Question

read the following scenario and answer the question(s) below. glass lake, located in a valley in low - forested mountains, for many decades of the 19th and early 20th centuries was a favorite picnic, recreation, and fishing site for people in surrounding towns and farms. however, in the middle of the 20th century, a trend began in which the privately owned farms in the lakes watershed were purchased by large agribusinesses. the decision was made to grow a profitable crop. the demand for quality fertilizers and pesticides increased several - fold by the end of the century. in addition, the combined population of the lakeside villages quadrupled during the same time. the lake experienced a slow degradation of water quality and biodiversity. sport fishing declined, and the lake became murky, while the sediments in the lake increased in depth. a biodiversity survey of the lake revealed a striking decline in nearly all animal species and in rooted plant life, especially where streams discharge into the lake. the immediate cause(s) of the decline most likely was/were - toxicity of nitrogen and phosphorus to wildlife - very low oxygen levels and lack of plants to support animal consumers - the fact that the past two winters were colder than usual - pesticide poisoning - natural declines in aging wildlife populations

Explanation:

The text mentions increased land - cultivation, use of fertilizers and pesticides, and discharge of nitrogen and phosphorus into the lake. These factors lead to toxicity and low oxygen levels, which are harmful to wildlife. The decline in wildlife populations is likely due to the toxicity of nitrogen and phosphorus and low oxygen levels caused by human - induced changes in the lake's ecosystem.

Answer:

toxicity of nitrogen and phosphorus and very low oxygen levels