One of the most dangerous environmental problems facing the world today is the increase in the number of plastics. They become a problem since when released into the environment, they take a long time to break down. Poor waste disposal techniques cause plastic waste to be littered all over. The accidental release and indiscriminate discarding of plastic has caused the waste to accumulate in the environment at a rapid rate. The waste is then transported by rivers and wind with the endpoint being the oceans. Plastic waste has become a popular element of marine litter since it is light in weight and durable in nature. Microscopic plastic particles have recently been identified as pervasive components of marine plastic. The national oceanic and atmospheric administration has classified microplastics to be less that 5mm in size. Microplastics can be categorized into primary microplastics which an are manufactured purposefully to be microscopic they are found in substances like toothpaste, cosmetics, shower gels and other personal care products. Secondary microplastics are derived when large plastic items break down, such as items from ships, fishing gears, etc. Many types of plastics are produced worldwide. However, the most commonly produced include polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC) polystyrene (PS), polyethylene terephthalate (PET) and poly-urethane (PUR). When they reach the ocean, they enter into the aquatic environment of marine life. The microplastics end up causing specific effects to the marine organisms.
Effects of Microplastics
Micro plastics end up causing the death of fish and prevents them from reaching maturity age. When the plastics enter into the oceans some young fish end up thinking that it is food, they end up preferring the plastic to their natural food sources which eventually starves them before they can reach their reproductive age. The microplastics have been found in the bodies of whales, seabirds, and fish. Marine organisms ingest the particles, but they are unable to digest them, this leads to a buildup in the digestive tracks of the animals which hinders the microorganisms from taking in more food, it diminishes the organisms feeding stimulus which can lead to starvation (Fossi, M. C, 2014). Studies have proved that the physiological consequences of crabs taking up polystyrene microspheres through their gills are minimal. When the crabs inhale polystyrene microspheres into their gills chambers, it leads to a small but temporary change in ion regulation and oxygen consumption.
Studies have shown that fish exposed to these materials during their developmental stage show stunted growth and experience increased mortality rates changing their behavior which could endanger their survival. The study revealed that larval perch which had access to microplastic particles ate the plastic only ignoring their natural food. Fish that are born in an environment that is rich in microplastic have reduced rates of hatching and developing to maturity (Wright, S. L., 2013).
A study done to check the impact of microplastics on the gills of crabs illustrates a damaging effect. Shore crabs being omnivores normally partake bivalves like blue mussel. In the process, they may feed on microplatics emanating from contaminated mussels resulting in a lessened provision of energy for growth. Also, the crabs ingest microplastics via their gill chambers that remain in their system for approximately 22 days. It is worth noting that microplastics are injurious to these animals since it lessens their fitness and alters their food consumption as well as energy distribution. The gills are primary region for acid-base balance, ionic and gaseous exchange for aquatic animals. In that regard, any aspect like contaminants or microbial growth, which impair the gills’ purpose has detrimental effects on the organisms. The marine contaminants like arsenite, silver, mercury, copper, cadmium, and dichlodiphenyltrichloroehtane (DDT) negatively affects ion exchange and osmoregulation (Andrew James Russell Watts, 2016).
Marine organisms that have ingested plastic tend to ignore chemical signals that normally warn them when predators are present. When an organism adsorbs microplastics on its surface, it lowers the steroid hormone level; it also leads to reproductive failure which can cause delayed ovulation. Microplastics can also lead to other physical effects such as injuries in the gut perforation, introduction of toxins in the body and delayed growth and death. The plastics can also alter marine habitats physical conditions. They affect the temperature and permeability on sandy beaches affecting animals that are dependent on temperature for the determination of the sex such as reptiles.
Chemical Effects of Ingesting Microplastics
Microplastics contain plasticizer known as additives which can be very harmful an example of an additive is di-butyl phthalate and biphenyl A (BPA), these substances are incorporated while the plastics are being manufactured to provide tensile flexibility and tensile strength. The microplastics tend to accumulate and adsorb toxic materials from the surrounding seawater such as organic pollutants and heavy metals. The chemicals are not bound to the microplastic surface, and as a result, when ingested they tend to leach into the animal tissues (Do Sul, J. A. I, 2014). The impacts from such chemical leaches include hepatic stress in fish, mortality and endocrine disruption.
Microplastics that float in the sea are capable of providing raft substrates for various microbes and avifauna such as algae and bacteria; they transport them to new areas where they have not been existing, this is capable of increasing the range of introduced species in a new environment. The new species invasion can be detrimental however not all the species transported are harmful.
Microplastics also have the possibility of being introduced into the food chain. Organisms in the lower trophic level are capable of microplastic ingestion and accumulation introducing them into the food web
There is an increase in the level of microplastic debris that is accumulating in the oceans. Aquatic microorganisms are susceptible to ingesting these particles. The increase in microplastics is also bound to increase the density of the benthos causing it to sink. The plastics are hazardous as they affect the species at the microorganism level by changing their development and their reproductive ability.
Microplastics cause a reduction in the number of the species through death; this allows them to modify the population structure of fish. To solve this problem of microplastic pollution the sources and transportation mechanisms need to be identified. The microplastics should not be introduced into the ocean. Mitigation strategies should be developed to provide cleanup programs that will be efficient and long-term. Studies also need to be carried out to determine the impacts of the chemicals that are associated with microplastics. All the members of the community have a role to play to ensure that plastic materials do not affect our environments. We need to think globally and act locally to be able to reduce the environmental threats that we face.