
By Kennedy Bucci and Chelsea Rochman
When you think of microplastic pollution, plastic debris less than five millimeters in size, you likely envision the ocean—probably because ocean gyres gained notoriety for being a microplastic soup.
But what about our lakes, rivers, forests and fields? They can be just as contaminated with microplastic debris as the oceans.
Until recently, these environments were described as conduits—ways for plastics to get to the oceans. But now we're seeing rivers, lakes and soil in a different light, as reservoirs for plastic particles.
We now know that agricultural land, surface waters, freshwater lakes and river sediments are also contaminated.
In the past five years, researchers have started to study the sources, fates and effects of microplastics in freshwater and terrestrial ecosystems, but only a handful of studies have been done so far.
Microplastics in Our Great Lakes
Here in North America, when we think of freshwater, we often think of the Laurentian Great Lakes. They hold more than one fifth of the world's freshwater, are the basis of billions of dollars in economic activity and are a point of pride for those living on their shorelines.
For the Indigenous peoples of Canada, the Great Lakes hold even more importance. There are more than 75 First Nations communities in the Great Lakes watershed, all of whom fish the waters for food or sport.
It is no secret, however, that the Great Lakes have had their share of ecological problems. Most have been caused by us, including the ongoing issues of nutrient-loading, invasive species like zebra and quagga mussels, tributary dams and reduced ice cover.
Recent research now shows the Great Lakes also contain microplastic pollution, with the highest concentrations in heavily urbanized areas, like Toronto and Detroit.
Plastic debris washed up on the shore of Lake Ontario, near TorontoKennedy Bucci, author provided
Another study found that a liter of sediment from the St. Lawrence River contained up to 1,000 spherical microplastics—on par with the world's most polluted marine sediments.
Microplastics are now globally distributed in freshwater lakes and rivers. They've been found in North America, Europe and Asia.
Contaminated Habitats, Contaminated Wildlife
Microplastics fill the digestive tracts of the wildlife that inhabit freshwater ecosystems.
In a Texas river basin, for example, 45 percent of captured sunfish had reportedly consumed microplastics. Another study found that 12 percent of gudgeons, a small bottom-dwelling fish, caught in a French stream had microplastics in their guts.
Closer to home, our lab has found that fish from the Great Lakes can have up to 40 microplastics in their digestive tracts. Many of these are microfibers—small strands of synthetic textiles, some of which come from our clothing.
In marine animals, microplastics can alter gene expression, cause inflammation in tissues and affect reproductive success. But we know much less about the effects in freshwater wildlife, which may be different from marine animals. For example, marine fish drink water, whereas freshwater fish absorb water through their gills and skin; this may lead to different exposure concentrations of microplastics.
Although some studies have examined population- and community-level effects, most have focused on the effects on individual animals. As a result, evidence regarding the effects of microplastics on populations of animals are scarce. We need to ask how these pollutants affect survival, reproduction and the interactions between species in a community.
Our lab is beginning to do just that. For example, an ongoing study is comparing the effects of a range of microplastics found in Lake Ontario, and measuring their effects on freshwater fish survival, development and reproduction.
Calling All Scientists
The oceans cover more than 70 percent of our globe. Still, the biodiversity on land and in freshwater is more than five times that in the oceans. In addition, the global population relies on freshwater and terrestrial ecosystems for food, water and recreation. As such, microplastic research must include all ecosystems.
We are using plastic products at an unprecedented rate, and have already generated an estimated 6,300 metric tons of plastic waste. Although some of this is recycled, about 79 percent is accumulating in landfills or the environment.
Moving forward, we must invest in gathering more scientific evidence about the sources, fate and effects of microplastics in terrestrial and freshwater ecosystems. At the same time, we know enough about plastic pollution to act.
As Canada takes presidency of the G7 this year, we applaud our government, which has committed to take leadership in preventing further contamination of the planet by plastic pollution.
Microplastics Pose Major Problems for Ocean Giants https://t.co/lcBWdD434h #Microplastics @PlasticPollutes @Oceana… https://t.co/wKuncYvPUJ— EcoWatch (@EcoWatch)1517853475.0
Kennedy Bucci is a graduate student at the University of Toronto. Chelsea Rochman is an assistant professor of ecology and evolutionary biology at the University of Toronto.
Reposted with permission from our media associate The Conversation.
- Redwoods are the world's tallest trees.
- Now scientists have discovered they are even bigger than we thought.
- Using laser technology they map the 80-meter giants.
- Trees are a key plank in the fight against climate change.
They are among the largest trees in the world, descendants of forests where dinosaurs roamed.
Pixabay / Simi Luft
<p><span>Until recently, measuring these trees meant scaling their 80 meter high trunks with a tape measure. Now, a team of scientists from University College London and the University of Maryland uses advanced laser scanning, to create 3D maps and calculate the total mass.</span></p><p>The results are striking: suggesting the trees <a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank" rel="noopener noreferrer">may be as much as 30% larger than earlier measurements suggested.</a> Part of that could be due to the additional trunks the Redwoods can grow as they age, <a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank" rel="noopener noreferrer">a process known as reiteration</a>.</p>New 3D measurements of large redwood trees for biomass and structure. Nature / UCL
<p>Measuring the trees more accurately is important because carbon capture will probably play a key role in the battle against climate change. Forest <a href="https://www.wri.org/blog/2020/09/carbon-sequestration-natural-forest-regrowth" target="_blank">growth could absorb billions of tons</a> of carbon dioxide from the atmosphere each year.</p><p>"The importance of big trees is widely-recognised in terms of carbon storage, demographics and impact on their surrounding ecosystems," the authors wrote<a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank"> in the journal Nature</a>. "Unfortunately the importance of big trees is in direct proportion to the difficulty of measuring them."</p><p>Redwoods are so long lived because of their ability to <a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank" rel="noopener noreferrer">cope with climate change, resist disease and even survive fire damage</a>, the scientists say. Almost a fifth of their volume may be bark, which helps protect them.</p>Carbon Capture Champions
<p><span>Earlier research by scientists at Humboldt University and the University of Washington found that </span><a href="https://www.sciencedirect.com/science/article/pii/S0378112716302584" target="_blank" rel="noopener noreferrer">Redwood forests store almost 2,600 tonnes of carbon per hectare</a><span>, their bark alone containing more carbon than any other neighboring species.</span></p><p>While the importance of trees in fighting climate change is widely accepted, not all species enjoy the same protection as California's coastal Redwoods. In 2019 the world lost the equivalent of <a href="https://www.worldwildlife.org/threats/deforestation-and-forest-degradation" target="_blank" rel="noopener noreferrer">30 soccer fields of forest cover every minute</a>, due to agricultural expansion, logging and fires, according to The Worldwide Fund for Nature (WWF).</p>Pixabay
<p>Although <a href="https://c402277.ssl.cf1.rackcdn.com/publications/1420/files/original/Deforestation_fronts_-_drivers_and_responses_in_a_changing_world_-_full_report_%281%29.pdf?1610810475" target="_blank" rel="noopener noreferrer">the rate of loss is reported to have slowed in recent years</a>, reforesting the world to help stem climate change is a massive task.</p><p><span>That's why the World Economic Forum launched the Trillion Trees Challenge (</span><a href="https://www.1t.org/" target="_blank" rel="noopener noreferrer">1t.org</a><span>) and is engaging organizations and individuals across the globe through its </span><a href="https://uplink.weforum.org/uplink/s/uplink-issue/a002o00000vOf09AAC/trillion-trees" target="_blank" rel="noopener noreferrer">Uplink innovation crowdsourcing platform</a><span> to support the project.</span></p><p>That's backed up by research led by ETH Zurich/Crowther Lab showing there's potential to restore tree coverage across 2.2 billion acres of degraded land.</p><p>"Forests are critical to the health of the planet," according to <a href="https://www.1t.org/" target="_blank" rel="noopener noreferrer">1t.org</a>. "They sequester carbon, regulate global temperatures and freshwater flows, recharge groundwater, anchor fertile soil and act as flood barriers."</p><p><em data-redactor-tag="em" data-verified="redactor">Reposted with permission from the </em><span><em data-redactor-tag="em" data-verified="redactor"><a href="https://www.weforum.org/agenda/2021/03/redwoods-store-more-co2-and-are-more-enormous-than-we-thought/" target="_blank">World Economic Forum</a>.</em></span></p>EcoWatch Daily Newsletter
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