Recent samples of deep ocean marine life contain tiny pieces of plastic, NPR reported. Aquatic species at those depths include some eaten by humans. How much trouble does Earth’s largest ecosystem—and our food supply—face?
The NPR article that broke the story said that a recent survey of larvaceans, which are tadpole-sized creatures that feed on plankton and other tiny organisms, revealed that every single larvacean captured by scientists contained some amount of plastic. In addition, plastics were found in the stomachs of one out of three lancetfish, which are larger fish known as “the dragons of the sea.” The implications for aquatic species—many of which make up a considerable amount of humanity’s food supply—are ominous.
Oceanic Fishing: Bad News and Good News
Although there are several alternatives to oceanic fishing, commercial fishing out on the sea is still a major industry—in some cases, perhaps too major. “Fishing has had a varied history since the mid-19th century,” said Dr. Sean K. Todd, the Steven K. Katona Chair in Marine Sciences at the College of the Atlantic in Bar Harbor, Maine. “Per species of fish, we have seen fisheries boom and bust. The list of species that are now overfished and commercially extinct is too long, indicating inadequate management methods; poor understanding of population dynamics; and in some cases, just pure unchecked greed.”
However, there are two prospective sources of good news. Dr. Todd pointed first to co-management, which he described as “a system whereby fishermen work together with local authorities to self-manage their operations.” Although he likened it to the fox guarding the henhouse, Dr. Todd said that co-management has shown considerable promise. Second is marine aquaculture, or “mariculture.” “We can now successfully farm many species of invertebrate, such as mussels,” he said. “In some cases, we can even grow fish, although we are still far from developing truly efficient fish culturing.” Should deep ocean fish continue to ingest plastic, this idea may need to come to fruition sooner rather than later.
Problems of Plastic
Plastic, one of the more versatile and useful inventions of recent history, casts a vaster net of problems over the ocean than we may initially have realized. Most of us have seen fish, turtles, or ducks caught in six-pack rings meant for cans of soda or beer, but cutting the rings with scissors isn’t enough to stem the issues.
“Plastic has all sorts of uses in today’s society, but it also has a long, long half-life,” Dr. Todd said. “Even that so-called ‘biodegradable’ plastic grocery bag may appear to decay to nothing, but in reality it has simply broken down to microscopic particles that are difficult to see without the aid of a microscope.”
Dr. Todd said this problem is twofold. First, ingesting plastics can be harmful or even fatal to marine life. “I have necropsied many marine mammals to discover the cause of death was ingestion of plastics that caused gut impaction. In one case, I extracted an entire plastic shopping bag from the gut of a seal that had blocked the exit of the stomach into the small intestine; it could not have been a pleasant death.”
Second, Dr. Todd cited the microplastics that are now being found in the deep ocean, though he expanded on the problem with an even more concerning possibility for aquatic and human life. “Microplastics can easily be accidentally ingested while organisms are feeding,” he said. “And they can actually absorb other kinds of chemical pollution and act to concentrate it. So an organism that consumes microplastics may be exposed to other toxic effects.”
Those organisms may already be in the nets of commercial fishermen bringing them back to shore.
Dr. Sean K. Todd contributed to this article. Dr. Todd holds the Steven K. Katona Chair in Marine Sciences at the College of the Atlantic in Bar Harbor, Maine. He received a Joint Honours undergraduate degree in Marine Biology and Oceanography from Bangor University in the United Kingdom and his master’s and doctoral degrees in Biopsychology at Memorial University of Newfoundland in St. John’s, Canada.