Science

Micro-sized plastics causing giant problems

Charlotte King

From toothpaste to exfoliators, microplastics can be found in almost every modern household. They are a relatively new phenomenon, but a recent study from Murdoch University has uncovered just how much they are affecting our environment and specifically ocean giants, and could even lead to their extinction.

The ocean giants in question are more precisely filter-feeders. These are large ocean animals such as fin whales, whale sharks and manta rays, who consume large amounts of water when feeding. Their digestive system then filters plankton and small food sources from the water. Unfortunately, Elitza Germanov of Murdoch University says they are put “under strain” due to the masses of microplastics entering the ocean which they are also filtering and digesting.

But what are microplastics? Microplastics are pieces of plastic which are 5mm or smaller in length, around the size of a sesame seed. They are roughly the same size as plankton, so can filter through the digestive system easily. Common microplastics include microbeads, often found in beauty products, and glitter. This means that almost all of us will own or have used a product containing some form of microplastic, and almost all of us have sadly contributed to this major environmental threat.

These microplastics pose multiple threats to ocean giants which are only just being discovered. The study conducted by Murdoch University found three main dangers: a loss in nutrient uptake, damage to the digestive system, and the consumption of toxins. Microplastics can lead to a decrease in nutrient uptake by ocean giants because are being consumed instead of plankton, which has a number of consequences including a reduction in energy and in egg production. They are also causing damage to the digestive system because they become lodged and block the digestive tract. In extreme cases, this can lead to death by starvation.

The consumption of toxins, however, is the main threat these microplastics pose to ocean giants. When these toxins are absorbed and they enter the body, it results in hormonal changes which can have detrimental effects on the growth and development of these sea creatures, and most importantly upon their reproductive abilities. Reduced fertility ultimately reduces the likelihood of these ocean giants having offspring, and this effect is magnified by the fact that ocean giants are long-lived animals who have very few offspring throughout their lives. Combined with reduced growth and development, we are left with a reality where more and more ocean giants are not reaching an age where they are able to reproduce, making population growth even more difficult. These are only two of the many consequences of these toxins.

Filter-feeders are found throughout the oceans, but they tend to reside in the areas which have the highest percentage of plastic pollution, which only makes the environmental consequences of microplastics worse. These areas include the Gulf of Mexico, the Bay of Bengal, the Coral Triangle and the Mediterranean Sea. In Australia, a whale washed up on the shore was found to have 6 square meters of sheet plastic in its digestive system along with 30 plastic bags. Another whale carcass found on French shores contained 800kg of plastic. It is estimated that in the Gulf of Mexico ocean giants swallow around 200 particles of plastic per day and in the Mediterranean Sea roughly 2000 particles.

These microplastics are undoubtedly majorly threatening ocean giants. The fin whale has no predator, yet both the fin whale and the whale shark are considered threatened species, and the manta ray is near threatened. The only explanation for their decline is human activity and the increase in microplastics which are having a damaging effect on their population numbers, bringing them ever closer to extinction. Germanov says these “charismatic and economically important species” must be protected because their decline will have larger effects on the marine ecosystem.

With these new insights made by Murdoch University, where do we go from here? Currently, 8.3 billion tonnes of plastic have been produced, with 79% of plastic going into landfill or the environment. If this same rate of plastic production continues we could see 12 billion tonnes of plastic produced by 2050. Perhaps it’s time to research how to remove this microplastic from the ocean before it’s too late.

Add Comment

Click here to post a comment

Your email address will not be published. Required fields are marked *

css.php