The following is a letter to the editor of an environmental magazine."Two studies of amphibians in Xanadu National Park confirm a significant decline in the numbers of amphibians. In 1975 there were seven species of amphibians in the park, and there were

While the author proposes introduction of trout as an explanation for the reduction in number of amphibians in Xanadu National Park, the following are possible alternate explanations for the decrease in number and diversity of amphibians at the park.

Climatic Changes: It is possible that during the period between 1975-2002, the habitats of amphibians have been shrinking due to climate changes. The area may have suffered periods of droughts and irregular rainfall, which would have limited the resources.

Competition for resources: There is a well known theory, that a population after a period of exponential growth, usually comes crashing down, as the huge population depletes all the resources. Since, the amphibians compete for the same resources, after reaching their peak around 1975, their population could have taken a sudden dive due to scarcity of resources.

Epidemics: The amphibians at the park may have succumbed to an epidemic to which amphibians are most susceptible. Some of the species could have developed immunity, thereby surviving the crisis, while others perished.

Tourists: Tourists disturbing the natural balance: The number of tourists visiting the National park may have dramatically increased during the time period. Tourists tend to pollute the environment, thereby disturbing the delicate eclological balance.