title: Respiration, growth and grazing rates of three ciliate species in hypoxic conditions.
abstract: Marine hypoxic episodes are affecting both marine and freshwater bodies all over the world. Yet, limited data exists with regard to the effects of decreasing oxygen on protist metabolism. Three ciliate species were therefore isolated from Hong Kong coastal waters. Controlled hypoxic conditions were simulated in the lab environment, during which time growth, respiration and grazing rates were measured. Euplotes sp. and a Oxytrichidae-like ciliate showed decreased growth and respiration below 2.5 mg O2 L(-1), however Uronema marinum kept steady growth and respiration until below 1.5 mg O2 L(-1). Euplotes sp. and the Oxytrichidae-like ciliate had the highest ingestion rate, which dropped significantly below 3.0 mg O2 L(-1). U.marinum grazing rates were affected at and below 1.5 mg O2 L(-1), correlating with their drop in growth and respiration at this lower concentration. This study illustrates the slowing metabolism of key grazing protists, as well as species-specific tolerance in response to hypoxia.
authors.affiliation: Hong Kong University of Science and Technology, Division of Life Science, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Emma
authors.initials: E
authors.lastname: Rocke
authors.affiliation: Hong Kong University of Science and Technology, Division of Life Science, Clear Water Bay, Kowloon, Hong Kong. Electronic address: liuhb@ust.hk.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Liu
mesh_terms: D000693:Anaerobiosis; D019069:Cell Respiration; D016798:Ciliophora / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D006723:Hong Kong; D010100:Oxygen / Q000032:analysis* / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*; D013045:Species Specificity
chemical_list: D010100:Oxygen
keywords: Ciliates; Grazing; Hypoxia; Metabolism; Respiration