Declining frog populations

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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.

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Now listen to part of a lecture on the topic you just read about.

None of the methods proposed in the reading offers a practical solution for slowing down the decline in frog populations. There are problems with each of the methods you read about.

First, seriously reducing pesticides in agricultural areas with threatened frog populations is not economically practical or fair. Farmers rely on pesticides to decrease crop losses and stay competitive in the market. If farmers in areas that are close to endangered frog populations have to follow stricter regulations regarding pesticide use, then those farmers would be at a severe disadvantage compared to farmers in other areas. They would likely lose more crops and have a lower yield than competing farms.

Second, the new treatments against the skin fungus you read about. Let me explain a couple of problems with this plan. The treatments must be applied individually to each frog, and so using them on a large scale is extremely difficult: it requires capturing and treating each individual frog in a population. Moreover, the treatments do not prevent the frogs from passing the fungus on to their offspring, so the treatments would have to be applied again and again to each new generation of frogs. So applying these treatments would be incredibly complicated and expensive.

Third, while it’s a good idea to protect lakes and marshes from excessive water use and development, that will not save frog populations. You see, water use and development are not the biggest threats to water and wetland habitats. The real threat is global warming. In recent decades, global warming has contributed to the disappearance of many water and wetland habitats, causing entire species to go extinct. Prohibiting humans from using water or building near frog habitats is unlikely to prevent the ongoing habitat changes caused by global warming.

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Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific methods proposed in the reading passage.

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Declining frog populations

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