Tuesday, December 6, 2011

November Showers

After a fairly sunny summer, there has been a lot of rain this fall. In November, discharge in many of our streams was approximately 10 times higher than during the summer, although the discharge in some streams has hardly changed. These differences in flow arise because some of our streams drain large watersheds (like stream 14, shown above in Nov and below in July) while others have tiny watersheds and appear to derive almost all of their water from springs (e.g., stream 8). These differences in discharge variability among streams likely translates into large differences in disturbance. Disturbance is known to play an important role in shaping stream food webs and ecosystems.

Below, Wyatt dances while he measures nutrient uptake in stream 14 sometime in July.

Since the summer, we’ve been measuring the magnitude of disturbance in each of our landscape streams. We use super glue to attach tiny pieces of flagging tape to 50 randomly selected rocks in each stream. The photo below shows a transect of flagged rocks in stream 7. The flagged rock at the bottom of the photo has been moved downstream away from the transect.

After three months, we return to each streams and determine whether each rock has moved. In sum, these rock movement measurements give us a metric of the degree of disturbance in each stream.

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