TOXIC OVERLOAD You are what you eat

Many marine organisms ingest plastic litter at sea, either directly through indiscriminate foraging behavior or indirectly through contaminated prey.

- PETER RYAN

Plastic has been recorded in the stomachs of about half of all the world’s seabird species and, given the ubiquitous nature of microfibres in the world’s oceans, it is likely that all species have been exposed to some ingested plastic.

So what? Seabirds often consume indigestible items, which they either regurgitate or excrete. The seabirds such as petrels and phalaropes that accumulate large plastic loads in their stomachs seldom regurgitate pellets and only excrete very small items. Yet these species evolved in an environment where they often eat pumice, seeds and other natural debris floating at sea. Like ingested plastics, pumice and seeds (and indigestible prey remains such as squid beaks) are gradually worn down in the stomach and excreted. So is eating plastic a problem?

Ingested plastic is thought to have three main impacts on seabirds. Firstly, it might block or damage the digestive tract, leading to injury or death. The blockage is a significant issue for turtles, but there are only a few records of seabirds with their guts obstructed by ingested plastic items – many fewer than are entangled in marine litter. In terms of internal injury, seabirds often swallow sharp objects such as spiny fish and crustaceans. Gull regurgitations frequently contain pieces of glass and metal, which are more likely to injure than plastic.