Gabriolans to join global effort to protect frogs
By Bruce Mason, Gabriola Sounder
Monday, April 28 2008
You can’t help but hear the choruses of frogs right now, but not all of us have listened to the dire warnings that amphibian populations are disappearing from habitats around the world.
The crisis caught humanity by surprise and only now are we beginning to fully grasp the scope of the problem. About a third of amphibian species are threatened with extinction. And mass disappearances of this magnitude have not been seen since the time of the dinosaurs.
Purnima Govindarajulu is an expert. Her research for a PH.D at the University of Victoria studied the big, green, bug-eyed alien bullfrogs with huge appetites that are invading southern Vancouver Island.
Subsequent post-graduate work led to the creation of The Bullfrog Project, a position as adjunct professor at UVic and small mammal and herpetofauna specialist with the Ecosytems Branch in the Wildlife Science Section of BC’s Ministry of Environment.
She is also involved with the BC Frogwatch Program. It’s fascinating and important work. And you can learn all about it at: www.env.gov.bc.ca/wld/frogwatch.
After the meeting on the phone from her office in Victoria, Govindarajulu told the Sounder that it was “gratifying and exciting” to speak to more than 60 people on a Friday evening and that she was impressed by the high level of knowledge in the audience.
She spoke for 45 minutes and answered questions for an hour and a half. Prior to the meeting and the following day - despite snow - she was able to visit five sites on Gabriola and collected eggs and several frogs.
Her message was two-fold. She wants folks to know that frogs are in trouble and also to watch for bullfrogs which were introduced to BC and are wreaking havoc.
You can see - and hear - the invasion in several lakes and ponds around Victoria, Duncan, Nanaimo and Parksville. The intruder is the American bullfrog, and its distinctive bwum, bwum, bwum bass serenade is signaling big trouble for Vancouver Island’s native frog species and aquatic ecosystems in general.
“A major problem is that these bullfrogs eat other frogs. Actually, they’ll eat just about anything, tadpoles, insects, fish, snakes, small mammals and birds, even other bullfrogs are all fair game; whatever they can fit into their huge mouths,” she said.
The Bullfrog Project - the product of years of research by Govindarajulu - is focused on public outreach, site monitoring and steward training to prevent expansion.
BC Frogwatch is a program to collect information on frog and toad populations in BC, a great project for school groups, or for adult naturalists, whose help is needed to find out how healthy BC’s frog and toad populations are - the more eyes and ears out there finding frogs, the better.
The meeting here was hosted by Gabriola Local Trust Committee and GROWLS (Gabriola Rescue of Wildlife Society) to begin to identify frog habitat with community volunteers, to help establish a long-term mapping and monitoring project, to protect amphibian habitat, and to put frog ponds on ecosystem maps.
Also delighted with the large turnout were Local Trustee Sheila Malcolmson and Liz Ciocea of GROWLS.
“Many people took the time to draw wetlands and streams onto the Islands Trust ecosystem maps,” said Malcolmson. “Nineteen people signed up as volunteers for long-term monitoring, which will be extremely helpful.
“Now that we have expert advice on what ponds to focus on, we will talk more with GROWLS volunteers about next steps,” she added.
Malcolmson said the Local Trust Committee can use the data to put development permits in place to protect wetlands and frog habitat, if precisely mapped, and if it is known what times of year are especially sensitive.
The global amphibian crisis
Like canaries in a mine shaft, this demonstrates how the world is changing. Traditional threats to species and ecosystems - such as habitat loss and pollution - are being compounded by new threats like climate change and emerging disease.
This is not simply an amphibian problem, but a human welfare issue.
Quick action is needed to save amphibians and ecosystems that support them and provide us with clean drinking water, clean air, and support the quality of life that too many of us take for granted.
A unified global response is required to tackle a crisis of this magnitude, harnessing the intellectual and institutional capacity of a conservation and research network at country, regional and global levels.
It is partly because many amphibian species require both particular aquatic and terrestrial habitats that amphibians throughout the world are in decline, since loss or degradation of either habitat can eradicate a population. Aquatic stages are particularly vulnerable to environmental changes.
Any slight alteration of water temperature, turbidity, dissolved oxygen levels, other characteristics of water chemistry, predatory regime, or physical complexity of habitat, can be harmful.
Because embryos develop in eggs that are laid in shallow water, it is also possible that increased ultraviolet radiation, caused by depletion of the earth’s ozone layer, plays a role in mortality.
Most amphibians have moist, sensitive skin, which is involved in both drinking and dermal respiration. Industrial pollution and pesticide run-off are threats at any life stage.
Recently, amphibian populations worldwide have been found to be infected with several types of fungi which cause dermal damage and mortality, including eggs.
In BC there are 13 species of frogs and toads and nine species of salamanders. Habitat destruction and range fragmentation are endangering a number of these.
Draining of wetlands, and flood-control measures in expanding urban and agricultural areas remove vast areas of habitat, and break historical distributions into disconnected fragments.
Clearing of forests, and secondary effects from logging practices, impact both larval and adult stages. Several species have very restricted ranges which make them highly vulnerable to aquatic habitat degradation or the introduction of predatory game or baitfish into breeding lakes.
Bullfrogs spreading in leaps and bounds in BC
Bullfrogs have been widely introduced around the world as the primary species for commercial frog-leg farming. Frog farms were promoted in BC after the Second World War as an employment venture for returning veterans.
These ventures were unprofitable and the bullfrogs were released into the wild.
They were also imported by aquatic garden supply companies for stocking backyard ponds. They spread from the original release sites and have now established populations on Vancouver Island between Victoria and Campbell River as well as on some Gulf Islands and the Lower Mainland.
Bullfrogs can prey on and out-compete native frogs. They are also thought to spread a newly discovered frog disease, called Bd or chytrid fungus, although they themselves aren’t affected.
It is very important that we prevent the further range expansion of Bullfrogs on Vancouver Island in order to preserve native biodiversity.
“Their range on the Island is expanding by about five kilometres a year, mainly near urban areas,” said Govindarajulu. So far, she’s found them in several dozen local lakes and ponds, including Victoria’s Elk and Beaver Lakes.
She concluded: “Once bullfrogs get established they pretty much clean out the competition. The easiest thing we can do is not move frogs around, which people still do, especially now that aquatic gardens and backyard ponds have become so popular.”
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