Due to biomagnification, there are certain species with a high concentration of heavy metals (e.g., mercury), leading to dietary advisories for vulnerable demographics (e.g., pregnant women and young children) to avoid these species. Given that these advisories are often most critical for species at the top of long marine food chains, which species would this advice most likely apply to?

• A. Cows (primary consumers, primarily eat grass).
• B. Shrimp (secondary consumers, feed on zooplankton).
• C. Alligators (secondary/tertiary consumers, feed on many species).
• D. Tuna (top predators, feed on predatory fish & invertebrates).

Answer: (D)

Verified step by step guidance

1. Understand the concept of biomagnification: Biomagnification refers to the process where the concentration of a substance, such as a heavy metal, increases in organisms at each successive level of the food chain.
2. Identify the position of each species in the food chain: Cows are primary consumers, shrimp are secondary consumers, alligators are secondary/tertiary consumers, and tuna are top predators.
3. Recognize that top predators are most affected by biomagnification: Since biomagnification results in higher concentrations of toxins at higher trophic levels, species at the top of the food chain are most likely to accumulate dangerous levels of heavy metals.
4. Apply this understanding to the given species: Among the options, tuna are top predators and are therefore more likely to have high concentrations of heavy metals due to biomagnification.
5. Conclude that dietary advisories are most critical for species like tuna, which are at the top of long marine food chains and thus have higher levels of accumulated toxins.