Practice AP Environmental Science questions on bioaccumulation, biomagnification, persistent pollutants, DDT, mercury, PCBs, and food chains.
Researchers are studying the stream ecosystem shown in the following diagram. They have identified five different zones based on the dissolved oxygen levels and biological oxygen demand as the water flows downstream. Biological oxygen demand is the amount of oxygen needed by bacteria and other microorganisms to break down organic material in water. Some of the most common fish and macroinvertebrate species found in each zone are listed in the diagram.
Dissolved Oxygen and Biological Oxygen Demand in a Stream Ecosystem
Explain how persistent organic pollutants can affect higher trophic levels in an aquatic food web.
Begin your response to this question at the top of a new page in the separate Free Response booklet and fill in the appropriate circle at the top of each page to indicate the question number.