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Attack of the Algae

During a walk through your local park, perhaps you’ve noticed the unsightly green films covering stagnant lakes or ponds. Upon closer inspection, these films can be deduced as ghastly amounts of algal blooms. Although you might brush this occurrence off and go about your daily life, algae overgrowth, also known as algal blooms, can have serious negative environmental consequences. In the age of industrial farming, harmful chemicals, and climate change, harmful algal blooms have emerged. In this blog, we will explore the negative environmental consequences of algae overgrowth and the methods you can take to prevent them.



In the correct conditions, algae can become wildly overgrown and damage the organisms surrounding it. Although algae can grow at all times of the year, even under ice, algae particularly grow during late summer and early fall. Blooms can last anywhere from several days to multiple months if conditions allow. This timing is mainly due to algae’s preference for warm temperatures with cyanobacteria, also called blue-green algae, preferring temperatures over 25 degrees Celsius. As the sun heats up the surface of the water during the spring, continuing throughout the summer into early fall, thermal stratification occurs where the surface of the water becomes warm while deeper bottom layers remain cold. This temperature difference results in density stratification, which creates a beneficial condition for algae to grow rapidly.

More light, which warms up stagnant water and provides energy for photosynthesis, creates optimal conditions for algae growth. Algae prefer conditions with more light, so some algae species, such as cyanobacteria, may control their buoyancy to position themselves higher in water columns to achieve this. Also, although algae can grow in turbid waters, algae prefer stable conditions in stagnant water due to its promotion of thermal stratification, which allows for density stratification.

The final optimal condition of algae overgrowth is eutrophication, which is the nutrient enrichment of water. Algae need the essential nutrients of nitrogen and phosphorus to grow. Phosphorus is known to limit algal growth in large amounts, while algae exposed to high amounts of nitrogen in waters often rapidly grow. Certain farming practices can cause eutrophication, as industrial farmers use great amounts of nitrogenous fertilizer to efficiently and quickly grow plants. Shoreline development, wastewater and sewage practices of dumping waste in water bodies, and urban stormwater runoff have also been known to deliver high amounts of nitrogen to waters and cause eutrophication.

Negative Consequences to the Environment

Although seemingly harmless floating on the surfaces of water, algae can have detrimental effects on the organisms surrounding them. Following the theme of the day, algae overgrowth tends to deprive organisms surrounding it of essential objects to their survival.

For one, algae often deprive plants and the animals below them of oxygen. On the occasional rainy day or under cloudy conditions, like many other plants, algae will undergo cellular respiration to survive. The massive amount of algal cells conducting photosynthesis in algal blooms often quickly depletes water sources of oxygen, leading to the deaths of many fish and other organisms.

Although plants do not seemingly need oxygen, that is a myth many people believe. Contrary to popular belief, plants do undergo cellular respiration, especially in conditions lacking mass amounts of sunlight, and require oxygen to do so. For the fish and other organisms in the water, many require aerobic conditions as well to survive. Because of this, algae overgrowth in bodies of water causes mass death.

Algal blooms also prevent sunlight from reaching plants below. Due to algae’s tendency to grow at the surface of waters, primarily from their need for warm conditions, and tendency to cluster, large patches of algae form, covering organisms below. Sunlight cannot reach through these thick films, leaving plants below without light energy to conduct photosynthesis. Their inability to conduct photosynthesis leaves them without glucose and, ultimately, without the ability to survive.

To put the final nail in the coffin, so to speak, algae releases toxins into the surrounding water. These toxins infect the water and can cause illness in humans and animals that may be deadly, contributing to the death toll caused by algae overgrowth.

Negative Consequences to Humans

As a human, you may feel some sense of compassion for these dying plants and animals in waters with algae overgrowth. In these scenarios, many humans still do not take any action due to the mindset that these issues do not impact them. However, algae overgrowth can negatively impact the health of individuals, as well as create the much-hated financial burden of higher prices on water treatment.

Algae are known to leak toxins into the surrounding water, which can cause symptoms including irritation of the skin, eyes, nose, or throat. More severely, it can also cause stomach pain, vomiting, diarrhea, headaches, fevers, fatigue, and neurological symptoms such as muscle weakness or dizziness, depending on how long contact was with the various toxins released by algae.

This risk is heightened by the fact that many water companies use the waters infected by toxins from algae overgrowth. Though water treatment is available, water purification does not always remove all substances that can make a person or animal ill. For the time it takes to purify these infected waters, and for the purification that doesn’t even remove all toxins, prices are heightened to cover the extra effort. Any individual drinking from waters with algae overgrowth, even after purification, risks health issues and is subjected to the long-hated costs of water purification.

How You Can Help

To prevent terrible cases of algae overgrowth in once-healthy waters, you can monitor waters for algal blooms. Several organizations, such as:

will assist in identifying toxic algae blooms before they break out. Once identified, you can report these suspected algal blooms to your state to prevent the overgrowth before it begins.

In addition to watching out for these overgrowths, as a civilian, you can prevent some nutrients from leaking into the waters by advocating for several solutions to nutrient pollution. For one, you can spread the message to farmers and anybody with their own garden to use fertilizers only in appropriate amounts and at appropriate times. Oftentimes, farmers and civilians alike use high amounts of fertilizer, despite there being no need for it, to ensure the growth of their plants. However, much of the fertilizer that is overused ends up in contact with water and contributes to nutrient pollution.

You can advocate for the use of better drainage systems, such as Subsurface Tile Drainage practices which are used in the Middle East. Better drainage systems may allow for water carrying high amounts of nutrients to gradually decrease in nutrient concentration as it is carried to other areas, while still providing proper drainage for crops.

To prevent high amounts of nutrient water from reaching bodies of water, you can also advocate for the use of more field buffers, such as trees, to use up the nutrients before they reach the water, or watersheds to direct the nutrient water flow to a more favorable area. Building fences to prevent livestock from reaching water sources and expelling more nutrients into the waters, and farmers reducing the intensity of field tilling to allow for less runoff, may also be beneficial actions to advocate for in your local community.



Algae overgrowth is caused by a variety of optimal conditions including warm temperatures, stagnant and stable water, high amounts of sunlight, correct seasonal times, and eutrophication of the water. Eutrophication, which is the nutrient enrichment of bodies of water, contributes to nutrient pollution, which can be prevented through various means such as field buffers, less tilling, preventing livestock from reaching water sources, watersheds, better drainage systems, and fertilizer in correct amounts. These actions can be advocated by civilians to prevent algae overgrowth.

Algae overgrowth is harmful to plants, animals, and humans, as it causes sickness through the toxins it releases, causing death and higher water purification costs; covers plants below preventing sunlight from reaching them; and depletes waters of oxygen, leading to the deaths of organisms surrounding these algae overgrowths. These overgrowths can be prevented further with civilians informing themselves of the signs of incoming algae overgrowth and reporting to state officials these issues before algae overgrowth can come to fruition. Overall, algae overgrowth is harmful to the environment and the organisms living in it, thus we must take measures to prevent them.

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Author: Karen Wong

Editor: Charlotte Wang


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