Marine water pollution is an increasingly alarming environmental issue involving the contamination of oceans and seas with chemicals, waste, and pathogens.
Among the various types of pollution, plastic pollution, especially due to microplastics, poses a serious threat to the health of both marine ecosystems and humans.
In this article we’ll explore the causes, effects and possible solutions to the growing problem of microplastics in our oceans.
What Are the Main Causes of Marine Pollution?
Marine pollution refers to the presence of external substances, often of human origin, that degrade water quality and endanger marine ecosystems and the species that inhabit them. These substances include chemicals, solid waste, excess nutrients and pathogenic microorganisms.
The primary causes of marine water pollution include:
- Industrial discharge: toxic chemicals, heavy metals and other hazardous substances released by industrial facilities and extractive activities.
- Agricultural runoff: Excessive use of fertilizers and pesticides that are carried by rivers and streams into the seas and oceans.
- Domestic wastewater: The release of chemical substances and pathogens through sewage systems and urban solid waste.
- Oil spills: Accidents involving oil tankers and offshore infrastructure that lead to oil being released into the ocean.
- Marine litter: Plastic items and other solid waste that end up in the sea as a result of human activity.
Plastic pollution
Plastic pollution is one of the leading sources of marine contamination. It’s estimated that approximately 8 million tons of plastic are dumped into the world’s oceans every year.
Plastic can take hundreds of years to break down, and in the meantime, it poses a major threat to marine life and ecosystems.
How Does Plastic Become Microplastic?
Let’s start by defining microplastics: these are plastic particles smaller than 5 millimeters in size (hence the prefix “micro”).
They can originate from the breakdown of larger plastic debris such as bottles, bags, and fishing nets, or they can be manufactured directly in the form of microbeads used in cosmetics and personal care products.
Exposure to ultraviolet rays from the sun, combined with the action of waves and ocean currents, contribute to the degradation and fragmentation of plastic waste, reducing it into microplastics.
Which microplastics can be found in the sea?
Microplastics come in various shapes and sizes. The main categories of microplastics found in the oceans include:
- Microbeads: tiny spherical plastic particles used in cosmetics, cleaning agents, and industrial abrasives.
- Fragments: Pieces of plastic that result from the breakdown of larger objects such as bottles, containers and packaging.
- Nurdles: Small plastic pellets used as raw material in the manufacturing of plastic products.
- Fibers: Thin strands of plastic released into the environment during the washing of synthetic fabrics such as polyester and nylon.
How do microplastics end up in the ocean and how much?
Microplastics can reach the ocean through a number of pathways, including:
- Wastewater discharge: microbeads and plastic fibers from personal care products and synthetic textiles enter sewage systems and eventually flow into rivers and seas.
- Waste disposal: Inadequately managed landfills and open dumps can allow plastic waste to spread into the environment and be carried toward the oceans.
- Fishing and maritime activities: abandoned fishing gear, damaged equipment and waste coming from boats can all release microplastics into the water.
- Coastal erosion and beach litter: the movement of waves and streams can transport plastic waste from beaches and shorelines straight into the sea.
It is estimated that between 15 and 51 trillion microplastic particles are currently floating in the oceans, with a total weight exceeding 250,000 tons.
What are the environmental impacts caused by microplastic pollution?
Microplastic pollution causes serious harm to marine ecosystems and fauna, including:
- Ingestion: Marine organisms such as fish, seabirds and invertebrates may accidentally ingest microplastics, which can lead to digestive blockages, malnutrition and even death.
- Chemical transport: microplastics can absorb toxic chemicals from the surrounding environment and carry them into the bodies of marine organisms that ingest them.
- Ecosystem alteration: the presence of microplastics can alter the structure and function of marine ecosystems, negatively affecting biodiversity and biological productivity.
Microplastics effects on marine organisms
Microplastics can have various negative effects on marine organisms: we previously discussed this in a dedicated article we encourage you to read.
We have outlined below the most severe and problematic impacts of microplastics on marine organisms:
- Physical injuries: ingested microplastics can cause digestive tract obstructions, cuts and ulcers in fish, seabirds, and marine mammals.
- Stress and behavioral changes: the presence of microplastics in the marine environment can lead to stress and alter feeding, reproductive and locomotor behaviors.
- Cellular damage: chemicals absorbed by microplastics may cause damage at cellular level, including oxidative stress and gene expression changes.
- Bioaccumulation and biomagnification: toxic substances linked to microplastics can accumulate in marine organisms and biomagnify through the food chain, potentially harming top predators, including humans.
Why are microplastics in seafood a risk to humans?
When fish ingest microplastics, human health can also be at risk. Toxic chemicals attached to microplastics may accumulate in fish tissues and subsequently be absorbed by the human body through seafood consumption.
The research on this subject is still evolving and more studies are needed to fully understand the extent and nature of these risks, but we already know some of the potential human health issues associated with microplastic ingestion:
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- The exposure to hazardous chemicals: microplastics can absorb and carry dangerous substances, such as pesticides, heavy metals and persistent organic pollutants (POPs). When microplastics are ingested through contaminated seafood or drinking water, toxic chemicals attached to them may be released and absorbed by the human body, increasing the risk of harmful effects.
- Endocrine disruption: These compounds can interfere with the body’s hormonal balance.
- Immune system effects
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- Gastrointestinal issues: while it’s rare for microplastics to accumulate in the human digestive system, concerns remain that ingesting large amounts could cause irritation, inflammation or blockages
- Potential carcinogenic effects
It’s important to note that research on the human health impacts of microplastics is still ongoing, and more studies are needed to fully understand the extent and nature of the risks.
In the meantime, reducing microplastic pollution and limiting exposure are crucial steps to protect both human health and the environment.
How many fish die because of plastic pollution?
Is hard to accurately estimate how many fish die due to plastic and microplastic ingestion as research is still limited and often focuses on specific species or regions.
However, it is widely acknowledged that a broad range of fish species is affected by plastic pollution, with potential impacts on mortality, growth and reproduction.
What can we do to reduce plastic pollution in the sea?
To limit marine plastic pollution, especially microplastics, we need to take action on multiple levels:
- Reduce single-use plastics: promote the use of sustainable and reusable materials to cut down on plastic waste.
- Recycle and waste management: improving how plastic waste is collected and recycled and promote more responsible disposal practices at home and in industry.
- Regulations and laws: enforce stricter laws to limit microplastic use in consumer products and control industrial and agricultural discharges into marine environments.
- Beach and shoreline cleanups: Organize coastal cleanup initiatives to remove plastic debris and prevent its breakdown into microplastics.
- Support research and innovation: promote research in microplastics, their effects on marine ecosystems and human health. Support new technologies for detection, removal, and treatment.
- Raise awareness: educate the people about the impact of microplastics on marine ecosystems and human health, and promote sustainable behaviors.
- International cooperation: working collectively at the global level to tackle microplastic pollution and develop shared strategies and policies to protect our oceans and seas. In this regard, a historic breakthrough has just occurred: the first international treaty for the protection of the oceans.
Marine water pollution caused by microplastics represents a major environmental challenge that demands coordinated, cross-sector action to be addressed effectively.
Protecting marine ecosystems – and, by extension, our own lives – from the impact of microplastics requires a joint commitment from governments, industries, NGOs, and citizens alike to reduce plastic production and consumption, to improve waste management and to promote sustainable and innovative solutions.
There’s still much we can do to care for the oceans that surround our planet. Some of the most relevant examples come from the United States, specifically from the iconic New York City, which has launched, in recent years, numerous initiatives to fight coastal pollution, giving us the demonstration that the game is far from over and we have the power to change the the fate of the world through the small choices we make every day.
Read our in-depth article to learn more.
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