Litter affects marine biota in many ways

Plastic rubbish accumulates in marine animals either through their search for food or unintentionally. Some animals are unable to distinguish litter from food items and eat pieces of plastic instead. For example, 80% of the nesting fulmars (seabirds related to seagulls) in the North Atlantic carry plastic rubbish in their stomachs. Indeed, the amount of plastic in fulmar stomachs has become one indicator of marine littering in that area.

Ghost nets continue to catch things all by themselves

There are also many lost or abandoned fishing gear in the sea, such as nets and trawls. These are collectively known as ghost nets.

A large portion of ghost nets continue to catch animals. Mammals, birds, and fish can become entangled in them. The problem is greatest when fishing gear gets caught on underwater structures, such as shipwrecks. In such cases, they do not land on the seabed.

Plastic waste kills hundreds of thousands of seabirds and marine mammals each year

Plastic waste causes the death of one million seabirds and one hundred thousand marine mammals worldwide every year. The most common causes of death are:

  • The digestive tract becomes blocked by debris. The animal starves or suffocates to death.
  • Animals become entangled in the litter, lose their ability to swim or fly, and starve to death or become prey.
  • Large pieces of plastic litter fragments into microlitter that is so small, it can even enter planktonic organisms. This sharp plastic litter damages their digestive systems.
An infographic about plastic litter in the food chain.
: If nothing is done, by 2025, there will be one kilogram of plastic for every three kilograms of fish in the sea. Marine animals become entangled in plastic litter, which can also clog their digestive tract. In addition, plastic trash contains harmful substances. Source: SYKE. Illustration: Kaskas Media Oy.

Not all of the effects of microplastics are known yet

Not all marine litter is visible to the naked eye. Microlitter can take the form of tiny ready-made pieces of plastic, such as the plastic microbeads found in cosmetic products. It can also be formed from small plastic chips or fragments, which are created as larger chunks of litter are physically abraded into ever smaller pieces. Some microplastics from the household end up in the sea after passing through wastewater treatment plants. These include, for example, pieces of fibre which have become detached from washing synthetic textiles.

Plastic ingredients and additives, such as plasticisers and flame retardants, can be harmful to marine organisms. In addition, plastic pieces are efficient at binding the harmful compounds in seawater. The smaller the particle, the greater its relative binding area. As a result, the concentrations of toxic substances in microplastics can be many times higher than those in water.

There is already a wealth of information on the harmful effects of visible litter on marine organisms. On the other hand, the information about the amount and importance of microlitter in the marine food web is scarce. It is difficult to predict the impact of toxic substances accumulated in plastic trash on organisms.

An infographic about the sources of microplastics.
Plastic is used everywhere in modern society. Thus, microplastics are transported to waterways by industry, households, transport, and from people's everyday lives. Microplastics carry toxic substances: both within the plastic itself and bound to its surface. Source: SYKE. Illustration: Kaskas Media Oy.