Lake Pleasant, Erie County, PA
Photo by Linda Steiner
Fighting to make my way along the shoreline, I squinted into the glare off the lake, as fierce winds whipped the brown-gray waves into frothy lines of white. Typical of spring, feisty drafts were testing the landscape, slashing the dried skeletons of grasses and teasels that hissed and crackled in the onslaught.
As the sun broke through, the lake writhed in grayish-green waves braided with ribbons of purest turquoise, as it threw back tinted images of the sky. The gusts hurled an amalgam of seasonal scents: a sharp tang of cow manure and soft spice of new greenery, suffused with faint undercurrents of lake mud.
Sigurd Olson penned his reflections of a spring morning: “Early morning in the wilderness is the time for smells …Winnow the morning air before it is adulterated with the winds and the full blaze of sunlight, and no matter where you happen to be, you will find something worth remembering.”
The land was breathing, scents rising like so many fiddleheads, uncurling from the depth of the warming earth. The winds carried the secrets of soil and life, flinging them joyfully into the air, to be carried over the fields. The lake tossed in a mad melee of springtime, churning its quiet winter waters into life.
A male red-winged blackbird called joyfully from the reeds; the males had arrived weeks ago, setting up territories to welcome home the females. Grackles flew over, cackling lustily as they landed in the alders. Through my binoculars, I could see a big-eyed killdeer sprinting in the quickening grass across the cove.
|northern leopard frog
Photo by Linda Steiner
As the sun rose higher and the winds began to die down, painted turtles eased out of the murk to arch their necks in the hot sun. Pond striders etched patterns among the shoots of lily pads, and a lone osprey high over the lake keened for fresh fish.
The transformation from late winter into spring switches from swift to sluggish and back again, driven by wind and sun. The breakup and decay of ice in the face of lengthening days signals the start of lake turnover, an annual complement of nature and science that determines the fate of food webs far from the lakeshore.
As the lake ice shrinks from the vernal sun, decaying and liquefying, the meltwater sinks until it reaches 39.2 degrees Fahrenheit (4 degrees Celsius). At that temperature, it ceases to shrink and begins to expand, becoming less dense. The lighter water rises and is stirred by thermal currents and wind, “turning over” the stratified layers of the lake and mixing them until the lake’s waters are the same temperature.
Donning hip boots, I slogged out among the cattails, making squelching sounds and sending frogs diving for cover. The shallows are a rich stew of decaying leaves; the alluvium that was once flora and fauna, rock and soil, all reduced to fine silt. Emerging from the muck were tender shoots. In evidence among them were eggs, thousands of tiny larvae of various species and the exoskeletons of the newly hatched.
The currents of spring turnover delve into the riches of the lake bottom, sending nutrients circulating through the lake water. The springtime bounty of nutrients provides phosphorus to algae and burgeoning shoots of submerged pond lilies. Increased oxygen levels fuel fish, eggs, tadpoles and countless aquatic insects. The springtime serves to bolster curlicue strings of toad eggs and tiny feather-gilled salamander larvae tiptoeing among cattail shoots and succors millions of mayfly larvae as they hatch and take flight, in turn strengthening populations of dragonflies, swallows and bats.
Vast armies of amphibians will sally forth from warm lake edges to move to field and forest where their flesh will become the bone and muscle of bigger predators that will, in turn, spread the bounty farther afield.
Spring turnover provides the jump-start to a season of life, something not seen in the stratified layers of summer and winter. Turnover time is just one part of the annual cycle of life; a small but essential part in the complex system of lake ecology.
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