Hundreds of Fish Species, Including Many That Humans Eat, Are Consuming Plastic
By Alexandra McInturf and Matthew Savoca
Trillions of barely visible pieces of plastic are floating in the world's oceans, from surface waters to the deep seas. These particles, known as microplastics, typically form when larger plastic objects such as shopping bags and food containers break down.
Researchers are concerned about microplastics because they are minuscule, widely distributed and easy for wildlife to consume, accidentally or intentionally. We study marine science and animal behavior, and wanted to understand the scale of this problem. In a newly published study that we conducted with ecologist Elliott Hazen, we examined how marine fish – including species consumed by humans – are ingesting synthetic particles of all sizes.
In the broadest review on this topic that has been carried out to date, we found that, so far, 386 marine fish species are known to have ingested plastic debris, including 210 species that are commercially important. But findings of fish consuming plastic are on the rise. We speculate that this could be happening both because detection methods for microplastics are improving and because ocean plastic pollution continues to increase.
Solving the Plastics Puzzle
It's not news that wild creatures ingest plastic. The first scientific observation of this problem came from the stomach of a seabird in 1969. Three years later, scientists reported that fish off the coast of southern New England were consuming tiny plastic particles.
Since then, well over 100 scientific papers have described plastic ingestion in numerous species of fish. But each study has only contributed a small piece of a very important puzzle. To see the problem more clearly, we had to put those pieces together.
We did this by creating the largest existing database on plastic ingestion by marine fish, drawing on every scientific study of the problem published from 1972 to 2019. We collected a range of information from each study, including what fish species it examined, the number of fish that had eaten plastic and when those fish were caught. Because some regions of the ocean have more plastic pollution than others, we also examined where the fish were found.
For each species in our database, we identified its diet, habitat and feeding behaviors – for example, whether it preyed on other fish or grazed on algae. By analyzing this data as a whole, we wanted to understand not only how many fish were eating plastic, but also what factors might cause them to do so. The trends that we found were surprising and concerning.
A Global Problem
Our research revealed that marine fish are ingesting plastic around the globe. According to the 129 scientific papers in our database, researchers have studied this problem in 555 fish species worldwide. We were alarmed to find that more than two-thirds of those species had ingested plastic.
One important caveat is that not all of these studies looked for microplastics. This is likely because finding microplastics requires specialized equipment, like microscopes, or use of more complex techniques. But when researchers did look for microplastics, they found five times more plastic per individual fish than when they only looked for larger pieces. Studies that were able to detect this previously invisible threat revealed that plastic ingestion was higher than we had originally anticipated.
Our review of four decades of research indicates that fish consumption of plastic is increasing. Just since an international assessment conducted for the United Nations in 2016, the number of marine fish species found with plastic has quadrupled.
Similarly, in the last decade alone, the proportion of fish consuming plastic has doubled across all species. Studies published from 2010-2013 found that an average of 15% of the fish sampled contained plastic; in studies published from 2017-2019, that share rose to 33%.
We think there are two reasons for this trend. First, scientific techniques for detecting microplastics have improved substantially in the past five years. Many of the earlier studies we examined may not have found microplastics because researchers couldn't see them.
Second, it is also likely that fish are actually consuming more plastic over time as ocean plastic pollution increases globally. If this is true, we expect the situation to worsen. Multiple studies that have sought to quantify plastic waste project that the amount of plastic pollution in the ocean will continue to increase over the next several decades.
While our findings may make it seem as though fish in the ocean are stuffed to the gills with plastic, the situation is more complex. In our review, almost one-third of the species studied were not found to have consumed plastic. And even in studies that did report plastic ingestion, researchers did not find plastic in every individual fish. Across studies and species, about one in four fish contained plastics – a fraction that seems to be growing with time. Fish that did consume plastic typically had only one or two pieces in their stomachs.
In our view, this indicates that plastic ingestion by fish may be widespread, but it does not seem to be universal. Nor does it appear random. On the contrary, we were able to predict which species were more likely to eat plastic based on their environment, habitat and feeding behavior.
For example, fishes such as sharks, grouper and tuna that hunt other fishes or marine organisms as food were more likely to ingest plastic. Consequently, species higher on the food chain were at greater risk.
We were not surprised that the amount of plastic that fish consumed also seemed to depend on how much plastic was in their environment. Species that live in ocean regions known to have a lot of plastic pollution, such as the Mediterranean Sea and the coasts of East Asia, were found with more plastic in their stomachs.
WATCH: People are ingesting plastic from drinking water but also through foods like shellfish, which tends to be ea… https://t.co/cKgzBYx2CF— Reuters (@Reuters)1608093600.0
Effects of a Plastic Diet
This is not just a wildlife conservation issue. Researchers don't know very much about the effects of ingesting plastic on fish or humans. However, there is evidence that that microplastics and even smaller particles called nanoplastics can move from a fish's stomach to its muscle tissue, which is the part that humans typically eat. Our findings highlight the need for studies analyzing how frequently plastics transfer from fish to humans, and their potential effects on the human body.
Our review is a step toward understanding the global problem of ocean plastic pollution. Of more than 20,000 marine fish species, only roughly 2% have been tested for plastic consumption. And many reaches of the ocean remain to be examined. Nonetheless, what's now clear to us is that "out of sight, out of mind" is not an effective response to ocean pollution – especially when it may end up on our plates.
Disclosure statement: Alexandra McInturf is affiliated with The Ethogram. Matthew Savoca receives funding from The National Geographic Society and the National Science Foundation.
Reposted with permission from The Conversation.
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Wisdom the mōlī, or Laysan albatross, is the oldest wild bird known to science at the age of at least 70. She is also, as of February 1, a new mother.
<div id="dadb2" class="rm-shortcode" data-rm-shortcode-id="aa2ad8cb566c9b4b6d2df2693669f6f9"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1357796504740761602" data-partner="rebelmouse"><div style="margin:1em 0">🚨Cute baby alert! Wisdom's chick has hatched!!! 🐣😍 Wisdom, a mōlī (Laysan albatross) and world’s oldest known, ban… https://t.co/Nco050ztBA</div> — USFWS Pacific Region (@USFWS Pacific Region)<a href="https://twitter.com/USFWSPacific/statuses/1357796504740761602">1612558888.0</a></blockquote></div>
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Comparing rime ice and glaze ice shows how each changes the texture of the blade. Gao, Liu and Hu, 2021, CC BY-ND
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While traditional investment in the ocean technology sector has been tentative, growth in Israeli maritime innovations has been exponential in the last few years, and environmental concern has come to the forefront.
theDOCK aims to innovate the Israeli maritime sector. Pexels<p>The UN hopes that new investments in ocean science and technology will help turn the tide for the oceans. As such, this year kicked off the <a href="https://www.oceandecade.org/" target="_blank" rel="noopener noreferrer">United Nations Decade of Ocean Science for Sustainable Development (2021-2030)</a> to galvanize massive support for the blue economy.</p><p>According to the World Bank, the blue economy is the "sustainable use of ocean resources for economic growth, improved livelihoods, and jobs while preserving the health of ocean ecosystem," <a href="https://www.sciencedirect.com/science/article/pii/S0160412019338255#b0245" target="_blank" rel="noopener noreferrer">Science Direct</a> reported. It represents this new sector for investments and innovations that work in tandem with the oceans rather than in exploitation of them.</p><p>As recently as Aug. 2020, <a href="https://www.reutersevents.com/sustainability/esg-investors-slow-make-waves-25tn-ocean-economy" target="_blank" rel="noopener noreferrer">Reuters</a> noted that ESG Investors, those looking to invest in opportunities that have a positive impact in environmental, social and governance (ESG) issues, have been interested in "blue finance" but slow to invest.</p><p>"It is a hugely under-invested economic opportunity that is crucial to the way we have to address living on one planet," Simon Dent, director of blue investments at Mirova Natural Capital, told Reuters.</p><p>Even with slow investment, the blue economy is still expected to expand at twice the rate of the mainstream economy by 2030, Reuters reported. It already contributes $2.5tn a year in economic output, the report noted.</p><p>Current, upward <a href="https://www.ecowatch.com/-innovation-blue-economy-2646147405.html" target="_self">shifts in blue economy investments are being driven by innovation</a>, a trend the UN hopes will continue globally for the benefit of all oceans and people.</p><p>In Israel, this push has successfully translated into investment in and innovation of global ports, shipping, logistics and offshore sectors. The "Startup Nation," as Israel is often called, has seen its maritime tech ecosystem grow "significantly" in recent years and expects that growth to "accelerate dramatically," <a href="https://itrade.gov.il/belgium-english/how-israel-is-becoming-a-port-of-call-for-maritime-innovation/" target="_blank" rel="noopener noreferrer">iTrade</a> reported.</p><p>Driving this wave of momentum has been rising Israeli venture capital hub <a href="https://www.thedockinnovation.com/" target="_blank" rel="noopener noreferrer">theDOCK</a>. Founded by Israeli Navy veterans in 2017, theDOCK works with early-stage companies in the maritime space to bring their solutions to market. The hub's pioneering efforts ignited Israel's maritime technology sector, and now, with their new fund, theDOCK is motivating these high-tech solutions to also address ESG criteria.</p><p>"While ESG has always been on theDOCK's agenda, this theme has become even more of a priority," Nir Gartzman, theDOCK's managing partner, told EcoWatch. "80 percent of the startups in our portfolio (for theDOCK's Navigator II fund) will have a primary or secondary contribution to environmental, social and governance (ESG) criteria."</p><p>In a company presentation, theDOCK called contribution to the ESG agenda a "hot discussion topic" for traditional players in the space and their boards, many of whom are looking to adopt new technologies with a positive impact on the planet. The focus is on reducing carbon emissions and protecting the environment, the presentation outlines. As such, theDOCK also explicitly screens candidate investments by ESG criteria as well.</p><p>Within the maritime space, environmental innovations could include measures like increased fuel and energy efficiency, better monitoring of potential pollution sources, improved waste and air emissions management and processing of marine debris/trash into reusable materials, theDOCK's presentation noted.</p>
theDOCK team includes (left to right) Michal Hendel-Sufa, Head of Alliances, Noa Schuman, CMO, Nir Gartzman, Co-Founder & Managing Partner, and Hannan Carmeli, Co-Founder & Managing Partner. Dudu Koren<p>theDOCK's own portfolio includes companies like Orca AI, which uses an intelligent collision avoidance system to reduce the probability of oil or fuel spills, AiDock, which eliminates the use of paper by automating the customs clearance process, and DockTech, which uses depth "crowdsourcing" data to map riverbeds in real-time and optimize cargo loading, thereby reducing trips and fuel usage while also avoiding groundings.</p><p>"Oceans are a big opportunity primarily because they are just that – big!" theDOCK's Chief Marketing Officer Noa Schuman summarized. "As such, the magnitude of their criticality to the global ecosystem, the magnitude of pollution risk and the steps needed to overcome those challenges – are all huge."</p><p>There is hope that this wave of interest and investment in environmentally-positive maritime technologies will accelerate the blue economy and ESG investing even further, in Israel and beyond.</p>
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