What Causes Algae?

What Causes Algae?

Algae are often misunderstood entities in the aquatic ecosystem. While they are essential for producing oxygen and serve as the base for food chains, excessive algae growth can cause several environmental and health problems. Algae such as blue-green algae (cyanobacteria) can produce toxins that harm humans and animals.

But is all algae dangerous? As a naturally occurring part of water systems, algae can become an issue when it grows excessively due to certain environmental factors. 

Algae growth is typically caused by a combination of excess nutrients (namely nitrogen and phosphorus), warm temperatures, sunlight, and low water flow or turbulence. The key is to identify and address the root cause of excessive algae growth to prevent it from becoming a major issue.

Fortunately, preventing and managing algae growth can be done relatively quickly. Let’s look at some common algae causes - and what you can do about them!

What Causes Algae in Ponds?

Algae can emerge - sometimes overnight - due to a number of factors. Some are completely normal, while others indicate an imbalance in your pond environment.

Excess Nutrients

The primary reason behind algae growth in ponds is an excess of nutrients, particularly nitrogen and phosphorus. These can come from sources like agricultural runoff, which is rich in fertilizers, and untreated sewage. 

Every year, an estimated 10 trillion gallons of untreated stormwater wash into water bodies, including ponds, influencing algae growth. That’s a lot of potential nutrients!

Besides agricultural runoff and sewage, there are a few other sources of excess nutrients that can feed algae blooms:

  • Fish waste
  • Excess organic matter (leaves, grass clippings)
  • Aquatic plants

These substances can be broken down by bacteria or converted to gas - both processes release nitrogen and phosphorus into the water. Algae blooms are usually most severe in shallow, slow-moving water, where these nutrients can accumulate over time. Unfortunately, this is often the case with ponds!

Water Conditions

Besides nutrient imbalances, the water's physical conditions also contribute to algae growth. Warm water and abundant sunlight offer a conducive environment for algae to flourish. These are particularly prominent issues during the spring and early fall. For example, still water on a sunlit afternoon is the perfect opportunity for an algae bloom.

Human Activities

Lakes often suffer from the same issues as ponds but on a much larger scale. Diverting more than 80 percent of a river's natural flow is not uncommon in parts of the western United States, leading to nutrient-rich, stagnant water bodies that are prime for algae growth. 

This leads to water quality issues and algae blooms that can even be seen from space. Additionally, runoff from agricultural lands can introduce excess nutrients into lakes, leading to the same problems as in ponds.

Environmental Factors

Natural occurrences such as extreme weather conditions can also lead to algal blooms in lakes. According to the EPA, more than 166 dead zones have been reported nationwide, many in lakes, where algae blooms have led to oxygen-depleted waters. You can imagine the havoc this has on aquatic life within lakes. Wind can also help create blooms by mixing deeper, nutrient-rich water with oxygenated surface water, providing an ideal environment for algae to thrive.

Which Algae Causes Harmful Algal Blooms?

Not all algae are harmful. It's primarily the blue-green algae, also known as cyanobacteria, that cause most freshwater blooms of public health concern. 

These can produce toxins harmful to aquatic life and humans, as well as taste and odor problems, or they may reduce water clarity. It is important to note that not all blooms pose a public health risk, but if you see signs of algae bloom, it's best to avoid contact with the water body and get advice from local authorities.

What Problems Does Algae Cause?

Health Risks

There are several different health risks associated with algae blooms. Cyanobacteria produces toxins that can ill humans and pets when they come into contact with the water or are exposed to aerosolized algal toxins through activities such as swimming, skiing, or boating. 

These illnesses may range from skin irritation to more severe conditions such as gastrointestinal issues, respiratory problems, eye irritation, or more severe neurological disorders.

Environmental Risks

In addition to the health risks posed to humans and pets, algae blooms can be detrimental to the environment as well. Algae blooms can consume large amounts of oxygen in the water, leading to a decrease in dissolved oxygen levels which is harmful for aquatic organism survival. Additionally, when the algae die and decompose,


What causes an algae bloom?

Algae blooms can be caused by various factors, including excess nutrients such as nitrogen and phosphorus, warmer water temperatures, decreased water flow, or changes in salinity. Human activities such as sewage disposal, fertilizer runoff from agricultural fields, or factory emissions can all contribute to an increase in nutrient levels, leading to an algae bloom.

What is an algal bloom?

An algal bloom is a rapid increase in algae population in an aquatic environment. Algae blooms can occur naturally, but excessive nutrient runoff from human activities can cause large-scale blooms that can harm aquatic ecosystems. Algal blooms are often visible as discolored patches or clouds on the water's surface.

Why do algal blooms occur?

Algal blooms occur when an overabundance of nutrients, such as nitrogen and phosphorus, is present in a body of water. When these nutrients are introduced in large quantities to an aquatic environment, they can increase algae's growth rate. This can cause population explosions that can deplete the water's oxygen levels, which can have devastating effects on aquatic species.

What can an individual do to help reduce nutrients and algal blooms?

There are a variety of ways that individuals can help reduce nutrient and algal blooms. Reducing fertilizer use, limiting water runoff from lawns or gardens, and not dumping any chemicals into bodies of water are some simple steps an individual can take to help reduce the number of nutrients entering aquatic environments.

Control Algae Causes with Living Water Aeration

As we’ve discussed, algae cause range from environmental factors to over-fertilization, but one of the best solutions is to introduce a form of biological oxygenation into any body of water. 

Controlled oxygenation encourages healthy bacteria growth that will naturally reduce algae and pollutants in your water. Consider using an aerator or fountain system in affected bodies of water to help control algal blooms.

At Living Water Aeration, we offer a variety of aerator and fountain systems that are designed to help you achieve healthy aquatic environments. Visit us online to learn more about our products, resources, and solutions for managing common algae causes. With our team’s expertise, you can be sure that your aquatic environment is safe and clean for everyone to enjoy!

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