Stages of Biological Magnification

Introduction

• For a pollutant to affect an ecosystem, it must first be introduced. Some ways this occurs are through spraying pesticides, chemicals dumped into water and factories leaking toxic substances. For a substance to accumulate it must be lipid-soluble, that is, it must be carried in fatty tissue and not break down after it's introduced to the environment. The chemical DDT is one example of a substance that causes great environmental damage. Water-soluble pollutants don't cause biological magnification because they are easily diluted and broken down.

Ingestion

• The primary level of the food chain is autotrophic species. Autotrophs produce their own food using environmental chemical nutrients and sunlight. Examples of autotrophs are plants and certain species of bacterium. Autotrophs consume inorganic environmental nutrients such as nitrogen or phosphorous to create food. When pollutants are introduced, autotrophs ingest mass amounts of these substances along with necessary inorganic nutrients. They accumulate large amounts of toxic substances as well, which they store for times when the nutrients are scarce. Once plants have ingested higher concentrations of a toxin than are present in the affected environment, biological magnification has started.

Consumption

• Once the plants have accumulated toxic substances, plant eating animals consume the toxic substances by eating the plants. Once ingested, these chemicals are stored in the animals' fatty tissue and remain there. Since these species require large amounts of food, the toxins can become more heavily concentrated in the bodies of these animals than were present in the plants the animals originally fed upon.

Continued Consumption

• The process continues as other animals consume the animals that originally fed on the plants that ingested the toxic substances. Thus, although a pollutant was originally introduced to one level of species, the toxin can spread throughout the entire ecosystem. These toxins may kill animals or cause neurological or physical damage. Further, toxins can affect reproduction and cause mutations. Humans are not immune to biological magnification. By eating contaminated animal and plant species, people can develop physical symptoms and diseases, including cancer.