Friday Weird Science: The Million Diatom Orgy

Sci is unfortunately unable to get her hands on the real journal article behind this week’s weird science. That’s because it isn’t out yet. But look for it soon in “Deep-Sea Research II”, which to Sci sounds a lot like an awesome sequel to an action-biography about Jacques Cousteau. I would definitely go and see those movies. I would buy them. SOMEONE SHOULD MAKE THESE MOVIES.
EDIT: GOT THE PAPER!!! Thanks very much to Dr. Sarno, who responded so quickly to my email. It should also be up online soon.
For this week’s Friday Weird Science, I present to you:
Sarno et al. “A massive and simultaneous sex event of two Pseudo-nitzschia species”. Deep Sea Research II, 2009.
aka: Massive Simultaneous Sex Event Documented
I bet journalists LOVE it when they get to use “sexually explosive” while covering marine biology. I would.
So what happened? In the Gulf of Naples off the coast of Italy, on Sept. 20, 2006, millions of diatoms of two different species came together for one crazy event.
Whoa there.

So what, you might ask, is a diatom?
Diatoms are a kind of unicellular algae (though they can clump together) that are one of the most common types of phytoplankton, a group that produces almost half of all the photosynthetic activity on the planet, and thus a whole heck of a lot of the planet’s energy. Know your phytoplankton. Love your phytoplankton.
Sci likes diatoms because they are pretty. They might be your ordinary, run of the mill photosynthesizers, but these little guys are covered with a cell wall made of silica, and in the right light this means they look very pretty indeed.
Somebody should totally turn these shapes into jewelery. I’d buy it.
So anyway, these diatoms live in the ocean as single cells, or forming little chains with each other. Diatoms can reproduce asexually without a problem, but it appears that this gathering was all about dancing with others instead of yourself. And for good reason. Because of their hard cell walls, reproducing asexually means that diatoms will get progressively smaller as they go. Sexual reproduction is necessary to restore maximum cell size. When the diatoms produce their haploid versions, the joining together (the two haploids form a body called a gamtanglia) happens before the rigid silica shall forms, allowing the diatom to expand to a larger size.
But no one had seen this sexual stage of the diatom life occur in the wild. You have to imagine that it’s happening all the time, but so far it had only been produced in the lab.
But in the warm Mediterranean on this fine day in 2006, the diatoms were GOING AT IT, expanding their population’s girth and number. Between 9-14% of the two species observed were producing gametes and joining with other gametes. This is the first time that this has been witnessed in the wild. The two species involves were Pseudo-nitzschia cf. delicatissima and P. cf. calliantha, pictured below:
diatom sex1.png
(The first two are delicatissima, the last is calliantha)
The authors of the study recorded not only the species and the percentage observed in mating, they looked at cell size:
diatom sex2.png
What you can see there are the two species of diatom represented, the calliantha being a little smaller than the delicatissima.. What you can also see, though, is small groups of cells in the higher size population, implying that the mating events going on were producing diatoms that were larger in size.
Heck, they even got pictures.
diatom sex5.png
In the top panel there, you can see the P. cf. calliantha, and the two diatoms that are merged up against each other (on the left) are the sexual stage. These are the gametes that have already fused. In panel B, you can see the auxospores, the haploid stage of the calliantha, waiting to get some action. Notice there that the cells are light and not surrounded by the darker, hard shell of silica, giving them more room to grow.
Extra pictures of the diatoms featured in the paper because I think they are pretty:
diatom sex3.png
But though you should love your pretty diatoms, this massive mating event might not be the best thing. Both Pseudo-nitzschia cf. delicatissima and P. cf. calliantha produce a toxin called domoic acid. This is a toxin that associated with this:
That’s a red tide, or harmful algal bloom. It’s red because the algae causing it are reddish, and there are so many of them that they are tinting the ocean.
So you might look at that and think “what? it’s algae! And they’re photosynthesizers, so it’s not like they’re depleting oxygen or anything!”
Well, no. But they produce this domoic acid, which is a neurotoxin that accumulates in things like shellfish. Which humans and other mammals like to eat. In marine mammals that eat the shellfish, you’ll get things like seizures, and in humans, you can get memory loss, brain damage, and death.
Pretty, yes. Pretty deadly. There was no red tide associated with this gathering, but now that they’ve caught them at it once, it might be possible to determine when diatoms are having their little orgies, thus making it possible to predict when red tides or high domoic acid might occur.
Also opens up an entire new phylum of porn.

7 Responses

  1. The internet: Pornography for all of earth’s creatures.

  2. So I’m guessing we have no clue why some diatom orgies result in red tides and others don’t?

  3. Did my comment get eaten by the spam filter, or was it useless?
    (re. the difference between red tide poison and domoic poison)

  4. Becca, I thought from reading it that both the diatom event and the red tide (algae) produced the toxin, but that people were hitherto only aware of the algae as a problem.

  5. Dinoflagellates (w/ tails) may produce red tide.
    Diatoms (no tails) may produce domoic poisoning.

  6. “The internet: Pornography for all of earth’s creatures.”
    Does diatom sex count as pornography if I can’t figure out where the naughty bits are?

  7. SEXY!!111!! But I don’t know about the jewelry, though I would have totally worn this in my gothier days.
    And yes, DD is correct. Harmful Algal Blooms (HAB) are not synonymous with red tide. Pseudo-nitzchia are toxic and form HABs, but they are not red. (Sometimes it’s possible to see them as greenish layers or swirls.) Red tides are formed by dinoflagellates, which may or may not be toxic, so not all red tides are HAB.
    Now on with your regularly scheduled algal orgies.

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