Predator Chemical Cue Effects on the Diel Feeding Behaviour of Marine Protists

• Published in: Microbial Ecology
• Main Authors: Arias, Anna, Selander, Erik, Saiz, Enric, Calbet, Albert
• Other Authors: Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España), Ministerio de Ciencia e Innovación (España)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Society for Applied Microbiology 2021
• Subjects: Copepodamide; Feeding rhythms; Grazing; Copepods; Microzooplankton; Dinoflagellate; Ciliates; Calanus finmarchicus
• Online Access: http://hdl.handle.net/10261/250200; https://doi.org/10.1007/s00248-020-01665-9; https://doi.org/10.13039/501100004837; https://doi.org/10.13039/501100003329; https://doi.org/10.13039/501100011033

9 pages, 4 figures, 3 tables, supplementary information https://doi.org/10.1007/s00248-020-01665-9 We have assessed the effect of copepod chemical cues on the diel feeding rhythms of heterotrophic and mixotrophic marine protists. All phagotrophic protists studied exhibited relatively high diurnal feeding rates. The magnitude of the diel feeding rhythm, expressed as the quotient of day and night ingestion rates, was inversely related to the time that phagotrophic protists were maintained in the laboratory in an environment without predators. In the case of the recently isolated ciliate Strombidium arenicola, the rhythm was lost after a few months. When challenged with chemical alarm signals (copepodamides) from the copepod Calanus finmarchicus at realistic concentrations (0.6–6 pM), S. arenicola partially re-established diurnal feeding. Conversely, the amplitude of the diel feeding rhythm for the ciliate Mesodinium rubrum was not affected by copepodamides, although the 24-h integrated food intake increased by approximately 23%. For the dinoflagellates Gyrodinium dominans and Karlodinium armiger, copepodamides significantly reduced the amplitude of their diel feeding rhythms; significant positive effects on total daily ingestion were only observed in G. dominans. Finally, the dinoflagellate Oxyrrhis marina, isolated >20 years ago, showed inconsistent responses to copepodamides, except for an average 6% increase in its total ingestion over 24 h. Our results demonstrate that the predation risk by copepods affects the diel feeding rhythm of marine protists and suggests a species-specific response to predation threats This work was supported by the FERMI project (CGL2014-59227-R; MINECO/AEI/FEDER, UE) and is a contribution of the Marine Zooplankton Ecology Group (2017 SGR 87). AA was funded with an FPI fellowship (BES-2015-074092) from the MICINN of Spain With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) Peer reviewed