Reality checks on microbial food web interactions in dilution experiments: responses to the comments of Dolan and McKeon

[摘要] Dolan and McKeon (2005) have recently criticized microzooplankton grazingrate estimates by the dilution approach as being systematically biased andsignificantly overestimated. Their argument is based on observed mortalityresponses of ciliated protozoa to reduced food in several coastalexperiments and a global extrapolation which assumes that all grazing in allocean systems scales to the abundance of ciliates. We suggest that theseconclusions are unrealistic on several counts: they do not account forcommunity differences between open ocean and coastal systems; they ignoredirect experimental evidence supporting dilution rate estimates in the openoceans, and they discount dilution effects on mortality rate as well asgrowth in multi-layered, open-ocean food webs. High microzooplankton grazingrates in open-ocean systems are consistent with current views on exportfluxes and trophic transfers. More importantly, significantly lower rateswould fail to account for the efficient nutrient recycling requirements ofthese resource-limited and rapid-turnover communities.

[学科分类] 海洋学与技术