Plankton analysis of the river continuum and serial discontinuity concepts in two northern Michigan streams.

Abstract

The purpose of this investigation was to determine how well the River Continuum Concept (RCC) and Serial Discontinuity Concept (SDC) apply to streams in northern Michigan, where stream sources are often in wetlands rather than mountainous regions. Drift algae samples were taken from ten sites each from the Black River, a wetland-fed stream and the East Branch of the Maple River, a lake-fed stream. Water was taken from the water column and allowed to settle. Samples were counted with cells identified to the generic level, and chlorophyll a analysis was performed. Results indicate that the unimpounded stream has a drift algae composition similar to that predicted by the RCC. The impounded stream has a spike of lentic plankton which persists for several kilometers, and has more riverine plankton and fewer benthic forms than the unimpounded stream. The reach of stream was too short to determine how long this discontinuity persists. The RCC and SDC appear to hold ture, with minor modifications, to the unique geology and topography of northern Michigan.