SEAPLEX

The first SEAPLEX results are out in the scientific literature! Scripps graduate students Pete Davison and Rebecca Asch found plastic in 9% of mesopelagic fishes. Press release:

Scripps Study Finds Plastic in Nine Percent of ‘Garbage Patch’ Fishes

SEAPLEX researchers estimate tens of thousands of tons of debris annually ingested by fish in middle ocean depths of North Pacific Ocean

Scripps Institution of Oceanography / University of California, San Diego

The first scientific results from an ambitious voyage led by a group of graduate students from Scripps Institution of Oceanography at UC San Diego offer a stark view of human pollution and its infiltration of an area of the ocean that has been labeled as the “Great Pacific Garbage Patch.”

Matt Durham, Jim Leichter and Pete Davison deploy a Matsuda-Oozeki-Hu Trawl at the North Pacific Subtropical Gyre during SEAPLEX.

Two graduate students with the Scripps Environmental Accumulation of Plastic Expedition, or SEAPLEX, found evidence of plastic waste in more than nine percent of the stomachs of fish collected during their voyage to the North Pacific Subtropical Gyre. Based on their evidence, authors Peter Davison and Rebecca Asch estimate that fish in the intermediate ocean depths of the North Pacific ingest plastic at a rate of roughly 12,000- to 24,000 tons per year.

Their results were published June 27 in the journal Marine Ecology Progress Series.

During the SEAPLEX voyage in August 2009, a team of Scripps graduate students traveled more than 1,000 miles west of California to the eastern sector of the North Pacific Subtropical Gyre aboard the Scripps research vessel New Horizon. Over 20 days the students, New Horizon crew and expedition volunteers conducted comprehensive and rigorous scientific sampling at numerous locations. They collected fish specimens, water samples and marine debris at depths ranging from the sea surface to thousands of feet depth (See SEAPLEX Oceanographic Equipment).

Of the 141 fishes spanning 27 species dissected in the study, Davison and Asch found that 9.2 percent of the stomach contents of mid-water fishes contained plastic debris, primarily broken-down bits smaller than a human fingernail. The researchers say the majority of the stomach plastic pieces were so small their origin could not be determined.

“About nine percent of examined fishes contained plastic in their stomach. That is an underestimate of the true ingestion rate because a fish may regurgitate or pass a plastic item, or even die from eating it. We didn’t measure those rates, so our nine percent figure is too low by an unknown amount,” said Davison.

Researchers collected confetti-sized flecks of plastic during the expedition.

Rather than a visible “patch” or “island” of trash, marine debris is highly dispersed across thousands of miles of the North Pacific Subtropical Gyre. The debris area cannot be mapped from air or space, so SEAPLEX researchers collected samples in 132 net tows (130 of which contained plastic) across a distance of more than 2,375 kilometers (1,700 miles) in an attempt to find the boundaries of the patch. The region, a “convergence zone” where floating debris in water congregates, is generally avoided by mariners due to its calm winds and mild currents. The North Pacific Subtropical Gyre has been understudied by scientists, leaving many open questions about marine debris in the area and its long-term effects on the marine environment.

“This study clearly emphasizes the importance of directly sampling in the environment where the impacts may be occurring,” said James Leichter, a Scripps associate professor of biological oceanography who participated in the SEAPLEX expedition but was not an author of the new paper. “We are seeing that most of our prior predictions and expectations about potential impacts have been based on speculation rather than evidence and in many cases we have in fact underestimated the magnitude of effects. SEAPLEX also clearly illustrates how relatively small amounts of funding directed for novel field sampling and work in remote places can vastly increase our knowledge and understanding of environmental problems.”

SEAPLEX was supported by the UC Ship Funds program, Project Kaisei/Ocean Voyages Institute and the National Science Foundation.

Ever since SEAPLEX was funded around two years ago, I have begun every one of my general audience talks (and even a few scientific ones) with a display of misleading and confusing headlines on the accumulation of trash in the North Pacific. According to these headlines, it’s twice the size of America, 3.5 billion …something…(they don’t say what), stretching from Hawaii to Japan. Most of these claims cannot be supported by any scientific data of which I’m aware.

As a scientist, it can be pretty frustrating to see these misconceptions repeated and repeated for years on end. That’s why the SEAPLEX team has done our best to accurately relay our observations from our own voyage to the North Pacific Central Gyre, and to refer people to reliable sources such as the NOAA Marine Debris Program’s FAQ. But I suspect the persistence of these misconceptions is why Oregon State University oceanographer Angelique White stated in a press release last week that the Great Pacific Garbage Patch is “grossly exaggerated.”

Since that press release and the ensuing media coverage, I’ve received many requests for clarification. If there’s no garbage patch, what the heck were we measuring back in 2009? But actually there’s no conflict between Dr. White’s statements and SEAPLEX findings. In this blog post, I’ll explain a few of the key points from the OSU press release.

“…it is simply inaccurate to state that plastic outweighs plankton, or that we have observed an exponential increase in plastic.”

Reports that plastic outweighs plankton stem from a 2001 study by Moore et al., published in Marine Pollution Bulletin. Most oceanographers, including myself, do not think that comparing the dry weight of plankton and plastic is a helpful way of understanding what is going on in the ocean. The reasons for this are somewhat technical, but you can read about them in this blog entry, which I wrote a year before I starting doing my own research on plastic in the North Pacific. I believe that this method is no longer much used – in a recent post at the Plastic Pollution Coalition’s blog, Marcus Eriksen of Algalita Marine Research writes “…it’s important to describe plastic to plankton ratios as an anecdote, but not worth quantifying.” Read his whole blog entry for the anti-plastic activist take on Dr. White’s press release.

As for an exponential increase in plastic, there is evidence that plastic debris increased from the 1960s and 1970s to the 1980s and 1990s. For example, a study by Robards et al. (1997) found more plastic in the stomachs of Arctic and subarctic seabirds in the late 1980s than between 1969-1977. After the mid-1980s, the trend becomes unclear. The only study of which I am aware that has measured this is Gilfillan et al. (2009). Using archived samples, they measured plastic in the California Current (not the gyre itself) in 1984, 1994, and 2007, and did not detect a significant increase.

“The studies have shown is that if you look at the actual area of the plastic itself, rather than the entire North Pacific subtropical gyre, the hypothetically “cohesive” plastic patch is actually less than 1 percent of the geographic size of Texas.”

In order to understand this, I emailed Dr. White directly, and she was happy to explain her calculations. First, remember that the vast majority, more than 90%, of the plastic found in the NPG are tiny – less than the size of your pinky fingernail. These pieces are spread out over the surface making them very hard to see with the naked eye. Mostly, the ocean just looks like ocean. In fact, here’s a photo I took smack in the middle of the “Eastern Garbage Patch” this fall:

But when you tow a fine-meshed plankton net through this same area, there are thousands of tiny plastic crumbs. They’re just really small, and fairly spread out on the surface of the ocean. Here’s a photo of the highest plastic densities I’ve ever seen in three trips to the Gyre, measured from a small boat on a glassy calm day. This is an area about the size of a dining room table.

So how can we reconcile finding plastic over 1,700 miles on SEAPLEX with Dr. White’s calculation that the “Great Pacific Garbage Patch” is just 1% of the state of Texas? There’s actually no conflict at all. Dr. White was looking at the area of the ocean’s surface covered by solid plastic, not where plastic pieces could be found. She calculated the area that would be covered by plastic if all tiny pieces were squished together into a solid “island.” Since the pieces are so small, that’s not very much area.

Many of the SEAPLEX scientists are considerably more concerned about the environmental impacts of these tiny pieces than we would be over a few larger pieces, or even a huge plastic island. There are many reasons for this, including toxins and the potential for such pieces to be ingested, but I think one of the most underrated impacts is the introduction of hard surfaces to an ecosystem that naturally has very few of them. Microbes, plants, and animals that live on hard surfaces are very different than those that live floating freely in the ocean, and adding all that plastic is providing habitat that would not naturally exist out there. To read more about our research, check out our webpage, or for a brief summary, this video podcast.

“If we were to filter the surface area of the ocean equivalent to a football field in waters having the highest concentration (of plastic) ever recorded…the amount of plastic recovered would not even extend to the 1-inch line.”

Once again, over 90% of the plastic pieces in the North Pacific Gyre are very small. There is no island, and the pieces are spread over the ocean’s surface. This photo of plastic and plankton collected on SEAPLEX represents an Olympic-sized swimming pool area of ocean (about 600 square meters).

When we painstakingly pick all that plastic out of the plankton samples, it is indeed a very small volume, only partially filling a container about the size of a nail polish jar (20 mL). However, in that tiny jar may be thousands and thousands of tiny pieces, collected in just 15 minutes of slowly towing a net along the ocean surfaces. Right now we don’t know what impact those pieces are having on the marine ecosystem, but we do know there are a lot of them, and that they can be found over a remarkably vast swathe of the North Pacific.

“Most plastics either sink or float,” White pointed out. “Plastic isn’t likely to be evenly distributed through the top 100 feet of the water column.”

This is true. Though we did find a few pieces of plastic at depth, most of the plastic that we observed on SEAPLEX was right on the ocean’s surface. Plenty of plastic debris has been found resting on the seafloor closer to shore – for example, one study conducted off central California found 6,900 pieces of debris per km2 (Watters et al 2010). I am not aware of any studies that have looked for plastic on the seafloor of the North Pacific Central Gyre – it’s pretty deep out there and considerable time and funds would be required.

Conclusion

Widespread misinformation, as is so common regarding plastic in the North Pacific, serves no one – not activists trying to ban plastic bags, not plastic manufacturers trying to develop ocean-degradable products, not groups developing methods to stop plastic pollution. Our role as scientists is to find out truths about the world, and to interpret and explain them. Debating what the data actually mean is a crucial part of the scientific process.

I think it is fantastic that so many groups and members of the public are passionate about what is happening in an obscure part of the ocean more than 1,000 miles away from any land. But the flip side of this interest is that the healthy scientific debate is going to be more public than usual. This is nothing to fear – in fact, I think it is a great window into how science is done. And I believe that this debate will ultimately be critical to finding a feasible solution to plastic pollution, whether than solution is based on land, at sea, or in legislative change.

Sources

I just got back from sampling the North Pacific Gyre with NOAA. We found visible plastic every day in the manta tows once we had entered the North Pacific High, which is the “Garbage Patch” area. The bridge watch also sighted some interesting floating trash – a lime green suitcase was the most unusual – though we weren’t quick enough to get a photo of it.

Brief daily updates about cruise activities were posted here, along with a fine selection of pretty pictures. And I’m always a big fan of science ship fashion – the combination of orange hardhat/workvest and blue-and-yellow boots is TOTALLY going to be the next big thing. (Though can I get a work vest designed to actually fit female anatomy? Please?)

Hello internets! I am back from a month of sailing from Hawaii to California on the tall ship SSV Robert C. Seamans. The Seamans is run by the Sea Education Association, where undergraduate and high school students can learn oceanography, maritime history, and seamanship aboard one of two gorgeous tall ships, one in the Atlantic, one in the Pacific. (The Southern Fried Scientist is an alumnus – anyone else out there?). The SEA vessels are well-equipped for research (PDF) with all the standard tools of oceanography – CTD, ADCP, winch & hydraulic J-frame, and so on – though it definitely is more challenging to maneuver under sail than by burning tons and tons of diesel fuel.

I was on board as a visiting researcher, continuing my work on the impact of plastic debris on zooplankton in the North Pacific Central Gyre. I did as many plankton tows as time allowed at the surface of the water, filtered lots of seawater to look for plastic particles too small to be caught by the net, and tested live zooplankton to see if they were ingesting plastic. I don’t know what the results are yet – in order to make the most of my time at sea, I just preserved samples as fast as possible, and will go through them now that I am back at the lab. (Also, looking in a microscope at sea makes me hurl.)

I was totally off the grid while at sea, so instead of trying to capture the full experience, I’m going to do a couple of posts on selected awesome moments and fantastic critters. If you want to know more, just ask in the comments – I can answer there or as an additional post. You can also check out SEA’s excellent Plastic blog for more on science under sail.

Awesome Moment #1

The cruise track was great for my work – we had to sail right through the north-center section of the gyre – but not so great for sailing. After we lost the trade winds north of Hawaii, we experienced very little wind until we got into the westerlies not far from California. I’m used to motoring around and it didn’t bother me much, but of course a tall ship is meant to sail, so the sailors (students as well as staff) all pined away for the wind.

The lack of wind did produce one glorious, wonderful moment – SWIM CALL! Swimming is strictly forbidden in the US research fleet due to a tragic incident with a white shark, so I’d never been swimming in the open sea before. (No, I was not worried about sharks. We had people acting as lookouts, visibility was amazing, and shark attacks are vanishingly, vanishingly rare.)

Conditions had to be exactly right to assure everyone’s safety, but we were lucky and the captain decided that the flat calm sea and lack of shark sightings meant that we’d be able to swim. Here I am paddling about, nothing between me and the giant isopods of the abyssal plain except 4000 meters of water.

I managed to borrow a mask & snorkel to hunt for jellies. I didn’t find any (though one of the other scientists did), but I did see single-celled acanthareans floating about, feeding with long pseudopods. It was incredibly cool to see these organisms alive and happy – it’s easy to forget that what we see catch in a net and store dead in a jar is very, very different than what exists in the ocean.

Next: ATTACK OF THE PTEROPODS!!!

[cross-posted at Deep Sea News]

[cross-posted at Deep Sea News]

The romance of the sea, at least in my mind, is tied to the Age of Sail. This might be because of the inherent beauty of tall ships, or maybe because of a wee bit obsession with Patrick O’Brian’s “Master and Commander” novels (all 20 books, plus the glossary, plus the recipe book…), or maybe because I’ve always wanted to sing a shanty while actually hauling on a rope. This summer, I’ll finally get my chance.

I’ll be sailing from Hawaii to California with Sea Education Association aboard the SSV Robert C. Seamans. (I wrote about their plastic debris cruise in the Atlantic a couple weeks ago). The primary mission of the cruise is student education, but they are very kindly letting me come aboard as a visiting researcher. In fact, I type to you from aboard the Seamans at the dock in Honolulu.

I’ll be continuing the research I started last summer on SEAPLEX, further exploring the impact of plastic debris on marine life in the North Pacific Subtropical Gyre. Since we think the highest concentrations of plastic are on the very surface of the ocean, I’ll be studying with surface-dwelling (neustonic) zooplankton to see if they are interacting with the plastic debris. And I’ll be continuing my studies of the fouling community – the animals that grow directly on the plastic.

So far life on the Seamans is much like life on any research vessel preparing for a cruise – there’s a lot of securing and adjusting and last-minute runs to Home Depot. But as soon as we leave the dock on Wednesday morning, I’m going to get to learn the proper way to haul on a rope and scrub the deck. I’m very, very excited.

I don’t know what the internet situation will be, but if possible I will post updates from our journey across the Pacific. You can also follow the ship’s Twitter feed @SEA_Seamans. See you all in four weeks!