Below the Surface
One windy day a couple of years ago, I waded into a shallow, rocky bay to go snorkeling for my first time in Hawaii. Looking down into turbulent water, I could see a few fish swimming near the surface. But when I put on my mask and slid into waist-high water, I was dumbstruck: I'd never seen so many fish. Nor could I have imagined discovering so many there at my feet. Mars or any other planet could not have amazed me more than that underwater scene.
Sometimes things are happening right at our feet, just below the surface, and we are practically clueless. A striking example in this issue is given in "New Visions for Lakeshores," our lead story on native aquatic plants. Lake lot by lake lot, Minnesota shores are losing acres of native vegetation. Like many seemingly small changes, the consequences of shoreline development multiply--in this case, rippling throughout the lake ecosystem.
The problem is this: Nearly every lakeside dweller wants a mowed lawn and a sandy beach. This past spring a Star Tribune supplement called "Water's Edge" ran this cover headline: "Dreaming of a home on the waterfront? Look inside for profiles of 10 areas in Minnesota and Western Wisconsin with shoreline to spare." I looked inside its 26 pages and could not find a single picture of a natural shore. Apparently, the beauty standard for lakeshore real estate is "clean-cut."
Through the work of the DNR, lake associations, watershed districts, and other groups, people are developing alternative visions of beautiful shores. But we need to talk more to spread the word. Sandy and Ed Herbert, homeowners on White Bear Lake, hope to make their water's edge one of the first neighborhood examples of how and why to restore native grasses, sedges, and wildflowers.
Perhaps worries about controlling mosquitoes and invasive non-native plants such as purple loosestrife have fed the urge to strip away plants. But tidiness leads some folks to pull out woody habitat too. A University of Wisconsin survey of 319 lakeshore owners found that 25 percent had removed downed trees and other wood from the water. Another survey showed that lakes with more cabins per shore had less wood in the water.
Further research has elaborated on what most anglers know: Fish need woody habitat. On a 40-acre lake without public access, university researchers put up a curtain to divide the lake in two. They removed more than 1,000 dead trees from one half, then monitored the effects on yellow perch and largemouth bass populations. Without wood for egg laying and hiding from bass, the perch population collapsed. With fewer perch to eat, bass hunted less desirable frogs, insects, and other prey; and bass growth rates declined. Bass spawning success decreased too.
To check bass nests, researchers snorkeled. Underwater fish photographer Eric Engbretson has also learned a lot by freshwater snorkeling. "The reason I was fishing all these years," he says, "was just to see the fish up close."
He has been amazed "to see how many fish are in the lake." Coming ashore after a photo dive, he sometimes meets anglers who've returned empty-handed. "Did you see any fish?" one might ask. "Thousands," he answers truthfully.
He finds most fish within snorkeling range--water 30 feet deep or less, within about 10 feet of shore. "It's all about habitat," he says. He's seen anglers cast from shore into waters raked clear of plants, logs, and rocks. According to Engbretson, those anglers are fishing "a stretch of desert." Fish have no reason to be there.
When it comes to ecosystems, simple is seldom, if ever, better. Perhaps no place in Minnesota has shown this more clearly than Cedar Creek Natural History Area. "A Place Apart" in this issue tells about the work of Cedar Creek researchers, who've designed elegant experiments that reveal the intricacies of natural communities and the value of biological diversity.
By design or default, we humans are conducting experiments on our lands and waters every day. Like researchers, we'd do well to watch what's happening below the surface.
Kathleen Weflen, editor