Spatio-temporal Patterns of Protozoan Communities in a Meso-eutrophic Reservoir (Esch-sur-Sûre, Luxembourg)

Abstract

The spatio-temporal distribution of the heterotrophic nanoflagellates (HNF) and ciliates was monitored in the reservoir of Esch-sur-Suˆre during the year 1999. Three main periods of protozoan development were observed, in early April, early May, and in July. On the basis of the seasonal dynamics, it appeared that the early spring development of protozoa was probably not controlled by resources or predators. The second protozoan development was progressively controlled by the increase of metazooplankton density that led to the clear water phase characterised by very low protozoan densities and biomasses. A summer development of protozoa was possible thanks to the development of bacteria and moderate metazooplankton densities due to the appearance of non-edible algae. Prorodontida, Halteriida and Strombidiida were the dominant ciliates in the upper part of the water column. A development of Tintinnida was moreover observed in spring whereas Philasterida and Sessilida developed in winter and summer. Ciliates occupied the entire water column in spring and were concentrated in the epilimnion and the metalimnion during the summer period where they fed on bacteria and algae.

Diversity and vertical distribution of planktonic ciliates in a stratified mesotrophic lake: relationship to environmental conditions

“…Oligotrichs are often reported as relatively common components of lacustrine protozooplankton, especially in the epilimnion (Zingel & Ott 2000, Zingel 2005). The vertical distribution reported here is similar to that observed by Műller et al (1991) in Lake Constance in Germany, and that seen in Esch-sur-Sure reservoir in Luxemburg (Jacquet et al 2005). The abundance of haptorids, most of which are known as predators, was highest in the epilimnion.…”

“…The bacterivorous Scuticociliatida were most abundant in the intermediate and deep layers, in harmony with bacterial densities in the hypolimnion, and probably also resulting from their tolerance to low oxygen concentrations. It is suggested that scuticociliates are more effective grazers at lower temperatures (Schőnberger 1994, Simek et al 1998, Jacquet et al 2005, which may be a further reason for their dominance in the deeper layers. In the meta-and hypolimnion, the abundance of metazooplankton that potentially prey on small-sized ciliates, tends to decrease with depth (Műller et al 1991, Zingel 2005, which may explain the high abundance of scuticociliates in the deeper layers.…”

“…Pace 1982;Macek et al 1996;Weisse & Müller 1998;Kalinowska 2000Kalinowska , 2004Mieczan 2007). In both freshwater and marine ecosystems significant vertical gradients of protozoan diversity exist, these apparently being influenced by the distribution of their prey, and physical and chemical variables (Ventelä et al 1998, Thouvenot et al 1999, Jacquet et al 2005. Several investigators suggest that ciliate abundance and biomass reach maximum values in the epi-and metalimnion, with the lowest in the hypolimnion.…”

Vertical microzonation of ciliates in cryoconite holes in Ecology Glacier, King George Island

“…The bacterivorous and omnivorous ciliates were more abundant in the bottom wa− ters. This vertical micro−distribution of algivorous and bacterivorous ciliates was similar to that previously observed in shallow lakes (Jacquet et al 2005). In this study, ciliates community was mainly composed of genera Prorodon, Oxytricha and Cinetochilum.…”

Reproducibility of a microbial river water community to self-organize upon perturbation with the natural chemical enantiomers, R- and S-carvone

“…The ability of the protists to rapidly respond to an increase in bacterial abundance could have contributed to the unusually low recovery of bacterial DNA from time points immediately following the removal of carvone (days 7, 12, 22). Jacquet et al (2005a, b) report that numbers of protozoa, comparable to that in the carvone treatments, removed up to 7.8% of bacteria in 24 h whereas Domaizon et al (2003) describe per capita grazing rates from 1.2 × 10 3 to 5.1 × 10 6 bacteria L −1 h −1 for heterotrophic flagellates and from 4.8 × 10 6 to 6.8 × 10 7 bacteria L −1 h −1 for mixotrophic flagellates. Hence, grazing by protists might have masked the otherwise rapid increase in microbial growth upon the addition of carvone.…”