Early Spring Disturbing Life on Northern Rivers
Monday, March 20, 2006
THE GLEN, N.Y. -- The winter-old river ice is creaking and groaning, shifting position. Spring has come early to the frozen upper Hudson River, and ice-out is just around the corner.
Lilliputian wildflowers will soon line the Hudson's banks. In what are known as riverside ice meadows, an ancient cycle of ice formation and melting gives rise to swamp candles, ladies'-tresses, wood lilies and other rare, diminutive flowers.
In New York's Adirondack Mountains, ice that forms on the river in winter is pushed onto its banks in spring; there it scours the sloping cobble shores, keeping them free of shrubs and small trees and leaving space for wildflowers to sprout in fragile, arctic-like ice meadows.
But the future for these floral pixies, which depend on late-melting river ice, is bleak. The number of days of ice on northeastern rivers has declined significantly in recent winters, said hydrologist Glenn Hodgkins of the U.S. Geological Survey (USGS) Maine Water Science Center in Augusta.
The trend could spell disaster for the ice meadows. It also signals trouble ahead for endangered Atlantic salmon and other fish, for wetlands plants and animals, and for Northern economies, all of which are sustained by winters with icy rivers.
If the pattern continues, say scientists, only in Currier and Ives prints will ice skaters twirl across frozen New England rivers.
"Northeastern rivers have 20 fewer days of ice cover each winter now than they did in 1936," said Hodgkins, who said the total now averages 92 days. "A lot of that decrease has occurred since the 1960s."
Hodgkins has studied 16 rivers in Maine, New Hampshire and Vermont. In recent years, the data show, 12 of the 16 rivers had much earlier spring ice-out dates.
"On average, ice-out dates were 11 days earlier in 2000 than in 1936," Hodgkins said. "These changes are linked to warmer temperatures in late winter and early spring."
Winter, it appears, is melting around the edges.
Research by Hodgkins and USGS scientist Robert Dudley also shows changes in early-spring stream flow across eastern North America from Minnesota to Newfoundland. Rivers are gushing with snow- and ice-melt as much as 10 to 15 days sooner than they did 50 to 90 years ago, based on USGS records.
Hodgkins and Dudley's results are scheduled to be published Tuesday in the online edition of the journal Geophysical Research Letters.