Author Archives: David Evans

A new study has found that shorttail fanskate populations may be being affected by plastic pollution.The skates mistake abandoned fishing nets and other debris for seaweed and attach their eggs to them, unaware that the debris could wash up on the shore where the eggs will dry out.Shorttail fanskates (Sympterygia brevicaudata) are considered near threatened by the International Union for Conservation of Nature (IUCN). In recent decades, plastic pollution has become a key environmental issue. An estimated 8 million metric tons of plastic waste enter the ocean each year, equivalent to a truckload of garbage dumped into the sea every minute — and it’s only projected to get worse. Scientists have reported that numerous marine species mistake plastic for food and ingest it, or become trapped in garbage, both of which can seriously threaten their survival. In addition, invertebrates and other marine organisms can become attached to floating plastic that travels long distances around the world, and scientists have warned that they risk becoming invasive alien species in their final destinations.
An iguana eating a plastic bag. Image courtesy of Galapagos Science Center.
A new study has revealed another problem with marine garbage, one that could be endangering Peru’s populations of shorttail fanskates (Sympterygia brevicaudata), a species of skate that is already considered near threatened by the International Union for Conservation of Nature (IUCN). The study’s authors report that it is common to see dead, dried-up skate egg cases attached to marine garbage washed up on beaches. The study was published in June in the journal Marine Pollution Bulletin.
But how do the eggs get caught in marine debris, and why do they die?
Hundreds of dead egg cases entangled in marine debris
In the city of Trujillo in northern Peru, members of the NGO ConservAccion conduct a survey of animals that, for various reasons, wash up on the area’s beaches. They’ve noticed that it it’s common to see skate egg cases attached to marine debris and that, most of the time the eggs have dried out, dooming the baby skates inside. Wanting to find out how widespread the problem is, the experts set themselves the task of counting all the eggs, identifying the type of garbage and plastic, and determining the places where this is most common.
“They are like little bags,” is how veterinarian Carlos Calvo-Mac, ConservAccion’s project director, described shorttail fanskate egg cases. “They are usually called mermaid’s purses, because they have that shape and even a leather-like texture,” he said.
Shorttail fanskate egg cases, photographed near Puerto Morín, Peru. Image by rob-westerduijn via iNaturalist (CC BY-NC 4.0).
“Skates do not give parental care; they simply lay their eggs,” said Miguel Valderrama Herrera, a fisheries biologist with ConservAccion and the study’s lead author. They make sure the eggs are fixed to something to prevent them from floating away. To enable this, the eggs have a tendril, “like a little rope that lets them attach, for example to algae,” he said.
In tropical seas, skates often attach the egg cases to coral, but they can use any structure, Valderrama said. This is how shorttail fanskates sometimes unwittingly choose marine debris, such as nets or other types of plastic, to deposit their egg cases. “What they don’t know is that these things, due to the action of the tide, can end up beached,” the biologist said. When it remains out of the water, the egg case dries out before it can hatch, and it dies.
During the shorttail fanskate’s spawning season between February and April, a group of eight people, made up of experts and volunteers, visited three beaches in the region of La Libertad, on the northern coast of Peru. They were looking for clusters of marine debris that had been in the sea for a certain period of time, to determine whether they contained egg cases.
Dried shorttail fanskate egg cases, which turn black when they dry, caught in marine debris. Image courtesy of ConservAccion.
In total, the researchers recorded 75 clusters containing 1,595 egg cases. Of these, 15.9% had presumably hatched. And of the total, 15.8% were still fresh, but the rest, 84.2%, had dried out.
The waste itself was mainly composed of plastic associated with fishing materials, primarily nets used by artisanal fishers. “These nets, made up of … a series of holes, are a tempting place for the skates to attach their eggs. The way they move in the water, being so light, can also imitate the movement of algae,” Valderrama said. Less frequently, the egg cases were also attached to fabric, rubber, foam plastic, metal, wood, paper or cardboard.
Most of the debris clusters and egg cases were found in the vicinity of the town of Puerto Morín, followed by the town of Salaverry and city of Huanchaco, according to the study. Valderrama said there were two reasons why most of the dried eggs were found in clumps of waste around Puerto Morín. “Puerto Morín survives almost exclusively from fishing and, being a bay, the clusters easily get trapped,” he said. The large number of egg cases found there have also led researchers to believe it may be a spawning ground for shorttail fanskates.
How much does the loss of all these eggs affect the shorttail fanskate’s survival?
Researchers analyze waste clusters while looking for shorttail fanskate egg cases. Image courtesy of ConservAccion.
A vulnerable species
Shorttail fanskates are typical of the shallow waters of the southeastern Pacific along the coasts of Ecuador, Peru and central Chile. They inhabit depths of 8-100 meters (26-328 feet), although they have also been accidentally caught by crustacean fisheries operating at depths down to 500 meters (1,640 feet), according to the study.
Even though fishers do not intentionally target fanskates, they are categorized as near threatened by the IUCN. Like sharks and chimaeras, skates are among the most threatened marine animals. In 2021, scientists classified one-third of the world’s species of sharks, rays, skates and chimaeras — 391 out of 1,199 species evaluated— as being critically endangered, endangered or vulnerable according to the IUCN. Species in these three IUCN categories are considered to be threatened with extinction.
In addition to being accidentally captured by nets and hooks set for other species, these animals “reproduce very little, so when they are affected by fishing or pollution, it can be very harmful,” Valderrama said.
A shorttail fanskate (Sympterygia brevicaudata). Image by ulrichzanabria via iNaturalist (CC BY-NC 4.0).
“Although there are numerous initiatives aimed at cleaning up solid waste on Peru’s beaches, I have yet to see any study on the impact of these campaigns. Do they really help?” said Calvo-Mac. According to the study’s authors, there’s a possibility WWF-Peru might install a fishing net recycling point in Puerto Morín.
WWF-Peru and Bureo, a fishing-gear recycling company, have already set up collection points in other areas along the Peruvian coast where fishermen can leave nets they no longer use and can learn about the impact of abandoning nets at sea. One of these points is on Los Organos beach, also located in the north of the country. “We saw truly great results just by offering this information and somewhere to deposit old nets,” said Aimée Leslie, WWF-Peru’s conservation director.
Banner Image: A washed-up egg case of a shorttail fanskate. Image by ulises_inf via iNaturalist (CC BY-NC 4.0).
This story was first reported by Mongabay’s Latam team and published here on our Latam site on May 24, 2023.
Seeking a sanctuary for Peru’s sea life: Q&A with Yuri Hooker

Citations:
Avila, C., Angulo-Preckler, C., Martín-Martín, R. P., Figuerola, B., Griffiths, H. J., & Waller, C. L. (2020). Invasive marine species discovered on non–native kelp rafts in the warmest Antarctic island. Scientific Reports, 10(1). doi:10.1038/s41598-020-58561-y
Valderrama-Herrera, M., Cardenas, S. A., Calvo-Mac, C., Celi-Vértiz, R. G., Chumpitaz-Levano, V. L., Flores-Miranda, W. E., … De-la-Torre, G. E. (2023). Rajids ovipositing on marine litter: A potential threat to their survival. Marine Pollution Bulletin, 191, 114941. doi:10.1016/j.marpolbul.2023.114941
Dulvy, N. K., Pacoureau, N., Rigby, C. L., Pollom, R. A., Jabado, R. W., Ebert, D. A., … Simpfendorfer, C. A. (2021). Overfishing drives over one-third of all sharks and rays toward a global extinction crisis. Current Biology, 31(22), 5118-5119. doi:10.1016/j.cub.2021.11.008

Animals, Biodiversity, Coastal Ecosystems, Conservation, Fish, Marine Animals, Marine Biodiversity, Marine Conservation, Marine Protected Areas, Oceans, Plastic, Pollution, Protected Areas, Rays, Sharks And Rays, Wildlife
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Plastic pollution has become such major problem that it’s threatening our human rights. That’s the view of two UN special rapporteurs (human rights advisers) who recently issued a joint statement, warning against the “overwhelming toxic tidal wave” of plastic endangering us and the environment “in a myriad of ways over its life cycle”. They called for urgent action on dealing with this global crisis.

Such a call could not be timelier, as governments have achieved disappointingly little so far. Yes, most restrict single-use plastic bags, or some other type of single-use plastics. But such measures are clearly not enough.

Even the UN treaty on plastic pollution, which has been agreed in principle and is currently being negotiated, is unlikely to produce fundamental change, at least in the short term. And there is no guarantee any new measures it leads to would have a different fate from the many existing plastic pollution laws that governments fail to implement.

Amid growing concerns over plastic pollution and weak governmental response to it, individuals and communities have been seeking action by resorting to courts. I recently published an academic study on the global tug of war over plastic going on in courts in more than 30 countries.

I found lots of different approaches. Some argue that their governments do not implement the existing laws. For instance, a group in the Philippines has persuaded the country’s supreme court to review the government’s implementation of solid waste management law.

Around 10 million tonnes of plastic waste enters the ocean each year.
Erlo Brown / shutterstock

Others claim that their governments do not consider the impacts of plastic pollution when allowing new factories making plastic products. One group of Māori in New Zealand recently appealed a decision to expand a billion-bottle-per-year water plant.

Some seek compensation from plastic-producing companies for dumping waste into rivers, such as the Texas residents who won a US$50 million (£39 million) settlement after finding billions of plastic pellets in their local waterways.

Local governments are also increasingly turning to courts claiming that businesses deceptively market their plastic products as recyclable. Cases like these send a clear message to the governments and businesses that individuals and communities are concerned about the impacts of plastic pollution and want more decisive action to stop it.

Only a small fraction will ever be recycled.
batuhan taskinkaya / shutterstock

But at the same time, all these cases are only one part of the picture. Increasing restrictions on plastic products also result in claims brought by businesses that oppose such measures, including the producers of plastic products as well as supermarkets and restaurants, and ask the courts to quash them.

Cases where businesses argue that restrictions on plastic products cause economic loss or are scientifically unsubstantiated are very common throughout the world.

Businesses also regularly challenge provinces or cities that adopt additional restrictions to the ones imposed by national authorities. Such cases send the message that our society is still massively dependent on plastic products, and so measures to address plastic pollution need to be systemic.

The role of courts in tackling plastic pollution

The courts’ involvement has direct consequences for any attempts to tackle this global crisis and for action on environmental and health protection more generally. For example, businesses might be able to persuade a court to declare local anti-plastic pollution measures invalid.

This happened in Mexico recently when the nation’s supreme court ruled a ban on single-use plastics by the state of Oaxaca was unconstitutional. The success of such cases can prompt other businesses to challenge local environmental and health protection measures.

On the other hand, if a court upholds such measures, other local governments may decide to follow the example of their neighbours and introduce such measures as well. If anti-plastic pollution measures already exist, they can be used to persuade the courts that further action should be taken.

Similarly, by holding businesses accountable for pollution resulting from various stages of plastic life cycle, courts help protect vulnerable individuals and communities from various human rights violations caused by plastic pollution.

No single country has a comprehensive response to plastic pollution. But many are gradually tightening up measures on single-use plastics which moves the world closer towards a comprehensive regulatory response to this crisis.

Courts will undoubtedly continue playing an important role in this process. Those concerned about plastic pollution will keep pressing for tighter regulation, while those who oppose regulation will have more restrictions to challenge.

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Two scourges of 20th century public and environmental health—microplastics and antimicrobial resistance—seem to be teaming up to birth a whole new worry.
The ocean is teeming with microorganisms. And since the mid-20th century, plastic. Scientists have previously discovered how plastic creates habitat and a handy transport system for marine microbes, including potentially harmful human pathogens. Now, researchers led by Sasha Tetu, a microbiologist at Macquarie University in Australia, have shown that chemicals leaching from marine microplastic pollution can alter the composition of microbial communities, making them more virulent and increasing the prevalence of antimicrobial resistance.
Tetu and her colleagues conducted their work in the lab. They collected samples of seawater, mixed them with the leachates from polyvinyl chloride (PVC), and analyzed how the DNA of the bacteria living in the water changed over six days.
PVC is one of the most common plastics, and like many other plastics, it leaches additives like metals, dyes, and stabilizers—compounds added to improve the plastic’s performance.
The scientists aren’t exactly sure how or why, but the plastic-addled bacteria increasingly carry genes related to higher virulence and antimicrobial resistance.
When they dug deeper into their results, they found that the effect is more complex than a blanket increase in resistance to all antimicrobials. Instead, the bacteria showed an increased abundance of genes that offer resistance to some classes of antimicrobials and a decreased prevalence of genes protecting them from other groups of antibiotics.
Likewise, the prevalence of genes that encode for certain types of virulence, such as mechanisms to suppress a host’s immune response, increased significantly, while those linked to other harmful activities decreased.
Many of the genes for antimicrobial resistance were identified in bacteria that are not known to be human pathogens. But this does not mean they do not pose a risk to human health, Tetu says. “Microbes have many different ways of sharing genes, often across distantly related lineages.”
Tetu says her research is a first step and that more investigation is needed to determine how plastic leachates may be affecting microbial communities. But the gist is that plastic exposure seems to select for hardier microbes, with increasing antimicrobial resistance being an unhappy little accident.
“Exposure to such leached chemicals,” says Tetu, “selects for a suite of opportunistic environmental microbes that are likely more metabolically versatile and also happen to carry a variety of genes associated with antimicrobial resistance.”
Emily Stevenson, a graduate student at the University of Exeter in England, studies how microplastics affect the spread of antimicrobial-resistant bacteria. She says this new research gets at important questions around how plastic exposure changes microbial communities. How well the laboratory findings translate into real-world conditions is hard to know, but Stevenson says it’s worrying.
“What I am particularly concerned about,” she says, “is where these leachates are antimicrobials themselves.” A lot of plastics are impregnated with known antimicrobials, such as triclosan. “If that is bioavailable to the bugs, then that would be adding a selective pressure, so they are likely to evolve antimicrobial resistance,” she adds.