Feeding behavior of Frontonia leucas (Ehrenberg) (Protozoa, Ciliophora, Hymenostomatida) under different environmental conditions in a lotic system

Abstract

The objective of this study was to record and describe the morphological changes and the ingestion mechanisms of Frontonia leucas (Ehrenberg, 1833) according to the food type and to relate the food ingested with the different environmental conditions in a lotic system, namely São Pedro stream, located in the municipality of Juiz de Fora, Minas Gerais, Brazil. We sampled three points on a monthly basis from August 2002 to June 2003, each of which receiving different levels of untreated sewage. We prepared culture media for the ciliate specimens containing filtered water from each point and the types of food observed inside F. leucas (cyanobacteria, diatoms, desmids and testate amoebas). We observed the ingestion mechanisms of F. leucas in vivo, under a phase contrast optical microscope, using instantaneous sampling and sequence sampling as behavior observation methods, noting the following parameters: dissolved oxygen concentration, pH, conductivity and water temperature. We noted the F. leucas ciliates ingesting diatoms and desmids at collection point 1 and filamentous cyanobacteria, testate amoebas (Arcella and Centropyxis) and rotifers at points 2 and 3. The present work records for the first time the ingestion of testate amoebas of the genus Centropyxis by F. leucas. We noted five ingestion mechanisms by F. leucas while feeding on cyanobacteria and testate amoebas of the genus Centropyxis, three of these related to the ciliary action and two involving physical changes in the cytoplasm. For ingestion of diatoms, desmid (Closterium) and Arcella, the mechanisms involving ciliary action alone were sufficient for ingestion, since these preys are smaller than the ciliate under study. The autecological data registered for F. leucas were 1.98-8.01 mg l-1 O2, pH 6.9-8.73, 58-390 µS/cm and 19.5-26.2ºC, confirming its ample ecological valence.

Eukaryal and archaeal diversity in a submerged sinkhole ecosystem influenced by sulfur-rich, hypoxic groundwater

“…The ciliates (Frontonia spp.) may also play a role as direct consumers of primary producers, as they were shown to consume diatoms and filamentous cyanobacteria (Dias and DAgosto, 2006). In contrast, the arthropod species we detected were not as abundant in surface clone libraries, but were more commonly found in the surface of the organic-rich sediment.…”

Microzooplankton feeding behaviour: grazing on the microbial and the classical food web of African soda lakes

“…and C. magnum showed high physical adaptability in food ingestion. Frontonia has a flexible cell wall (Dias & D'agosto, 2006) and we observed this species ingesting filaments substantially longer than its own body. C. magnum shows few size restrictions feeding on phytoplankton because of its own large body size.…”

“…To our knowledge, only qualitative studies have been conducted on Frontonia sp. (Dias & D'agosto, 2006); grazing rates, however, have been reported for rotifers of the genus Brachionus and especially for B. plicatils. Most studies have been conducted with nanoalgae cultures and yielded rates in the range of 2-5 9 10 5 lm 3 ind -1 h -1 (Hansen et al, 1997;Navarro, 1999;Montagnes et al, 2001).…”

Free-living ciliates from a perturbed marsh in Central Mexico: some notes about taxonomy and ecology

“…Also, Debastiani et al (2016) found a positive correlation between the presence of bacterivorous ciliates and total coliforms. During the dry season, omnivorous ciliates were more frequent than the remaining groups, likely due to the advantages for a wider diet feeding on algae, protists and small metazoan (Foissner and Berger, 1996;Dias and D'Agosto, 2006).…”