Effects of microzooplankton growth and trophic interactions on herbivory in coastal and offshore environments

Copepod feeding in the ocean: scaling patterns, composition of their diet and the bias of estimates due to microzooplankton grazing during incubations

“…Furthermore, the use of the dilution method to estimate microzooplankton grazing is not free from criticisms and uncertainties (Dolan et al, 2000;Agis et al, 2007;Modigh & Franze, 2009) and actually encompasses not only strictly defined microzooplankters (e.g. ciliates and dinoflagellates), but also grazing by heterotrophic nanoflagellates and multi-level trophic cascade effects (Calbet, 2008;Calbet et al, 2008;First et al, 2009). This targeting of the wrong trophic guilds further complicates any attempt to make such corrections.…”

The role of ciliates, heterotrophic dinoflagellates and copepods in structuring spring plankton communities at Helgoland Roads, North Sea

“…For example, to overcome nonlinear feeding responses due to food saturating conditions, a modified protocol can be used (Paterson et al 2008; this study). To prevent nutrient limiting conditions in the experimental vessels, often dialysis bags are incubated in situ (Landry 1993;Sommer et al 2005a, b;Aberle et al 2007) or nutrients are added in excess to the dilution series (Landry 1993;Fonda Umani et al 2005;First et al 2009) in bottle incubations. As we wanted to keep conditions in microzooplankton und copepod grazing experiments comparable, we chose the second alternative (bottle incubations), that was also necessary for correction of trophic cascade effects in the copepod grazing set-up (Nejstgaard et al 1997(Nejstgaard et al , 2001Fonda Umani et al 2005).…”

Microzooplankton grazing before, during and after a cyanobacterial bloom in Vancouver Lake, Washington, USA

“…heterotrophic flagellates) feeding on even smaller and more abundant pico-or nanophytoplankton -then, as dilution increased, the larger micrograzers could have been selectively removed, allowing the smaller grazers to exert higher grazing pressure on phytoplankton compared to less dilute treatments. Such top down trophic interactions within the protist community have been observed in a range of aquatic environments, as well as in a set of dilution experiments conducted in the Arabian Sea (reviewed in Verity & Smetacek 1996), and were recently modeled to occur in dilution experiments by First et al (2009). This process could translate into a negative grazing rate, where net phytoplankton growth was higher in the undiluted treatments.…”