the Queensland coast near the Whitsunday Islands and the towns of Proserpine and Bowen.  Apparently 60,000 odd people were without power after the landfall.  Its not the most densely populated part of the Queensland coast, but apparently Ului was a very tightly wound storm with a lot of energy close to the center.  Today will reveal how much damage occured; cross fingers...

What do expectant parents and the Chilean earthquake have in common?

The recent Chilean earthquake was a disaster on a mind-boggling scale; one that had its genesis beneath the sea.  The temblor, and all those in Chile before it, including the biggest ever recorded anywhere, resulted from the Nazca plate sliding down under the South American plate, under the sea to the South West of Santiago.  Well, it doesn't exactly slide, I always imagined it would sound like a creaking door if you could speed up the process a few zillion times.  The upward pressure this collision puts on the South American plate is immense and produces the longest mountain range in the world, the Andes.

Anyway, this most recent slip, which shifted about 10 meters and registered 8.8 on the Richter scale, caused a small tsunami.  Now some researchers from Scripps and UCSD want to know whether it was because of the sea floor movement itself, or because the quake triggered undersea landslides ("slumping") that produced the wave.  They are going to do some nifty multi-beam sonar work to map the seafloor changes in unprecedented details.  Sonar technology has become a really cool tool these days; the same sorts of benefits that new parents reap when they ultrasound their new bundle of joy also give scientists a fantastic new view on the sea floor.  Just check out this example of a shipwreck revealed by NOAA's nautical survey side-scan sonar.

Sunday, March 21, 2010

Bon Voyage, Plastiki

Some enterprising folks have built a tri-maran out of 12,000 two liter plastic softdrink bottles.  Dubbed the "Plastiki", she took to sea today, on her maiden voyage from San Francisco to Sydney.  Along the way, the Plastiki will serve as a floating demonstration platform for sustainable technologies, and will spend some quality time in the Great Pacific Garbage Patch, where vast amounts of floating plastic debris are becalmed in the heart of the enormous gyre current of the North Pacific.

Follow the Plastiki on Flickr here, and on their website here.  Best of luck and kind winds, folks.  If you begin to lose buoyancy, I guess you can always reach overboard and grab another bottle from among the flotsam, you know, to repair the hull with.  :-/

Friday, March 19, 2010

Ului inches closer

Looks like Ului will cross the coast right over the Whitsunday Islands.  Good luck to the folks in Proserpine and Bowen.







This picture from the Australian Bureau of Meteorology

Cyclone Ului approaching the Queensland coast

Cross your fingers for the people of Queensland, Australia, who are facing an impending cyclone, Ului.  It was just downgraded to a Category 2, but you never relax with these things right?  Tourists and researchers have been evacuated from Heron Island and several others, but it looks like it might cross a little further north.  Here's hoping it avoids major populated areas.

Whale sharks arrive early at Ningaloo Reef, Australia

I have never been to Ningaloo (great name, right?) - its WAY on the other side of Australia from where I grew up - but its a fascinating place.  Whale sharks gather there every year, and this year it looks like they turned up earlier than usual.  Whale shark aggregations are amazing events and the one at Ningaloo is one of the biggest.  Why gather? Why Ningaloo?  Why then?  How do they know where to go?  These are just some of the great mysteries of whale shark gatherings; its amazing that we know so little about the worlds largest fish.

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.

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