Disappearing Wetlands

By Kathleen Hourihan
Cole Harbour Regional High
Dartmouth, Nova Scotia

It's springtime and if you don't live in the city, you've probably been hearing the spring peepers. Even if you do, you're probably still familiar with the "peep peep!" of these tiny orange frogs that appear as early as March in Nova Scotia. You've probably been hearing these frogs every spring for your whole life, but what you may not realize is that you're hearing less and less frogs.

Every year, more and more of Canada's wetlands are being destroyed. About 90% of wetlands within or near to city centres no longer exist. These marshes, swamps, and ponds are the main habitats for amphibians and many other animals. Pollution, building development, road construction, logging and agriculture all contribute to the destruction of frogs' habitat every day. As well as being important to animal life, these wetlands are crucial to the overall health of the environment.

These wetlands help control flooding and drought by absorbing snow melt and rain in the spring, and gradually releasing water in drier times. Plants that are indigenous to the wetlands help reduce global warming by reducing the carbon dioxide in the atmosphere and replacing it with oxygen. Even though no one likes mosquitoes and black flies, they are essential to the food chain and their life cycles mainly take place in our wetlands.

Since the 1800s, an estimated 8 million hectares (20 million acres) - one-seventh of Canada's total wetlands - have been drained or lost. A lot of those that haven't been destroyed have been polluted beyond restoration. Amphibians, such as frogs, are very sensitive to environmental changes and pollutants. One of the most startling ways that this shows up is the mutation in frogs. In many places in the United States, as well as here in Canada, reports of frogs with extra hind legs or the wrong number of eyes, feet or other appendages have turned up over the past few years.

One possible explanation is retinoids in pesticides. Retinoids are powerful molecules that can stimulate growth of any limb anywhere on the body. When there are extra retinoids, or retinoids in the wrong place, an extra limb or body part can grow. Retinoids have been known to cause birth defects in humans, when pregnant women took the acne treatment Accutane. Methoprene is a pesticide that is widely used against mosquitoes and other flies. It works to prevent the insects from growing into reproducing adults. It is so strong that one teaspoon is enough for an acre of land. However, this pesticide is not used in all locations where deformed frogs have been found. Other possible causes include parasites and ultra-violet radiation.

The Museum of Natural History in Halifax has a way you can help monitor the frog population and the condition of our wetlands. Frogwatch is an environmental and educational program that is for anyone interested. To join or to find out more, visit the museum or check out their Frogwatch website.