The Floating Life – A Tale of the Vortex

Guest Essay by Kip Hansen —  22 May 2022

There has been an interesting pre-print paper released and it received a rather odd reception in the science section of the New York Times.

The paper is “High Concentrations of floating life in the North Pacific Garbage Patch” by  Fiona Chong, Matthew Spencer, Nikolai Maximenko, Jan Hafner, Andrew McWhirter and  Rebecca R. Helm. The abstract is available here and a full text .pdf file can be found here.

I conversed with Rebecca Helm by email.  She was happy that the paper got any wide notice at all, but somewhat perplexed that it was nearly entirely misunderstood.  The paper is not about garbage, floating plastic (pelagic plastic), or the mostly-imaginary Great Pacific Garbage Patch. 

A brief note about the Great Pacific Garbage Patch: To quote NOAA: ” The name “Pacific Garbage Patch” has led many to believe that this area is a large and continuous patch of easily visible marine debris items such as bottles and other litter—akin to a literal island of trash that should be visible with satellite or aerial photographs. This is not the case. While higher concentrations of litter items ocan be found in this area, much of the debris is actually small pieces of floating plastic that are not immediately evident to the naked eye.”  And here.

The image used in the NY Times is taken by Ben Lecomte who set out to swim the Pacific, right through the Great Pacific Garbage Patch (GPGP).  It is a typical ball of abandoned or lost fishing nets and lines rolled into a mass in a similar manner in which dust bunnies are formed under your bed.  This mass of nets was not found in Locomte’s swim across the Pacific – at least it is not mentioned or pictured on his pages about the Pacific expeditions. The image used by the New York Times is not on Lecomte’s web site, but is from another time and place.  Lecomte’s  web site is here.  The web site features what appears to be a staged picture of Lecomte with pelagic plastic.  It takes several minutes to realize that Lecomte’s web page contains only four images of any real pelagic plastic.  Meaning?  Either they did not find much while swimming the entire breadth of the GPGP, or contrary to the stated purpose of their expedition, they chose not to take or display images of their findings.    

Why even mention Lecomte then?  Our authors say ”To test our hypothesis that garbage patches may also be neuston seas, including the NPGP, we conducted a community science survey through the NPGP with the sailing crew accompanying long-distance swimmer Benoît Lecomte (https://benlecomte.com/) as he swam through the NPGP (The Vortex Swim).”  [Note: the eastern North Pacific Subtropical Gyre in the area of the North Pacific “garbage patch” (NPGP).]

The authors of this paper were not looking for floating plastic but rather for the floating lifeforms known collectively as “marine neuston”.  These are the type of things they found: 

The top left image is of a “By-the-wind sailor” [Velella]. Pictured to the left are dried sails that had been blown ashore which I found on the beach at Cape Canaveral, Florida.  

The authors’ state “we hypothesize that floating life is also concentrated in other gyres with converging surface currents.”  Floating life is known to be concentrated in the Atlantic Ocean in the gyre that forms the famous Sargasso Sea in the Subtropical North Atlantic.  The authors speculated that the same could or should also be true in the eastern North Pacific Subtropical Gyre in the area of the North Pacific “garbage patch” (NPGP).  Ben Lecomte was staging an “expedition” by swimming through the Great Pacific Garbage Patch …giving the authors a chance to do a little citizen science.

The crew of the sail boat accompanying Lecomte dragged “Either a Manta trawl (width x height: 0.9 m x 0.15 m) [mouth size about 3 feet by 6 inches] or a neuston net (width x height: 1 m x 0.25 m) [ mouth size about 3 feet by 10 inches]  was towed along the sea surface for 30 minutes at each site with an attached General Oceanics Mechanical Flowmeter (model 2030R) to measure the approximate water volume filtered by the trawl”. 

The results were interesting.  The limited data collected by the project showed that, yes, neuston were being concentrated within the eastern Pacific gyre in exactly the same way that floating plastic bits were being concentrated.    Here’s the types of things they found in their trawl nets:

They found the neuston they were looking for, plus a lot of other living things, and bits of floating non-living things:  wood, rock, rope and plastic.  The wood, the rope (probably polypropylene, which floats) and the plastic are expected….but not the rock. 

The highest numbers of both neuston and plastics bits was found in a single sample taken in a slick:  “Within our study, a patchy distribution of neuston and plastic at the surface may be due to small-scale (sub-mesoscale) surface dynamics like slicks, and may be important for neuston predation and reproduction. We found the highest concentration of both neuston and plastic in a slick (SJR_019), and this is true for other studies as well.”

Most of the material visible is the floating lifeforms, neuston.  There is a bit of plastic rope in Panel b and a few obvious chips of plastic.   One unfortunate thing in the study, for which Dr. Helm apologised, is that the photos of the trawl samples contain no ruler or scale that allows us to judge size.  The paper itself does not have detailed tables of object counts, nor does the supplemental.   In Fig 4a we see that the density of neuston and plastic bits per meter2 align very nicely. 

Bottom Line:

A nice little piece of work that supports the original hypothesis that the Pacific gyres should be concentrating all floating objects, not just plastics, but especially the lifeforms collectively known as neuston:   “neuston and plastic both appear to be concentrated by similar physical forces. Surface features like slicks that further concentrate neuston, may be important for neuston life history, and we found evidence that neustonic animals are reproducing in the NPGP”.

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Author’s Comment:

This is an example of a good effort by researchers receiving recognition – but for the wrong reasons.  I suppose the NY Times covered it because it contains the words “Garbage Patch” and not because it is an interesting hypothesis confirmed by a neat bit of research. 

Dr. Rebecca Helm was kind enough to answer my questions and send me the supplemental file.

I admit to a long-time fascination with “By-the-wind sailors” – little jellyfish-like animal, a hydrozoa, with their little stiff sails that cause the wind to push them along on the surface of the sea.  I have only spent half a lifetime at sea, while they spend their entire lives sailing along….. However, I have never seen a live by-the-wind-sailor on the high seas despite many thousands of miles sailing less than four feet above the surface of the ocean, only dead ones on the shore.    

I have seen many odd lifeforms feeding at the sea surface, especially at night, and have seen the things that feed on them as well, including the rare Greater Bulldog Bat (or Fisherman Bat).

As for the rock . . . . . Early in our Caribbean adventure, I found a rugby ball shaped and sized piece of floating pumice rock, well rounded by washing onto and off of beaches, which traveled with us, and, wrapped in a rope net,  was used as a marker buoy on occasion.   It was returned to the sea, in the middle of the Gulf Stream, first being etched with our boat name and dates, on our last voyage home.  If you find it, let me know.

Thanks for reading.

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via Watts Up With That?

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May 21, 2022 at 08:52PM

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