A closed artificial stream for conducting experiments requiring a controlled species pool |
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Authors: | Terry Flum Gary L Huxel Cheri S LaRue Bart Hardison Jeffrey R Duncan James A Drake |
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Institution: | (1) Graduate Program in Ecology, 108 Hoskins Hall, University of Tennessee, 37996 Knoxville, TN, USA;(2) Department of Zoology, M313 Walters Life Sciences Building, University of Tennessee, 37996 Knoxville, TN, USA |
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Abstract: | Experimental testing of ecological theory in the field is often difficult because of the number of factors influencing the
test system. Adequate control of relevant variables may require the use of laboratory microcosms for the performance of proper
experimental tests. Our efforts to study the effects of species invasion sequence on community structure and ecosystem properties
of the developing system, requires that the experimental systems be closed. To meet our demanding experimental requirements,
we have designed a closed artificial stream that permits careful control over algal species introductions while minimizing
the risks of contamination by unwanted species. In assessing the performance of these streams, we examined the variability
among experimental replicates in water chemistry parameters and biomass accumulation. Those water chemistry parameters that
were not greatly influenced by biological processes in the streams (Ca, Mg, bicarbonate, and sulfate) had average coefficients
of variation less than 10%. Those parameters that were clearly influenced by biological processes (P, N, Fe, and Si) had average
coefficients of variation ranging from 13.5%–40.4%. Ash free dry mass had an average coefficient of variation of 23.3%, but
chlorophyll a was much more variable at 183%. This pattern of variation indicates that the artificial streams performed well in terms of
replicability, but some experimental goals may require carefully conceived designs that adequately partition sources of variation
in biologically mediated variables to obtain satisfactory results. |
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Keywords: | artificial stream algae periphyton variability nutrients |
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