MODENUTTI Beatriz Estela
congresos y reuniones científicas
When eating a prey is risky: the interaction between mixotrophic ciliates and planktonic predators.
B. MODENUTTI,; WOLINSKI, LAURA; E. BALSEIRO,
Congreso; SAME 15; 2017
In deep transparentlakes, the dark pigmented mixotrophic ciliate Stentor araucanus inhabits the upper layers of the epilimnion andis very resistant to ultraviolet radiation (UVR). The cyclopoid copepod Mesocyclops araucanus also inhabitsthese lakes and can feed on the ciliate. Here we analyzed if the ciliatepigment called stentorin may result photosensitizing for predators. We studiedthe diel vertical migration (DVM) behavior of M. araucanus, and the presence of stentorin in field-collectedcopepods evaluating in the laboratory the rate at which the copepod can releasestentorin. We conducted feeding experiments with this ciliate and analternative ciliate prey without stentorin, subsequently exposing both sets todifferent light treatments. When feeding on S.araucanus, the copepod became photosensitized and suffered high oxidativestress (high glutathione S-transferase). The reduced glutathion levels showedthat the oxidative status of the copepod fed on Stentor increased from dark to visible and ultraviolet radiation.However, we also determined that exposure to only visible light was sufficientto cause oxidative stress. In the field, we observed that Mesocyclops displays a much wider DVM than other crustaceans. Thefact that Mesocyclops can move alongthe water column displaying DVM protects the copepods from stentorinphotosensitization during daytime. Our findings are the first to show aphotosynthesizing compound of a zooplankton prey item that may cause a differentialvertical behavior of predators in order to minimize the negative effect.