Section 6
Chapter 5,389

Estimation of phyto plankton decomposition rates using 2 stage continuous flow studies

Rodgers, P.W.; Depinto, J.

Water Research 17(7): 761-770


ISSN/ISBN: 0043-1354
Accession: 005388035

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A 2-stage continuous flow (TSCF) system was used to quantify phytoplankton decomposition rates and to characterize the decay process as a function of phytoplankton species, phytoplankton physiological state, and the presence and character of a decomposer community. A TSCF system allowed a steady-state phytoplankton culture, grown in the 1st stage, to be the feed to a darkened 2nd stage decomposition culture. A mass balance on the phytoplankton biomass in the 2nd stage quantitatively assessed the magnitude of the decomposition rate. The results of 12 experimental runs revealed that the relative order of decay rates among 3 phytoplankton species tested was Microcystis (blue-green) > Asterionella (diatom) > Scenedesmus (green). The results also suggest a strong dependence of decay rates on the presence and origin of the decomposer community in the 2nd stage. A decomposer community originating from a hypereutrophic lake accounted for higher decay rates than did an inoculum from mesotrophic waters of Lake Ontario [North America]. Phytoplankton cultures not receiving a poser inoculum exhibited low decay rates indicative of endogenous respiration. Finally, 2 concurrently run TSCF experiments, where the only difference was the dilution rate in the lit 1st stage, illustrated that suboptimal growth rates of phytoplankton result in a stress condition that renders the population more susceptible to death and decomposition.

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