By Sherwood ‘Woody’ Wilkes
For the Salisbury Post
Every spring and even during warming trends in the middle of winter, we begin to hear the cacophony of nature, singing out for all to know that blue skies and mild weather is upon us. Plants and animals that signal the relative health of the environment or the presence of pollution or danger are called indicator species.
Spring peepers, a diminutive frog, are considered an indicator species. They announce the arrival of a beautiful warm day. Spring peepers sound off in huge numbers when the temperature is rising; giving us a sign that spring is coming.
Amphibians are considered the world’s universal indicator of the health of the environment. Frogs, toads, salamanders and newts are all amphibians. They have a unique characteristic of absorbing moisture and chemicals through their skin. If a water source such as a pond, lake, creek or river is contaminated, amphibians will be one of the first species to” indicate” that there is a problem.
This means that the presence or absence of healthy populations of amphibians tells us a revealing truth about the relative health of the environment. As they absorb pollutants through their skin, often the population of that species will change. The population will either increase or diminish. Scientists study the presence or absence of amphibians in an ecosystem giving insight into the general health of that ecosystem.
If an ecosystem is in danger of threatening contaminants, individuals in the population may develop odd appearances such as having extra limbs or display odd behavior. Hence, the birth of five-legged frogs or the two headed turtle. Further analysis of a declining amphibian population might reveal very specific environmental pollutants and changing water regimens. These become early warning signs that the ecosystem is changing and gives us an opportunity to correct the problem before the damage becomes irreversible.
One of the great indicators of a healthy aquatic ecosystem is the presence of freshwater mussels. More than three quarters of indigenous North Carolina mussels are rare and in declining numbers specifically due to water pollution and heavy metal toxicity. If we clean up the water, the mussel population will rebound. What a great way for scientists to easily “measure” the recovery and general health of an ecosystem.
Often the presence or absence of certain plants will not only identify the type of habitat that we are in, but the relative health of that habitat. An example of that is the endangered Schweinitz’s sunflower that indicates a healthy Piedmont prairie. The presence of the Schweinitz’s sunflower demonstrates an open prairie habitat where other rare plants can be found such as the Georgia aster or the smooth coneflower. The presence of this prairie habitat then tells us to look out for the Prairie warbler, the Henslow sparrow or the Bobwhite quail. Why is this important? The presence of these rare plants indicates a healthy Piedmont prairie ecosystem.
Did you know a common cricket can tell us about the weather? They can warn us of changing weather and are considered another type of indicator species. Try this experiment at home. On a beautiful starlit night, count the number of chirps from a cricket in 15 seconds, and then add 37 to that number. The total will be very close to the actual Fahrenheit temperature.
There are examples of indicator species everywhere identifying ecosystems, their health, the changing of a season or even the temperature outdoors. The next time you go outside today and every day, stop, look and listen to nature all around you and take notice of the indicators of the environment.
Woody Wilkes is with A Walk in the Woods, an environmental education company that provides outreach wildlife programs. Contact him at 704-436-9048 or visit www.awalkinthewoods.us.