It is not new that plastic is everywhere and that it is the most common type of marine litter. It is a very resistant material, too much for the use we give it sometimes, and it means that it never ends up completely disappearing from the marine environment.

Plastic waste can come in many sizes, shapes, and come from a wide variety of sources. Due to the action of certain environmental and biological factors, they are fragmented into smaller and smaller pieces until they become microplastics. The National Oceanic and Atmospheric Administration (NOAA) establishes that a plastic fragment is considered microplastic when its diameter is less than 5 millimeters, and if it has a diameter less than 0.001 it is called nanoplastic.

A few weeks ago we developed a series of contents for a project in collaboration with Lush Spain on microplastics, and we designed this infographic, which tries to explain in a summarized way the problem of microplastics and how they affect marine life.

What can we see in this infographic?

The illustration represents, vertically, the different entry sources of microplastics to the sea and how they can affect the marine food chain.

Let’s start from the beginning: a summary of the main sources of waste that end up reaching the marine environment. Are these the only ways for plastic and microplastic fragments to reach the sea? No, unfortunately, there are many other sources and residues that generate microplastics and that end up affecting the marine environment. Those described here are examples of the most common sectors or wastes that, due to their components or intrinsic processes, generate plastic and microplastic fragments and these end up reaching the marine environment in various ways.

A very common example of waste that ends up in our seas is wet wipes. These wipes are often improperly disposed of through the sewage system, as is the case with other plastic items such as cotton swabs, condoms or pads. This causes that, in addition to clogging the sewer systems, they disintegrate into microplastic particles that end up in seas and oceans. According to a study made by the OCU, no wet wipe, even if it is announced as biodegradable, degrades more than 5% after two months, due in part to the mixture of synthetic fibers that compose them and the preservative substances that these products are impregnated with.

In the illustration, we can also see the different processes of plastic fragmentation, summarized in two. On the one hand, the fragmentation of plastic particles occurs due to the physical and chemical wear generated by some processes (industrial treatments and procedures, freight transport, transport and mobility by road, among others). Another way to generate plastic fragments is through biological fragmentation, that is, the interaction of living organisms with these plastic fragments.

Depending on the size, density and composition, these microplastics can end up in the sand of the beaches, floating in the water if they are not very dense, in the sediments or, if they are more dense microplastic particles, they can end up sinking in the sea.

Either way, how do microplastics affect the marine food chain?

It is proven that the small plastic fragments that reach the marine environment are incorporated into the marine food chain, for example, through zooplankton, which ingests them by mistake and accumulates them by not being able to digest them. A study carried out in 2016 showed that the ingestion of microplastics by zooplankton negatively affected the feeding, survival and fertility rates of copepods.

The problem of the presence of microplastics in the marine environment does not only affect the smallest organisms. As seen in the infographic, it also reaches species of bivalves, pelagic fish, marine mammals, crustaceans, demersal fish, and mesopelagic fish. At these higher trophic levels, the concentration of plastic fragments is increasing and they have been detected in the interior of more than 40% of the species of whales, dolphins, porpoises, sea turtles and about 36% of the species of seabirds.