Water Pollution: Algal Bloom, Eutrophication, And Marine Debris

by | Aug 12, 2022 | Pollution, Water Pollution

Home » Pollution » Water Pollution: Algal Bloom, Eutrophication, And Marine Debris

Water pollution happens when water bodies get contaminated with substances that make them unsuitable for drinking, cooking, swimming, cleaning, etc. The contaminants can include bacteria, trash, chemicals, and parasites. All forms of pollution, like air and land pollution, eventually make their way to water sources. Particles causing air pollution can settle onto lakes and oceans. Substances that pollute land can seep into the ground and end up in the water table, eventually making their way to a river and finally the sea.

Water pollution can cause diseases and even act as a poison. Bacteria and parasites can occur in poorly treated sewage water and make their way to drinking water sources. When consumed, they can cause digestive problems such as diarrhea and cholera. Toxic chemicals, herbicides, and pesticides from farms, homes, and industries can cause immediate death. They can even cause neurological problems and cancer. Water pollutants enter our bodies when we use water for drinking and cooking. When they reach the digestive tract, they can further travel to other organs and cause various illnesses. Skin irritations can occur when you come in contact with polluted water while washing clothes or swimming.

Water pollution even affects plants and animals living in water bodies. It can destroy water ecosystems. Sometimes, aquatic animals may survive in polluted waters with chemicals in their bodies. But when we eat these animals, we may either get mildly sick or develop strong toxic symptoms.

In this article, we’re going to look at the different ways water bodies can get polluted and water pollution’s effect on us and the environment.

Algal Bloom

Algal blooms occur when excess nutrients like phosphorus and nitrogen flow from farms and industries into water bodies. The high concentration of these nutrients causes algae to grow faster than the ecosystem can handle. Warmer temperatures can accelerate this process. The overgrowth of algae blocks sunlight from reaching underwater plants. It also consumes oxygen, leaving less of it available for aquatic animals. The algae consume oxygen when it dies, making it almost impossible for aquatic life to survive.

During a ‘bloom’, algae produce toxins that make water unsafe. It can cause fish to die off. Water pollution due to algal blooms can impact human health through consuming contaminated seafood, skin contact, and swallowing water during swimming, rifting, or other recreational activities. The worst part is that water or seafood contaminated by toxins from algal blooms is odorless and tasteless, so there is no way we can even know that we’re consuming contaminated food. Even freezing and cooking cannot destroy the toxins.

This conceptual diagram depicts the environmental factors that lead to harmful algal blooms in the Potomac River. The diagram compares ideal bloom conditions to poor bloom conditions.


Scientists and researchers have documented harmful algal blooms for more than a century. However, they’ve said that the number and frequency of cases have recently increased. An international research team analyzed the relationship between phosphorus concentrations and cyanobacteria growth in 1,500 European lakes. Cyanobacteria are toxin-producing microorganisms that are harmful to human health. They found that 23% of water bodies in Spain and 50% in Germany and the Netherlands exceeded WHO recommended levels.


Eutrophication and algal blooms have much in common. In fact, eutrophication is the process by which harmful algal blooms occur. It happens when aquatic environments become enriched with nutrients, causing excessive plant and algal growth.

Eutrophication sets off a chain reaction in aquatic ecosystems. Excessive nutrients cause the overabundance of algae and plants. These eventually die off and decompose, producing large amounts of carbon dioxide. High concentrations of carbon dioxide lower the pH of seawater by a process called ocean acidification. Acidic waters slow the growth of fish and shellfish. It even affects the formation of shells in bivalves. This leads to fishermen not being able to catch as much seafood. Smaller seafood harvests drive up prices.

The United States National Ocean and Atmospheric Administration (NOAA) suggested the use of bivalve mollusks to reverse eutrophication in estuaries, rivers, mouths, and other coastal areas. Bivalve mollusks are filter-feeders. The mollusks feed on phytoplankton (algae) and detritus, therefore effectively removing nutrients from the water.

Shellfish aquaculture can provide economic benefits through nutrient reduction. Fewer nutrients in the water mean healthy fish populations. Therefore, fisherfolk can harvest a healthy amount of fish from the ocean, providing us with affordable seafood prices and keeping the economy running.

Marine Debris

Free photos of Beach

Marine debris is a persistent water pollution problem. There is a variety of marine debris polluting our oceans and waterways. They can range from tiny microplastics (smaller than 5 mm) to abandoned fishing gear and vessels.

Marine debris has negatively impacted hundreds of marine species worldwide. Marine debris can harm or kill an animal when it ingests the smaller particles or becomes entangled in larger ones like plastic bags and fishing nets. It can also interfere with navigation and threaten human health.

Humans are the source of all marine debris. The debris originates largely from land and enters the ocean. 80% of all marine debris comes from land-based sources. Some marine debris sources include littering, poor waste management practices, sewers, and stormwater discharge.

Marine debris can cause water pollution by the leaching of heavy metals and other contaminants from particles into the water. These pollutants and chemicals can accumulate in seafood, making them harmful for consumption. Some organisms may even mistakenly feed on microplastics. When larger ones eat these organisms, the microplastics become part of their tissues. In this way, microplastics can travel up the food chain, eventually entering our bodies.

The solution to water pollution through marine debris involves prevention and clean-up. Plastics are an everyday item in our society today. We must change our approach to the way we use plastic. We also need collective, focused clean-up efforts. The next time you’re walking on the beach and see litter, remember the damage it can cause to marine animals and your own health. Pick up that litter and throw it in a trash can. Small steps like these make a big difference, and who knows, maybe someone seeing you pick up litter might get inspired and do the same, setting up a chain reaction of good practice.

Also Read: Algal Blooms: What Impact Do They Have On The Environment?


  • Dr. Emily Greenfield

    Dr. Emily Greenfield is a highly accomplished environmentalist with over 30 years of experience in writing, reviewing, and publishing content on various environmental topics. Hailing from the United States, she has dedicated her career to raising awareness about environmental issues and promoting sustainable practices.


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