Approximately more than 10 million tons of plastics and plastic debris are discarded by the humans in to the ocean every year. These plastics starts to float initially when bigger in size and eventually starts to degrade and then breaks down in to smaller pieces called microplastics. Numerous researchers has cited that microplastics are the predominant particles found in the digestive tracts of more than 100 different marine species, causing physical, chemical and biological hazards to the Marine animals.
Microplastics and Marine Aggregates
The marine aggregates are the sinking particulate matter with rich potential source of carbon in the marine water column. These marine aggregates form the food chain in the ocean and they are the potential feeding zone for oysters and other bivalve molluscs. This marine aggregate is one the source of transport mechanism of microplastics to the sea floor. The marine aggregates transport the microplastics to the marine water column which in turn is transferred vertically downward to the sea floor. Thus the marine aggregate paves way for the microplastics to enter in to the marine food web.
Several researchers found that the microplastics have induced toxic effects in microalgae causing decrease in photosynthesis and reduction in population growth. Moreover, microalgae have ability to colonize plastic debris and interact with them changing their properties with environmental behaviour affecting their environment.
Microplastics and Marine Animals
The interaction between microplastics and marine animals were studied by numerous researchers by collecting marine aggregates and mussels as samples from the ocean. They found that 73 percent of the marine aggregates contain plastic particles and more than 90 percent of the microplastics measured are less than 1 millimeter.
The researchers detected microplastics in the biodeposits or digestive gland or gut of the mussel. More than 40 percent of the micro plastic particles were either rejected in the mussel’s pseudofeces or discharged as undigested material in feces. Normally, mussels can digest their food within a matter of minutes but the plastic particles took days to digest.
Marine Animals and Human Food Chain IntMeraction
The Marine animals like mussels, oysters were consumed by humans as they have the most impressive profile of nutrition content. Mussels are good source of vitamins and also minerals, such as zinc, which helps to build immunity and to a certain extent of iron and folic acid. Mussels and other bivalves like oysters and clams are eaten by humans without removal of the gastrointestinal tract. The gastrointestinal tract of these bivalves if contains microplastics as biodeposits may enter the pathway of the human food chain.
Disposal of plastics and plastic debris in to the ocean is not only an alarming threat to the marine animals but it could also be a threat to the human food chain. It is yet to discover whether the microplastics possess risk to human health. Recently WHO reported that more intensive studies are required to draw firm conclusion about the toxicity of the microplastics and the available data are not alarming. But answering to this question is urgent. Because it is not just the marine environment, the air we breathe, the water we drink, and the food we eat, were also found to contain microplastics. Even the salt we use for cooking was found to contain microplastics. If someone finds microplastics in salt, there may be an option to choose another salt. But if we pollute the ocean with plastics, it is not an option but inevitable to lose nutritious food from ocean, marine ecosystem, and ultimately our health.