title: Determining parameters of the numerical response.
abstract: The numerical response, the change in specific growth rate with food concentration, is a fundamental component of many aquatic microbial studies. Accurately and precisely determining the parameters of this response is essential to obtain useful data for both aut- and synec-ological studies. In this work we emphasize four points that are often ignored in designing numerical response experiments: (1) the inclusion of subthreshold concentrations (i.e., where growth rate is negative) in the experimental design; (2) an appropriate allocation of effort, i.e., the superiority of choosing more individual prey concentrations rather than replicating fewer; (3) the potential superiority of replicating experiments rather than simply replicating treatment in a single experiment; and (4) the placement of most measurements near the lower end of the concentration gradient, well below the asymptote, possibly following a geometric progression. We illustrate the first point by examining a small subset of published data on planktonic oligotrich ciliates and then, using a Monte Carlo simulation, rigorously evaluate the experimental design, supporting the remaining points.
authors.affiliation: School of Biological Sciences, University of Liverpool, BioSciences Building, Crown Street, L69 7ZB, Liverpool, UK. dmontag@liv.ac.uk
authors.forename: D J S
authors.initials: DJ
authors.lastname: Montagnes
authors.forename: J A
authors.initials: JA
authors.lastname: Berges
mesh_terms: D000818:Animals; D002455:Cell Division / Q000502:physiology; D016798:Ciliophora / Q000254:growth & development* / Q000378:metabolism*; D003198:Computer Simulation; D020387:Food Chain; D008954:Models, Biological; D009010:Monte Carlo Method; D009716:Numerical Analysis, Computer-Assisted