Causes, Effects and Solutions To Algal Bloom on Aquatic Ecosystems

An algal bloom is the rapid increase of the algae population in aquatic ecosystems, both in fresh and marine waters, where it is known as either a water bloom or a marine bloom, respectively.

Basically, algae thrive where there is an abundance of two nutrients — phosphorus and nitrogen, usually caused by runoff of nutrients (animal waste, fertilizers, sewage) from the land.

Algal blooms are mainly composed of bio-toxins and are characterized by a distinct discoloration of water due to many pigmented algae cells.

The colors of these blooms range from green, red, brown, and yellow. However, the major types of algal blooms are cyanobacteria (blue-green algae) and red tides (red algal blooms).

Together with water hyacinth, algal blooms form some of the most common forms of eutrophication, a biological process known to deplete the supply of oxygen, leading to the death of animal life

This article seeks to help you better understand the causes, effects, and possible solutions for an algal bloom.

Causes of Algal Bloom in Aquatic Ecosystems

Algal blooms can’t just be attributed to a single cause. The condition can emanate from a variety of causes, some of the common ones including:

1. Runoff of Nutrients

An algal bloom mostly happens when there are large amounts of nitrogen and phosphorus in water. These nutrients are washed away from lands and farms heavily riddled with nitrogenous and phosphatic fertilizers.

Rain acts as an agent by washing these leachable nutrients from the soil into water bodies such as rivers and streams, which eventually end up in large reservoirs such as lakes and oceans.

These nutrients are also deposited into waterways through drainage systems. Due to poor sewage treatment, untreated raw sewage finds its way into water bodies, and because it is rich in nitrogen compounds such as nitrates and ammonia, it causes algal bloom.

Water pollution, particularly the discharge of poorly treated or untreated industrial waste into waterways, releases raw toxic waste into water systems. This wastewater contains nutrients and compounds such as nitrogen, lead, and phosphorus, eventually resulting in the dense growth of algae.

2. High Temperatures

High Temperatures

The global world is facing the destruction of the ozone layer caused by global warming. But did you know that global warming causes more than just the high temperatures we feel?

That’s true — and algal bloom is among the other factors triggered by global warming. Conducive temperature is needed for certain bacteria to survive in and out of water, and global warming seems to turn our water bodies into one favorable environment for algae.

In addition, the exceedingly high temperatures experienced due to global warming have led to the rapid decomposition of nutrients such as nitrates and ammonia, which are easier forms for bacteria to use up and grow in quantity.

3. Presence of Dead Organic Matter

In the atmosphere and water, various types of bacteria exist, each seeking appropriate environments for growth and sustenance. Similar to other bacteria, the algae bacterium thrives in the presence of deceased organisms in water.

Combined with the nutrients within the water, the decomposition of organic matter fosters the proliferation of algae, ultimately resulting in the formation of an algal bloom.

4. Slow-moving Water

Algal blooms thrive in expansive bodies of stagnant water. Many types of blue-green algae specifically favor stable water conditions characterized by low flows, extended retention times, gentle winds, and minimal turbulence.

Conversely, some algae species prefer conditions involving mixing and turbidity. In such environments, disturbances are reduced, explaining their limited growth in water bodies with rapid flow rates, such as rivers and stream

5. Light

When blue-green algae populations are exposed to long periods of high light intensity (photo-inhibition), they experience a reduction in their populations.

However, their optimal growth occurs intermittently when exposed to high light intensities, a situation common under the water surface where the light environment is fluctuating.

Blue-green algae have higher growth rates than any other group of algae, even under low light conditions or in turbid water. This ability to adapt to variable light conditions gives cyanobacteria a competitive advantage over other algal species.

6. Turbidity

The water column’s suspended particles and organic matter (flocs) cause turbidity. High turbidity occurs when water runs through the system (high discharge after a rain event). Low turbidity occurs when only a small amount of suspended matter is present in the water column.

The slow-moving or stagnant water can cause low turbidity, allowing suspended particles to settle out of the water column. When turbidity is low, more light can penetrate through the water column, creating optimal conditions for algal growth. In return, growing algae creates a turbid environment.

Slow-moving Water

Effects of Algal Bloom on Aquatic Ecosystems

Some of the main effects of algal bloom include:

1. Endangerment to Human Health/life

Algal blooms produce toxins that reduce the suitability of water for human consumption. Their large presence in the water and their well-propagating sequences lead to quick contamination of water, posing a health hazard to humans.

Strong irritation, itching, and even skin diseases can be experienced when such contaminated water comes into contact with the human skin.

2. Death of Aquatic Life

For any living organism to survive, they need oxygen for respiration. Fishes and other aquatic life depend on the oxygen dissolved in water. Similarly, for the algae bacterium to survive, it needs oxygen.

However, in plant life, a high mode of propagation and dense growth in a very short period increases competition for oxygen, leading to an imbalance in the aquatic ecosystem and suffocation of aquatic animals like fish.

More deaths of aquatic animals means more food for the algae, leading to faster propagation and, in the long run, deterioration of aquatic life.

3. Ocean Dead Zones

Death of Aquatic Life

Nutrient pollution can create dead zones in water with little or no oxygen, where aquatic life cannot survive. Also known as hypoxia, these areas are caused by algal blooms consuming oxygen as they die and decompose. This can result in the massive deaths of aquatic life.

As a result, the area around the algal blooms will be a dead zone with dead animal and plant life alike. The resulting foul smell may affect the rest of the aquatic life, sending them further away from the area.

Over 166 dead zones have been documented nationwide, affecting water bodies like the Chesapeake Bay and the Gulf of Mexico. The Gulf of Mexico dead zone is the largest in the United States, measuring 5,840 square miles. It occurs every summer because of nutrient pollution from the Mississippi River Basin, an area that drains 31 upstream states.

4. Strain on Economies

The presence of algal bloom makes transport on waterways cumbersome, increasing water transport costs and even forcing some traders to opt for more expensive means of transport, such as air. Countries that have realized the growth of algal blooms too late have to seek alternative transport routes to engage in trade, resulting in economic losses.

Also, since the growth of algal blooms leads to the death of aquatic life, there can be widespread losses to fishermen who depend on fishing as an income-generating activity. Moreover, the concept and process of treatment of the algal bloom is a costly affair and often requires millions of taxpayers’ money.

5. Strain on Industries

Algal blooms badly affect fishing and shellfish industries, killing fish and contaminating shellfish. Annual losses to these industries from nutrient pollution are estimated to be in the tens of millions of dollars.

Besides, some industries, for example, food processing companies, only require clean water from water bodies to drive their production. This means that algal blooms will cause additional water treatment costs to get clean water, leading to increased overhead costs.

6. Losses in the Tourism Industry

Death of Aquatic Life

With the dense growth of algal blooms on natural recreational water surfaces, the tourism industry suffers greatly as the resulting foul smell and dead zones mean there are no fishes to watch, no available ways to navigate the water, and no swimming or boating activities.

7. High Water Utility Bill for Domestic Consumers

With algal blooms contamination or not, people still need water for consumption. The municipality will have to invest in water treatment processes that eliminate the toxins caused by algal blooms.

In some cases, extensive growth of algal blooms may lead to scarcity of fresh drinking water if the town or community depends on the contaminated source as the only one for distributing consumption water.

All these increase the treatment costs and the water demand, which dramatically raises domestic consumers’ water utility bills.

8. Algae Affect the Food Chain

Sometimes, harmful algal blooms create toxins detrimental to fish and other animals. After being consumed by small fish and shellfish, these toxins move up the food chain and can impact larger animals like sea lions, turtles, dolphins, birds, and manatees.

Even if algal blooms are not toxic, they can negatively impact aquatic life by blocking out sunlight and clogging fish gills.

9. Ozone Pollution

Airborne nitrogen compounds like nitrogen oxides help form other air pollutants, such as ground-level ozone, a component of smog that can restrict visibility.

Wind and weather can carry ozone many miles from urban to rural areas. Ozone pollution can damage trees and harm the appearance of vegetation and scenic areas.

10. Reduced Property Value

Clean water raises the value of a nearby home by up to 25 percent, whereas waterfront property values can decline because of the unpleasant sight and odor of algal blooms.

11. Acid Rain

The nutrient pollution in the air causes acid rain, which damages lakes, streams, estuaries, forests, and grasslands across the country.

Some Interesting Solutions to Algal Bloom

Despite all the sad stories about algal blooms; how they affect our health, environment, ecosystem, economy, and other aspects, the good news is that all isn’t lost.

There’s still something we can do to reduce or even prevent the condition from happening in the first place. Here are some solutions to algal bloom:

1. Proper Sewage Treatment

Proper Sewage Treatment

In a bid to limit the presence of nitrogen and phosphorus in water, there is a need to treat sewage water using the recommended waste treatment procedure — the five-step process that ensures optimal treatment.

Disinfection and tertiary treatment, involving the removal of components like nitrogen and phosphorus through processes such as nitrification, along with eventual sludge treatment, are imperative measures.

These processes are essential to prevent the introduction of excessive nutrients into primary water sources like rivers, lakes, oceans, and streams, ensuring the protection and preservation of these ecosystems.

Quality water treatment processes also ensure people are consuming safe water and, above all, protect aquatic life.

2. Reduction of Pollution and Water Wastage on a Personal Level

To achieve the global environmental conservation goals of minimal pollution, it has to start with individual initiatives by minimizing wastage, recycling, and reusing to save the environment.

When this is done by all people at home, at work, or at school, it can work towards reducing the overall nutrient load into water bodies and even ease the water treatment process. Ultimately, it can aid in minimizing the dense growth of algae in the water.

3. Optimal Fertilizer Application

Fertilizers have to be used by farmers to boost crop yields by providing them with deficient nutrients. However, it can be done optimally by utilizing options such as top dressing or spraying, depending on the nutrients administered. Farmers are advised to consult with agricultural experts about the mode and quantity of fertilizer to use.

Employing the most desirable practices and applying the right amounts of fertilizers can ensure both the optimal growth of the crops as well as balanced toxicity or nutrient concentration in the soil.

On the onset of rain, it would mean only small quantities of chemicals are washed into waterways, reducing the incidence of algal bloom.

Even for lawn and garden care, apply fertilizers only when necessary and at the recommended amount. Don’t apply fertilizer before windy or rainy days or in an area near waterways. Also, store unused fertilizers and dispose of empty containers properly.

4. Use of Hydrogen Peroxide

Use of Hydrogen Peroxide

The compound has been used as an effective treatment against algal blooms. This is suitable for smaller water bodies such as large ponds or small lakes for the easy monitoring of the compound’s impact and the aquatic life.

5. Ultrasound Bloom Treatment

This technology focuses on ultrasonic sound waves in water bodies to look for algal blooms and to control their growth if discovered — reducing algae growth by up to 90%. All this is tried and tested; thus, no harm comes upon aquatic life as it is 100% environmentally friendly with the added advantage of low operational costs.

This treatment monitors large water bodies and can determine whether the threat of algal bloom is present or not based on the prevailing conditions.

These waves are sent over the top layer of the water bodies to counter the buoyancy, making them sink and disable photosynthesis. The algae eventually die due to the absence of light.

6. Use of Non-toxic Cleaning supplies at Home

Choose non-toxic, phosphate-free detergents, soaps, and household cleaners at home and while washing your car. Use the amount of detergent or soap sparingly; more is not better.

Select the proper load size for your washing machine. Only run your clothes or dishwasher when you have a full load. Use a commercial car wash that requires disposing of wastewater properly, and many of them filter and recycle their water. Try to minimize runoff by reducing water use and use a sink or toilet, or the grass to empty wash water outside.


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About Rinkesh

A true environmentalist by heart ❤️. Founded Conserve Energy Future with the sole motto of providing helpful information related to our rapidly depleting environment. Unless you strongly believe in Elon Musk‘s idea of making Mars as another habitable planet, do remember that there really is no 'Planet B' in this whole universe.