HR: 10:30h
AN: NB42F-01 [Abstracts]
TI: The Effects of Zebra Mussels on Nitrogen Cycling and Sediment Physiochemical Characteristics: A Laboratory Experiment.
AU: * Bruesewitz, D A
EM: dbruesew@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AU: Tank, J L
EM: tank.1@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AU: Bernot, M J
EM: kemp.5@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AB:
Many ecosystems experiencing anthropogenic nitrogen loading have also been invaded by zebra mussels (ZM), therefore it is
important to understand how these human-induced changes interact. In particular, ZM may impact biogeochemical
transformations. We hypothesized that high NH4+ waste from ZM will increase sediment nitrification rates, and
increase NO3--N available for denitrification. To test this prediction, aquaria were stocked with either no ZM or
10,000 individuals m-2. Sediment nitrification (via nitrapyrin-inhibition technique), denitrification (via
chloramphenicol-amended acetylene block technique), and sediment O2 profiles (using microelectrodes) were measured
weekly for 1 month. The presence of ZM increased nitrification and denitrification rates over initial conditions throughout
all weeks (RM ANOVA, p<0.05). Sediment nitrification in the ZM aquaria increased to 47 ± 2.1 μ g NH4+
-NgAFDM-1h-1 by the 3rd week in comparison to 24 ± 4.4 μ g NH4+ -NgAFDM-1h-1 in
control aquaria. Sediment denitrification peaked at week 2 in the ZM aquaria at 330 ± 24 μ g N2O
gAFDM-1h-1 but remained low in control aquaria throughout. There was a stronger correlation between nitrification
and denitrification rates in the presence of ZM (R=0.32, 0.12 respectively). These results, in addition to more frequent
hypoxia in sediment oxygen profiles, suggest closer coupling between nitrification and denitrification when ZM are present.
DE: 1803 Anthropogenic effects
DE: 1806 Chemistry of fresh water
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly