In recent years, many frog species around the world have declined in numbers or even gone extinct due to changes in their environment. These population declines and extinctions have serious consequences for the ecosystems in which frogs live; for example, frogs help play a role in protecting humans by eating disease-carrying insects. Several methods have been proposed to solve the problem of declining frog populations.
First, frogs are being harmed by pesticides, which are chemicals used to prevent insects from damaging farm crops such as corn and sugarcane. Pesticides often spread from farmland into neighboring frog habitats. Once pesticides enter a frog’s body, they attack the nervous system, leading to severe breathing problems. If laws prohibited the farmers from using harmful pesticides near sensitive frog populations, it would significantly reduce the harm pesticides cause to frogs.
A second major factor in frog population decline is a fungus that has spread around the world with deadly effect. The fungus causes thickening of the skin, and since frogs use their skin to absorb water, infected frogs die of dehydration. Recently, researchers have discovered several ways to treat or prevent infection, including antifungal medication and treatments that kill the fungus with heat. Those treatments, if applied on a large scale, would protect sensitive frog populations from infection.
Third, in a great many cases, frog populations are in decline simply because their natural habitats are threatened. Since most frog species lay their eggs in water, they are dependent on water and wetland habitats. Many such habitats are threatened by human activities, including excessive water use or the draining of wetlands to make them suitable for development. If key water habitats such as lakes and marshes were better protected from excessive water use and development, many frog species would recover.
Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific methods proposed in the reading passage.