HR: 11:30h
AN: NB32A-05    [Abstracts]
TI: Effects of large woody debris addition on organic matter retention and nutrient uptake in three headwater streams in the Upper Peninsula of Michigan
AU: * Rosi-Marshall, E J
EM: erosi@luc.edu
AF: Loyola University Chicago, Department of Biology 6525 N. Sheridan Road, Chicago, IL 60626
AU: Tank, J L
EM: tank.1@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556
AU: Hoellein, T
EM: thoellei@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556
AU: Entrekin, S A
EM: sentreki@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556
AU: Lamberti, G A
EM: Gary.A.Lamberti.1@ND.EDU
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556
AB: To examine the influence of large woody debris (LWD) on organic matter retention and nutrient uptake, we added 25 logs (0.4m x 2.4m) to three replicate 100m reaches in tributaries of the Jumbo River, MI. We collected 1yr of pre-treatment data in upstream control and downstream treatment reaches before adding logs in May 2004. We measured nitrate, ammonium, and phosphate uptake velocity (v_f), organic matter retention as depositional velocity (_dep) using releases of stick, leaf and fine particle analogs, and physical characteristics such as geomorphology and transient storage. After 9 months, the logs altered stream geomorphology: distinct scour/deposition zones revealed gravel formerly buried by sand and increased the number of pools. In Walton Creek, average reach velocity declined; however, transient storage has not increased in any of the three streams. In Shane and State Creeks, during late summer there was an increase in organic matter retention, but after autumn leaf-fall differences disappeared. To date there has not been an increase in demand for nitrate, phosphate or ammonium. In summary, the experimental LWD addition rapidly changed stream geomorphology, e.g. number of pools and benthic substrates, but there appears to be a time-lag in biological response to LWD addition.
DE: 1845 Limnology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly