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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Periphyton
REEXAMINATION OF THE FACTORS THAT LIMIT PRIMARY PRODUCTION IN A LAKE ONTARIO TRIBUTARY RECEIVING SALMON MIGRATIONS.
M.J. Connerton1, J.V. Mead1, C.A.S. Hall1, N.H. Ringler1, and P.S. Rand2. 1Department of Environmental and Forest Biology, State University of New York College of Environmnental Science and Forestry, Syracuse, NY 13210 USA, 2Department of Zoology, North Carolina State University, Raleigh, NC 27695-7617 USA
Results from a previously published study indicated that phosphorous was not limiting primary production in Lake Ontario tributaries and that salmon migrations were unlikely to substantially increase the rate of primary productivity in these already fertile streams. The objectives of our study were to reexamine the factors that limit primary productivity in Lake Ontario tributaries using several methods. We measured irradiance, temperature, water chemistry, and primary production simultaneously using benthic chambers. A piecewise linear regression model explained 78% of the variance in gross primary production (GPP). Irradience, temperature, and soluble reactive phosphorus were significantly correlated to GPP. We tested for phosphorus and/or nitrogen limitation of GPP and the potential effect of decaying salmon in spring using nutrient diffusing substrates and salmon carcasses in a randomized complete block design with six treatments and three replicates at three sites. Results indicated that salmon treatment effects were not significant, however treatment effects for phosphorus and nitrogen + phosphorus were significant within sites. We discuss the reasons for differences between our results and those from the previous study.
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