Diel changes in the microstratification of the metalimnetic community in Lake Cisó

Abstract

The microstratification of the metalimnetic community in Lake Ciso was followed through the die1 cycle by means of a fine sampler with syringes spaced at 3 cm intervals. Populations were sharply stratified. The uppermost part of the metalimnion was occupied by the rotifer Anuraeopsisfissa. Next, layers of the ciliate Coleps hirtus and the flagellate Cryptomonas phaseolus were found. Finally, purple sulfur bacteria appeared at the bottom part of the metalimnion. Although in lower abundances, characteristic populations of ciliates were found at each depth: Strombidium inhabited zones with oxygen, while Plagiopyla and Metopus lived at depths with sulfide. Several members of the community moved vertically about 20 cm during the die1 cycle. Cryptomonas performed larger vertical migrations of 40 cm. This organism concentrated at the upper metalimnion during the day, and dispersed through the lower metalimnion during the night. At night, Cryptomonas lived in an environment without oxygen and with sulfide concentrations up to 0.6 mM.

Long-term Changes and Seasonal Development of Phytoplankton in a Strongly Stratified, Hypertrophic Lake

“…The maximum of cryptophytes was located at the border of the euphotic layer, in almost anaerobic conditions. Cryptophytes are tolerant to the anaerobic environment as they can migrate to the metalimnion, being in the upper layers in the daytime and in the lower part of the metalimnion at night (Gasol et al, 1991). According to Lindholm et al (1985), the vertical maximum may be very thin (only a few centimeters).…”

“…Due to thermal stratification, the upper water layer is isolated from the lower part and also from the sediments (Scheffer, 1998), which causes differences in biological and chemical parameters. The gradients of light, temperature, oxygen and inorganic substances combine and cause a variety of microhabitats (Davey & Heany, 1989;Reynolds, 1992;Gasol et al, 1991;No˜ges & No˜ges, 1998). The stratification processes are important for phytoplankton, providing advantages to some species and influencing the community structure, which tends to be more complex than in shallow lakes.…”

Components, structure and fluxes of the microbial food web in a small, stratified lake

“…l), where the ciliates are (Pedros-Alio et al 1995). Moreover, Cryptornonas migrated daily to spend the night in sulfide containing waters (Gasol et al 1991a), thus reducing its preddtory lusses (Pedros-Alio et al 1995). To obtain balanced conditions that agree with observations of stable biomass, the predation by algivorous ciliates should be roughly equivalent to the growth of Cryptornonas, and this would result in doubling times of 9 d for Cryptornonas and 12 d for algivorous ciliates (40 % gross growth efficiency; Jonsson 1986).…”

Stratification of the microbial community inhabiting an anchialine sinkhole

“…A dense body of literature has examined the spatial distributions of zooplankton, phytoplankton, bacteria and viruses within lake systems and has demonstrated the re-occurrence of stratification of planktonic abundance, community composition and activity, which occurs in concomitance with a variety of biophysical parameters (e.g. Gasol et al 1991, Weinbauer & Hofle 1998, Goddard et al 2005. Anchialine systems, however, often incorporate unique physicochemical characteristics, including polymodal oxygen profiles (Humphreys 1999) possibly generated by the subterranean tidal influx of marine waters, and the manner that microbial populations are distributed and interact within these complex physical settings is virtually unknown.…”