The Nature of My Pond

Ponds are critical to the environment in other ways. Their absorbent properties help soak up vast amounts of rainwater and runoff, decreasing the risk of flooding in many areas and preventing erosion damage to the banks of streams and rivers. They also store water during periods of drought and help maintain healthy levels of groundwater. Williams provides an apt analogy: “Ponds act like big sponges. By absorbing peak water flows they can attenuate flooding. They also help provide base flows during droughts by storing water and releasing it slowly into the surface streams.” Indeed, natural ponds support wetlands and help prevent their further loss by holding the water so vital to their continued existence.

At the same time, Williams says, the plants in and around ponds filter nitrogen and phosphorus out of the water. Unchecked, these substances act as fertilizers to algae and other aquatic plants that can clog rivers, foul lakes and deplete oxygen in the water. And, he adds, “the vegetation contributes to the clarity of the water in the pond itself.”

Ponds exist in many different forms, but all are basically holes in the ground that hold water. The ideal pond, from an ecological point of view, is a wetland – a quiet body of water so shallow that rooted plants can grow on the bottom. “Any depression that holds water, either for a few weeks or permanently, that’s a pond,” says Neil Morris, a biologist and environmental consultant based in Inglewood, Ontario. “And true ponds are shallow,” he says, explaining that most plant life does not grow much below about a metre as the sun’s rays do not penetrate any deeper.

Some ponds, like ours, were dug as watering holes for cattle but have now reverted to a more natural state. Then there are stream ponds, where the flow of a stream slows and widens, allowing the growth of pondweeds, cattails and stoneworts in the shallows. Beaver ponds, created by these busy creatures as they build their dams in or near rivers and streams, are important habitat for mallards, blue-winged teals, ring-necked ducks, hooded mergansers and black ducks. Ponds form in abandoned gravel pits and stone quarries, and many of Ontario’s ponds have been dug for aesthetic purposes. Ducks Unlimited, for instance, actively promotes the creation of wildlife ponds like ours as a way of restoring lost wetland throughout North America.

As I was quickly learning, our unassuming little pond, lifeless and bleak as it had first appeared, is home to a remarkable chain of living things. The first clue came in the middle of an unseasonably mild night in late April that first year, when a symphony of enthusiastic chirping split the night and woke up both of us. Until that moment, only the eerie yipping of coyotes or the occasional bellowing of our neighbour’s cattle had broken the silence of the winter darkness. Suddenly the night was alive with a teeming orchestral performance: millions of tiny spring peepers – four-centimetre-long frogs – buried deep in the cold mud beneath the icy surface of our pond for the winter, had come to life all at once, raising an enthusiastic racket.

Ponds are crucial to amphibians such as frogs, toads and salamanders, says Morris, not just because their survival depends on their skin being moist, but also because they must reproduce in water. Many biologists consider frogs to be the ecological equivalent of the canary in the mine: abundant populations indicate a healthy environment. By the time the peepers have finished breeding in our pond, the slippery green leopard frogs, Ontario’s most common frog species, have laid their eggs and, in mid-June, the shallow waters at the edge of the pond are alive with wriggling black tadpoles. They’re followed by the warty American toad, which lays its long strings of eggs in the water in early summer.

By then, too, bright blue damselflies and shimmering green dragonflies are hovering over the surface of our pond and clinging to the reeds. They mate in flight and then deposit their eggs in the water to overwinter as nymphs, or larvae. Like amphibians, aquatic insects spend all or part of their lives in water, where their presence is an indicator of pond health.

More surprises emerged from the seemingly barren banks of the pond. As the weather warmed, clumps of sedges, rushes and grasses appeared at the water’s edge. I noted the stiff, sharp-edged spike rush with its burr-like seed heads (a food source for birds), the long, slender chairmaker’s rush, waving plume-like reed grass, shiny broad-leafed pickerel weed and, of course, the ever-present cattails. As May gave way to June, the previously uncluttered water began filling with pondweeds, some floating on the surface, others submerged and rooted to the bottom. All provide food and shelter for fish, snails and other aquatic life. Many species of duck, Williams tells me, feed heavily on the emerald green carpet of duckweed, whose amassed minuscule floating leaves I had mistakenly assumed were algae. Other plants – arums, water lilies, ferns, smartweeds and cresses – are habitat to countless shorebirds, amphibians and small mammals. Many plant roots filter algaeproducing phosphates and nitrates, as well as toxins introduced by agricultural spraying. Some roots provide nourishment – the sweet, tender cattail roots are a favourite food of muskrats.

One day, I saw the brown back of a muskrat move through the water and then disappear under the weeds. We noted that the steep south bank of our pond was a warren of muskrat dens and worn footpaths. Herons and mallards came to visit. A pair of red-tailed hawks hunted from the bare branches of a dead elm. Killdeer sprinted through the long grass near the pond’s edge. Tree swallows careened through the air, swooping low and scooping up the mayflies that feed on the organic debris and countless microscopic one-celled creatures that contribute to the complicated inner life of ponds.

Small ponds like mine provide an ideal microcosm for understanding the interconnectedness of all life. The most important link between things is the production and consumption of food. At the bottom of the food chain (though it is more like a web than a chain) are phytoplankton: millions of algae, flagellates, diatoms, desmids and bacteria. These are a food source for as many as 30,000 species of protozoans, as well as herbivorous insects and worms – midges, mayflies and leeches – which, in turn, are eaten by carnivorous fish, crayfish, frogs and turtles. The small carnivores then serve as prey for larger carnivores, such as birds of prey, foxes and raccoons. If a plant or animal is not eaten, explains Dave Featherstone, an ecologist with the Nottawasaga Valley Conservation Authority, it dies and decomposes, becoming the nutrient material necessary to fuel plants.

Watching our pond come alive that first year made us want to help improve its value as a habitat. One weekend in late spring, Basil and I bought two potted weeping willows, which we planted on the west bank. We also purchased a hundred native seedlings – highbush cranberry, dogwood, spruce and larch – and planted them on the berm between the pond and the wetland, creating a buffer zone between the surrounding farm fields and the pond. Williams explains: “You always want to have a good buffer of undisturbed vegetation, and tree roots strengthen the buffer, controlling water flow and preventing soil erosion.”

Morris, too, talked to me about the benefits of planting trees around a pond: “Vegetation helps hold onto groundwater,” he said, “and trees also provide shade, keeping the temperature of the water down, which is generally a good thing because it makes them less vulnerable to drought.” Last summer, during a prolonged dry spell, little was left of our pond but a few large puddles dotted with muddy islands, on which a litter of four baby muskrats munched cattail roots in the sunshine. I feared that the drought had spelled the end of our pond, but a rainy fall soon filled it to the brim and, by late December, we were ice-skating on its frozen surface.

One cool and overcast day this June, Williams dropped by to advise us on what else we can do to enhance our pond and its surroundings. As we tramp through the hayfield behind the barn toward the pond, which is not visible until we are nearly upon it, a light rain begins to fall and I silently thank the weather gods. Last summer, we lost 10 or 20 percent of the 3,000 trees we planted because of a drought. Most of the rest are still too small to be seen above the long grass. Williams’s clean-cut features under the blue Ducks Unlimited cap betray nothing as he surveys the scene. Thanks to heavy snowfalls last winter, the water in the pond is higher than ever. But I can feel my mood sinking as I reflect on the fact that I’ll likely be dead before those trees become the forest of my imagination. The rain picks up, but Williams seems oblivious to it.

We wade carefully into the shallows, the mud sucking at our boots. Williams sees jewelweed starting to grow at the water’s edge. “That’s floating-leaf pondweed, a good oxygenator,” he says, pointing to what look like slender leaves on the surface of the water. He plucks a tiny leaf from another plant and rubs it between his thumb and forefinger, releasing the scent of fresh spearmint. Williams shows me succulent horsetail, feathery mare’s tail, arrow arum and wild celery, which I had missed previously. And there are some plants even he cannot name without a field guide.

He suggests that we find an old log and lay it in the shallows in the hope that painted turtles will use it to bask in the sun. Then Williams looks around and delivers his verdict. “This,” he says, “is a very nice little wetland. I can’t think of anything you can do to improve its function. You have excellent vegetation diversity. Your pond is well situated, away from human habitation and the road; it has a good buffer zone of plants and trees. It’s adjacent to hayfields, which don’t produce large quantities of nitrogen and toxins.”

He pauses and the rain falls harder, decorating the pond’s surface with radiating rings like a million silver bangles. Blackbirds screech into the rising wind.

“Every living thing,” Williams says at last, “needs water.” And all at once, this simple and profound idea fills me with hope. It may not be Walden, but the earth beneath my feet seems buoyant indeed.

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