Rocky Mountain National Park was established in 1915, one year before the creation of the National Park Service. The mandate of the National Park Service is to preserve and protect areas of exquisite beauty and cultural value for the benefit and enjoyment of future generations. National parks mean many things to many people, and, in often stirring words, a National Parks and Conservation Association report states the National Park System is a magnificent and uniquely American gift to the American people and the world. In the early years of the Service, park superintendents actively promoted and developed parks to accommodate visitors. Then, as now, parks represented a democratic ideal, that even the greatest treasures should be available to all. Seventy five years ago, however, park managers saw little need for active management of natural resources, unless it was to enhance visitors' experience. And few managers saw the need for a stable and independent research program on which to base management decisions. Thus began a legacy of erratic, often passive, resource management based more on politics and in-house studies than on validated scientific informa tion. The world is a different place than it was 75 years ago. Human population growth, changes in land use, and ever more sophisticated technology affect the very fabric of life on Earth. As local-, regional-, and global-scale changes occur from human tampering with the environment, the integrity of natural ecosystems is threatened worldwide."

The diatom Didymosphenia geminata (Lyngbye) Schmidt is emerging as an organism with an extraordinary capacity to impact stream ecosystems on a global scale. In recent years, streams in New Zealand, North America, Europe, and Asia have been colonized by unprecedented masses of "didymo" and its extracellular stalks (fig. 1). This diatom is able to dominate stream surfaces by covering up to 100 percent of substrate with thicknesses of greater than 20 cm, greatly altering physical and biological conditions within streams. This species is expanding its geographic range in North America and the rate that nuisance blooms are reported by the public and local media are increasing, yet little scientific investigation of the phenomenon in North America has been initiated.