The key difference between eutrophication and algal bloom is that eutrophication is a process by which excessive growth of algae occurs due to release of nutrients, including nitrates and phosphates, into water bodies in larger quantities, while the algal bloom is the mass of phytoplankton rapidly grown in the water body as a result of eutrophication.
Anthropogenic activities have disturbed the environmental balance. Their activities cause water, soil and air pollution, affecting different levels of the biosphere. Excessive release of fertilizers, sewage and waste effluents is one of the main factors that pollute water bodies, which lead to eutrophication. Eutrophication is the excessive growth of algae in water bodies. And, this algal masses or bloom of phytoplankton are called algal blooms. Eutrophic water bodies turn into green colour due to algal blooms. Moreover, the rapid growth of algae negatively affects all other aquatic organisms.
CONTENTS
1. Overview and Key Difference
2. What is Eutrophication
3. What is Algal Bloom
4. Similarities Between Eutrophication and Algal Bloom
5. Side by Side Comparison – Eutrophication vs Algal Bloom in Tabular Form
6. Summary
What is Eutrophication?
Eutrophication is a process which occurs due to the excessive release of nutrients into water bodies. Nutrient enrichment develops due to excessive release of fertilizers including nitrates and phosphates, industrial and domestic sewage effluents, detergents etc. This leads to the uncontrollable growth of algae (algal bloom), which is the starting point for different harmful phenomena. The excessive growth of algae blocks the penetration of sunlight into the bottom of the water body causing the death of different aquatic plants including algae due to insufficient sunlight for photosynthesis. Microorganisms start to decompose dead plant materials in the water body. During decomposition, toxic gasses and materials accumulate in the water, causing water pollution.
Figure 01: Eutrophication
Moreover, due to the activity of decomposing microorganisms on a larger scale, the BOD (biological oxygen demand) level of water increases. BOD is the amount of dissolved oxygen in water needed for decomposing microorganisms to convert organic matter into inorganic matter. Due to the insufficient oxygen levels in water and the presence of toxic compounds, the death of fish, shellfish crabs, molluscs, and other aquatic animals takes place. Due to this phenomena, the activity of decomposing microorganisms increases further, which lead to the formation of more toxic compounds and release of bad odour.
In addition to these, the other animals including humans that interact with eutrophic water bodies are also negatively affected. Moreover, eutrophication also leads to the decrement of the aesthetic value of a water body.
What is an Algal Bloom?
Algal bloom is a rapid growth of cyanobacteria and microscopic algae in a water body due to eutrophication. In fact, this is the condition where there is a great increase or bloom of phytoplankton in the water body. Algal bloom comprises mainly of microscopic, unicellular alga. Due to algal blooms, the water appears in green colour. Algal blooms block the penetration of sunlight to the bottom of the water bodies. This leads to the death of different plants, including algae due to insufficient sunlight for photosynthesis.
Figure 02: Algal Bloom
Ultimately, microorganisms act on the dead organic matter in the water body and thus, the biological oxygen demand increases. Furthermore, during the microbial decomposition, different toxic material such as gasses are released into the environment.
What are the Similarities Between Eutrophication and Algal Bloom?
- Eutrophication causes algal blooms due to enrichment of water bodies by nitrates and phosphates in larger quantities.
- Algal blooms and eutrophication are serious environmental problems.
- Both lead to the death of aquatic flora and fauna.
- Water bodies become green in colour due to both phenomena.
- They are responsible for the depletion of the oxygen level in the water body.
- Moreover, they reduce water quality.
What is the Difference Between Eutrophication and Algal Bloom?
Eutrophication is the richness of nutrients, especially nitrates and phosphates in a water body. On the other hand, the algal bloom is the rapid growth and accumulation of microscopic algae and cyanobacteria in a water body. So, this is the key difference between eutrophication and algal bloom. Besides, as a result of eutrophication, the excessive growth of algae takes place. As a result of algal bloom, light penetration into the water body decreases and causes the death of aquatic flora and fauna.
The following table summarizes the difference between eutrophication and algal bloom.
Summary – Eutrophication vs Algal Bloom
Eutrophication is the accumulation of high concentration of nutrients in a water body, especially nitrates and phosphates, received from the runoff water of agricultural lands. It causes algal blooms. Algal blooms are the large quantities of microscopic algae and cyanobacteria rapidly grown in water bodies. So, this summarizes the difference between eutrophication and algal bloom.
Reference:
1. Lallanilla, Marc. “Find out How Eutrophication Causes Deadly Algal Blooms.” The Spruce, The Spruce, 15 Aug. 2019, Available here.
2. “Algal Bloom.” Wikipedia, Wikimedia Foundation, 23 Nov. 2019, Available here.
Image Courtesy:
1. “Eutrophication” By eutrophication&hypoxia (CC BY 2.0) via Flickr
2. “Toxic Algae Bloom in Lake Erie” By Jesse Allen and Robert Simmon – NASA Earth Observatory (Public Domain) via Commons Wikimedia