you're reading...


A Swirling Sea of Plastic

Article: Brach, L., Deixonne, P., Bernard, M-F., Durand, E., Desjean, M-C., Perez, E., van Sebille, & ter Halle, A. (2018). Anticyclonic eddies increase accumulation of micro plastic in the North Atlantic Subtropical gyre. Marine Pollution Bulletin, 126, 191-196. https://doi.org/10.1016/j.marpolbul.2017.10.077 

Plastic Problems

Remember that plastic fork you threw away after lunch, the plastic wrap on the cucumber you bought from the grocery store, or the straw that was inadvertently placed in your glass without even asking? While these items may be a one time use for us, they persist in the environment for extremely long periods of time. Instead of going away, the plastic materials break down into smaller and smaller pieces. While it’s easy to see how turtles or fish become trapped in large plastic bags, it’s harder to see the impacts of tiny plastic fragments, which are often referred to as microplastics (Figure 1). Though small, they can have an enormous impact when ingested by marine animals. Plastic contains harmful chemicals that impact the animal’s ability to feed and reproduce. This further impacts us, as plastics ingested by animals lower on the food chain eventually work their way up the chain into our very own food sources.

Figure 1. This shows an example of microplastics observed in the Azores. While it does not show what exactly was collected by Brach and co-authors, it offers an example for what typical micro plastics look like as a reference for the types of particles collected in the North Atlantic Subtropical gyre. Image source: https://commons.wikimedia.org/wiki/File:RaceforWater_PeterCharaf_MicroplasticsAzores_(2).jpg.

Much of this plastic ends up in the ocean, but it can be challenging to determine how much plastic is actually there and to know where exactly the plastic is located. Estimates suggest between 90,000 and 250,000 metric tons (about 550 million pounds!) of plastic are floating in the sea (Cozar et al., 2014; van Sebille et al., 2015), but that corresponds to only 1% of the estimate for plastic waste inputs in 2010 (Jambeck et al., 2015).  This means that we are polluting more plastic than we estimate with current models. Brach and co-authors aim to improve how we monitor and assess the amount plastic present in the ocean.


Where does the plastic go? 

Identifying where the plastic debris collects is an active area of research. Most plastics end up accumulating in ocean gyres, such as the Great Pacific Garbage Patch. Ocean gyres are extremely large and flow patterns are caused by wind and Earth’s rotation in each of the major oceans. While gyres are key to ocean circulation, smaller scale water transport   mechanisms may also play a very important role. This study zooms in to smaller scale water circulation to determine how eddies influence the location of plastic debris. 

Eddies occur throughout much of the ocean. They are typically under 100 km, that is about 900 times as long as a football field (small relative to the gyres!). There are two types of eddies, cold and warm core, named for the temperature of water at their center. Cold core eddies swirl in a counterclockwise motion in the northern hemisphere and the center of the ring tends to have colder water. Warm core eddies are the opposite; they swirl clockwise, are warmer in the middle. The ocean sea surface is not flat, and some of the variation in sea surface height is caused by eddies. The warm core eddies domed surface will have a higher surface height in the middle, whereas cold core rings dip down in the center.

One method to determine the location and type of eddies is using satellite altimetry. The satellite sends a signal down to earth and this signal bounces back to the satellite. Using the location and time it took for the signal to return, we can determine the sea surface height. Figure 2 shows a general example of how the ocean surface height varies  in space from data collected using satellite altimetry.

Figure 2. This shows variations in the sea surface height measured by satellite altimetry. Image source: https://en.wikipedia.org/wiki/Ocean_surface_topography.

In this study, the variation in height ranged from 3 to 40 cm different from the average surface height (fascinating that we can detect such small changes all the way from space!). Satellites are useful when studying the global ocean because they repeatedly take images of Earth’s surface covering a much larger area than one might cover during time on a ship. Since plastics are too small to detect from space, this study combines eddy locations from satellite imagery with plastic quantities from ship surveys to see whether eddies are influential in the distribution of marine plastic.


To test how eddies affect the distribution of plastic in the ocean, researchers collected water samples from areas of the ocean that coincided with the location of eddies. They chose the ship sampling track by conferring with satellite data daily to ensure that they travelled through eddies. They were able to pass through both a warm core and a cold core ring. 

Since they were not able to use the satellite imagery to measure plastic concentrations, they combined the information of where eddies occurred with measurements of the plastic quantities collected while on the ship. The water samples were collected by dragging nets off of the boat along the surface of the water. The nets were made of a very small mesh to collect debris that has broken down into tiny pieces of plastics which they then counted and weighed. Figure 3 shows an example of a net tow that can be used to collect plastic debris from the surface ocean. They used a computer software imaging tool to measure the length and width of the debris.

Figure 3. Example showing how nets are towed along the surface to collect plastic debris. Image obtained from NOAA News Archive 102810, Image ID: fish2416, NOAA’s Fisheries Collection, 2010 taken in the North Pacific Gyre.


In general the plastic concentrations observed in this study are consistent with typical observations in the North Atlantic subtropical gyre and in some locations they found over 300,000 pieces of plastic per square kilometer. To put this in perspective, 250,000 pieces per square kilometer of plastic would be like having about 1,000 pieces of plastic on each acre of land you own. However, these sampling sites aren’t our backyard – they are extremely far away from the actual plastic garbage source. 

When comparing the plastic concentrations from the cold and warm core eddies, they observed 20,000 pieces/km2 in the cold core eddy and 170,000 pieces/km2 in the warm core eddy, which means that the warm core eddy had 9.4 times more plastic than the cold core at the surface. It is interesting that they observed greater concentrations in the warm core eddy because warm core eddies downwell water. This means the water is being pushed down. As the water is transported to depth, it may bring plastic down, too. This implies that there may even be more plastic hiding at depth that is not observed in the samples collected.


Overall, this study combined observations of eddies from space with plastic abundance data collected from a ship. Researchers observed more plastic in the warm core eddy than the cold core eddy. This suggests that eddies play an important role in the location of plastics at the sea surface. However, this study only sampled two eddies. Despite limitations, this opens up opportunities for future research to look at the role of eddies in plastic distribution and transport in greater detail. This offers the opportunity for scientists to analyze past trawl datasets and corresponding satellite imagery to see if similar conclusions can be drawn from other sample sites and times of plastic data collection. Establishing linkages between satellite data and measurements of plastic from water samples is important because one day we may be able to obtain global satellite coverage estimates of plastic concentrations. Estimating plastic concentrations from space would allow us to more readily detect how plastic concentrations fluctuate with time and could even inform future cleanup projects. Considering the negative impacts of plastic on marine ecosystems, being able to predict where plastics will accumulate is critical for ocean health.


Additional references-

Cozar, A., Echevarria, F., Gonzalez-Gordillo, J.I., Irigoien, X., Ubeda, B., Hernandez-Leon, S., Palma, A.T., Navarro, S., Garcia-de-Lomas, J., Ruiz, A., Fernandez-de-Puelles, M.L., Duarte, C.M., 2014. Plastic debris in the open ocean. Proc. Natl. Acad. Sci. U. S. A. 111 (28), 10239–10244. 

Jambeck, J.R., Geyer, R., Wilcox, C., Siegler, T.R., Perryman, M., Andrady, A., Narayan, R., Law, K.L., 2015. Plastic waste inputs from land into the ocean. Science 347 (6223), 768–771. 

van Sebille, E., Wilcox, C., Lebreton, L., Maximenko, N., Hardesty, B.D., van Franeker, J.A., Eriksen, M., Siegel, D., Galgani, F., Law, K.L., 2015. A global inventory of small floating plastic debris. Environ. Res. Lett. 10 (12). 


No comments yet.

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 6 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 9 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 11 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 11 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com