Plastic All-You-Can-Eat Buffet

So in the previous post we looked at the cycle of plastic from creation, through use, to its life in the ocean. But how and why does it prove to be so (unfortunately) popular with marine life?

Marine plastics which are small enough or degraded pieces make their way onto the menu of marine animals due to their ease of ingestion. Their nice colours are also very attractive as they closely resemble other creatures. Let’s look at the northern fulmar and leatherback turtle as examples:

Leatherback Turtles:

• These animals are an important predator of jellyfish and can consume up to 73% of their own body-weight in jellyfish when preparing for their southern migration. Now take the below image into account. In a study by Mrosovsky et al. (2009) it was found that in 371 leatherback autopsies, 37.2% contained plastic in their digestive tracts (the first mention of this in 1968). However, of these, only 8.7% were said to have died from plastic blockages preventing normal food ingestion. This may seem small but if we think back to their time of increased consumption for migration, they may feel full before they really are, causing death due to lack of available energy. Other problems may be seen down the food chain. If these turtles are dying then their former pray might be left to over consume their pray. This is just one of many feedbacks that could be experienced from a fall in numbers of leatherback turtles.

The Northern Fulmar:

• A study by Avery-Gomm et al. (2012) into the effects of plastic pollution on the northern fulmar bird (from the Northeast Pacific), found that of the 67 studied, 92.5% contained plastic in their stomachs. This is seen much closer to home too with another study looking at the northern fulmar around the North Sea, finding 95% of the 796 birds studied had ingested plastic, clearly mistaking it for food they usually eat like squid, fish, shrimp and jellyfish. The video below shows the contents of several marine birds' stomachs so you can better visualise the extent of consumption:

Many marine animals are affected by the ingestion of plastics with studies only now beginning to understand the adverse effects this is having across the food chain. It is clear from the literature that more research is needed to further understand these impacts but it doesn't take a scientist to know that a plastic diet is not healthy.

Next week we'll look at plastic ingestion further up the food chain: humans.