Wednesday, April 25, 2018

What Doesn't Krill Us Makes Us Stronger: Ocean Water Mixing By Tiny Organisms

        Swarms of tiny oceanic organisms known as zooplankton may have an outsized influence on their environment. New research at Stanford shows that clusters of centimeter-long individuals, each beating tiny feathered legs, can, in aggregate, create powerful currents that may mix water over hundreds of meters in depth.




     Although the work was carried out in the lab, the finding is the first to show that migrating zooplankton – or indeed any organism – can create turbulence at a scale large enough to mix the ocean’s waters. The work could alter the way ocean scientists think about global nutrient cycles like carbon, phosphate and oxygen, or even ocean currents themselves.




      A brine shrimp (below) tethered in place generates flow with its swimming motion, made visible with an overlaid time lapse of particles suspended in the water. Photo credit: Isabel Houghton.




      “Ocean dynamics are directly connected to global climate through interactions with the atmosphere,” said Dr. John Dabiri. “The fact that swimming animals could play a significant role in ocean mixing – an idea that has been almost heretical in oceanography – could therefore have consequences far beyond the immediate waters where the animals reside.”




        Dr. Dabiri, who was the senior author on the work published April 18, 2018, in Nature, added that the findings could also help scientists understand how the ocean sequesters carbon dioxide from the atmosphere and lead to updates in ocean climate models.




      “Right now a lot of our ocean climate models don’t include the effect of animals or if they do it’s as passive participants in the process,” Dabiri said.


      One of the most common zooplankton, krill are among the most abundant marine organisms and migrate daily in giant swarms, heading hundreds of meters deep by day and up to the ocean’s surface by night to feed.



      Dr. Dabiri knew that in terms of forces that drive the mixing of oceans, wind and tidal currents are thought to play the largest role. But he wondered if giant zooplankton migrations could also be involved – an idea first proposed by oceanographer Walter Munk in 1966, and since then debated but never systematically explored. {Dr. Munk, at 100 years of age, is still quite current (pun definitely intended!)}.

      Dr. Dabiri and graduate student Isabel Houghton tried to answer that question not in the ocean but in the relatively controlled environment of large water tanks in the lab. The pair worked to create flow environments that mimic the ocean with saltier water on the bottom of the tank and less salty water on the top. The resulting gradient mirrors ocean conditions that any organism would need to disrupt in order to cycle nutrients between the ocean’s surface and water deep below.




      “There’s no appreciable deep mixing of oxygen or carbon dioxide in the ocean if you can’t overcome the stabilizing influence of salinity and temperature gradients,” Dr. Koseff said.

      In the lab, the group was looking to see whether the tiny organisms they studied – mostly brine shrimp (also known as sea monkeys) as a stand-in for less lab-hardy krill – are simply churning water locally, leaving the gradient intact, or redistributing salt into a more uniform mixture. If they can mix layers in the lab, chances are they can do the same in the ocean, the group argued.








      To carry out the study, Houghton placed brine shrimp in the tank and activated laser or LED lights from either above or below, because brine shrimp are attracted to light, so they migrated toward the source. When she reversed the lights the tiny creatures scurried to the other end in a migration that lasted about 10 minutes.




      With cameras closely recording the animals’ movements, the group has been able to measure the individual water eddies surrounding each brine shrimp and the larger currents in the tank. From these, they’ve shown that turbulence from individual organisms aggregates into a much larger turbulent jet in the wake of the migration.

     What’s more, those flows were powerful enough to mix the tank’s salt gradient. “They weren’t just displacing fluid that then returned to its original location,” Houghton said. “Everything mixed irreversibly.”

     Before this work, scientists had thought that krill and other zooplankton could only create turbulence in their own size range – on the order of centimeters. That’s hardly enough to move nutrients on a meaningful scale. Now it appears that zooplankton have the capacity to mix ocean waters, at least regionally. Furthermore, Dr. Dabiri said their findings might not just apply to organisms like krill in the upper kilometer of the ocean, but also to jellyfish, squid, fish and mammals that swim even deeper, potentially churning the entire water column.




     Dr.Dabiri said his lab members need to verify their findings in the ocean, which will involve finding and following swarms of krill in locations as diverse as the California coast and frigid Antarctic waters. But if they continue to see mixing at the scales the lab work suggests, the findings could change the way ocean scientists think about the role of animals in influencing their watery environment – and potentially our climate on land.

     These ocean mixers are vastly different from the mixers we had at Smith College (or are they?)

     Did you ever order sea monkeys?
Steph

53 comments:

  1. When I first saw that brine shrimp / ocean mixing story, I wondered whether you'd pick it up, and was dearly hoping for a link to an old Sea Monkey ad. As always, you didn't disappoint!

    Never ordered Sea Monkeys per se, but I did buy brine shrimp eggs and hatched them to feed to angelfish, back when I had an aquarium, in my youth.

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    1. jan, I remember those ads so clearly.

      We ordered some sea monkeys and were mightily disappointed. They were not at all glamorous like the ad!

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    2. The best educational toy my sister and I got one Christmas was the Visible Woman. Remember her?

      Next to our dog Wilbur who arrived as a puppy, the VW was the gift I remember most.

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    3. Funny, my mind also immediately leapt to sea monkey memories the moment I saw brine shrimp. I guess if you're of a certain age and spent too much time reading comic books....

      The counselors at summer camp ordered sea monkeys, and all were equally disappointed. It was around that time (I was 9) that I realized advertising was a scam, and I really wanted that as a career.

      Visible woman (and man) were definitely pretty cool. Still are, plenty on ebay.

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    4. eco, I had the opposite reaction to advertising scams from the sea-monkey debacle. I beat my "tiny (un)feathered legs" so fast I scooted as far from advertising as possible, mixing currents along the way ;-). Happily, I landed in geology. (And you landed in architecture, eh?)

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    5. I had a very cynical youth, which hasn't really changed much.

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    6. Hmmmm. "The name Cynic derives from Ancient Greek κυνικός (kynikos), meaning 'dog-like', and κύων (kyôn), meaning 'dog' (genitive: kynos)."

      Maizie says "hruff?!" {She doesn't have a cynical bone in her body; though she enjoys many a bone.}

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  2. No experience with sea monkeys - or Smith mixers, even though I went there! I found the post fascinating, though, particularly thinking about possible implications for climate models.

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    1. Joanne, sea-monkeys, I understand but never going to a Smith mixer?! Wow. Actually you (luckily) missed sticky, warm beer on the floor, busloads of frat boys from Ivy League schools, and lots of loud music. What a time! ;-)

      Yes, it does have some wide-ranging implications for climate models.

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    2. I'm not much of a chimer-in-er (sounds better out loud than written!) on blogs, but can't resist this one. First, VERY interesting post, reminds me of the whole butterfly-beating-its-wings-somewhere-far-away thing. My sister bought sea monkeys with such enthusiasm, and I dimly recall these tiny things sort of floating around...pretty disappointing. Not unlike Smith mixers!

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    3. Hello and welcome, SmithHaven! I bet I can guess your house at Smith :-).

      I agree about those little motions making a big effect elsewhere.

      And the parallels between sea-monkeys and Smith mixers was so true. {I wonder if they still have them.} Those glamorous sea-monkeys in the ads were exactly like the Dartmouth and Yale boys we thought we'd enjoy mixing with. Ha!

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    4. LOL! Maybe that was my salvation. I didn't need to look for Ivy frat boys as I had a (proudly non-frat) high school sweetheart faithfully writing to me from UVM. Our 36th anniversary will be in a few weeks.

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    5. Congrats, Joanne, on almost 36 years of wedded bliss.

      I always wondered why the U of Vermont is not just abbreviated UV. It was one of the schools to which I was accepted; never got an answer to that question, though. . .Perhaps your spouse knows?

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    6. I know without even having to ask him! UVM comes from the Latin name of the school Universitas Verdis Montis - University of the Green Mountains. It was founded in 1791, the same year that Vermont became the first state added to the original 13.

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    7. Thanks, Joanne. Mystery solved and no duckduckgoing needed!

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  3. I was surprised to learn that I've seen brine shrimp breeding ponds every time I've flown into SFO.

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    1. We're proud of our rainbow coalition here. You can learn more from this video. The host was a bit of a cornball, but he had his charms.

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    2. Hue knew?

      Quite the salty dog!

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  4. Could we please get a geologist's take on how Oman's rocks could save the planet? I get suspicious when I see lots of references to "carbonate" without identifying which carbonate. Isn't a carbonate what you'd get after reacting a metal like calcium or lithium with CO2. (E.g, the lithium hydroxide scrubbers in spacecraft and submarines.) If these rocks are so great at absorbing CO2, is the only problem really that we haven't spread them around on the surface enough?

    And, as long as we're asking for geologists' perspectives, how about Ryan Zinke?

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    1. Yes, jan, it seems to be a surface area thing; exposing calcium (to make CaCO3) or calcium and magnesium (to make dolomite or dolostone) to take CO2 out of the air and/or out of percolating waters requires fresh surfaces. The Dutch researchers' crushed rock idea is interesting. But, these rocks are by no means unique to Oman. It would be best to crush rocks in situ, if at all.

      Blech, Ryan Zinke--though the video made me laugh (sadly at times). Bears' Ears, sigh. Zinke certainly has not studied it "as a geologist." Square dancing with VP's wife. I missed all that supplementary "geologic training" at Smith.

      Another Zinke quote: "Florida is different in the currents -- I'm a geologist -- it's different in geology." Maybe we need to send in the krill to attack Zinke in those currents.

      Sheesh, current events can be both demoralizing and promising.
      . .

      Ah, it's different in geology.

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  5. Steamboat Geyser erupting in Yellowstone NP. I was there in the winter of 1988 and saw several unusual geysers erupting; they were geysers we had to cross-country ski into. I don’t believe Steamboat was one of them, though. I do recall Castle Geyser erupting over lunch one day.

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    1. Whoops: Try this instead:

      https://www.washingtonpost.com/national/energy-environment/yellowstone-geyser-erupts-for-3rd-time-in-6-weeks/2018/04/27/c8698538-4a6d-11e8-8082-105a446d19b8_story.html?utm_term=.4eb0bc8d62ab

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  6. Important news in space science. Perhaps smart phones can figure it out with a cha t ap.

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    1. Yes, eco, I got sucked in with thoughts of rock ets! Do any of you use a double space after periods?

      While I was there reading about spaces, I found this about a device fitting in a lizard's cloaca. {Warning: Don't read over breakfast.}

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  7. The Rainbow Mountain of Peru, which we've discussed previously, is in the news this week, under threat from tourism. (Maybe we should be careful about highlighting places of natural beauty to the millions of readers of this blog? Maybe it's inevitable that it becomes as Yogi Berra carped: "Nobody goes there anymore -- it's too crowded!"

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    1. Thanks for the link, jan. Indeed, I am sure the millions of readers of Partial Ellipsis of the Sun have flocked to Rainbow Mountain.

      Things have changed since the original post in October of 2016. Vinacuna now has a Wikipedia page, 45 is president, and we now know that melting glaciers may be what exposed the Rainbow Mountain.

      Not sure I noted this before, but my friend was visiting Machu Picchu in Peru in October 2016, even as I wrote the initial post. She heard no mention of Rainbow Mountain while there. How quickly things change in 1.5 years!

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    2. Rainbow Mountain does look pretty cool, better when it's sunny, which seems to be infrequent, judging only by the photos on Google Maps.

      May be better to visit Artist's Palette in Death Valley. Okay, not quite as geometrically spectacular, but a lot easier to get to with less environmental impact. And last time I was there you only had to walk 10 minutes to escape the auto-attached touring hordes. And WW has noted lots of amazing sites - Make America Geologic Again!

      Similarly we have our own Machu Picchu in Chaco Canyon - I've got to get over there - Mesa Verde, which I hear has been a bit overrun, and other sites in SW Colorado, Aztec Ruins, etc.

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    3. eco, I like Make America Geologic Again. The Artist's Palette looks intriguing. I was in Death Valley but once and never saw those colors.

      Yes, plenty to explore in the US!

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    4. Like anything with color, Artist's Palette is best with a low angle sun. It's been years, but I recall I was last there in mid afternoon in late January - pretty good but probably better later, though some colors get subsumed in the shadows. Both Golden Canyon and the big dunes at the north end are great at the end of the day.

      Just came across this very geeky website, I never knew so much of Star Wars was filmed in Death Valley. It's 109° on Tatooine now, too much for this tourist.

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    5. We were on a dendrochronology field trip, on our way from U of AZ to the White Mountains and Inyo National Forest to see the ancient bristlecone pines. Death Valley was really just a drive-through. It was November and quite pleasant, if a bit chilly. I also did not know so much of Star Wars was filmed there. Wow, 109 degrees in May!

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    6. Probably not a lot of dendro action in Death Valley. But I understand there's a lot for the geologist. I just like pretty picture.

      I've only visited the bristlecones in Great Basin; they have the advantage of not being crowded because of the 1.5 mile hike at high altitude.

      They have the disadvantage of the 1.5 mile hike at high altitude. Actually it's not bad, though there is a little adjustment to 10,000 feet for us low-lifers.

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    7. Yes, altitude adjustment is such a thing! Going from Tucson at 2389' above sea level to over 10,000' was an adjustment, even for a 20-year-old.

      My son had the advantage of going from 5280' in Denver to sea level in Providence, RI. His coach was amazed at his stamina.

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  8. Replies
    1. Was the walking robot reading those large scan codes on walls and pillars? I am wondering if it needs to have those to operate?

      I'd not seen Black Mirror. The combo is scary.

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    2. According to the text accompanying the Boston Dynamics video on YouTube, "The QR codes visible in the video are used to measure performance, not for navigation."

      Black mirror is great, all four (so far) seasons. Really captures the techno-zeitgeist. This episode ("Metalhead") may have been the most depressing. The first episode of Season 1 ("National Anthem") may have been the best. The third episode of Season 2 ("The Waldo Moment") presaged the Rise of Trump by a couple of years. I have a T-shirt, which I first saw at the Women's March in NYC, that says, "This Episode of Black Mirror Sucks!"

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    3. Thanks for the scoop on the QR codes, jan.

      I saw snippets of the "National Anthem" series premiere. Interesting and bizarre. Black Mirror is a cool name.

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    1. "Arrowsmith" joins "Elmer Gantry" and "It Can't Happen Here" on the re-read pile.

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    2. Wow. It's so cheap and easy to do!

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    3. Oh, to unsee that image!

      Oh, to "undo" the word unsee!

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    1. Darn. And so problematic to see it in the big city. . .

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    2. Indeed. Could be just the thing to distract the world from Gaza, and Korea, and Iran, and Mueller...

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    1. It’s in the top 3 of “Why I became a geologist” for most geologists I know.

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    2. And do the others include:
      - they thought the stoners in school were cool?
      - they think putting on a rock show will finally make them cool?
      - they'll finally make the bedrock?
      - they can explore orogenous zones with miners? (okay, that was creepy)

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  12. For those who like watching a meltdown spewing forth that doesn't involve Twitter, CNN is live "streaming" the Hawaiian volcano. Way cool. Or hot.

    A client I met with this morning said she has a friend whose house was destroyed. My somewhat crass response is anyone living to the east-southeast of Kilauea has not been paying attention and thinking a little. I recall a new island is slowly springing up off the eastern shore.

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    1. I must agree about the hot spot and geography. Likewise, folks buying beachfront property almost anywhere seems unwise.

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    2. It's not like the volcano is that surprising, it's rock-it science. The natives have known this for a long time.

      Pacifica is a small coastal town about 10 miles south of SF. Every winter there's a new round of TV excitement over which buildings will plummet from the eroding sandstone cliffs.

      My office is about 10' above sea level, looking forward to my waterfront property, and then my underwater property - at least it's a rental.

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  13. New post on "An Extraterrestrial Empanada, A Space Ravioli, and A Planetary Baguette: Simulating Saturn’s Moons" is now up.

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