One of the questions that I am most frequently asked when talking about the amphibian decline is: “Why should we care?” Usually the answer that people are looking for is not just that amphibians have “intrinsic value”, but rather they want to know what important role these creatures serve in the ecosystem. Over the past few years, several studies have tried to answer that question by quantifying the ecosystem role of amphibians.
There are several ways in which amphibians serve to benefit the environment. Perhaps the most obvious is their role as predator and prey in the trophic food web. The position of amphibians in a food web can be shown using a graph of the carbon:nitrogen isotope ratio. The further towards the top of the graph (and the higher the nitrogen content), the higher in the trophic food web a species is likely to be.
Additionally, amphibians are an especially important link in the environment due to the dual life of many species. Species of amphibians that have aquatic free-living tadpoles can help to tie the aquatic ecosystem into the terrestrial system. When one of these species goes extinct, it can be the equivalent of losing two species rather than one.
A team of researchers conducting studies relating to the decline of frogs observed the effects of tadpoles on nutrient cycling and algal growth in a neotropical stream where tadpoles were still present as compared to one where they were extirpated. They found that tadpoles significantly decreased the volume of particles and diversity of algal growth in streams where they were present. In the stream in El Cope, where tadpoles were still found, there was also a greater amount of nitrogen found in organic matter. In addition, in an interview during the PBS Documentary Frogs: The Thin Green Line, Dr. Karen Lips from the University of Maryland remarked that in many streams where frogs had gone extinct, the rocks had become dangerously slippery with algae. This evidence highlights the importance of conserving amphibians and their roles in the ecosystem.