Miquel Canals: "It is not necessary for humans to have reached all the seabeds to have damaged them."

BarcelonaSouthwest of Pylos, Greece, lies the deepest point in the Mediterranean Sea, in the so-called Calypso Trench. Specifically, 5,267 meters separate the surface from the deepest point. The landscape of an inhospitable desert sunk in the darkness of the sea would be the most predictable scenario, but researcher Miquel Canals' team has confirmed that there is human presence even at the deepest point in the Mediterranean. Remains of garbage bags, cans, and plastic bottles are some of the traces identified by a manned submarine that descended into the trench with the help of pioneering technology.

The images of garbage in the deepest trench in the Mediterranean are shocking, but what relevance do these results have in the scientific world?

— First, it shows us that our footprint, our waste, reaches places that, at first, are unimaginable. This is the deepest trench in the Mediterranean, more than 5,100 meters, but we also know that there are other trenches at much greater depths in other oceans, where waste has also been found.

Were you able to determine what types of trash you found?

— Yes, although we haven't conducted a study of the polymer composition. Of the total, 88% were plastics, primarily polypropylene and polystyrene. That is, these are the bottles we use for soft drinks, water, plastic bags, garbage sacks, etc.

What route could the garbage have taken?

— Some large garbage bags suggest they were thrown from a ship, and that by carrying heavier items inside, the bag sank to the deepest point in the sea. This practice is prohibited, but either we continue to pay for actions carried out years ago or it continues to be done. On the other hand, plastic bottles are a particularly "interesting" type of trash because they usually contain legible information about the brand, manufacturer, date, place of manufacture, etc. This information allows you to trace their origin and year. The bottles mainly come from Greece, Italy, and the countries closest to the Calypso Trench.

How long can it take from the moment a plastic is consumed until it ends up on the seabed?

— We haven't determined this yet in the samples from this research, but in other work we've done, we've found bottles that were a week old and bottles that were up to fifteen years old.

The first evidence of the presence of waste on the planet's seabed dates back to 1975. How has waste changed then and now?

— To answer this question, we face a very serious problem. The first dives in the deep ocean, in this case at a depth of more than 200 meters, were made in 1958. Since then, some 44,000 have been made. This may seem like a lot, but this effort has only been able to directly observe 0.001% of the deep ocean. If there are places where a certain amount of waste was found in the 1980s and it has since returned, it may have been seen that it is more or less the same, or there may also be places where there is a lot of waste. But the truth is that we are aware that any projection we make could be very wrong.

The level of degradation cannot be known because there is not enough material to compare.

— Of course. The question is: "Is all this we've observed representative?" Because it's a very small part. At least it indicates something, and any projection of how much debris there is on the seabed with current data could easily be a huge underestimate. Every time we go to places that had never been visited before, you find sites and say: "Wow, I didn't think this would also be damaged by humans." It's not necessary to have arrived for there to be human presence. Before, the custom was to throw everything old into the ravines, where it ends up in the sea, and when there's a heavy rain, all this ends up directly on the seabed and in the trenches, where it stabilizes.

One of the study's unique features is that the images were recorded by a manned team. How was this vehicle built?

— The construction was an epic endeavor, with all sorts of moments, but it was ultimately built to become the centerpiece of the Five Deep Expeditions project. This name, the Five Trenches Expedition, referred to the five deepest trenches in each of the world's five major oceans. This meant that the autonomous vehicle had to be certified to descend to 11,000 meters or more, because the deepest, the Challenger Trench in the Pacific, is 10,950 meters deep.

These vehicles are not known for being very spacious.

— Of course not. Despite the fact that the pressure-bearing sphere is only 90 millimeters thick, it only fits two passengers, because it only has an internal diameter of one and a half meters. It's not exactly spacious. The other factor is time: the vehicle has a range of 16 hours, and descending to 11,000 meters takes about three. You spend six hours between going up and down, leaving you with a few hours left to navigate. It also anticipates a serious incident; in this mode, you have 96 hours of survival. If not, alea iacta este.

Did the same two people travel to all the operations?

— No, various people have come forward. Perhaps the person who has made the most contributions is Víctor Vescovo himself, who provided the funding for the research. But there have also been those from scientists to people interested in dissemination, journalism, and various other commitments.

What does commitments mean?

— Even politicians have descended. There are countries where, if you want to go there to do an immersion and you come from America, they tell you, "Listen, the king's son must descend." Well, the king's son descends. In other words, it's a very diverse range of people and figures. Among them are people we could say of the jet set or the world of celebrities.