To understand how microplastic pollution is affecting the ocean, scientists need to know how much is there and where it is accumulating. Most data on microplastic concentrations comes from commercial and research ships that tow plankton nets – long, cone-shaped nets with very fine mesh designed for collecting marine microorganisms.
But net trawling can sample only small areas and may be underestimating true plastic concentrations. Except in the North Atlantic and North Pacific gyres – large zones where ocean currents rotate, collecting floating debris – scientists have done very little sampling for microplastics. And there is scant information about how these particles’ concentrations vary over time.
To address these questions, University of Michigan research assistant Madeline Evans and I developed a new way to detect microplastic concentrations from space using NASA’s Cyclone Global Navigation Satellite System. CYGNSS is a network of eight microsatellites that was launched in 2016 to help scientists predict hurricanes by analyzing tropical wind speeds. They measure how wind roughens the ocean’s surface – an indicator that we realized could also be used to detect and track large quantities of microplastics.
Our series on the global ocean opened with five in depth profiles. Look out for new articles on the state of our oceans in the lead up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.
Looking for smooth zones
Annual global production of plastic has increased every year since the 1950s, reaching 359 million metric tons in 2018. Much of it ends up in open, uncontrolled landfills, where it can wash into river drainage zones and ultimately into the world’s oceans.
Researchers first documented plastic debris in the oceans in the 1970s. Today, it accounts for an estimated 80% to 85% of marine litter.
The radars on CYGNSS satellites are designed to measure winds over the ocean indirectly by measuring how they roughen the water’s surface. We knew that when there is a lot of material floating in the water, winds don’t roughen it as much. So we tried computing how much smoother measurements indicated the surface was than it should have been if winds of the same speed were blowing across clear water.
This anomaly – the “missing roughness” – turns out to be highly correlated with the concentration of microplastics near the ocean surface. Put another way, areas where surface waters appear to be unusually smooth frequently contain high concentrations of microplastics. The smoothness could be caused by the microplastics themselves, or possibly by something else that’s associated with them.
By combining all the measurements made by CYGNSS satellites as they orbit around the world, we can create global time-lapse images of ocean microplastic concentrations. Our images readily identify the Great Pacific Garbage Patch and secondary regions of high microplastic concentration in the North Atlantic and the southern oceans.
Tracking microplastic flows over time
Since CYGNSS tracks wind speeds constantly, it lets us see how microplastic concentrations change over time. By animating a year’s worth of images, we revealed seasonal variations that were not previously known.
We found that global microplastic concentrations tend to peak in the North Atlantic and Pacific during the Northern Hemisphere’s summer months. June and July, for example, are the peak months for the Great Pacific Garbage Patch.
Concentrations in the Southern Hemisphere peak during its summer months of January and February. Lower concentrations during the winter in both hemispheres are likely due to a combination of stronger currents that break up microplastic plumes and increased vertical mixing – the exchange between surface and deeper water – that transports some of the microplastic down below the surface.
This approach can also target smaller regions over shorter periods of time. For example, we examined episodic outflow events from the mouths of the China’s Yangtze and Qiantang rivers where they empty into the East China Sea. These events may have been associated with increases in industrial production activity, or with increases in the rate at which managers allowed the rivers to flow through dams.
Better targeting for cleanups
Our research has several potential uses. Private organizations, such as The Ocean Cleanup, a nonprofit in The Netherlands, and Clewat, a Finnish company specializing in clean technology, use specially outfitted ships to collect, recycle and dispose of marine litter and debris. We have begun conversations with both groups and hope eventually to help them deploy their fleets more effectively.
Our spaceborne imagery may also be used to validate and improve numerical prediction models that attempt to track how microplastics move through the oceans using ocean circulation patterns. Scholars are developing several such models.
While the ocean roughness anomalies that we observed correlate strongly with microplastic concentrations, our estimates of concentration are based on the correlations that we observed, not on a known physical relationship between floating microplastics and ocean roughness. It could be that the roughness anomalies are caused by something else that is also correlated with the presence of microplastics.
One possibility is surfactants on the ocean surface. These liquid chemical compounds, which are widely used in detergents and other products, move through the oceans in ways similar to microplastics, and they also have a damping effect on wind-driven ocean roughening.
Further study is needed to identify how the smooth areas that we identified occur, and if they are caused indirectly by surfactants, to better understand exactly how their transport mechanisms are related to those of microplastics. But I hope this research can be part of a fundamental change in tracking and managing microplastic pollution.
[The Conversation’s science, health and technology editors pick their favorite stories.Weekly on Wednesdays.]
These “microplastics”, which are derived from petrochemicals extracted from oil and gas products, are settling in dust around the house.
Some of these particles are toxic to humans — they can carry carcinogenic or mutagenic chemicals, meaning they potentially cause cancer and/or damage our DNA.
We still don’t know the true impact of these microplastics on human health. But the good news is, having hard floors, using more natural fibres in clothing, furnishings and homewares, along with vacuuming at least weekly can reduce your exposure.
What are microplastics?
Microplastics are plastic particles less than five millimetres across. They come from a range of household and everyday items such as the clothes we wear, home furnishings, and food and beverage packaging.
We know microplastics are pervasive outdoors, reaching remote and inaccessible locations such as the Arctic, the Mariana Trench (the world’s deepest ocean trench), and the Italian Alps.
Our study demonstrates it’s an inescapable reality that we’re living in a sea of microplastics — they’re in our food and drinks, our oceans, and our homes.
We found 39% of the deposited dust particles were microplastics; 42% were natural fibres such as cotton, hair and wool; and 18% were transformed natural-based fibres such as viscose and cellophane. The remaining 1% were film and fragments consisting of various materials.
Between 22 and 6,169 microfibres were deposited as dust per square metre, each day.
Conversely, polyvinyl fibres (synthetic fibres made of vinyl chloride) were two times more prevalent in homes without carpet. This is because the coating applied to hard flooring degrades over time, producing polyvinyl fibres in house dust.
These chemicals can leach from the plastic surface once in the body, increasing the potential for toxic effects. Microplastics can have carcinogenic properties, meaning they potentially cause cancer. They can also be mutagenic, meaning they can damage DNA.
How much are we exposed to? And can this be minimised?
Roughly a quarter of all of the fibres we recorded were less than 250 micrometres in size, meaning they can be inhaled. This means we can be internally exposed to these microplastics and any contaminants attached to them.
Using human exposure models, we calculated that inhalation and ingestion rates were greatest in children under six years old. This is due to their lower relative body weight, smaller size, and higher breathing rate than adults. What’s more, young children typically have more contact with the floor, and tend to put their hands in their mouths more often than adults.
Children under six inhale around three times more microplastics than the average — 18,000 fibres, or 0.3 milligrams per kilogram of body weight per year. They would also ingest on average 6.1 milligrams of microplastics in dust per kg of body weight per year.
For a five-year-old, this would be equivalent to eating a garden pea’s worth of microplastics over the course of a year. But for many of these plastics there is no established safe level of exposure.
Our study indicated there are effective ways to minimise exposure.
First is the choice of flooring, with hard surfaces, including polished wood floors, likely to have fewer microplastics than carpeted floors.
Also, how often you clean makes a difference. Vacuuming floors at least weekly was associated with less microplastics in dust than those that were less frequently cleaned. So get cleaning!
Mitchell P. Jones, Vienna University of TechnologyFungi — a scientific goldmine? Well, that’s what a review published today in the journal Trends in Biotechnology indicates. You may think mushrooms are a long chalk from the caped crusaders of sustainability. But think again.
Many of us have heard of fungi’s role in creating more sustainable leather substitutes. Amadou vegan leather crafted from fungal-fruiting bodies has been around for some 5,000 years.
More recently, mycelium leather substitutes have taken the stage. These are produced from the root-like structure mycelium, which snakes through dead wood or soil beneath mushrooms.
You might even know about how fungi help us make many fermented food and drinks such as beer, wine, bread, soy sauce and tempeh. Many popular vegan protein products, including Quorn, are just flavoured masses of fungal mycelium.
But what makes fungi so versatile? And what else can they do?
Show me foamy and flexible
Fungal growth offers a cheap, simple and environmentally friendly way to bind agricultural byproducts (such as rice hulls, wheat straw, sugarcane bagasse and molasses) into biodegradable and carbon-neutral foams.
Fungal foams are becoming increasingly popular as sustainable packaging materials; IKEA is one company that has indicated a commitment to using them.
Fungal foams can also be used in the construction industry for insulation, flooring and panelling. Research has revealed them to be strong competitors against commercial materials in terms of having effective sound and heat insulation properties.
Moreover, adding in industrial wastes such as glass fines (crushed glass bits) in these foams can improve their fire resistance.
And isolating only the mycelium can produce a more flexible and spongy foam suitable for products such as facial sponges, artificial skin, ink and dye carriers, shoe insoles, lightweight insulation lofts, cushioning, soft furnishings and textiles.
For other products, it’s the composition of fungi that matters. Fungal filaments contain chitin: a remarkable polymer also found in crab shells and insect exoskeletons.
Chitin has a fibrous structure, similar to cellulose in wood. This means fungal fibre can be processed into sheets the same way paper is made.
When stretched, fungal papers are stronger than many plastics and not much weaker than some steels of the same thickness. We’ve yet to test its properties when subject to different forces.
Fungal paper’s strength can be substituted for rubbery flexibility by using specific fungal species, or a different part of the mushroom. The paper’s transparency can be customised in the same way.
Growing fungi in mineral-rich environments results in inherent fire resistance for the fungus, as it absorbs the inflammable minerals, incorporating them into its structure. Add to this that water doesn’t wet fungal surfaces, but rolls off, and you’ve got yourself some pretty useful paper.
A clear solution to dirty water
Some might ask: what’s the point of fungal paper when we already get paper from wood? That’s where the other interesting attributes of chitin come into play — or more specifically, the attributes of its derivative, chitosan.
Chitosan is chitin that has been chemically modified through exposure to an acid or alkali. This means with a few simple steps, fungal paper can adopt a whole new range of applications.
For instance, chitosan is electrically charged and can be used to attract heavy metal ions. So what happens if you couple it with a mycelium filament network that is intricate enough to prevent solids, bacteria and even viruses (which are much smaller than bacteria) from passing through?
The result is an environmentally friendly membrane with impressive water purification properties. In our research, my colleagues and I found this material to be stable, simple to make and useful for laboratory filtration.
While the technology hasn’t yet been commercialised, it holds particular promise for reducing the environmental impact of synthetic filtration materials, and providing safer drinking water where it’s not available.
Mushrooms in modern medicine
Perhaps even more interesting is chitosan’s considerable biomedical potential. Fungal materials have been used to create dressings with active wound healing properties.
Although not currently on the market, these have been proven to have antibacterial properties, stem bleeding and support cell proliferation and attachment.
Fungal enzymes can also be used to combat bacteria active in tooth decay, enhance bleaching and destroy compounds responsible for bad breath.
Then there’s the well-known role of fungi in antibiotics. Penicillin, made from the Penicillium fungi, was a scientific breakthrough that has saved millions of lives and become a staple of modern healthcare.
Many antibiotics are still produced from fungi or soil bacteria. And in an age of increasing antibiotic resistance, genome sequencing is finally enabling us to identify fungi’s untapped potential for manufacturing the antibiotics of the future.
Mushrooms mending the environment
Fungi could play a huge role in sustainability by remedying existing environmental damage.
For example, they can help clean up contaminated industrial sites through a popular technique known as mycoremediation, and can break down or absorb oils, pollutants, toxins, dyes and heavy metals.
They can also compost some synthetic plastics, such as polyurethane. In this process, the plastic is buried in regulated soil and its byproducts are digested by specific fungi as it degrades.
These incredible organisms can even help refine bio fuels. Whether or not we go as far as using fungal coffins to decompose our bodies into nutrients for plants — well, that’s a debate for another day.
But one thing is for sure: fungi have the undeniable potential to be used for a whole range of purposes we’re only beginning to grasp.
It could be the beer you drink, your next meal, antibiotics, a new faux leather bag or the packaging that delivered it to you — you never know what form the humble mushroom will take tomorrow.
We all know it’s wrong to toss your rubbish into the ocean or another natural place. But it might surprise you to learn some plastic waste ends up in the environment, even when we thought it was being recycled.
Our study, published today, investigated how the global plastic waste trade contributes to marine pollution.
We found plastic waste most commonly leaks into the environment at the country to which it’s shipped. Plastics which are of low value to recyclers, such as lids and polystyrene foam containers, are most likely to end up polluting the environment.
The export of unsorted plastic waste from Australia is being phased out – and this will help address the problem. But there’s a long way to go before our plastic is recycled in a way that does not harm nature.
Know your plastics
Plastic waste collected for recycling is often sold for reprocessing in Asia. There, the plastics are sorted, washed, chopped, melted and turned into flakes or pellets. These can be sold to manufacturers to create new products.
The global recycled plastics market is dominated by two major plastic types:
polyethylene terephthalate (PET), which in 2017 comprised 55% of the recyclable plastics market. It’s used in beverage bottles and takeaway food containers and features a “1” on the packaging
high-density polyethylene (HDPE), which comprises about 33% of the recyclable plastics market. HDPE is used to create pipes and packaging such as milk and shampoo bottles, and is identified by a “2”.
The next two most commonly traded types of plastics, each with 4% of the market, are:
polypropylene or “5”, used in containers for yoghurt and spreads
low-density polyethylene known as “4”, used in clear plastic films on packaging.
The remaining plastic types comprise polyvinyl chloride (3), polystyrene (6), other mixed plastics (7), unmarked plastics and “composites”. Composite plastic packaging is made from several materials not easily separated, such as long-life milk containers with layers of foil, plastic and paper.
This final group of plastics is not generally sought after as a raw material in manufacturing, so has little value to recyclers.
China banned the import of plastic waste in January 2018 to prevent the receipt of low-value plastics and to stimulate the domestic recycling industry.
Following the bans, the global plastic waste trade shifted towards Southeast Asian nations such as Vietnam, Thailand, Malaysia, and Indonesia. The largest exporters of waste plastics in 2019 were Europe, Japan and the US. Australia exported plastics primarily to Malaysia and Indonesia.
Australia’s waste export ban recently became law. From July this year, only plastics sorted into single resin types can be exported; mixed plastic bales cannot. From July next year, plastics must be sorted, cleaned and turned into flakes or pellets to be exported.
This may help address the problem of recyclables becoming marine pollution. But it will require a significant expansion of Australian plastic reprocessing capacity.
What we found
Our study was funded by the federal Department of Agriculture, Water and the Environment. It involved interviews with trade experts, consultants, academics, NGOs and recyclers (in Australia, India, Indonesia, Japan, Malaysia, Vietnam and Thailand) and an extensive review of existing research.
We found when it comes to the international plastic trade, plastics most often leak into the environment at the destination country, rather than at the country of origin or in transit. Low-value or “residual” plastics – those left over after more valuable plastic is recovered for recycling – are most likely to end up as pollution. So how does this happen?
In Southeast Asia, often only registered recyclers are allowed to import plastic waste. But due to high volumes, registered recyclers typically on-sell plastic bales to informal processors.
Interviewees said when plastic types were considered low value, informal processors frequently dumped them at uncontrolled landfills or into waterways. Sometimes the waste is burned.
Plastics stockpiled outdoors can be blown into the environment, including the ocean. Burning the plastic releases toxic smoke, causing harm to human health and the environment.
Interviewees also said when informal processing facilities wash plastics, small pieces end up in wastewater, which is discharged directly into waterways, and ultimately, the ocean.
However, interviewees from Southeast Asia said their own domestic waste management was a greater source of ocean pollution.
A market failure
The price of many recycled plastics has crashed in recent years due to oversupply, import restrictions and falling oil prices, (amplified by the COVID-19 pandemic). However clean bales of PET and HDPE are still in demand.
In Australia, material recovery facilities currently sort PET and HDPE into separate bales. But small contaminants of other materials (such as caps and plastic labels) remain, making it harder to recycle into high quality new products.
Before the price of many recycled plastics dropped, Australia baled and traded all other resin types together as “mixed plastics”. But the price for mixed plastics has fallen to zero and they’re now largely stockpiled or landfilled in Australia.
Several Australian facilities are, however, investing in technology to sort polypropylene so it can be recovered for recycling.
Doing plastics differently
Exporting countries can help reduce the flow of plastics to the ocean by better managing trade practices. This might include:
improving collection and sorting in export countries
checking destination processing and monitoring
checking plastic shipments at export and import
improving accountability for shipments.
But this won’t be enough. The complexities involved in the global recycling trade mean we must rethink packaging design. That means using fewer low-value plastic and composites, or better yet, replacing single-use plastic packaging with reusable options.
The authors would like to acknowledge research contributions from Asia Pacific Waste Consultants (APWC) – Dr Amardeep Wander, Jack Whelan and Anne Prince, as well as Phil Manners at CIE.
To start dealing with Australia’s mounting plastic crisis, the federal government last week launched its first National Plastics Plan.
The plan will fight plastic on various fronts, such as banning plastic on beaches, ending polystyrene packaging for takeaway containers, and phasing in microplastic filters in washing machines. But we’re particularly pleased to see a main form of biodegradable plastic will also be phased out.
Biodegradable plastic promises a plastic that breaks down into natural components when it’s no longer wanted for its original purpose. The idea of a plastic that literally disappears once in the ocean, littered on land or in landfill is tantalising — but also (at this stage) a pipe dream.
Why ‘biodegradable’ ain’t that great
“Biodegradable” suggests an item is made from plant-based materials. But this isn’t always the case.
A major problem with “biodegradable” plastic is the lack of regulations or standards around how the term should be used. This means it could, and is, being used to refer to all manner of things, many of which aren’t great for the environment.
Many plastics labelled biodegradable are actually traditional fossil-fuel plastics that are simply degradable (as all plastic is) or even “oxo-degradable” — where chemical additives make the fossil-fuel plastic fragment into microplastics. The fragments are usually so small they’re invisible to the naked eye, but still exist in our landfills, water ways and soils.
So it’s best to avoid all plastic labelled as biodegradable. Even after the ban eliminates fragmentation — the worst of these — there’s still no evidence remaining types of biodegradable plastics are better for the environment.
Compostable plastics aren’t much better
Compostable plastic is another label you may have come across that’s meant to be better for the environment. It’s specifically designed to break down into natural, non-toxic components in certain conditions.
Unlike biodegradable plastics, there are certification standards for compostable plastics, so it’s important to check for one the below labels. If an item doesn’t have a certification label, there’s nothing to say it isn’t some form of mislabelled “biodegradable” plastic.
But most certified compostable plastics are only for industrial composts, which reach very high temperatures. This means they’re unlikely to break down sufficiently in home composts. Even those certified as “home compostable” are assessed under perfect lab conditions, which aren’t easily achieved in the backyard.
And while certified compostable plastics are increasing, the number of industrial composting facilities that actually accept them isn’t yet keeping up.
Nor are collection systems to get your plastics to these facilities. The vast majority of kerbside organics recycling bins don’t currently accept compostable plastics and other packaging. This means placing compostable plastics in these bins is considered contamination.
Even if you can get your certified compostable plastics to an appropriate facility, composting plastics actually reduces their economic value as they can no longer be used in packaging and products. Instead, they’re only valuable for returning nutrients to soil and, potentially, capturing a fraction of the energy used to produce them.
Finally, if you don’t have an appropriate collection system and your compostable plastic ends up in landfill, that might actually be worse than traditional plastic. Compostable plastics could release methane — a much more potent greenhouse gas than carbon dioxide — in landfill, in the same way food waste does.
So, you should only consider compostable plastics when you have a facility that will take them, and a way to get them there.
And while the National Plastics Plan and National Packaging Targets are aiming for at least 70% of plastics to be recovered by 2025 (including through composting), nothing yet has been said about how collection systems will be supported to achieve this.
In Australia, systems for recycling the most common types of plastic packaging are well established and in many cases operate adequately. However, there are still major issues.
For example, many plastic items can’t be recycled in our kerbside bins (including soft and flexible plastics such as bags and cling films, and small items like bottle lids, plastic cutlery and straws). Placing these items in your kerbside recycling bin can contaminate other recycling and even damage sorting machines.
What’s more, much of the plastic collected for recycling doesn’t have high value “end markets”. Only two types of plastic — PET (think water or soft drink bottles and some detergent containers) and HDPE (milk bottles, shampoo/conditioner/detergent containers) — are easily turned back into new plastic containers.
The obvious answer then, is to eliminate problematic plastic altogether, as the National Plastics Plan is attempting to do, and replace single-use plastics with reusable alternatives.
Little actions such as bringing your reusable water bottle, coffee cup and cutlery, can add up to big changes, if adequately supported by businesses and government to create a widespread culture shift. So too, could a swing away from insidious coffee capsules, cling wrap and cotton buds so many of us depend on.
Opting too, for plastic items made from recycled materials can make a big impact on the feasibility of plastic recycling.
Plastic in the ocean can be deadly for marine wildlife and seabirds around the globe, but our latest study shows single-use plastics are a bigger threat to endangered albatrosses in the southern hemisphere than we previously thought.
Eighteen of the world’s 22 albatross species live in the southern hemisphere, where plastic is currently considered a lesser threat. But the amount of discarded plastic is increasing every year, mostly leaked from towns and cities and accumulating near the shore.
Single-use items make up most of the trash found on coastlines around the world. Seven of the ten most common items — drink bottles, food wrappers and grocery bags — are made of plastic.
When albatrosses are found struggling near the shore in New Zealand, they are delivered to wildlife hospitals such as Wildbase Hospital and The Nest Te Kōhanga. A recent spate of plastic-linked deaths spurred us to dig a little deeper into the risk of plastic pollution to these magnificent ocean wanderers.
A thousand cuts: plastic and other threats
Of the 107 albatrosses of 12 species we examined, plastic was the cause of death in half of the birds that had ingested it. In the cases we examined, plastic deaths were more common than fisheries-related deaths or oiling.
We compared these cases with data on plastic ingestion and fishery interaction rates from other studies. Based on our findings, we used statistical methods to estimate how many albatrosses were likely to eat plastic and might die from ingesting it, and how these figures compared to other major threats such as fisheries bycatch.
We found that in the near-shore areas of Australia and New Zealand, the ingestion of plastic is likely to cause about 3.4% of albatross deaths. In more polluted near-shore areas, such as those off Brazil, we estimate plastic ingestion causes 17.5% of all albatross deaths.
Because albatrosses are highly migratory, even those birds that live in less polluted areas are at risk as they wander the global ocean, travelling to polluted waters. Our results suggest the ingestion of plastic is at least of equivalent concern as long-line fishing in near-shore areas.
For threatened and declining albatross species, these rates of additional mortality are a serious concern and could result in further population losses.
Deadly junk food for marine life
Not all types of plastic are equally deadly when eaten. Albatrosses can regurgitate many of the indigestible items they eat.
Soft plastic and rubber items (such as latex balloons), in particular, can be deadly for marine animals because they often become trapped in the gut and cause fatal blockages, leading to a long, slow death by starvation. Plastic is difficult to see with common scanning techniques, and gut blockages often remain undetected.
We recommend that wildlife hospitals, carers and biologists consider gastric obstruction when sick albatrosses are presented. Our publication includes a checklist to help in the detection of gastric blockages.
We would like to acknowledge our New Zealand and Australian colleagues who contributed to this research project. Veterinarians Baukje Lenting and Phil Kowalski care for injured seabirds and other wildlife at The Nest Te Kōhanga at Wellington Zoo. Veterinarian Megan Jolly cares for injured wildlife at Wildbase Hospital and vet pathologist Stuart Hunter provides a nationwide wildlife pathology service at Wildbase pathology at Massey University. David Stewart conducts threatened species research and monitoring at the Queensland state government’s Department of Environment and Science.
How do we save whales and other marine animals from plastic in the ocean? Our new review shows reducing plastic pollution can prevent the deaths of beloved marine species. Over 700 marine species, including half of the world’s cetaceans (such as whales and dolphins), all of its sea turtles and a third of its seabirds, are known to ingest plastic.
When animals eat plastic, it can block their digestive system, causing a long, slow death from starvation. Sharp pieces of plastic can also pierce the gut wall, causing infection and sometimes death. As little as one piece of ingested plastic can kill an animal.
About eight million tonnes of plastic enters the ocean each year, so solving the problem may seem overwhelming. How do we reduce harm to whales and other marine animals from that much plastic?
Like a hospital overwhelmed with patients, we triage. By identifying the items that are deadly to the most vulnerable species, we can apply solutions that target these most deadly items.
We tested these expert predictions by assessing data from 76 published research papers incorporating 1,328 marine animals (132 cetaceans, 20 seals and sea lions, 515 sea turtles and 658 seabirds) from 80 species.
We examined which items caused the greatest number of deaths in each group, and also the “lethality” of each item (how many deaths per interaction). We found the experts got it right for three of four items.
Flexible plastics, such as plastic sheets, bags and packaging, can cause gut blockage and were responsible for the greatest number of deaths over all animal groups. These film plastics caused the most deaths in cetaceans and sea turtles. Fishing debris, such as nets, lines and tackle, caused fatalities in larger animals, particularly seals and sea lions.
Turtles and whales that eat debris can have difficulty swimming, which may increase the risk of being struck by ships or boats. In contrast, seals and sea lions don’t eat much plastic, but can die from eating fishing debris.
Balloons, ropes and rubber, meanwhile, were deadly for smaller fauna. And hard plastics caused the most deaths among seabirds. Rubber, fishing debris, metal and latex (including balloons) were the most lethal for birds, with the highest chance of causing death per recorded ingestion.
The most cost-efficient way to reduce marine megafauna deaths from plastic ingestion is to target the most lethal items and prioritise their reduction in the environment.
Targeting big plastic items is also smart, as they can break down into smaller pieces. Small debris fragments such as microplastics and fibres are a lower management priority, as they cause significantly fewer deaths to megafauna and are more difficult to manage.
Flexible film-like plastics, including plastic bags and packaging, rank among the ten most common items in marine debris surveys globally. Plastic bag bans and fees for bags have already been shown to reduce bags littered into the environment. Improving local disposal and engineering solutions to enable recycling and improve the life span of plastics may also help reduce littering.
Lost fishing gear is particularly lethal. Fisheries have high gear loss rates: 5.7% of all nets and 29% of all lines are lost annually in commercial fisheries. The introduction of minimum standards of loss-resistant or higher quality gear can reduce loss.
incentivising gear repairs and port disposal of damaged nets
penalising or prohibiting high-risk fishing activities where snags or gear loss are likely
and enforcing penalties associated with dumping.
Outreach and education to recreational fishers to highlight the harmful effects of fishing gear could also have benefit.
Balloons, latex and rubber are rare in the marine environment, but are disproportionately lethal, particularly to sea turtles and seabirds. Preventing intentional balloon releases and accidental release during events and celebrations would require legislation and a shift in public will.
The Pacific Ocean is the deepest, largest ocean on Earth, covering about a third of the globe’s surface. An ocean that vast may seem invincible. Yet across its reach – from Antarctica in the south to the Arctic in the north, and from Asia to Australia to the Americas – the Pacific Ocean’s delicate ecology is under threat.
In most cases, human activity is to blame. We have systematically pillaged the Pacific of fish. We have used it as a rubbish tip – garbage has been found even in the deepest point on Earth, in the Mariana Trench 11,000 metres below sea level.
And as we pump carbon dioxide into the atmosphere, the Pacific, like other oceans, is becoming more acidic. It means fish are losing their sense of sight and smell, and sea organisms are struggling to build their shells.
Oceans produce most of the oxygen we breathe. They regulate the weather, provide food, and give an income to millions of people. They are places of fun and recreation, solace and spiritual connection. So, healthy, vibrant oceans benefit us all. And by better understanding the threats to the precious Pacific, we can start the long road to protecting it.
The series opens with five profiles delving into ancient Indian Ocean trade networks, Pacific plastic pollution, Arctic light and life, Atlantic fisheries and the Southern Ocean’s impact on global climate. It’s brought to you by The Conversation’s international network.
The ocean plastic scourge
The problem of ocean plastic was scientifically recognised in the 1960s after two scientists saw albatross carcasses littering the beaches of the northwest Hawaiian Islands in the northern Pacific. Almost three in four albatross chicks, who died before they could fledge, had plastic in their stomachs.
Now, plastic debris is found in all major marine habitats around the world, in sizes ranging from nanometers to meters. A small portion of this accumulates into giant floating “garbage patches”, and the Pacific Ocean is famously home to the largest of them all.
Plastic debris in the oceans presents innumerable hazards for marine life. Animals can get tangled in debris such as discarded fishing nets, causing them to be injured or drown.
Some organisms, such as microscopic algae and invertebrates, can also hitch a ride on floating debris, travelling large distances across the oceans. This means they can be dispersed out of their natural range, and can colonise other regions as invasive species.
And of course, wildlife can be badly harmed by ingesting debris, such as microplastics less than five millimetres in size. This plastic can obstruct an animal’s mouth or accumulate in its stomach. Often, the animal dies a slow, painful death.
Seabirds, in particular, often mistake floating plastics for food. A 2019 study found there was a 20% chance seabirds would die after ingesting a single item, rising to 100% after consuming 93 items.
And since floating plastics in the open ocean are transported mainly by ocean surface currents and winds, plastic debris accumulates on island coastlines along their path. Kamilo Beach, on the south-eastern tip of Hawaii’s Big Island, is considered one of the world’s worst for plastic pollution. Up to 20 tonnes of debris wash onto the beach each year.
Similarly, on uninhabited Henderson Island, part of the Pitcairn Island chain in the south Pacific, 18 tonnes of plastic have accumulated on a beach just 2.5km long. Several thousand pieces of plastic wash up each day.
Subtropical garbage patches
Plastic waste can have different fates in the ocean: some sink, some wash up on beaches and some float on the ocean surface, transported by currents, wind and waves.
Around 1% of plastic waste accumulates in five subtropical “garbage patches” in the open ocean. They’re formed as a result of ocean circulation, driven by the changing wind fields and the Earth’s rotation.
There are two subtropical garbage patches in the Pacific: one in the northern and one in the southern hemisphere.
The northern accumulation region is separated into an eastern patch between California and Hawaii, and a western patch, which extends eastwards from Japan.
Our ocean garbage shame
First discovered by Captain Charles Moore in the early 2000s, the eastern patch is better known as the Great Pacific Garbage Patch because it’s the largest by both size (around 1.6 million square kilometers) and amount of plastic. By weight, this garbage patch can hold more than 100 kilograms per square kilometre.
The garbage patch in the southern Pacific is located off Valparaiso, Chile, extending to the west. It has lower concentrations compared to its giant counterpart in the northeast.
Discarded fishing nets make up around 45% of the total plastic weight in the Great Pacific Garbage Patch. Waste from the 2011 Japan tsunami is also a major contributor, making up an estimated 20% of the patch.
Each year, up to 15 million tonnes of plastic waste are estimated to make their way into the ocean from coastlines and rivers. This amount is expected to double by 2025 as plastic production continues to increase.
We must act urgently to stem the flow. This includes developing plans to collect and remove the plastics and, vitally, stop producing so much in the first place.
Fisheries on the verge of collapse
As the largest and deepest sea on Earth, the Pacific supports some of the world’s biggest fisheries. For thousands of years, people have relied on these fisheries for their food and livelihoods.
But, around the world, including in the Pacific, fishing operations are depleting fish populations faster than they can recover. This overfishing is considered one of the most serious threats to the world’s oceans.
Humans take about 80 million tonnes of wildlife from the sea each year. In 2019, the world’s leading scientists said of all threats to marine biodiversity over the past 50 years, fishing has caused the most harm. They said 33% of fish species were overexploited, 60% were being fished to the maximum level, and just 7% were underfished.
The decline in fish populations is not just a problem for humans. Fish play an important role in marine ecosystems and are a crucial link in the ocean’s complex food webs.
Not plenty of fish in the sea
Overfishing happens when humans extract fish resources beyond the maximum level, known as the “maximum sustainable yield”. Fishing beyond this causes global fish stocks to decline, disrupts food chains, degrades habitats, and creates food scarcity for humans.
The Pacific Ocean is home to huge tuna fisheries, which provide almost 65% of the global tuna catch each year. But the long-term survival of many tuna populations is at risk.
For example, a study released in 2013 found numbers of bluefin tuna – a prized fish used to make sushi – had declined by more than 96% in the Northern Pacific Ocean.
Developing countries, including Indonesia and China, are major overfishers, but so too are developing nations.
Along Canada’s west coast, Pacific salmon populations have declined rapidly since the early 1990s, partly due to overfishing. And Japan was recently heavily criticised for a proposal to increase quotas on Pacific bluefin tuna, a species reportedly at just 4.5% of its historic population size.
Experts say overfishing is also a problem in Australia. For example, research in 2018 showed large fish species were rapidly declining around the nation due to excessive fishing pressure. In areas open to fishing, exploited populations fell by an average of 33% in the decade to 2015.
So what’s driving overfishing?
There are many reasons why overfishing occurs and why it is goes unchecked. The evidence points to:
Let’s take Indonesia as an example. Indonesia lies between the Pacific and Indian oceans and is the world’s third-biggest producer of wild-capture ﬁsh after China and Peru. Some 60% of the catch is made by small-scale ﬁshers. Many hail from poor coastal communities.
Overfishing was first reported in Indonesia in the 1970s. It prompted a presidential decree in 1980, banning trawling off the islands of Java and Sumatra. But overfishing continued into the 1990s, and it persists today. Target species include reef fishes, lobster, prawn, crab, and squid.
Indonesia’s experience shows how there is no easy fix to the overfishing problem. In 2017, the Indonesian government issued a decree that was supposed to keep fishing to a sustainable level – 12.5 million tonnes per year. Yet, in may places, the practice continued – largely because the rules were not clear and local enforcement was inadequate.
Implementation was complicated by the fact that almost all Indonesia’s smaller fishing boats come under the control of provincial governments. This reveals the need for better cooperation between levels of government in cracking down on overfishing.
What else can we do?
To prevent overfishing, governments should address the issue of poverty and poor education in small fishing communities. This may involve finding them a new source of income. For example in the town of Oslob in the Philippines, former fishermen and women have turned to tourism – feeding whale sharks tiny amounts of krill to draw them closer to shore so tourists can snorkel or dive with them.
Tackling overfishing in the Pacific will also require cooperation among nations to monitor fishing practices and enforce the rules.
And the world’s network of marine protected areas should be expanded and strengthened to conserve marine life. Currently, less than 3% of the world’s oceans are highly protected “no take” zones. In Australia, many marine reserves are small and located in areas of little value to commercial fishers.
The collapse of fisheries around the world shows just how vulnerable our marine life is. It’s clear that humans are exploiting the oceans beyond sustainable levels. Billions of people rely on seafood for protein and for their livelihoods. But by allowing overfishing to continue, we harm not just the oceans, but ourselves.
The tropical and subtropical waters of the Pacific Ocean are home to more than 75% of the world’s coral reefs. These include the Great Barrier Reef and more remote reefs in the Coral Triangle, such as those in Indonesia and Papua New Guinea.
Coral reefs are bearing the brunt of climate change. We hear a lot about how coral bleaching is damaging coral ecosystems. But another insidious process, ocean acidification, is also threatening reef survival.
Ocean acidification particularly affects shallow waters, and the subarctic Pacific region is particularly vulnerable.
Coral reefs cover less than 0.5% of Earth’s surface, but house an estimated 25% of all marine species. Due to ocean acidification and other threats, these incredibly diverse “underwater rainforests” are among the most threatened ecosystems on the planet.
A chemical reaction
Ocean acidification involves a decrease in the pH of seawater as it absorbs carbon dioxide (CO₂) from the atmosphere.
Each year, humans emit 35 billion tonnes of CO₂ through activities such as burning of fossil fuels and deforestation.
Oceans absorb up to 30% of atmospheric CO₂, setting off a chemical reaction in which concentrations of carbonate ions fall, and hydrogen ion concentrations increase. That change makes the seawater more acidic.
Ocean acidification is also a problem for the fishes. Many studies have revealed elevated CO₂ can disrupt their sense of smell, vision and hearing. It can also impair survival traits, such as a fish’s ability to learn, avoid predators, and select suitable habitat.
However, ocean acidification does not affect all marine species in the same way, and the effects can vary over the organism’s lifetime. So, more research to predict the future winners and losers is crucial.
This can be done by identifying inherited traits that can increase an organism’s survival and reproductive success under more acidic conditions. Winner populations may start to adapt, while loser populations should be targets for conservation and management.
One such winner may be the epaulette shark, a shallow water reef species endemic to the Great Barrier Reef. Research suggests simulated ocean acidification conditions do not impact early growth, development, and survival of embryos and neonates, nor do they affect foraging behaviours or metabolic performance of adults.
But ocean acidification is also likely to create losers on the Great Barrier Reef. For example, researchers studying the orange clownfish – a species made famous by Disney’s animated Nemo character – found they suffered multiple sensory impairments under simulated ocean acidification conditions. These ranged from difficulties smelling and hearing their way home, to distinguishing friend from foe.
It’s not too late
More than half a billion people depend on coral reefs for food, income, and protection from storms and coastal erosion. Reefs provide jobs – such as in tourism and fishing – and places for recreation. Globally, coral reefs represent an industry worth US$11.9 trillion per year. And importantly, they’re a place of deep cultural and spiritual connection for Indigenous people around the world.
Cutting greenhouse gas emissions must become a global mission. COVID-19 has slowed our movements across the planet, showing it’s possible to radically slash our production of CO₂. If the world meets the most ambitious goals of the Paris Agreement and keeps global temperature increases below 1.5℃, the Pacific will experience far less severe decreases in oceanic pH.
We will, however, have to curb emissions by a lot more – 45% over the next decade – to keep global warming below 1.5℃. This would give some hope that coral reefs in the Pacific, and worldwide, are not completely lost.
Clearly, the decisions we make today will affect what our oceans look like tomorrow.
In my career as a marine biologist, I’ve been fortunate enough to visit some of the most remote islands in the world. These beautiful places continue to remind me why I have this job in the first place, but they also bring home the pervasive influence of human societies. Uninhabited bird colonies on the Canadian West Coast, remote tropical Japanese islands, and tiny bits of land in South East Asia all have one thing in common: plastic waste on the beach.
When at home in Sweden, I regularly swim and sail in the Baltic Sea. But agricultural fertilisers and other types of pollution have created dead zones where fish either leave or suffocate. Meanwhile, offshore fisheries and aquaculture farms in many parts of the world overharvest and pollute the water. We know what proper management of these activities could look like, but political will has so far not been equal to the challenge.
That may be about to change. A recent agreement between 14 heads of state – together representing 40% of the world’s coastline – promised to end overfishing, restore fish stocks and halt the flow of plastic pollution into the ocean within a decade.
Pollution, plastics and unsustainable seafood may look like isolated problems, but they influence each other. As nutrients run off farmland and into the sea, they affect the conditions fish need to thrive. Pollution makes our seafood less healthy and overfishing is pushing some fish stocks beyond their capacity to renew themselves.
It’s in everyone’s interests to protect the ocean. Clean seas would be more profitable and research suggests that better managed fisheries could generate six times more food than they do currently. The exclusive economic zones of coastal states would be more productive if every country agreed to protect the high seas. And sailing in the Baltic Sea would be much nicer if the boat didn’t have to plough a thick, green sludge.
So how can the world make progress – and what’s holding us back?
As part of the recent agreement between 14 heads of state, the participating countries – Australia, Canada, Chile, Fiji, Ghana, Indonesia, Jamaica, Japan, Kenya, Mexico, Namibia, Norway, Palau and Portugal – committed to a number of goals within their national waters, including investment in zero-emission shipping, eliminating waste and ensuring fisheries are sustainable. The aim is to ensure all activity within these exclusive economic zones is sustainable by 2025.
The countries agreed to fast-track their plan for action, rather than work through the UN. Their combined national waters roughly equal the size of Africa. They each have clear stakes in the continued functioning of ocean ecosystems and economies, so this pragmatic approach makes sense. That’s a sentiment that businesses could no doubt respect. After all, there are no economic opportunities in a dead ocean.
The agreement is an encouraging message from political leaders, and these states can leverage vast sums of money and resources to effect change. But the ocean is home to a dozen global industries, and around 50,000 vessels traverse it at any one time. Clearly, we need more than governments to deliver on this ambitious agenda.
My scientific colleagues and I have been developing a global coalition of businesses concerned with sustainable seafood. Our strategy is to find “keystone actors” within the private sector – companies with a disproportionate ability to influence change due to their size and strength.
The seafood industry is vast, and includes some of the largest companies in the world – from entire fisheries, to aquaculture farms and feed processors. After four years of working together, change within the participating companies is accelerating. For example, Nissui, the world’s second-largest seafood company, has evaluated their entire production portfolio for sustainability challenges.
Collaboration between scientists and businesses is vital to delivering commitments made by governments. Scientists can help define the problems, and business can develop, pilot and scale solutions. For instance, we’re developing software that can automatically detect which species of fish are caught on vessels, to radically improve the transparency of seafood production.
The ocean has been a source of inspiration, imagination and adventure since the beginning of time. It has fed us and generated livelihoods for billions. Politicians have stood serenely on the sidelines for some time now, content to be passive observers of deteriorating ecosystems. But the era of passive observation may finally be coming to an end.