Q: We have a man-made frog pond at our cottage, which has been home to many frogs since we bought our place in 2007. This year, we arrived in the spring to find the water murky, with green slime floating on top. There are no frogs to be found. We have never done maintenance of any kind from year to year, but I did trim out some cedars that were filling in too close to the pond. What could be the cause of the disappearance, and how do we go about restoring the quality of the water to bring back our frogs?—Sandy Spence, Tobermory, Ont.
A: You’re right that something’s up with the water. “The green slime is likely algae, which could mean the water quality in the pond has decreased because of excess nutrients,” says Rachelle Fortier with the Toronto Zoo’s Adopt-a-Pond program. Frogs are extremely sensitive to changes in their environment. “They often die or leave the area if conditions are not ideal,” she says.
So what happened? It’s hard to say for sure, but excess nutrients can often come from external sources—fertilizers, for example. We’re not suggesting that using fertilizers. But a neighbour might be. Depending on the size of the pond, even a small
