Marine debris is becoming one of the most terrifying threats to wild animals and the marine environment as a whole. There are two main ways in which it causes harm: One is by ingestion and the other is by strangling.
When they ingest plastic, the digestive tracts of seabirds become clogged, after which their stomachs can suffer from stomach ulcers and similar wounds. Also, if they have plastics in their stomach, they believe that they are full and thus stop eating, eventually starving to death（Kühn et al. 2015）.
It is believed that the toxic chemical substances that are added to plastics during production as well as the contaminating substances which the plastics absorb from the seawater while drifting in the sea may also affect seabirds（Rochman 2015）.
When seabirds become tangled up in plastic debris, they get caught or get hurt and they cannot go to seek food. Furthermore, when parent birds use plastic debris to build their nests, the chicks get entangled and cannot leave the nest.
The ingestion of plastic by adult seabirds is well known among all over the world, however albatross chicks are also well-known consumers of plastic. Regarding the chicks of other seabird species, such as black-legged kittiwakes, their actual state is not yet entirely understood.
An Irish research team investigated the chicks of three kinds of seabirds living there, namely black legged kittiwakes, northern fulmars and great cormorants. They investigated the stomach contents of chicks that had vomited and checked to see if there were any plastics there（Acampora et al. 2017）.
When scientists investigate plastic ingestion by seabirds, they usually dissect the dead birds on the beach or in the nest to inspect their stomach contents. However, this does not enable them to tell whether the healthy seabirds also eat plastic or not.
When the scientists do an individual survey of seabirds, they put tags on them, and in order to put the tag on, they first have to catch them.
When seabirds are caught by human hands, they often vomit their stomach contents. It is not yet known whether this is because they are stressed or whether they are trying to protect themselves. Either way, scientists can determine whether healthy looking seabirds are actually eating plastics or not by checking these stomach contents.
As the result of the Irish research team’s investigation, it was found that all three species of seabird chicks had pieces of plastic in them, whereby the northern fulmar chicks had ingested significantly more plastic debris than the other chicks（Acampora et al. 2017）.
It became quite obvious that even the chicks that have not left their nest are threatened by plastic debris.