Today, I’d like to introduce the concept of a bio-indicator. In the past, I have given out a number of examples of biomimicry, but how many of you know are aware of the idea of bio-indicators? These are organisms that will be initially (and greatly) affected when the environment is stressed. In the past, coal miners would take canaries into the mine with them, as the birds were very sensitive to leaking methane gas that could result in an explosion. Today, we are all aware of (and with good reason somewhat worried about) our close connection to the environment. Of the many animal bio-indicators, my favorite is the frog.
Frogs have a three-part life cycle consisting of an aquatic egg, an aquatic tadpole, and the semi-aquatic adult. The key word for all of its life stages is “aquatic”, for changes to the environment often first show up in the water. Altered salinity, nutrients, and the presence of toxic chemicals can affect the frog at any of its life stages. Their eggs are separated from the water by only a thin membrane, and both tadpoles and adults have a specialized semi-permeable skin that readily lets in environmental contaminants. The loss of frogs due to environmental change creates multiple problems for their ecosystem. Leftover frog egg membranes act as a fertilizer for algae, which then acts as a water filter. Adult frogs are hungry and effective pest control agents, unless you are fond of mosquitoes. Frog eggs, tadpoles, and adults provide food for an ecosystem’s worth of other animals, particularly birds and snakes. There are also direct connections between frogs and humans. This week, the Nobel prizes were awarded, and in the past, ten percent of all the prizes ever given for physiology have been awarded to scientists studying frog skin. The popular Fire Belly Toad produces bellykinin, a secretion medically useful in reducing high blood pressure. White’s Tree Frog produces caerin, a secretion that is being investigated for its effectiveness in reducing HIV transmission. Today worldwide, my favorite bio-indicator the frog, is rapidly disappearing. The silence, where there was once a chorus of singing and croaking should be ringing in our ears like an alarm clock, that something is not well with the world in which we live.