The common frog (Rana temporaria) usually begins spawning 1st of April in western Sweden, but this year like last year, they were a week late because of the unusually long winters. As usual, they deposited their roe in the shallow water on my, after snowmelt, flooded lawn and just like all previous years, I had a hard work to carry all the roe to the lake when the water receded so that the roe wouldn’t dry out. The frogs seem to count on me to help them.
A week after the common frog finished their spawning the moor frog starts with their.
During the weeks the frogs spawn the water is boiling with love drunken frogs and the air is filled with the males' calls.
Very fascinating!
I hope every spring will begin in the same way but I fear that it might not be the case.
Why frogs?
Most of us have as children had some form of relationship with frogs. We have hunted, captured and kept them as pets, bred them and studied them ... Some of us have frightened girls with them - who, in turn, pretended to be afraid, some of us have kissed them, hoping that they were enchanted princes, we have “Leaped frog”, sung “Little frogs” and so on.
Even adults take an interest in frogs. The pharmaceutical industry is exploring the thousands of substances found in the skin of amphibians to find active substances as cures for a variety of human diseases. The West African clawed frog (Xenopus laevis) has for many years played a major role in pregnancy tests. Frogs also play an important role in the ecosystem as being both prey and predator, and are unsurpassed in keeping pests at bay.
But all this is now threatened to end in the very near future. Frogs are becoming increasingly rare and many of today's children have never even been near a live frog.
Frogs are dying out
After having been in existence for more than 360 million years it is now expected that more than one third of the amphibians will disappear in the near future. Research shows that we are facing the biggest mass extinction since the dinosaurs died out.
There are several reasons for this mass death.
- Habitat destruction or fragmentation of populations - such as roads and livestock grazing.
- Newly introduced species will eat or outcompete existing species.
- Overexploitation - Wild animals are caught and used as food, pets or medicine.
- Climate change - Amphibians are very sensitive to changes in temperature and humidity.
- UV-B radiation - This has significantly increased in the atmosphere over the past 20 years. The radiation damage frog eggs, reduces the immune system in adult frogs and operate synergistically with contaminants, pathogens and climate change.
- Chemical contaminants - pesticides, heavy metals and nitrogen-based fertilizers.
- A combination of new diseases and less resistant amphibians.
- Environment-related malformations.
The biggest threat to the amphibians is the fungal disease Chytridiomycosis. The fungus Batrachochytrium dendrobatidis has spread over the globe from South Africa with the West African clawed frog (Xenopus laevis). The increasing temperatures make frogs extra susceptible to fungal infection.
Don’t spread the fungus
During the official “Year of the frog” 2008 there was much talk about the threats to amphibians but since then it appears that the general public has forgot this serious situation.
The fungus has recently been found in a few places in southern Sweden and the risk is severe that it spreads across the country.
Due to lack of resources no mapping of fungal presence has been made yet which is worrying because the disease can be spread with fishing equipment, boots etc. which are not disinfected before being used in an uninfected body of water.
However, it seems as if the amphibians in good health have a better resistance to the fungus than expected and that it is primarily the populations living in water already affected by environmental disturbances that are wiped out. The temperature rise caused by the on-going climate change is one such factor, pollution is another.
It would be very sad, in many respects, if our amphibians disappear.
Be careful not to move water between different water bodies if you do not know for sure that they are uninfected by the chytrid fungus.
We need the frogs!
Jan
