Question

A fish-eating bird species was found to have a specific, heavy metal concentration of 700,000 ppt (parts per trillion). The conclusion based on the data is

• A. Air pollution may have caused this bird species to inhale dangerous amounts of heavy metals while migrating.
• B. The entire population of the bird species, from which this sample was taken, died.
• C. The population of this bird species exploded, causing an ecosystem imbalance.
• D. Pollutants tend to collect in areas of land where this bird species nests.
• E. This bird species is at a high trophic level on the food chain.

Answer 1

The correct option is E This bird species is at a high trophic level on the food chain.

Organisms at higher trophic levels in a food chain can experience biomagnification, which is the accumulation of environmental toxins (such as heavy metals) in living tissue. Organisms at lower trophic levels accumulate small amounts of toxins through their food. Because organisms at the next highest trophic level eat many of the lower-level organisms, they take in higher amounts of the toxins. At the highest trophic levels, increased concentrations of toxins in organisms’ tissues can be dangerous. This bird tissue has a high concentration of a specific heavy metal, so the species must be at a high trophic level. Therefore, the correct answer is option E.