Describe how DDT moves through an aquatic food chain. Explain how this almost resulted in the extinction of the bald eagle.
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http://www.learner.org/jnorth/tm/DDT.html
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To understand how DDT moves through an aquatic food chain and its impact on the bald eagle, you can review the information provided in the link you shared (http://www.learner.org/jnorth/tm/DDT.html). However, I can give you a brief explanation.
DDT (dichloro-diphenyl-trichloroethane) is a pesticide that was widely used during the mid-20th century. It was effective in killing pests like mosquitoes and agricultural insects. Unfortunately, after its application, DDT doesn't break down easily and accumulates in the environment.
When DDT is sprayed on crops or the ground, it can be washed into nearby water bodies, such as lakes and rivers, through the process of runoff. Once in the water, DDT is primarily absorbed by microscopic algae and plankton.
Small aquatic organisms, like zooplankton and small fish, then consume the contaminated algae and plankton. As these small organisms are being eaten by larger fish, the DDT that accumulated in them is also transferred up the food chain.
This process is known as bioaccumulation. As predatory fish consume smaller contaminated fish, they accumulate higher levels of DDT in their bodies. The toxin continues to build up as it moves up the food chain.
The bald eagle, being at the top of the aquatic food chain, is significantly impacted by this bioaccumulation of DDT. When the eagles consume DDT-contaminated fish, the toxin is stored in their fatty tissues. As more and more DDT-laden fish are ingested by the eagles over time, the concentration of this harmful chemical in their bodies continues to increase.
The accumulation of DDT in the bald eagle's system disrupts its calcium metabolism, making their eggshells thin and fragile. As a result, when the female eagles lay eggs, the fragile shells often break during incubation, leading to a decreased reproductive success and ultimately endangering the species.
The link you shared (http://www.learner.org/jnorth/tm/DDT.html) provides more detailed information on the effects of DDT on bald eagles and the efforts made to address this issue.