Okay the question is:
Why would there be differences in the pesticide levels found in different species? Atlantic Puffin (feeds on small fish) and its pesticide levels are lower compared to Double-crested Cormorant (fees on larger fish) and Leach's Storm-Petrel (feeds on small organisms near the surface of the water), why would this be?
The differences in pesticide levels found in different species can be attributed to several factors:
1. Trophic level: Pesticides tend to accumulate as they move up the food chain, a process known as biomagnification. As smaller organisms consume contaminated food sources, the pesticides present in those sources are absorbed and accumulate in their tissues. When larger organisms, such as the Double-crested Cormorant, feed on these smaller organisms, they ingest a higher concentration of pesticides, resulting in higher pesticide levels in their bodies compared to species that feed at lower trophic levels, such as the Atlantic Puffin and Leach's Storm-Petrel.
2. Diet composition: Species with different diets will be exposed to different sources of pesticides. For example, the Atlantic Puffin predominantly feeds on small fish, which may have lower concentrations of pesticides compared to larger fish that the Double-crested Cormorant feeds on. Similarly, Leach's Storm-Petrel primarily feeds on small organisms near the water's surface, which are likely to have lower pesticide levels compared to larger fish.
3. Feeding behavior: Feeding behavior also influences pesticide exposure. Double-crested Cormorants are known to dive deeper and stay submerged for longer periods while feeding. As a result, they have a higher likelihood of encountering and ingesting prey that exists in deeper waters, where pesticide contamination levels tend to be higher. In contrast, Atlantic Puffins and Leach's Storm-Petrels predominantly feed closer to the water's surface, where pesticide concentrations are typically lower.
It's important to note that these differences in pesticide levels among species are not fixed or universal. They can vary depending on the specific location, environmental conditions, and the presence or absence of pesticide use in the surrounding areas. Monitoring and studying these variations in pesticide levels help in understanding the potential risks that different species may face due to exposure to pesticides.