A deluge struck California over the holidays. With almost daily downpours, my rain gauge recorded thirteen inches in less than two weeks. Trees fell. Cables snapped. Thousands lost power. For a while, our neighborhood became an island, with roads flooded in every direction. During a typical winter, rain collects in shallow depressions in the land, called vernal ponds. This year entire fields turned to lakes.
Named for Spring (vernum in Latin), the transient pools pass through three phases–Aquatic, Flowering and Drought– in their brief lifespans. They appear like mirages in the dark of winter when low-lying areas flood. In Spring they burst into full-throated glory as life surges in and around them. Under the summer sun, water evaporates, and the exposed earth dries and cracks. Once-vibrant nurseries turn into dead zones.
Unlike brooks that babble and rivers that run, vernal ponds, with no inlets or outlets, are almost surreally still. Their glass-smooth surfaces mirror the sky, with clouds skidding across by day and galaxies shimmering by night. But in their stillness and silence, life stirs—often in forms that exist nowhere else on the planet.
Some 200 plants grow in California’s vernal ponds—most native annuals with survival strategies that evolved over tens of thousands of years. When inundated, some absorb oxygen through long, hollow stems; some, directly from water; some, from floating leaves that absorb enough air for the entire plant.
The fleeting ponds, as a poet put it, “midwife Spring into summer.” Wildflowers, including sun-bright Goldfields, white Meadowfoam and blue-tipped Downingia, carpet the shores in vibrant hues. Their urgent mission: Attract pollinators and produce abundant seed to lie dormant underground, patiently awaiting next winter’s wet kisses.
No fish swim in ponds destined to die. Safe from finned predators, fresh-water amphibians and invertebrates—including rare frogs and salamanders—mate, lay eggs and move on. Some crustaceans have evolved in perfect harmony with the ephemeral waters. Tiny ostrocods or seed shrimp, for instance, hatch from eggs that survived the harsh dry season. As detritivores, they eat almost anything organic and grow quickly, reproducing and leaving behind the next generation of desiccation-defying eggs.
Ostrocods and other pond inhabitants provide food for millions of migrating birds and waterfowl on the Pacific Flyway. Terrestrial wildlife—racoons, deer, rabbits, weasels, fox, coyotes—also converge at the local watering holes. As the final dregs of moisture evaporate, these visitors leave tracks cemented in the hardened earth.
Large or small, vernal ponds remind me of Brigadoon, the Scottish village in the classic musical that comes to life for one day every hundred years. The first time I discovered a gleaming pond in a field that had been dry just weeks before, I was as stunned as if a bag-pipe-playing Highlander had suddenly materialized.
Vernal ponds, whatever their size, still seem magical to me. They open themselves to the heavens, drink the rain, glow with sunshine and starlight, offer respite to the hungry and weary, leave seeds for tomorrow. Then they silently fade away, like Brigadoon, into the mists of memory.
Photo: University of California, Davis
