A modified dilution method reveals higher protozoan growth rates than the size fractionation method

The Effect of Dissolved Polyunsaturated Aldehydes on Microzooplankton Growth Rates in the Chesapeake Bay and Atlantic Coastal Waters

“…For example, the dominant dinoflagellates in this study, P. minimum and K. veneficum , are also prey for other microzooplankton [ 58 ]. The same applies to Balanion spp., Lohmanniella oviformis , and other small-sized ciliates, which can be kept below their reproductive potential by larger microzooplankton in bottle experiments [ 25 , 36 , 56 , 59 ]. In this study, some nanoplankton -sized ciliates, e.g., Lohmanniella oviformis , grew faster at low and intermediate PUA concentrations than in control bottles, indicating the presence of trophic cascades.…”

Growth rates of common pelagic ciliates in a highly eutrophic lake measured with a modified dilution method

“…Lower rates observed during eld works in size fractionation experiments are explained by food limitation of ciliate growth, but also by underestimating growth rates due to grazing between heterotrophic protists, because size fractionation does not remove predators of the same size as the organisms studied (Müller 1989;Leakey et al 1992;Leakey et al 1994;Macek et al 1996;Wallberg et al 1999;Carrias et al 2001). Recently, Rychert (2013) and Franzé & Modigh (2013) have demonstrated that grazing among heterotrophic protists does indeed cause underestimated ciliate growth rates measured with the size fractionated method. e second problem is that ciliate growth is usually measured during a 24-hour incubation period since this includes any possible diel growth rhythms (Carrick et al 1992;Jakobsen & Strom 2004;McManus & Santoferrara 2013) and is long enough to detect ciliate growth with the size fractionation method.…”

“…To estimate their role in matter turnover, not only their biomass but also their growth rates have to be measured (Müller 1989;Leakey et al 1992;Cleven & Königs 2007;Lai et al 2014). ere are direct, reliable methods to measure algal (that of autotrophic protists) and bacterial production under natural conditions, but assessment of protozoan production (that of heterotrophic protists) is much more di cult (Rychert 2013).…”

“…e second problem is that ciliate growth is usually measured during a 24-hour incubation period since this includes any possible diel growth rhythms (Carrick et al 1992;Jakobsen & Strom 2004;McManus & Santoferrara 2013) and is long enough to detect ciliate growth with the size fractionation method. However, such long incubation periods lead to the deceleration of biological processes (Carrick et al 1992;McManus 1993;Rychert 2013), and di erent containment e ects such as ciliate grazing on bacterial bio lm that develops on internal bottle surfaces (e.g. Macek et al 1996).…”

Annual production to biomass (P/B) ratios of pelagic ciliates in different temperate waters

“…It was suspected (Verity 1986;Taylor & Johannsson 1991;Leakey et al 1994b;Nielsen & Kiørboe 1994;Macek et al 1996) that this difference resulted, at least partially, from the methodological constraints of the method, which did not relax grazing pressure efficiently. Further studies performed with the modified dilution method (Franzé & Modigh 2013;Rychert 2013) clearly demonstrated that the ciliate growth rates measured with the size fractionation method are significantly underestimated because of internal predation within microzooplankton communities. Consequently, the application of allometric equations for predicting the potential ciliate growth rates is much more reliable than previously thought.…”