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Algae Bloom

What Is Algae?

Algae are entities that are widespread all throughout the world. They are growing in various sizes, shapes, and colours. They may live alone or they may grow on other organisms’ surfaces, on rocks or in the soil. Such species are critical as they make a lot of the oxygen on Earth that animals and humans require for breathing. A few of these entities such as seaweed resemble plants. In fact, they are neither animals nor plants. Rather, they belong to a class of living entities known as protists. These highly differ in size and are increasing in many different ecosystems. Microscopic algae in oceans and lakes, or phytoplankton, float or dive. Phytoplankton is so tiny that one thousand of them could be accommodated on a pin’s head. The largest species of algae are coral and can range from the bottom of the ocean to the surface of the water up to 100 m (300 ft).

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Table of Content:

  1. Importance of Algae
  2. What is an Algae bloom?
  3. What are the Causes of Algae Bloom

Though most of the species thrive in seawater or freshwater, they do grow in soil, plants, and animals like tortoises and polar bears, and in or below porous rocks such as sandstone and calcareous. They can withstand an extensive range of temperatures and can expand deep inside the polar ice in hot springs, on snowbanks.

There are numerous groups of living organisms in the algae (singular algae). These are habitually found in moist environments or water bodies and by photosynthesis absorbing light energy, turning inorganic substances with the absorbed energy into simple sugars. Almost all algae have photosynthesizing parts. In contrast to other photosynthetic bacteria such as green and purple bacteria, they produce oxygen. Some one-celled algae completely depend on external energy sources and their photosynthetic apparatus has been either lost or reduced.

Explore: NEET MCQs on Algae

Importance of Algae

As a Source of Oxygen

Algae are responsible for more than 30% of the total oxygen produced by photosynthesis. Some figures suggest that approximately 50% of oxygen requirement of terrestrial animal is supplemented by algae. Mineral degradation in water may lead to a decrease in algal population, which results in death of fish due to oxygen depletion.

As a Source of Food

Algae are primary producers. They are extremely important because a large number of aquatic animals are heavily dependent on algae for their food requirements.

As an Indicator of Pollution

Algae growth is an indicator of water contaminants. Increase in mineral content of water due to agricultural chemicals and fertilizers, which are rich in nitrogen and phosphorus, lead to the rapid growth of algae in the water body. Heavy metals, when taken by algae in high quantity, lead to inhibition of plant’s growth.

As a Provision of Habitat

Large algae species provide habitats to many other organisms. E.g. Kelp forests are large algae ecosystems, which provide shelter to many animals such as snails, shrimps, sea urchins, etc. More than one species of kelp may be present in a Kelp forest.

Also Read:  What is Blue-Green Algae?

What is an Algae bloom?

An algal bloom or algae bloom is a rapid increase or aggregation in the algae population of freshwater or marine water systems and is often identified by water discolouration of their pigments. The term algae encompass most types of aquatic photosynthetic organisms, including macroscopic, multicellular organisms such as seaweed and small, single-celled organisms such as cyanobacteria. A kelp forest is an example of a macroscopic blooming algal.

Algal blooms are the result of a nutrient, such as fertilizer runoff nitrogen or phosphorus, entering the water environment and causing excessive algae growth. An algal bloom affects the entire ecosystem; it can yield beneficial outcomes, such as simply feeding higher tropical levels to more harmful effects, preventing sunshine from entering other species, inducing oxygen loss in the atmosphere, and secreting toxins into the environment depending on the individual. The process of nutrient oversupply leading to the growth of algae and depletion of oxygen is called eutrophication.

What Are The Causes of Algae Bloom?

1. Excess of Nutrients

Algal proliferation is caused mostly by the accumulation in the water of large quantities of phosphorus and nitrogen. These minerals were wiped away from fields and farmland where nitrogen and phosphatic fertilizers are deeply contaminated with. Rains are instrumental in wiping away these leachable nutrients from the soil into water bodies like streams and rivers that gradually end up in large ponds like oceans.

Such nutrients are also collected via drainage systems into waterways. Untreated, raw sewage finds its way into water bodies due to poor sewage treatment and because it is rich in nitrogen compounds like ammonia and nitrates, it leads to algal bloom.

Water pollution, in particular, the leakage into rivers of crudely treated or untreated industrial waste contributes to the introduction of pure toxic waste into water systems and as it contains contaminants and substances such as lead, nitrogen, and phosphorus; the result is heavy growth of algae.

2. Presence of Dead Organic Matter

There are generally many types of bacteria present both in the atmosphere and in water. They are all looking for suitable growth and nutrition media. So, like other bacteria, by the inclusion of dead species in water, the algae bacterium is activated. The dead organic matter, together with the nutrients in the water, ends up propagating the growth of algae in water leading to the blooming of algae.

3. High Temperatures

The world faces the depletion of the ozone layer caused by global warming. This is one of the main reasons why algal bloom is fast-growing. For certain bacteria to live both in and out of the water, a favourable temperature is needed.

The excessively high temperatures encountered as a result of global warming have resulted in the accelerated decomposition of nutrients such as nitrates and ammonia, which are simpler ways to use and expand in quantity for bacteria.

4. Slow Moving Water

Algal blooms require huge quantities of water that are nearly yet to grow. Their proliferation in these waters is less troubling and this explains their confined growth in fast-flowing streams and rivers.

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Frequently Asked Questions


What is the meaning of algal bloom?

The rapid increase or aggregation in the algae population of freshwater or marine water systems is termed an algal bloom. It is often identified by water discolouration due to the algae’s pigment. The term algal bloom typically refers to the rapid multiplication of microscopic algae rather than macroscopic ones.


What causes algal bloom?

The major cause of algal bloom is the excessive aggregation of nutrients like phosphorus or nitrogen. Sometimes dead organic matter, together with the nutrients in the water, ends up propagating the growth of algae in water leading to the blooming of algae.


What is a harmful algal bloom?

A HAB or harmful algal bloom is the one that causes negative impacts to other organisms by producing toxins. Sometimes they can just lead to severely low oxygen levels and thereby resulting in the death of organisms.

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