The plastic pollution of our oceans is one of the biggest environmental issues of our time. If the trend of plastic pollution in the oceans continues as business as usual, by 2050 there might be more plastics in the oceans than fish. One of the biggest contributions to plastic pollution of the oceans are ghost nets that are floating through the oceans, entangling and killing wildlife. A little less obvious are microscopic plastic particles that are either entering the ocean directly or being degraded from larger plastics.
What are microplastics?
Microplastics refer to any type of plastic that is smaller than 5mm in diameter. They are found in many hygiene products such as hand soaps and face cleansers (primary microplastics). By using these products the microscopic plastic fragments often escape treatment screens of wastewater plants and enter the ocean. Also, larger plastic fragments in the ocean slowly degrade into smaller pieces due to changing environmental conditions such as sunlight, heat, wind and waves posing a threat for marine life (so called secondary microplastics).
Microplastics can be found in every type of marine system, from sandy beaches and surface waters to deep sea sediment. It is estimated that up to 51 trillion microplastics are currently floating around the ocean, which equals 236,000 tonnes. Little is known about microplastics and their impacts on marine and human health yet. However, what is known about the impact of microplastics is quite scary.
Why are microplastics so harmful to marine life?
The fine plastic particles are being accumulated by filter feeders such as oysters and ingested by other marine animals such as seabirds, dolphins, crabs and fish. Concerns of the health effects of microplastics are growing. It has been shown that nanoplastics can even penetrate fish’s brains and result in abnormal behavior, reduces their ability to hunt, delayed growth and reduced food intake.
Unfortunately, especially eating shellfish might pose a serious threat to human health as well. It has been shown that when eating a portion of mussels, up to 90 plastic particles are consumed with it.
But, what about ghost gear and microplastics?
The scary truth is, we do not know how much ghost gear contributes to the microplastic problem of our oceans. Little to no research has been done to determine the contribution of ghost nets to smaller plastic particles. However, it is safe to assume that ghost gear adds up to the microplastic problem in a huge way. Ghost gear is floating in the oceans for up to 600 years killing marine life if not being collected. During this time it breaks down into smaller and smaller pieces and eventually end up as microplastic particles in the marine food chain and therefore, on our plate. Small particles of fishing ropes have been found in crabs and scampi, however, the urgency for further research on this topic cannot be stressed enough.
Further reads
https://journals.openedition.org/factsreports/5257
https://www.nationalgeographic.org/encyclopedia/microplastics/