Plastic has only been around for 60-70 years and almost all of it still exists in some form today. Our Oceans are filled with plastic and the effects on marine life are devastating. A recently published study estimates there are between 15-51 trillion pieces of plastic in our oceans. Not one square mile of surface anywhere on earth is free of plastic pollution. Traces of microplastics have been found from the deepest ocean floor bed to the highest mountain peak.
We as humans, do not fully understand – nor are capable of accurately predicting – the extent to which plastic pollution will affect marine life in the long term. What we do know for certain is that we only have a few years to reverse the damage we have done before it’s too late. It has been predicted that by 2015, there could be more plastic in the ocean than fish.
Let’s look at the five main ways plastic pollution affects marine life:
Plastic disrupts the nutrient balance in our oceans
Microplastics – plastics smaller than 5mm in size – are a huge threat to large filter feeders, such as Whales or Manta Rays. Filter feeders swallow hundreds of cubic metres of water a day to capture their food, and this makes them particularly vulnerable to the exposure to toxins contained in plastic. These toxins can alter the hormones which regulate their body’s growth and development, in addition to their metabolism and reproductive functions. The movement of whales across the oceans plays a major role in the transport of nutrients – of which thousands of species rely on for food. When these magnificent, gentle animals rise from the cold, rich waters of the deep to the warm surface, they stir our waters and distribute nutrients to the rest of the food chain. They are considered almost as important as tides or winds in mixing the Ocean.
Humans have reduced the abundance of many large marine vertebrates, including whales, to only a small percentage of their pre-exploitation levels. Plastic pollution constitutes a major threat to the survival of whales, and if the whales are decimated, so will the rest of marine life.
Sea animals consume plastic
Unfortunately, we have all seen images of beautiful marine creatures entangled in plastic or dead seabirds with their stomach filled with colourful plastic fragments. Plastic becomes a killer when it reaches the ocean and some species are more vulnerable than others. A sea turtles favorite food, for example, is jellyfish, which can be easily mistaken for plastic. When they consume a plastic bag, their belly inflates like a balloon, forcing them to the surface and preventing them from diving back in the deep. Discarded fishing gear is also a huge threat, it entangles marine turtles and can drown or render a turtle unable to feed or swim. Today, three of the seven existing turtle species are critically endangered.
It is believed that 700 species could go extinct as a result of plastic pollution. Today’s estimates indicate that at least 267 species worldwide have been affected by plastic pollution, including 84% of sea turtles, 44% of all seabirds and 43% of all marine mammals.
Plastic destroys coral reefs
Plastic pollution speeds up the growth of pathogens in the ocean. The conclusion of a recent study highlights how coral reefs that come into contact with plastic are 89% more likely to contract diseases. This number becomes even more worrying when we consider that 60% of reefs are already seriously damaged and that half of the Great Barrier Reef has already been bleached to death. Coral reefs are essential for the survival of our oceans. They provide habitats and shelter for many marine organisms as well as adjusting carbon and nitrogen levels in the water and producing essential nutrients for marine food chains. These incredible living organisms also offer a service to all communities living on the coastline as it protects them from the damaging effects of wave action and tropical storms.
Plastic poisons our food chain
Plastic has been detected in almost all levels of the oceanic food chain. From the smallest of marine organisms, namely plankton, to the largest of predators, such as whales and sharks. Microplastics enter our oceans in various different ways. As we all know, plastic material does not biodegrade but only breaks down into smaller microscopic particles which are then consumed by fish and enter the food chain. The second main way microplastics enters our oceans is though synthetic fabrics washed in washing machines. The contamination of the marine food chain starts when a species consumes organisms of a lower level in the food chain which has microplastics in the gut or tissue. This then creates a domino effect by spreading to larger species, all the way to ending up in our plate when we, in turn, consume fish that has been exposed to our own plastic pollution. This is a solid example of how everything on our planet is so deeply connected that we, as humans, cannot think that our actions won’t come back to hit us right in the head.
Plastic diminishes the growth of plankton and algae
Another important fact that few people seem to know is that 70% of the Earth’s oxygen is produced by marine plants, with the remaining 30% is produced by rainforests.
Just as deforestation is decimating the amount of oxygen produced by trees, plastic is drastically reducing the capability of our oceans to compensate for our increasing carbon dioxide emissions. The Great Pacific Garbage Patch, twice the size of Texas, stretches for hundreds of miles across the North Pacific Ocean and is one of the most frightening examples of how much human activity is violating the planet. This huge floating island blocks sunlight from reaching plankton and algae below the surface thus preventing them from growing. As previously mentioned, the ocean produces oxygen through the plants (phytoplankton, kelp, and algal plankton) that live in it. These plants produce oxygen as a byproduct of photosynthesis, a process which converts carbon dioxide and sunlight into sugars the organism can use for energy. So it goes without saying that the impacts of this huge floating monster can have enormous unseen impacts on our planet and its delicate balance.
The research on the effects of plastic on our marine life is terrifying and it’s the result of the disposable lifestyle humanity has adopted. Changing our consumption habits and pledging to cut our single use plastic to a minimum is the single best tool we have today to fight plastic pollution. It’s not too late to make a difference.