Scientists created a tool to find out how many species are at risk from plastic pollution. The computational model allows to give a quick answer on the impacts that the contamination is having and thus accelerate the decision making to solve the problem.
Various scientific studies predict that the entry of plastic pollution into aquatic systems will triple in the next 20 years. The premonition is alarming because it is currently estimated that some 8 million metric tons of plastic waste already enter the ocean each year. This means that every minute a truck full of garbage is dumped into the sea.
The impact of this contamination is immediate. Turtles, birds, fish and other marine animals are at risk of dying either because they become entangled in the plastic floating in the sea or because they ingest it by mistaking them for food.
However, the threat comes not only from large plastics that we can see with the naked eye, but also from microplastics, particles smaller than 5 millimeters, which are of special concern to science because they are literally inside everyone. In fact, a scientific study published in 2019 concluded that, on average, a person consumes the equivalent of a credit card of plastic weekly.
The presence of plastic in our bodies and that of animals has already been proven, but the question that science is trying to answer now is, is that affecting health? A team of scientists from the University of Exeter, the Galapagos Conservation Trust (GCT) and the Galapagos Science Center, are working to try to answer that question.
After evaluating the presence and distribution of plastic pollution on San Cristóbal Island in the Galapagos archipelago, the researchers built a tool to quickly assess which species would be most affected in this place, considered one of the most emblematic of the planet in the conservation of biodiversity.
After applying this tool, the scientists found that 27 species in Galapagos were at risk of serious damage from ingesting plastics or becoming entangled in them. But the most relevant of these results, published in the journal Science of The Total Environment, is that the tool will be an important support to promote and accelerate decision-making to solve the problem of plastics, says Juan Pablo Muñoz, co-author of the investigation.
“Sometimes governments, faced with the need to handle disposable plastic and take quick actions, tell you ‘okay, give me the data,'” adds the researcher from the Galapagos Science Center. The problem is that gathering that information can take five years or more, and experts agree that action needs to be taken today. With this instrument, Muñoz assures, the researchers will be able to answer “Don’t worry, I’ll give you the data tomorrow. Let’s make the regulation, let’s make the change, let’s make the policies, because here is the information ”.
How did they manage to build this super model?
Step one: measure the severity of the contamination
The first thing the scientists did was evaluate the composition and distribution of plastics at 17 points on San Cristóbal Island, an area of great importance for conservation since it is home to, among other species, the largest colony of Galapagos sea lions (Zalophus wollebaeki) and two unique subspecies of marine iguanas.
The experts took samples on beaches and in surface seawater from both tourist and remote sites, where visitors do not have access, and also from the interior of seven species of marine invertebrates such as oysters, sea cucumbers, urchins or snails.
The result was that all the marine habitats on the island of San Cristóbal are contaminated with plastics. In 13 of the 14 sandy beaches sampled, the scientists observed the presence of macroplastics, that is, of elements and fragments larger than 5 millimeters. “In certain places you can find almost 5000 pieces of plastic per 50 square meters. Things that you can see with your eyes: covers (bags), toothbrushes, bottles, fishing items, buoys, etc.,” says Muñoz.
The highest levels of contamination were found on the beaches facing east, where the Humboldt current passes, and one of them is Punta Pitt, a site that “is home to the Godzilla marine iguanas that, like much of the Galapagos wildlife is not found anywhere else in the world,” the study notes. The problem is aggravated if it is considered that the population of this species is less than 500 individuals.
In addition, microplastics were found in all seawater and seabed samples and also in the seven invertebrate species examined. In this regard, Jen Jones, the lead author of the research ensures that “these animals are a crucial part of the food webs that support the largest species that live in the Galapagos Islands and its surroundings.”
Previous studies had already determined that the plastic garbage that ends up in Galapagos comes mainly from Peru and mainland Ecuador. Thus, although the pristine image of this important conservation site might give the impression that the islands are protected from plastic pollution, this study shows, once again, that this is not the case. Most worryingly, according to David Santillo of the Greenpeace Research Laboratories at the University of Exeter, “this situation will only get worse if we don’t drastically change our use of plastics.”
Step two: build the tool
The next step was to create a computational model that allows researchers to quickly determine which animals could be most affected by contamination. For this, the researchers created a list with all the species of San Cristóbal and entering different variables of their natural history, such as their habitat, their diet, their biology or their conservation status (that is, if it is considered that their populations are healthy or are Near Threatened, Threatened, Endangered, or Critically Endangered).
“You enter all those parameters that we already know and the model throws you a risk number (to which the animal is exposed either by ingestion of plastics or by entanglement),” explains Muñoz. An added value to this tool is that it can be applied anywhere. “For example, if you are in Chile, you can measure the risk for animals on Easter Island or in the Juan Fernández archipelago,” says the expert. That is why Colombian, Costa Rican, Peruvian, Chilean scientists, among others, also participate in the research to see which species are most affected in the region.
In the case of San Cristóbal, the model showed that 27 marine species are at risk. All had a score greater than 10, says the study, “which indicates the probability of serious injury or death due to ingestion of plastic or entanglement,” says the researcher. Of all these species, 15 are fish and of them 13 are sharks, five are reptiles (iguana and four species of turtles), five are seabirds and two are mammals.
“The highest scoring fish were the iconic hammerhead shark (Sphyrna lewini) and the whale shark (Rhincodon typus) due to their conservation status Critically Endangered and Endangered respectively,” the study notes. But the species with the highest score in the analysis was the Galapagos sea lion (Zalophus wollebaeki) “with 251 incidences of entanglement registered between 1995 and 2003, 54% linked to fishing garbage and 46% to other garbage such as packing straps, most of which were registered around the port of San Cristóbal,” the publication states.
Step three: check the data in the field
Currently, scientists have already advanced to a third stage that consists of verifying the data in the field for greater precision. “Let’s not forget that the model is theoretical,” recalls Muñoz. “It is something that we are seeing on a computer and that we believe happens in reality,” he explains.
At this stage, the experts were able to confirm that all the species that the model identified as vulnerable are indeed at risk, thus confirming that the tool works. But in addition, thanks to field work and the photographic and video records collected, the experts added another nine species to that list, that is, so far in total there are 36 species at risk due to plastic contamination.
Of those species, the researchers selected three that are at high risk to advance to a fourth stage of the study that is still in development. The objective is to give them a medical check-up and try to answer the question of how plastics are affecting their health.
One of the species chosen for this evaluation was marine iguanas. The scientists examined these animals at nine different sites across the Galapagos archipelago with different loads of plastic pollution. “We took stool samples from them and we did a complete analysis of their health, just like when you go to the doctor,” explains Muñoz. The analysis includes a visual check-up, during which wildlife veterinarians feel the iguana’s organs to rule out any abnormalities, weigh them, measure them, and take a blood sample. “That blood sample is taken to a portable laboratory that we have and all its blood chemistry is measured,” adds the researcher. With all that data,
Taking the stool sample is not that simple. “It is very important to take the sample when you see the animal that is defecating, because if it touches the ground, for example, or if you collect a sample that is on the ground and that you did not certify that it comes from such an animal, it may be that it has been contaminated with micro plastics from the other side and that is not that these are inside the iguana ”, explains the scientist.
But the biggest challenge at this stage was with the second species the scientists selected for the health assessment: sea turtles.
“Last year we put them in some pools that we take to the field so that they are quiet. We put special diapers on them that are not plastic and we were literally there all day, all night and they didn’t defecate,”says Muñoz. To solve this difficulty, the scientists performed an endoscopy on the turtles, which required complex logistics. “Three veterinarians who were experts in doing field endoscopies had to come, bring an electric generator and all that endoscope to the remote places where we did the work, which is a super aggressive, rocky, volcanic stone environment,” says the expert. After the success of the operation, what follows will be to evaluate the results of these samples and of the other examinations that, as well as the iguanas, were also performed on the turtles.
Another of the selected species was the bigeye fish, an endemic species to the Galapagos, that is, it does not live anywhere else in the world. This fish is part of the diet of the inhabitants of the archipelago. The advantage of being a commercial species is that researchers will be able to examine the inside of your body. “We can humanely euthanize it, open it up in the laboratory and examine it completely,” explains Muñoz.
When the research results are ready, scientists will be able to shed light on the big question of whether plastics are affecting the health of animals in Galapagos. However, the answers cannot be categorical, since even if the results indicate that the health of the species is affected, it is possible that this is also due to other factors. Getting an accurate answer requires even more research. However, experts say that immediate action is necessary. “I don’t think you really need to have a verification, an accurate verification that microplastic is causing cancer in humans to act,” says Muñoz.
Last year, the research team won a £3.3 million grant from the UK government to investigate and tackle plastic pollution in the Eastern Pacific. However, the subsidy has been reduced by 64% due to the health emergency caused by the pandemic.
To collaborate with this project, the scientists have called on all the people who have visited Galapagos to complete a small survey to find out if they have seen animals entangled in plastic or ingesting them. By sharing photos or videos of these interactions with them, the registry of animals at risk can be more complete.
To access the survey, click on this link: https://arcg.is/5ajXr
Read the coverage by Michelle Carrere for Mongabay Latam via El Comercio (Peru) at https://elcomercio.pe/tecnologia/ecologia/galapagos-36-especies-estan-en-riesgo-por-contaminacion-con-plasticos-noticia/?ref=ecr
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