Bye bye Plastics Scare: Krill can Digest Plastic

Antarctic Krill

Antarctic Krill. By Krill666.jpg: Uwe Kils I am willing to give the image in 1700 resolution to Wikipedia Uwe Kils – Krill666.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=14871367

Guest essay by Eric Worrall

Scientists have discovered Antarctic Krill can digest or at least break up lumps of plastic into even smaller lumps – but when the krill were force fed large quantities of radioactive plastic over an extended period their ability to digest plastic deteriorated.

Krill found to break down microplastics – but it won’t save the oceans

Digestion of plastic into much smaller fragments ‘doesn’t necessarily help pollution’, Australian researchers say

A world-first study by Australian researchers has found that krill can digest certain forms of microplastic into smaller – but no less pervasive – fragments.

The study, published in Nature Communications journal on Friday, found that Antarctic krill, Euphausia superba, can break down 31.5 micron polyethylene balls into fragments less than one micron in diameter.

Unfortunately, Dawson said, krill were unlikely to provide a solution to the levels of plastics and microplastics polluting the oceans.

“It’s not necessarily helping plastic pollution, it’s just changing it to make it easier for small animals to eat it,” she said. “It could be a new source of plastics for the deep ocean.”

A study by Newcastle University in December found microplastics in the stomachs of deep-sea creatures from 11km deep trenches in the Pacific Ocean.

Dawson said microplastics that had been digested by krill were also too small to be detected in most oceanic plastic surveys, meaning the level of microplastics in the ocean could be higher than currently assumed.

Read more: https://www.theguardian.com/environment/2018/mar/12/krill-can-turn-microplastics-into-nanoplastics-study

The abstract of the study;

Turning microplastics into nanoplastics through digestive fragmentation by Antarctic krill

Amanda L. Dawson, So Kawaguchi, Catherine K. King, Kathy A. Townsend, Robert King, Wilhelmina M. Huston & Susan M. Bengtson Nash

Microplastics (plastics <5 mm diameter) are at the forefront of current environmental pollution research, however, little is known about the degradation of microplastics through ingestion. Here, by exposing Antarctic krill (Euphausia superba) to microplastics under acute static renewal conditions, we present evidence of physical size alteration of microplastics ingested by a planktonic crustacean. Ingested microplastics (31.5 µm) are fragmented into pieces less than 1 µm in diameter. Previous feeding studies have shown spherical microplastics either; pass unaffected through an organism and are excreted, or are sufficiently small for translocation to occur. We identify a new pathway; microplastics are fragmented into sizes small enough to cross physical barriers, or are egested as a mixture of triturated particles. These findings suggest that current laboratory-based feeding studies may be oversimplifying interactions between zooplankton and microplastics but also introduces a new role of Antarctic krill, and potentially other species, in the biogeochemical cycling and fate of plastic.

Read more: https://www.nature.com/articles/s41467-018-03465-9

The expression of concern about nano-plastic seems a stretch. Breaking micro-plastic into smaller chunks, making it available to even more versatile and varied microorganisms further down the food chain, is likely enough to effect complete clearance. Anyone who has ever owned a boat knows how difficult it is to protect fuel from contamination by the ubiquitous fungus and bacteria which thrives in sea water. It seems highly likely that at least one other organism, somewhere in the world’s oceans, has developed a taste for our plastic waste.

Correction (EW): the plastic wasn’t radioactive, I misread “Triturated” as “Tritiated” (h/t Phil)

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81 thoughts on “Bye bye Plastics Scare: Krill can Digest Plastic

    • It would increase the rate the polyethyelene breaks down, as microparticles have much more surface area exposed to the beasties that can digest that plastic.

      • Correct. The smaller the particles are, the more surface they have in proportion to their mass and the easier it is for bacteria to do the rest. Incidentally, this is not just the case with plastic-eating bacteria, but in general. Wherever bacteria are at work. The remark in the article that Krill’s ability to shred plastic waste could not solve the problem was obviously not thought through.

      • I’ve noticed that when I eat peanuts that the human digestive tract is also not all it could be. I don’t want to go into details, but I get the impression sometimes that something is getting a free pre-chewed meal. So what is eating the rest of my peanuts? It could be a similar process at work.
        Just an observation.

      • I’ll not go into details… but I admit I’ve been just skimming climate scare news articles, and the mental digestive tract is not all it should be, there are not enough hours in the day to identify and refute every hysterical point. Someone downstream from me is getting pre-chewed alarmism that is easier to digest. Who is consuming this stuff??

    • Just was we know now that bis phenol A is metabolized by many more organisms than first expected, including mammals, we are underestimating the ability off microorganisms to take advantage of a new carbon source. When I was a kid, formica was becoming popular and the scare was that we would eventually be up to our ears in formica. It was only 10–20 years later that fungi eating formica became a problem as it ate the finish off many counter tops and other surfaces. Life will indeed find a way.
      Also, the micrpplastics are not going to be a clearing problems for larger organisms as they will simply excrete them with other fecal material. Size does matter.

      • Even at 31 micron, it’s essentially sand, which pretty much any animal can and does accidentally eat on a routine basis. 1 micron is dust.

      • Yep. That plastics are degraded in the environment has been known for a long time now.
        And there is no evidence that the longer lived small particles are any more harmful than the other inorganic and organic particles that make up sand, silt, mud, or soil. The current “scare” is a scandalous exercise in wilful scientific ignorance. I can’t believe that people are still swallowing this nonsense (pun not intended).
        In reality, the issue is not really any different than that of soluble compounds: Analytical techniques today enable genuine researchers and agitators to detect compounds and materials at extremely low levels, far lower than in the past. But just because something can be detected, that doesn’t mean it is harmful. Plants themselves produce a whole galaxy of molecules which are often there to make life difficult for a creature/predator that eats them.

    • It is highly unlikely that such material (plastics) have not a niche bacteria, alga, or other lifeforms that could not subsist on them, as they offer very high energy returns.
      Here is on they have found… http://science.sciencemag.org/content/351/6278/1196
      Or worms https://news.stanford.edu/pr/2015/pr-worms-digest-plastics-092915.html
      Or caterpillars maybe https://www.washingtonpost.com/news/speaking-of-science/wp/2017/04/24/these-pesky-caterpillars-seem-to-digest-plastic-bags/?utm_term=.47a2141dc728
      And even fungi maybe https://www.seeker.com/fungi-digest-plastic-trash-discovery-news-1766491802.html

  1. I believe it was George Carlin who said that the Earth wants plastic for itself. It’s incorporated into a paradigm: the Earth plus plastic.
    (Yes, I have watched that video at least 3 dozen times. Well, 3.5. Okay, it was really 4.25 times.)

  2. Plastic. Long chain, reasonably stable, and tough hydrocarbon compounds. Considering the rate at which evolution happens in smaller organisms, there are probably several out there that actually use the stuff for their structural elements.

    • that actually use the stuff
      ======!
      there is. a fungus in the tropics that eats rubber. thus the move to silicone dive gear.
      there is also a fungus that eats floppy disks and video tape. put something in a dark warm moist place in the tropics and something will probably figure out how to eat it. jungle rot certainly eats people and pretty much anything else.

      • And don’t forget about fungus that can etch inorganic coating and glass substrate of lens. Submicron particles of saturated C-C chains should be piece of cake…

    • Polyethylene should be no more difficult for wee beasties to digest than chitin or cellulose.

      • Cellulose is a polysaccharide. AKA plastic sugar. The only problem switching from polysaccharide to polyethlyene is that the digestive enzymes tend to be optimized to the substrate. Like termite guts.
        Maybe use genetic modification of termite gut biology into a form that will degrade polyethylene. There is a marine based organism that does the same job as land termites. Some kind of worms. Try to modify the worm digestive enzymes into forms that will degrade polyethylene. Eventually, biology evolves to survive on whatever can be digested.

      • Cellulose is a polymer of D-glucose, very tasty when you can produce the cellulases enzymes like cellulomonas genus. PE on the other hand require lots more work…

      • Here somes beasties that have “solved” the problems of PE inertness: “Two bacterial strains capable of degrading PE were isolated from this worm’s gut, Enterobacter asburiae YT1 and Bacillus sp. YP1. Over a 28-day incubation period of the two strains on PE films, viable biofilms formed, and the PE films’ hydrophobicity decreased. Obvious damage, including pits and cavities (0.3–0.4 μm in depth), was observed on the surfaces of the PE films” [https://pubs.acs.org/doi/abs/10.1021/es504038a].

    • Fluorocarbons will last for long times — maybe even geological times; Teflon (polytetrafluoroethylene, ptfe) especially.
      Subduction into a hot zone will destroy ptfe, but that’s about all. Oh, and falling into the sun. 🙂

      • Also very resistant to bacterial attack. Several molluscs use fluorides in their exoskeletons – want to bet that some won’t (if they haven’t already) switched over to the superior fluorocarbons?

      • As George Carlin said, the earth will survive with plastic and nano technology BUT humans maybe not. We really have turned our oceans into a plastic dump. If only the greenies would get focused.

      • Really? My work with pipeline failures seemed to suggest that baby termites were weaned on Teflon. 🙂

      • Wouldn’t surprise me if sometime in the future the environmentalists will require us to dump plastic into the oceans. In order to feed the bacteria that have gotten hooked on the stuff.

  3. krill were force fed large quantities of radioactive plastic
    =============
    what next. mutant killer krill.
    better to force feed the researchers large quantities of radioactive plastic and see if this affects their appetite.

  4. Hmmm….. I wonder if the reduction in plastic particle size is simple mechanical reduction via the equivalent of krill mastication… or is it from a bacteria in their diminutive digestive tract?

    • The article was open source! Looks like mostly mechanical reduction of particle size, both in mastication and within the internal ‘digestive mill’. Bacterial contributions were not addressed but also not ruled out.

  5. From the paper–
    “ Despite the properties of pristine polymers, all plastics, even those with chemical stabilisers, will eventually degrade in the environment.”
    “ Of the 165 images taken, 2 images were excluded on the basis of chitinous material ….”
    This suggested to me that a control using other more commonly encountered undigestible similarly size particles would be interesting. Krill live in clear water but there are always floating materials around, but such controls might still be inadequate.
    From abstract of one of the citations on mussels, which might be bettered expected to be able to handle small particles.–“ The short-term pulse exposure used here did not result in significant biological effects.” Similar results for oyster larvae in another cited article– “ In conclusion, while micro- and nanoplastics were readily ingested by oyster larvae, exposure to plastic concentrations exceeding those observed in the marine environment resulted in no measurable effects on the development or feeding capacity of the larvae over the duration of the study.” Oysters do well, even better, in cruddy looking water so their tolerance is not unusual.
    There was legitimate toxicological concern that manufactured hydrocarbons might be a bigger problem than those naturally occurring. Did it take a long time to get around to studying these and then based on amounts (cosmetics)?. Is the chemical nature of the colloidal sizes accurately known?

  6. No surprise. There is an enormous amount of oil naturally seeping into the ocean every second. There is whole ecosystem that feeds on it. Same for methane and other natural gas. On land tar pits exist in California, Trinidad, Canada and many places. Just face it – oil is just composted critters from a long time ago – not so different from your garden compost heap except many many more years old, buried and baked from natural thermal heat and under pressure from sediment weight.
    Oil is Mother Nature’s Fuel – the suns energy trapped by plants and the critters that eat them.

  7. In this case the species being studied (krill) were more intelligent than the researchers – by a very long shot.

  8. ” … but when the krill were force fed large quantities of radioactive plastic over an extended period their ability to digest plastic deteriorated. … ”
    Well fancy that. Fussy little critters.
    One wonders what they were thinking.
    Biologists are great.

  9. In nano sizes, it’s almost certain to be completely biodegradable. Plastics of all kinds become brittle and break up by weathering. The fact the fine pieces are spheres is evidence of “wear” by abrasion and chemical diminution. If plastic bottles and other forms are quickly reduced to millimetric particles, then sub-millimetre sizes and then taken in by krill at 30 microns and passes at 1 micron, why would the reduction stop. A highschool chemistry student knows (used to know?) that reduction in grain size greatly increases exposed area of a material which increases its vulnerability to chemical attack. Hey, the stuff is hydrocarbon based which is carbohydrates to biota in fine particles. Take it from a mining engineer!
    Also an experiment must be conducted to do a proper mass balance of the degradation. Examining size reduction from injestion is not quantitative of the process. If one can keep krill alive and add in a measured weight of -30 micron plastic into the tank, then in time one can measure what remains. It’s trivial to expect the mass to reduce. A good scientific test but, sorry, you’ll have to go to a different publication than the guardian to get it published.

  10. ” … meaning the level of microplastics in the ocean could be higher than currently assumed. …”

    Well, if the quantity of plastic is “currently assumed”, then you could with equal credibility and validity ‘quantitatively’ “assume” something else to be true, or at least a useful alternative reality.
    This is easy.

  11. In the pacific high all the barneculs stick to everything and sink everything over time. Ed bray on the schooner de Viento.

  12. …Correction (EW): the plastic wasn’t radioactive, I misread “Triturated” as “Tritiated” (h/t Phil)…
    I’d be surprised if it didn’t have some level of radioactivity – pretty much everything emits residual levels of radiation. Which must be a gift for any activist: “You are letting your children play with toys made from Scary radioactive plastic..!!!”
    I wonder what levels of radiation you get from home-grown broccoli?

  13. And there are bacteria that digest the black blob. The “green” blight, including windmills and photovoltaic panels, not so much.

  14. Let’s also not forget water is the universal solvent.. given enough time it will dissolve anything.

  15. From personal experience and over half a century of observation, I have noticed that the indigestible gets a passthrough for some other critter to chew on. Fast forward to the bottom of the food chain (no pun intended) in some deep ocean trench where the undigested residues of the indigestible are gathered, there they will be subducted into the planet’s own recycling mass-burn furnace.
    From where after an aeon or two, even the most indigestible plastic residues will return volcanicly to the surface reduced to their original natural components…. just an hypothesis!
    Cheers
    Bahamamike

  16. Pochas94
    Crude oil from the Gulf disaster was not consumed by bacteria.
    I have it on the best authority:
    It all ended up in the “Bermuda Triangle”.
    🙂
    Bob Hoye

  17. Microbes eat the little bits of plastic. This has been known since 2011 — why it is repeatedly ignored and unreported in Oceanic Plastics research is a mystery to me. The smaller the bits, the faster it is consumed by microbes.
    In this study, they fed krill tiny bits of brand new plastic, un-degraded by time, sun, water and not yet partially digested by microbial action.
    There was no evidence of digestion of plastic by krill. The krill just mechanically fragmented the plastic beads.
    However, once excreted by krill and subsequently digested by microbes, the plastic isn’t plastic anymore — its just chemicals — like everything else.

    • As I recall, plastic bits in the ocean turned out to be attachment substrates for bacteria and microbiota.
      I wonder whether the Krill, knowing a good thing, ingested the plastic bits to eat the attached micro-organisms. And then excreted the now surface-cleaned plastic beads to let them go another round. 🙂

      • Pat ==> You are right about the first bit — all kinds of microbiota attach themselves to floating plastic bits — sometimes so many that they eventually sink.
        In the experiment being considered here, they used brand new plastic spheres.
        It is important to note, that as far as this experiment is concerned, the krill did not digest the plastic — they just fragmented them by mechanical means into smaller (very very small) bits.
        It is those very very small bits that will be rapidly consumed by microbes.

  18. But I LIKE paying $0.10 per paper bag at my local Safeway store. It makes me feeeeeeel good about myself. That I am saving the world’s oceans from all the third world trash … wait … you mean my plastic bags all were neatly deposited into the sanitary landfill that I pay $52.00/mo. to use? Nevermind. But I am STILL gonna feeeeeeel superior to you.

  19. Concerning plastic floating around in the oceans, I must admit it hardly appeals to my personal aesthetic standards. That of course is something different from being hysterical about it. I just primarily wonder how stuff ends up there, although in developing world I can see many ways, through rivers and coastal areas; and of course fishing nets.
    Anyway, “doing something” to “clean up” the ocean or – in an alternate vision – to mine the ocean for plastic resources and use it for some purpose, has at least my sympathy. You may have probably heard of the “Ocean Cleanup Project” by the young entrepreneur Boyan Slat, who just happens to live next-door from me. He collected millions by means of crowd funding and is by now testing a new prototype in deep waters.
    See https://www.theoceancleanup.com
    At least he is beating the Krill competition to it.
    Thoughts, anybody?

    • cyrilthruthseeker March 13, 2018 at 8:01 am: “Thoughts, anybody?”
      WR: From above:
      Ed bray just a hanger on.sence about 2007. March 12, 2018 at 9:11 pm
      “In the pacific high all the barneculs stick to everything and sink everything over time. Ed bray on the schooner de Viento.”
      Kip Hansen March 13, 2018 at 7:06 am
      “Microbes eat the little bits of plastic. This has been known since 2011 — why it is repeatedly ignored and unreported in Oceanic Plastics research is a mystery to me. The smaller the bits, the faster it is consumed by microbes.”
      Kip Hansen March 13, 2018 at 10:06 am
      “Pat ==> You are right about the first bit — all kinds of microbiota attach themselves to floating plastic bits — sometimes so many that they eventually sink.”
      It seems all floating plastic will desintegrate and/or will sink. But I don’t know about the time frame. As far as I know, not much research – if any – has been done on this subject. So far, nature seems to be able to handle this itself.
      What I do know is that any object (!) in the open sea attracts ‘life’. Ships, platforms, weeds, plastic bags. And any object will be covered with chalky (= heavy) objects that in the end will make the object (if originally floating, like plastic bags) sink. But again: I don’t know about the time frame. For plastics: after 5, 10, 15 years? Earlier? Later? It will depend on local conditions like temperature as well.

    • Much of the plastic is thrown overboard from merchant shipping. This is because disposal in port is very expensive as it must go through quarantine. This could be easily fixed I’m thinking. Charge them for the plastic they must have thrown overboard if they turn up in port with no trash.

  20. One documentary I saw kinda shot itself in the foot. It was predictably scare-mongering about floating plastic, but then let out some video & comments that floating plastic actually attracted life around it as protection in the otherwise barren open ocean. Not saying floating plastic is all good of course, but it’s not as simple as made out to be.

  21. Ecofreaks contaminate their own trousers in abject panic at the thought that nature might provide a solution for a human waste problem and in so doing, take away from these societal parasites one of their props for ecopuritannical self-aggrandisement.

  22. The authors seem like many climate scientists: Their research points to the problem being over-blown, but they still try to insist it is as worse as they thought.
    The also make some pretty foolish comments, such as:

    Microplastics are fragments of less than 5mm in diameter. Krill cannot consume anything greater than 2mm in diameter.
    “They are not going to be able to eat a drink bottle,” Dawson said.

    Indeed. That is what the wind and the waves and sunlight/oxygen/ozone does. What kind of a dipstick would suggest that the krill will eat the bottles whole?

    • Maybe it was the mutant krill that were fed the radioactive plastic.
      (Sorry Eric, I couldn’t resist.)

    • ‘Microplastics are fragments of less than 5mm in diameter. Krill cannot consume anything greater than 2mm in diameter.
      “They are not going to be able to eat a drink bottle,” Dawson said.
      Technically… they could still nibble. Not that I can think of a reason why they’d feel compelled to.

  23. So we should keep dumping plastic in the ocean because some bacteria might evolve that can dissolve it?

    • My understanding is that the majority of the plastic in the oceans that comes from the US doesn’t get there because we “dump it” in the oceans. Most of it gets there by being carried by the fresh water courses which all eventually lead to the oceans. A plastic bag in Indiana blows around and ends up in a stream or ditch that drains into the Wabash river and ends up entering the Gulf of Mexico via the Mississippi river. In my view, pollution or litter is bad, no matter if Krill eat plastic or not just as an oil spill is bad, even if bacteria eat and break down petroleum products are not.

  24. One wonders if the term of a human lifetime would enough time to explain to these people the concept of surface to volume ratio.

  25. Three questions from an ignorant truck driver.
    Are not krill the most prolific arthropods on earth?
    Since many marine species rely on krill as a food source, including the Blue Whale, which is as far as we know now the largest animal to have ever lived on earth; Is there a potential for plastic eating krill to be toxic to the food chain?
    What do Krill poop when they eat plastic?

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