The main difference between bioaccumulation and biological magnification is that bioaccumulation is the building-up of toxic chemicals in the body of a living organism. But, biological magnification is the increase of the toxic chemicals in amount each time they move up a food chain. Furthermore, organisms take toxic chemicals into the body either through the skin or through ingestion, causing bioaccumulation. But, in biological magnification, toxic chemicals start in small amounts at the lower trophic levels of the food chain and gradually increase in amount when it moves to the higher trophic levels.
In brief, bioaccumulation and biological magnification are two processes by which toxic chemicals accumulate at different levels of a food chain. Generally, the factors that determine the concentration of the toxic chemicals in a particular level of the food chain include persistence, food chain energetics, and the rate of excretion.
Key Areas Covered
1. What is Bioaccumulation
– Definition, Process, Importance
2. What is Biological Magnification
– Definition, Process, Importance
3. What are the Similarities Between Bioaccumulation and Biological Magnification
– Outline of Common Features
4. What is the Difference Between Bioaccumulation and Biological Magnification
– Comparison of Key Differences
Key Terms
Bioaccumulation, Biological Magnification, Food Chain, Toxic Chemicals
What is Bioaccumulation
Bioaccumulation is the building up of substances in the body of living organisms. Generally, organisms uptake toxic chemicals such as pollutants, including pesticides, through the skin or via ingestion. And, this accumulation is a gradual process. It occurs when the absorption rate of the chemical is higher than its rate of excretion. Prior to excretion, these chemicals undergo catabolism in order to breakdown them into excretable forms. Therefore, in order to persist for a longer time, the chemical has to have a longer biological half-life without undergoing catabolism. It is why bioaccumulation increases the risk of chronic poisoning even when the concentration of the toxic compound in the environment is not very high. At a certain level, symptoms specific to the type of chemical may be manifested.
Figure 1: Bioaccumulation
Furthermore, bioaccumulation refers to the uptake of toxic compounds through all possible sources, including air, water, soil, etc. Bioconcentration, on the other hand, is the uptake of toxic substances from water alone. Besides, these toxic chemicals are mainly lipophilic and fat-loving. Therefore, they accumulate in the fat tissues of the organism.
What is Biological Magnification
Biological magnification is the concentration of toxic compounds successively through the trophic levels of a food chain. Generally, the three factors that determine the biological magnification of a particular chemical are persistence, food chain energetics, and rate of excretion. Basically, these toxic chemicals cannot be broken down by environmental processes. Therefore, they are persistent. The concentration of them also increases progressively when they move up a food chain. Therefore, the concentration of a particular toxic substance is low at the lower trophic levels in contrast to the concentration of that particular chemical at higher trophic levels. Hence, the higher trophic level contains the highest concentration of the toxic chemical.
Figure 2: Biological Magnification
Moreover, the rate of excretion is the third factor to determine the biological magnification of a toxic compound. Here, the internal degradation of the chemical is slow due to less water solubility. Consequently, this results in less catabolism, which in turn reduces the rate of excretion.
Biomagnification is the method by which certain substances, including pesticides or heavy metals in rivers, lakes or ocean, progressively concentrate at the higher trophic levels of a food chain. Typically, these substances are incorporated into the diet of small organisms such as zooplankton that represent the lower trophic levels of the aquatic food chains. After that, they reach into the small fish, large fish, birds, animals, and even to humans that are at a higher trophic level.
Similarities Between Bioaccumulation and Biological Magnification
- Bioaccumulation and biological magnification are two processes of accumulating toxic chemicals in different levels of a food chain.
- They describe the movement of toxic compounds through various trophic levels of a food chain.
- Generally, these toxic chemicals accumulate in the tissues of living organisms.
- The factors that determine the concentration of the toxic chemicals in a particular level of the food chain include persistence, food chain energetics, and the rate of excretion.
Difference Between Bioaccumulation and Biological Magnification
Definition
Bioaccumulation refers to the gradual accumulation of substances such as pesticides or other chemicals in living organisms. Biological magnification, on the other hand, refers to the concentration of a toxic chemical in the tissues of tolerant organisms at the successively higher levels in a food chain.
Significance
While bioaccumulation is the process of building-up of toxic chemicals in the body of a living organism, biological magnification is the increase of the toxic chemicals in the amount each time they move up a food chain.
Correspondence
Organisms take toxic chemicals into the body either through the skin or through ingestion, causing bioaccumulation. In biological magnification, toxic chemicals start in small amounts at the lower levels of the food chain and gradually increase in amount when it moves to higher levels.
Importance
Moreover, bioaccumulation results in chronic poisoning even when the concentration of the toxic compound in the surrounding environment is not too high, but biological magnification results in higher concentrations of toxic substances at the higher trophic levels of a food chain.
Conclusion
Bioaccumulation is the accumulation of toxic substances in organisms. Basically, these substances are fat-loving and, accumulate in the fat tissue. Bioaccumulation results in the chronic poisoning of these substances, forming substance-specific symptoms at a certain concentration. In contrast, biological magnification is the concentration of toxic substances through the trophic levels of a food chain. Therefore, the lower trophic levels of the food chain contain a lower concentration of the toxic substance while the highest trophic level contains the highest concentration of it. Hence, the main difference between bioaccumulation and biological magnification is their significance.
References:
1. Vinzant, Alisa. “Bioaccumulation and Biomagnification: Increasingly Concentrated Problems!” Catalina Island Marine Institute, 7 Feb. 2017, Available Here.
Image Courtesy:
1. “Bio-magnification in a pond ecosystem” By Estefaniajmz – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “The build up of toxins in a food chain” By Øystein Paulsen (CC BY-SA 3.0) via Commons Wikimedia
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