A World Safer For Frogs Is A World Safer For Us All : Frogs Are Important ‘Bio-Indicators’

Frogs are referred to as ‘ bio indicators’ – early warning systems telling us that whatever is happening to them is going to happen to us as well. This creature is telling you about the area that it lives in. For example, having lots of frogs in an area tells scientists that the water is good and the environment is healthy. If frogs are suddenly missing from an area or their population is shrinking, this tells you that the air, water and land is changing… Researchers are beginning to believe that a high incidence of UV radiation resulting from ozone layer depletion combined with the presence of a disease caused by pesticides and other chemicals- may be at the heart of worldwide declines of frogs…


frogs-are-important-bio-indDuring the monsoons in my constituency, the frogs cross the road. The car-drivers keep a “frogwatch” because I get paranoid if I think we are going to squash one. Over the years, the frog population has decreased. The drivers are relieved because like most people they find frogs ugly. But I know, that my constituency, which was one of the most pristine areas of India, is now heading for trouble. Frogs keep insect populations in check, eating large numbers of insects every night. Frogs and tadpoles are eaten by birds, fish, snakes, other reptiles and some mammals. But apart from this, frogs are an extremely important species in measuring the health of the environment.
Frog skin is unusual. It binds tissue and fluid in, like human skin, but it is also porous, allowing air and water to pass directly through it. In fact, frogs do not drink water through their mouths at all – it is absorbed through the skin on their lower abdomen. Frog-eggs are not protected by any hard shell and tadpoles have thin permeable skin. Because of this porous skin, which allows water to pass directly into the body cavity without being filtered through the stomach, frogs are susceptible to pollutants in the environment.
This is why frogs are referred to as ‘ bio indicators’ – early warning systems telling us that whatever is happening to them is going to happen to us as well. This creature is telling you about the area that it lives in. For example, having lots of frogs in an area tells scientists that the water is good and the environment is healthy. If frogs are suddenly missing from an area or their population is shrinking, this tells you that the air, water and land is changing.
In India the Rana Tigrina- the common frog which we have all seen as children, is almost gone. The main reason is dissection in schools and the illegal export for frogs legs through Bangladesh and Singapore. Other reasons are habitat loss for residential development; the filling of creeks and ponds; deliberate burning of forests reserves and surrounding hillslopes by the forest departments to stop fires; insufficient clean freshwater sources; the use of pesticides and herbicides, especially near and in waterways; climate change and drought; road kills; household accidents such as being squashed in windows, doors; being sprayed with Dettol and other chemicals; lacerations from gardening equipment ; and cruelty : the deliberate killing by children and poisoning by adults. My brother in law’ s favourite pastime was to take a tennis racquet and squash them when they came to the pond at the back of our house.
People are dramatically impacting insect numbers because of the rampant use of insecticides and herbicides in their yards. When insects aren’t being poisoned, they are losing their food supply as each big tree gets cut down. As they form the base level of the food chain, a decrease in insect levels results in a decrease of all other living beings. The lack of food stresses frogs and they become highly susceptible to disease.
Baffling scientists further, amphibian declines are not necessarily occurring in “likely” places where human impacts are obvious, such as cities and suburbs prone to development and pollution; some of the most noted and dramatic declines are happening in “protected” areas such as national parks. No one has given a generalised reason for this die-off. Diseases or pollutants that have decimated a species in one part of the world may be absent in another region that has also experienced a mysterious die-off.
In India the Rana Tigrina- the common frog which we have all seen as children, is almost gone. The main reason is dissection in schools and the illegal export for frogs legs through Bangladesh and Singapore. Other reasons are habitat loss for residential development; the filling of creeks and ponds; deliberate burning of forests reserves and surrounding hillslopes by the forest departments to stop fires; insufficient clean freshwater sources; the use of pesticides and herbicides, especially near and in waterways; climate change and drought; road kills; household accidents such as being squashed in windows, doors; being sprayed with Dettol and other chemicals; lacerations from gardening equipment ; and cruelty : the deliberate killing by children and poisoning by adults. My brother in law’ s favourite pastime was to take a tennis racquet and squash them when they came to the pond at the back of our house.
Researchers are beginning to believe that a high incidence of UV radiation resulting from ozone layer depletion combined with the presence of a disease caused by pesticides and other chemicals- may be at the heart of worldwide declines.
It is not just disappearance, whole colonies of frogs have been found with deformities. Pollutants commonly result in the death of the egg or tadpole, but may result in the production of abnormalities in the adult frog. Field scientists have found frogs with missing legs, extra legs, misshapen legs, paralysed legs that stuck out from the body at odd places, legs that were webbed together with extra skin, legs that were fused to the body, and legs that split into two half-way down. They have also found frogs with missing eyes. A one-eyed frog had a second eye growing inside its throat.
Zoologists at Oregon State University presented the first major field study at the National Academy of Sciences which concludes that the levels of ultraviolet, or UV-B, radiation now found in sunlight can cause physical deformities in amphibians, a problem that has alarmed researchers around the world. These findings serve as an ominous early warning of some of the real impacts of global climate change. In this experiment, more than 90 per cent of the salamander embryos that were not shielded from UV-B radiation either died or hatched with deformities. These were not artificially-elevated levels of UV-B light. These salamanders were exposed to nothing more than natural levels of sunlight while living in their normal habitat.
Studies such as this suggest that people should be taking climate change and rising levels of ultraviolet light very seriously. High levels of ultraviolet light exposure in humans has been linked to cataracts, immune suppression and cancer. And we can expect more.
How can you help frogs survive? Start by noticing them. Check where heavily traveled roads separate wintering (deep lakes) and breeding habitats (ponds or marshes). If you notice many road-killed frogs, you have probably located a crossing. Try to post frog crossing signs or build culverts. Some people even collect frogs in buckets and carry them across the busy roads! Plant your area with as much vegetation as you can so that the insects increase. Put freshwater ponds in your parks with bushes around them. Don’t use chemicals in or around your house. All chemicals are swept into waterbodies. Build a frog pond at least 30 cm deep (60 cm is much better) and as wide as you can manage so that frogs can access the water during dry periods and hopefully breed during the summer.
A frog-friendly environment includes access to clean freshwater, shelter from the heat, and ample food. While we’re fixing up our local environment for frogs, we’ll be improving it for ourselves. Adopt a wetland or a forest pond and defend it against urbanisation.
Remember, a world safer for frogs is a world safer for us all.

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