You've heard about the risks that plastic pollution poses to marine animals - choking, entanglement, drowning - but did you know that predators, like penguins, are at risk from plastics and other forms of pollution even if they manage to avoid pieces of plastic entirely?

Bioaccumulation and biomagnification?

Bioaccumulation is a process where an organism absorbs a chemical, often an undesirable one, at a faster rate than it can destroy or excrete it, so it builds up in the organism's tissues. A natural example of this is "red tide" where shellfish accumulate toxins from algae, even though the algae themselves are not concentrated enough to be highly toxic.

Biomagnification occurs when organisms that have already bioaccumulated chemicals are eaten. Chemicals can become concentrated as they move up the food chain. An example of this is in penguins - which are affected by heavy metals like mercury that they absorb from the fish they eat, which in turn ate smaller fish or plankton that absorbed it from the surrounding water. The result is penguins with significantly higher levels of mercury than the surrounding ocean.


Plastic particles both leach chemicals and absorb others from the environment. As these particles are readily consumed by many organisms at the bottom of the food chain, these chemicals become bioaccumulated.

Furthermore, when predators like penguins consume prey, they also consume their stomach contents - meaning penguins are also consuming microplastics directly. Microplastic is found in all corners of the ocean, and even the most distant Antarctic penguins are affected.

How does it affect penguins?

Long story short, we don't know - we know penguins are being affected, but exactly in what ways is still a subject of debate. We do know that bioaccumulated toxins have significant impacts on other animals, like endocrine disruption in humans, so it's fair to assume that similar impacts are being made on penguins, which we know are the subject of biomagnification of toxins like mercury.

What lesson should we take?

The vast majority of plastic pollution in the oceans comes from land, which means you have the power to reduce it. If you're already recycling, here are three small extra things you can try to reduce your microplastic output:

  • Use the Beat the Microbead app to choose bathroom products without microplastic.
  • Choose clothing with natural fibres over synthetic ones.
  • Set your washing machine to its slowest, coolest setting.

Follow the March of the penguin:

If you missed the QR code tour during your Two Oceans Aquarium visit and would like to catch up on the extra penguin information that was shared, you can do so here: