Affiliation:
1. Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, Passeig Joan de Borbó s/n, E-08039 Barcelona, Spain
Abstract
We studied the dynamics of two populations of anaerobic ciliates,
Plagiopyla
sp. and
Metopus
sp., and of their potential prey, heterotrophic and phototrophic purple bacteria, in Lake Cisó throughout a 1-year cycle. The abundance of both ciliates was very low (less than 2 individuals per ml). During mixing,
Plagiopyla
ciliates exhibited high clearance rates (about 100 nl ciliate
-1
h
-1
), its integrated abundance increased with a net doubling time of 47 days, and its potential doubling times, as calculated from the number of bacteria consumed, ranged between 5 and 8 days. During stratification, the activity of
Plagiopyla
ciliates was reduced and the population decreased; this was related to the higher amounts of sulfide present. The impact of predation by the
Plagiopyla
population on bacterioplankton was found to be insignificant, less than 0.1% of bacterial biomass consumed per day. Thus, anaerobic ciliates cannot control the bacterioplankton in Lake Cisó because of both the low abundance over the period studied and the low feeding rates during certain periods. A review of available field studies suggests that this conclusion can be extrapolated to most other anoxic systems.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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